REESE LIBRARY 1 UN I VE RSITY OF CALI FORNIA; '-I () BACTERIOLOGY. APPLIED TO THK CANNING AND PRESERVING .OF. FOOD PRODUCTS EDWARD W. DUCKWALL Published by THE TRADE, Baltimore, Md. 1899. Oopyrighted, 1899 ; all rights reserved. INDEX. Acetic Add Bacteria, 20, 8i .^robic, 26, 29, 43 Agar Peptone Meat Jelly, . ^ 50 Alkaloid Poisons, 10, 26, 29, 102 Anaerobic, 20, 26, 29, 31, 43, 50, 64, 67, 78 Anaerobic Bacteria Cultures, 50 Anthrospore, J5 Antiseptics, 8, 29, 69, 79, 97 Apparatus for Study of Bacteria, 47 Appert of Paris, 71 Apples, 63 Aspergillus Glaucus, 17, 46, 96 Babes, 28 Bacillus Amylobacter, 20, 23. 39, 41, 54, 78 Butyricus, 20, 54, 78 " Comma or Cholera, 10, 27, 59, 102 " Cyanogenus, 57. 99 " Diphtheria or Klebs-Loeffler, .... 9» 33i 59. 102 " Erythrosporus, 57 " Fluorescens Putidus, 57. 83 Lactici Acidi, 19, 23, 37, 54, 81, 99 " Panificans, 25 Prodigiosus, 23, 55, 58, 82 Subtilis, 25, 42, 52, 57, 83 " Tetanus, 10, 31, 45, 6r, 102 " Typhoid, 10, 29, 60, 102 " Viscosus, 2T, 55, 83, 104 Bacteria, 4, 5 Bacteria, Dead, 7, 9 Bacterial Multiplication, 37. 95 Bacterium Pasteurianum, 20 Benzoic Acid, 70 Benzoate of Sodium, 70, 78 Berries, 63 Bitterness, 103 Black Rot in Tomatoes, 91 Black Spots in Corn, 91 Black Torulse, 91 Boracic Acid, 70 83593 INDEX. Boro-Glyceride, Bonilloti, Brefeld's Pure Culture Method, Brieger, Brownian Motion, Butyric Ferments, . Cadaverine, Calcium, Canning, History of Canning, Scientific Principles of Can Making Methods, Early Carbolic Acid, Catsup, .... Cells, .... Cherries, Chili Sauce, Chilling Canned Goods, Chloride of Zinc, Choline, .... Chutney, Cleanliness, Cocci, Cohn's Pure Culture Method, Conidia, Conidiaspore, Continuous Heating, Corn, .... Corn, Dry Pack, Corn, Moist Pack, Corn, Sour, Corn, Whiteness of. Creosote, Culture, Media, Deep Wells, Delafontaine, Diplococci, Discontinuous Heating Process, Drying As a Preservative, Duckwall, Thomas, Dyes, Bhrenburg, Electricity, . Endospore, Enzymes, Evaporation As a Preservative, Eucalyptol, . Fermentation, Fertilizing, ... Fish, .... Flagella, . . . . Fluid Culture Media, . . 70 48 . 52 10 . . 2 i » 35 ,54 • 10 . 26 72 71 63 • 72 70 97 15. 39> 65, 102 • • 63 96 90 69 10 • • 96 66 15 52 17 79 97 17 81 19, 63, 71 81 78 84 . 78 84 80, 82, 88 • 78 lOI 47 45 II J5 48, 84 104 71 16, 25, 33, 52 23 106 15, 23 41 103 70 9, 81, y ?5, 103 44 100 14, 29 47 INDEX. Formic Acid, . 70 Formic Aldehj'de, . . 70 Freezing, .... . 27, 67, 88, 102 Gelatine, . . . . 20, 50 Gelatinized Meat Peptone Medium. Koch, . 50 Germicides, . . . . . 31. 69, 97 Halibut, .... . . lOI Hanging Drop Cultures, . • 51 Hansen, . ' . . 28 Hay Bacteria, . . . . . • 25, 42, 52, 57, 85 Ice Cream, . • . . . II, 102 Inoculating Media, . 51 Invertin, .... . 41 Klebs, . • 52 Klebs-Ivoeffler Bacteria, . . 10, 33, 59. 102 Koch, . 27, 52 Koch's Pure Culture Method, . . 52 Kraut, . . . . . 103 Kuhn's Methylene Blue, . 51 Lactic Fermentation, • 19. 23, 37, 42. 52, 63, 83, lOI Leaks, .... . 80 Leptrothrix, . * . . 15 Light EfiFect on Bacteria, . . 30. 105 Lima Beans, .... 63 Lister's Pure Culture Media, 52 Meats, .... . loi, 102, 104 Meat Soups, 96, 104 Milk,- 12, 19, 20, 27, 33, 42, 48, 55, 63, 102 Molasses, . 21 Mold, 17, 39, 46, 67, 79, 96, 103 Monilia Candida, . 19. 97 Mucor Racemosus, . 19, 23, 96 Muller, Otto Friederich, . 5 Muscarine, . ^ 10 Mycodernia Aceti, 20 Mycoderma Cerevisae, . 16, 59, 78 Mycoderma Vini, . 16, 69 Mytilotoxiue, . II, 12 Neurine, .... . 10 Oysters, .... . 63, 102 Pasteur, .... . 6, 7, 20, 21, 28, 38 Pathogenic Bacteria, , 26 to 36, 44, 102 Peaches, .... . 62 Pears, .... 63 Peas, ..... 19, 62, 92 Pencillium Glaucum, • 17, 46, 96 Peptonization. . 42 Permanganate of Potassium, . 70 Phenol, . . . . •70 Phenyl-Acetic Acid, . 70 Phenylproprionic Acid, . 70 VI INDEX. Pickles 103 Pigment Forming Bacteria, 22, 52, 55, 82 Pineapple, ..... 63 Plums, ...... .... 63 Pouchet, ..... 27 Preserves, 103 Preserving Processes, lOI Processing, ..... 62, 81, 84, 93 Ptomaines, . . 23, 27 to 45, 102 Pure Cultures, .... 47, 51, 82, 103 Putrefaction, .... . • . 19 to 3T, 43 Putrescine, .... 10, 27 Registered Temperature, 84 Resistant Bacteria to Heat and Antiseptics, 25, 42, 63 to 93 Roberts Pure Culture Methods, 52 Saccharomyces, .... 16, 36, 39, 95 " Cerevisias, 16, 59, 78 " Apiculatus, 23, 58 Ellipsoideus, . . 59, 78 Salicylic Acid, .... . 70, 77, 91, 96, 99 Salt, . 102, 103 Smoked Meats and Fish, •. ' . . .102 Soldering Solutions, . 69, 103 Solid Culture Media, . 50 Soups, ..... 96, 99, 104 Sour Corn, ..... . 78, 79. 88 Sour Tomatoes, .... 2, 95 Spirilla, : 15 Spontaneous Generation, 5 Spores, ...... . 14, 20, 25, 37, 83, 84, 88 Spring Bottoms in Canned Goods, 65 Staining, ..... 14, 25, 33, 52 Stanley's Observations in Africa, 32 Steptococci, ..... 15 Sturgeon, ....'. lOI Sterilization, ..... 26, 48, 62, 81, 84, 93, 105 Sugar, ..... 102 Sulphurous Dioxide, .... 70 Surface Water, .... 45 Swells, ...... 78, 80 Steam Retorts, .... 72, 83, 90 Temperatures, .... 27, 39, 62, 66, 81, 85 Terebine, . . . . 70 Tetanine, ..... 13, 31 Tetanotoxine, .... 12 Thymol, ..... .70 Tomatoes, ..... • 63, 95 Tomato Catsup, .... . 96 Tomato Pulp, .... 96 Tomato Soup, ..... , 102 Tyndall, . 6 to 7, 26. 85 INDEX. Tyrotoxicon, Tyrotoxine, Vacuum, Van Laer, Van Leeuwenhoek, Anthony, Vibrios, . Vinegar, Villiers, . Waste Material, Winslow, Isaac, Wood, . X Rays, . ^ooglae, 13 13 64 22 5 15 21 . 28 67, 88 • 71 41 30, 105 15 MICRO PHOTOGRAPHS AND FIGURES- Figure i. Sour Tomato Juice, ** 2. Different Forms of Bacteria, *' 3. Saccharomyces, .... " 4. Saccharomyces, . . . . . ** 5. Mycoderma Yini and Cerevisiae, " 6. Pencillium Glaucus, " 7. Monilia Candida, .... ** 8. Bacilli Lactici Acidi, '* 9. Bacillus Butyricus, .... " 10. Bacillus Butyricus Amylobacter, . '* II. Mycoderma Aceti. Bacterium Pasteurianum, ** 12. Bacillus Viscosus, .... '• 13. Putrefactive Bacteria in Bouillon, ** 14. Saccharomyces Apiculatus. Pineapple Juice. '* 15. Bacillus Subtillus on Bouillon, . '* 16. Comma Bacilli. .... " 17. Typhoid Bacilli, ..... " 18. Tetanus Bacilli, .... " 19. Klebs-Loeffler Bacilli, .... " 20. Mold Fungi Submerged in Corn Juice, " 21. Bacteria Found in Swelled Can of Corn, Page 2. 14. 15. 16. 16. 17- 18. 19. 20. 21. 21. 22. 23- 24. 25. 27. 29. 31. 33. 79- 80. 22 and 23 24. Pencillium. Fermenting Tomato Juice Showing Degree of Increase, . . . . ' Aspergillus Glaucus Conidia 96, 97- 98. SUBJECTS. CHAPTER I. Page i. Introduction— Cause Leading to the Study of Bacteriology — Sour Toma- toes. CHAPTER II. Page 4- Bacteria Defined— Forms — Multiplicity— Functions Divided Into Two Classes— Discoveries— Spontaneous Generation— Bacteria in the Atmosphere — Lister's ' Antiseptic System -Microscopical Observa- tion— Chemistry of Fermentation Ptomaines— What Class of Bac- teria Produces These Poisons — Result of Ptomaine Poisoning. CHAPTER III.- Page 13. Bacteria— Manner of Propagating — Description of Various Forms — Characteristics — Mold Fungi. CHAPTER IV. Page 19. Bacteria Commonly Found in Decomposing Fruit and Vegetables— Micro- scopical Views and Descriptions— Characteristics— Sterilization. CHAPTER V. Page 26. Pathogenic Bacteria— Studied Because of the Poisons Produced When Acting on Food Products— Different Kinds of These Bacteria Stud- ied—Their Action on Various Food Products Described. CHAPTER VI. Page 36. Fermentation -Object of Study Is to Prevent— Alcoholic Fermentation and the Germs Which Cause It— Putrefaction— Disease Fermenta- tion—Products of Fermentation— Descriptive Examples— Enzymes —Lactic Fermentation -Benefits to Plants and Animal Life— Fer- mentation Defined in a Broad Sense. CHAPTER VII. Page 47. Directions For Studying Bacteria— Methods to Obtain Pure Cultures- Apparatus to Facilitate the Study— Inoculation of Solid Culture Media— How to Cultivate Anaerobic Organisms— Hanging Drop Cul- tures—Staining. X SUBJECTS. CHAPTER VIII. Page 53. A Summary of the Characteristics of Various Organs Found in Food Products— Bacillus Lactici Acidi— Bacillus Butyricus— Bacillus Amylobacter— Bacillus Prodigiosus— Bacillus Viscosus— Bacillus Fluorescens Putidus— Bacillus Erythrosposus — Bacillus Cyanoge- nus— Bacillus Subtilis— Saccharomyces Apiculatus— Saccharomyces Ellipsoideus— Saccharomyces Cerevisae— Comma Bacillus — Klebs- Lceffler Bacillus— Typhoid Bacillus— Tetanus Bacillus. CHAPTEn IX. Page 62. Scientific Principles Involved in Canning and Preserving -Temperature- Vacuum — Anaerobic Bacteria and Their Action — Forms Growing in an Anaerobic State— Spring-Bottoms in Canned Goods- Causes — Precautions— Cleanliness— Disposal of Waste Material— Soldering Solutions. CHAPTER X. ^ Page 69. Antiseptics and Germicides — Various Chemicals Used As Such. CHAPTER XI. Page 71- History of Canning — Discoverers— Appert, of Paris— Isaac Winslow, of Maine— Thomas Duckwall and Albert Fisher, of Ohio— Early Can Making and Machinery — Steam Retorts— Processors and Man- agers. CHAPTP:r XII Page 75. Two Methods of Canning Corn— Selection of Seed — Planting — Moist Process — Dry Pack— Whiteness— Swells— Sour Corn— Differentia- tions Between Swells and Sour Corn— Cause of Sour Corn— Steril- ization — Experiments With Various Temperatures For Steriliza- tion—A Perfect Process — Discontinuous Process — Processing — Black Spots in Corn— Peas — Planting Process — Tomatoes — Various Uses of Tomatoes For Making Table Condiments — Use of Anti- septics — Arguments For and Against Their Use— Oysters— Meats — Fish— Preserving Methods — Salting — Smoking— Sugar— Drying — Evaporating— Pickles— Sauer Kraut— Soups. CHAPTER XIII. Page 104. Summing Up— Bacteria Studied— Products Canned and Preserved— Sterilization Studied— Mysteries Cleared Up— Recommendations — For the Study of Bacteriology— Electricity the Coming Agent For Sterilization— X-Rays— Finis. PREFACE. So far as we know there has never appeared a book written on the subject of Bacteriology, especially as it applies to the canning and pre- serving industries. That this science should be studied and applied by all persons engaged in such business is a generally conceded truth, and it is with the hope that a great deal of good will be accomplished, and a great many of the mysteries, that have caused so much loss to our pack- ers, may be cleared up. It is indeed marvelous how nearly hand in hand practical work and science travel, for looking through the history of these industries we find methods discovered, devices employed and formulae adopted and used as the results of innumerable experiments, and where these methods, devices, and formulae were successful, a true scientific principle was found which ought to have been seen from the beginning, and the great losses in experiments and experimenting saved. How many men who fill the positions of superintendents, managers, processors et al., know anything at all about the scientific part of their work ? How many men engaged in these enterprises are groping along in the dark relying on traditions and formulae handed down as a positive success, and who never awaken to the weakness of their management until something new turns up, until some new menace presents itself ? Processors have their rules by which to work, because, for some unknown reason to them, the goods will spoil if treated otherwise. Do you know that years ago Tyndall and Pasteur gave the scientific principle to the world, and against the greatest opposition proved their theories ^nd deductions to be absolutely cor- rect ? After all the experiments made in this business we find that these scientists struck the key note and unfolded to us a line of study that gives us understanding. It is with the hope that a higher knowledge of the canning and preserving industries may be obtained here that this little work is launched among the productions of this day. The Author. OK THK UNIVERSITY CHAPTER I. INTRODUCTION. CAUSE LEADING TO THE STUDY OF BACTERI- OLOGY. SOUR TOMATOES. In the fall of 1891, a peculiar trouble came to my notice, with a large pack of tomatoes. Many cans when opened appeared to be in good condition, bright, red and sound, but possessing a most nau- seating, sour taste. Believing that this was due to a careless use of the soldering solution, chloride of zinc, I had made a careful analy- sis and could find but a slight trace of this. I was then puzzled to know just what caused the trouble and so I decided to make some experiments. The analysis showed a liberal quantity of butyric and lactic acid, also a trace of acetic acid. Fearing that we had been using a flux which was not pure, an analysis proved the theory to be incorrect and it then dawned upon me that the same old trouble that I had many times seen in packing corn, had in some unac- countable way taken possession of the tomato canning. Cor- responding with others engaged in packing tomatoes, I found that several had experienced trouble of this nature to some extent but not to such an extent as to cause alarm in the canning of to- matoes. I knew that many canners had experienced heavy losses in canning corn and some fruits, where the seeds were left in the can. No one seemed to know what to do under the circumstances ; liberal rewards were offered to anyone who could save the corn, etc., by some of the canners who were losing so much goods, and I knew of several who were severely imposed upon by unscrupulous persons, who claimed to know how to prevent the complications. Up to this time I had never given a thought to the scientific principles involved in canning and preserving. Talking over the rules with experienced processors, I found that they were carrying on their work in a blind way and following rules which the ex- pensive teacher, Experience, had given them without inquiring into the principles of scie^jce. So long as no new complications pre- sented themselves they got along all right, but when the conditions changed, and the products were coming in too fast, and the changes 2 BACTERIOLOGY IN CANNING. in the weather were unusual, the canners suffered losses because they were following iron-clad rules and durst not launch into new channels lest their losses would prove overwhelming. They fol- lowed the ''rule of thumb" and if losses came they were put down as inevitable and they called them a part of the expense of canning. Realizing that it was time to begin a scientific study of the processes of canning and preserving and that it was necessary to know how to meet all these difficulties which were constantly aris- ing, and so follow the example set by the brewers after Pasteur had revealed the nature of their troubles with sour beer, I decided to take up the study of bacteriology and apply the knowledge to this busi- ness. Since that time I have constantly studied this science and the further I go the more light it throws upon the subject, and I am now prepared to say that every man who is engaged in these enterprises should immediately begin to give some of his attention to the sub- ject. By arranging a little room and procuring a few instruments, the subject could be studied during the dull seasons and the knowl- edge applied during the canning season when the actual process of canning begins. Another incentive for taking up the study of bacteriology and applying the knowledge to this industry, was my hope that goods of a very superior quality might be obtained, simply because with a certain knowledge of just how to treat each kind of goods to in- sure its perfect sterility, and therefore its keeping qualities, without doing anything in excess of its requirements, to wit, if under certain conditions a temperature of 250° P". for seventeen minutes, would keep tomatoes, and if you were scientifically correct, you would avoid processing the same goods thirty minutes. By this you would get a better flavor and of course your scientific knowledge should receive the credit. As I stated before, I decided to take a course of study in this science, which I did. I took up a number of experi- ments with sour tomatoes, which I will now explain because they have a bearing on a part of the work which is to follow. I opened a number of the sour cans of tomatoes, and after filtering some of the ' juice through a cheese cloth, examined it under the power of a microscope of 1000 diameters. I found quite a number of small round globules, which at that time I was unable to understand. They seemed to be motionless except a slight quivering which is termed Brownian motion. There were small rods and little fine dots sometimes alone, sometimes in pairs, and looked like ants. There were also small forms barely perceptible and one or two 'specimens of a very large germ. The view given in the accompany- Figure i MAGNIFIED X looo. BACTERIOLOGY IN CANNING. 3. ing plate is just as it was taken. I left this juice under a cover - glass in a warm room for two days and it remained practically un- changed, and I believed that the germs were dead and so they were. To determine that this souring of tomatoes was caused prior to the processing was my only solution, because the germs were lifeless. I took a number of cans and heated them, and I could determine which were sour because they would be slow to draw in again, due to the presence of a small quantity of carbonic acid gas which had been absorbed by the tomato and which the heating had liberated. The gas, as I afterward found out, was that which had been capped in the can while the tomatoes were fermenting before processing. Taking a number of swelled cans of tomatoes in various degrees of fermentation, I cut them open and filled new cans with the con- tents and immediately gave them thirty minutes boiling, at 212^ F. I had four cans. A, B, C and D. A was taken from a can very badly swelled and hot with fermentation. D was taken from a can which had just started to ferment, and B and C were taken from cans which were bulged out just a little more than D. After processing these cans in water for thirty minutes, I took them out, chilled them and set them to one side to await results. D drew in first and it was several days before A finally looked all right, but it was quite short in weight and not nearly full. I decided to open these cans and de- termine if I had anything similar to my sour tomatoes, and you may imagine my surprise to find them almost exactly the same; espe- cially was this true of B, C and D, while A represented an unusual example, being too violent. It was evident then that our sour toma- toes were sour before the processing and that the heat had killed the organisms, but the unpleasant results of the fermentation were absorbed by the tomatoes in the can together with whatever car- bonic acid gas was present in the fermenting tomatoes. The ques- tion then arose, where and when was this fermentation started and what were the causes. We found that about twenty per cent, of the entire pack had suffered during the month of September when the weather had been quite warm, and warm rains had been frequent. The farmers had brought in the product very fast and we were bothered with a gray mold whenever the tomatoes stood in the boxes for a few hours. The peculiar manner of our canning had been to heat the filled cans in steam boxes and then take them to the capping machines. It frequently happened that "these would accumulate ahead of the automatic capping machines, particularly when something would get out of order about them, when they would sometimes stand for a 4 BACTERIOLOGY IN CANNING. half hour in a temperature of 90° to 100^ F. Here then was where the fermentation started and this was the secret of the whole trouble. A scientific knowledge would have obviated this difficulty at once and saved a severe loss. During the next season I verified this theory by making actual experiments in this line, by taking a number of cans and allowing them to stand in a warm place for a considerable time and also taking some which did not stand. The former were without exception sour and unfit for food after the pro- cess, while the latter were perfectly good in every respect. CHAPTER II. BACTERIA DEFINED. FORMS. MULTIPLICITY. FUNCTIONS. DIVIDED INTO TWO CLASSES. DISCOVEKIES. SPONTANEOUS GENERATION. BACTERIA IN THE ATMOSPHERE LISTER'S ANTISEPTIC SYSTEM. MICROSCOPICAL OBSERVATIONS. CHEMISTRY OF FERMENTATION PTOMAINES. WHAT CLASS OF BACTERIA PRODUCES THESE POISONS. RESULT OF PTOMAINE POISONING. We will now take up the study of bacteria, particularly the varieties peculiar to the destruction of the various products which are canned in hermetically sealed packages. We will study their hfe^ history, their mode of propagation and the conditions most favor- able for their development. We will also go into the subject to de- termine safe methods to guard against their action. Bacteria are the lowest form of living things. They are organ- isms of various forms and shapes, round, rods, ellipsoid, thread, spiral, dumb-bell, spindle, etc. Each is a small speck of protoplasm called a cell and exceedingly small. Micrococci measure about i^Thss part of an inch in diameter. They multiply with marvelous rapidity and if suitable conditions were all right one germ of many varieties could produce or multiply to the extent of 5000 billions in three days. Such conditions however do not ordinarily exist and many of them die of¥ because of peculiar changes produced by their own action on the medium, upon which they are thriving. The use- fulness of many of these bacteria in destroying accumulated vege- table and animal matter is very great. If it were not for these minute organisms all this matter would accumulate and would not be reduced to elementary forms so necessary for new plant and ani- mal life. All things that die would remain and the animal and vege- table kingdoms would soon become extinct. A dead animal or dead BACTERIOLOGY IN CANNING. 5 vegetation under the action of these germs is with wonderful rapidity reduced to the elementary forms to nourish new vegetable and animal Hfe. We may divide for our consideration bacterial life into two distinct classes, viz : those which merely act as ferments and are not disease producing in man, and those which produce disease. With the former we have largely to deal because it is by their action that the complications arise in the preservation of food products. But we have also something to say of the latter because of the results of their action at times on food products, causing ptomaines which are alkaloids, and deadly poison to man, and which have been the cause of so much discussion among medical men in the late years, from the fact that people have at times died from eating certain kinds of fish and meat. Cheese and ice cream have been known to cause the death of persons under most seemingly unaccountable circum- stances. As a rule bacteria are colorless and refractile in a clear liquid but may be colored and identified by their affinity for certain kinds of dyes which give them a clear outline and makes them easy to study under a suitable instrument. The first man to discover that there was such a thing as bacteria was Anthony van Leeuwenhoek,a native of Delft, Holland, who in 1675, with only a crude instrument of his own design, discovered minute organisms with motility in de- cayed matter. He says : *'I saw with very great astonishment that there were many small animals which moved about in a most arnus- ing manner, the largest of these showed the liveliest and most active motion, moving through rain water or saliva like a fish of prey darts through the water ; this form, though few in numbers, was met with everywhere. A second form moved round often in a circle; these were present in greater numbers. They were tiny, in addition they moved forward so rapidly that they tore through one another like a swarm of midges and flies buzzing in and out between one another. I had the impression that I saw several thousand in a single drop of water or saliva which was mixed with the matter under observation not larger than a grain of sand. Some were curved, some straight, lying irregularly and interlaced." These re- markable statements made at so early a date, give us the first his- tory of the rod shaped bacteria bacilla, spirilla and round shaped micrococci. These statements caused a great deal of excitement and research by scientists, and many peculiar theories were advanced. Otto Friederich Muller, of Copenhagen, was the first man who un- dertook to classify the different kinds of bacteria, and he certainly 6 BACTERIOLOGY IN CANNING. made remarkable progress, considering the very crude microscopes made in his time. Other scientists took up the work and the oppo- sition took the ground that these scientists were not deaHng with germs, but merely albuminoid matter found in the air. The matter was not cleared up until the time of Tyndall and Pasteur, who brought the science out of its chaotic state and proved their work step by step, and it is due to the two men who overthrew the theory of spontaneous generation that this science is to-day on such a sure footing. For many years the theory that these organisms were a spon- taneous production of decaying matter, was generally accepted as truth. When meat was exposed in hot weather, it soon filled with worms, and it was thought that they generated of themselves, until someone covered it with wire gauze and the flies deposited their eggs on the wire and proved the fallacy of the theory. The belief in spontaneous generation was entertained by many scientists prior to and contemporaneous with Pasteur, among whom most notably were Schultz and Von Liebig. They took infusions of mutton broth ' and different vegetables, and having sterilized them perfectly by heat so that no micro-organisms were visible under the microscope, they allow them to stand open and exposed to the atmosphere for several days, examining them constantly. Suddenly putrefactive organisms and ferments peculiar to the infusion, would make their appearance most unaccountably to them, so they advanced the theory that life was spontaneous, and even built up a framework for the existence of all living things on this theory. Tyndall and Pasteur were not believers in this theory, and took up a series of ex- periments to demonstrate that the germs were deposited from the air or atmosphere. They had very great difficulties to contend with, because it was generally thought that these low forms of life were easily destroyed by boiling at a temperature of 212^ F. It was found however, that many of their infusions would break down, become turbid, evolve carbonic acid gas, after having been subjected to the boiling temperature for several hours. The opposition strength- ened themselves in their theory because they, too, had tried these experiments, and the result was that in nearly all cases they were unsuccessful in preserving their infusions, especially those made from meats and some vegetables, which had bacteria of more resist- ant power than others. After making various experiments in test tubes where the glass was drawn to a fine point at the top to allow the steam to escape during the heating, and while still boiling they closed the escape by melting the glass together, they were enabled to BACTERIOLOGY IN CANNING. 7 obtain many perfectly sterile infusions, which kept for a number of years perfectly clear and transparent. They adopted various tem- peratures, both continuous and discontinuous, and were able to sterilize any kind of fluid. Their failures in many cases were due to their test tubes not being full of liquid so that the air space be- tween the boiling liquid and the point of exit would contain the dry spores of bacteria which would afterward develop when the liquid cooled off. Having accomplished the overthrow of the theory of sponta- neous generation, Tyndall even went further and demonstrated by the question of a doubt that the atmosphere furnished these low forms of life. He made a pure air chamber and covered all over on the inside with glycerine; this chamber had windows through which he passed an electric beam. So long as there was any float- ing matter within the chamber, the light would be refracted just as a ray of light passing through a dark room is refracted by the particles of dust, which we have all seen. When the light ceased to be refracted and the beam passed entirely through the chamber without lighting it, it was evident that the particles had settled and stuck fast to the glycerine. In this chamber then he placed many different kinds of sterilized infusions and they kept without show- ing any signs of breaking down or fermenting. It is to these two geniuses, Pasteur and Tyndall, that we owe all that we know of the method of sterilizing, and their deductions come to us who are in the canning and preserving industries, as a solution of all our troubles. Bacteria, then as we learn, are present everywhere in the free atmosphere, and we find them present in quantities or numbers in proportion to the amount of organic matter which is undergoing decomposition. They are present in the air, clinging to dust or any floating matter and if no suitable medium is found by them to en- able them to vegetate they become hard and dry, and in the course of time will die. Pasteur, however, demonstrated that many varie- ties would live for two years. When we consider the vast amount of organic matter which is undergoing decomposition every year, the grass, the leaves, all vegetation and animal life, it is no wonder then that the atmosphere is everywhere laden with countless num- bers. Many of the different varieties are useful directly to man; the butyric ferment for instance is so useful in ripening cheese and making butter, that this form is cultivated and employed in some of the best creameries, just as the brewers cultivate and sow their yeast. Just how or when these low forms of life first made their ap- pearance, we do not know, but it is likelv that thev have existed 8 BACTERIOLOGY IN CANNING. since creation, and their origin like that of every living thing, is shrouded in mystery. It is a surprise that the existence of this world of living things should have remained unknown to man through so many centuries. When we think of the incalculable value of such knowledge, we wonder how man could get along without knowing of their existence. The dreaded diseases came on man and he called them the plague, sent by God upon man. We are thinking of the terrible plague, the Black Death, which made its appearance and nearly depopulated the world at one time. The superstitious people crowded together, offered prayers and made offerings, used charms and did everythin'g imaginable to stop the progress of the disease. They did not know that it was caused by these low forms of life, for if they had known it, they could have taken sanitary meas- ures to stop it. In the late Civil War, limbs were amputated with- out the use of the carbolic acid spray, and men died of gangrene and blood poisoning. Lister was the discoverer of the antiseptic spray to keep the germs in the air from acting on the tissues, when surgical operations were performejd, and we can now see where many brave and valiant soldiers perished from blood poisoning where this car- bolic spray would have saved their lives. Owing to the minuteness of these organisms the study of their life and nature becomes a science, and is a field for advanced re- search. It is not like taking up the study of things we can see with the naked eye, and watch from day to day their habits and purposes and results, but it is a study when only a small field of observation can be watched for a limited time and the results can only be studied as we watch their action through a powerful microscope. With the best instruments obtainable in this advanced age, we find ourselves limited for the want of sufficient light, for the greater the magnifying power of the glass, the greater amount of light is re- quired, and it must be a peculiar light too, not glaring as the direct rays of the sun, but the soft rays of light reflected as from white clouds or the electric light. Owing to the transparency of most of these organisms it is necessary, especially for the examination of the smaller forms, to use certain kinds of dyes, otherwise you might exanxine a field and very few forms would be visible. It is very in- teresting to watch the working of bacteria on the particular sub- stratum that you wish to examine. For instance, if you desire to ex- amine fermenting corn you would take some of the juice and put a small quantity under a cover glass, which is a very thin piece of glass about ^^-g- of an inch in thickness, and when you brought the field to a proper focus you would find a very turbid view and BACTERIOLOGY IN CANNING. 9 you would be unable to gain much of an idea of the germs you wished to examine. You could filter a small quantity of sweet juice and then by dipping a needle in the fermenting juice, transfer some of the germs to this and then transfer a small quantity to the plate, and place the cover glass over this to diminish evaporation, then you could watch the active bacteria begin their work of decompo- sition. In coloring the bacteria, a small quantity of methyl blue or eosine will often bring them clearly to view. It is in the results of bacterial action that we are most interested, as they bring about chemical action and change the atoms from one group of molecules to another and form new compounds and create gases. If, for in- stance, we take sugar and allow the yeast plant to work on a pre- pared solution, we find that it is broken up into different forms. We will represent one molecule of sugar by its atomical symbols which is CeHiiOe which is six atoms each of carbon and oxygen and twelve atoms of hydrogen. By the action of the yeast plant, which is called saccharomyces we get 2CO2 (carbonic acid) -f 2C2 HeO (alcohol) which are two distinct substances and not resembling at all. Now if the putrefactive ferment butyricus amylobacter acts on the alcohol we will have 2C2H6O (alcobol)=C4H802 (butyric acid)+ 2H2 (hydrogen) or if we let the lactic ferment act directly on the sugar in conjunction with the butyric ferment, we will have the sugar converted directly into lactic acid which in its turn is converted into butyric acid, carbonic acid and hydrogen. CeHia Oe (sugar) = 2C3H6O3 (lactic acid) = C4H8O2 (butyric acid -f 2H2 {hydrogen). Thus we see our molecule of sugar broken up first into two molecules of lactic acid which in its turn is broken up into two fatty acids, and two molecules of hydrogen, or in other words one mole- cule of sugar broken up into five molecules, which is the tearing down process of these organisms to reduce or decompose sub- stances into elementary forms. I do not mean to say that the pro- cess ends where I have brought it, for there are still lower forms of bacteria which take up the work and reduce these molecules still further until they take simple forms, even elementary forms. I think the above chemical formulae should be very interesting and instructive, as they give you the idea of bacterial action better than any description in words. We have been describing the action of certain bacteria which act only on dead matter which are not classed properly with the disease germs. To be sure if we take into our stomachs fermenting substances we are liable to suffer with some disorder, and perhaps 10 BACTERIOLOGY IN CANNING. severe sickness, but the difference between this action and the action caused by disease germs properly speaking is very great. We will enter into a description of the various diseases produced by this class of bacteria further than to observe their action on certain foods which when taken into the stomach produce certain kinds of poison- ing, resembling arsenic and strychnine. Brieger obtained from pure cultures of the typhoid bacillus acting on some suitable medium, a ptomaine which termed typhotoxin, and from the tetanus bacillus he obtained tetanotoxin. The vegetable kingdom furnishes many substances that have an alkaline reaction, combine with the acids and form salts, which if injected into animals or taken into the stomach cause poisoning, viz: nicotine, morphine, brucine, strych- nine and hydrocyanic acid. So these bacteria of disease or patho- genic organisms, which are of vegetable nature, can produce poisons in food products where they may happen to find a substra- tum favorable to their growth. In plainer language then, since the higher order of plant life can furnish these dreadful poisons, so the lower vegetable forms produce poisons just as deadly and of nearly the same reaction as the higher forms. Nearly all the known patho- genic organism produce poisons which would properly be termed ptomaines. Putrescine (C4H12N2), cadaverine (C5H16N2) are ptomaines, the latter is produced by an action of the cholera bacil- us on egg albumen. Neurine (C5Hi2(NO) ), and choline CsHisN O2, are also produced in putrefying flesh by the agency of patho- genic bacteria. We find also another poison growing naturally in a kind of poisonous mushroom and also produced in putreying fish by bacteria. This ptomaine is muscarine (C5H15NO2), and acts on the muscles when eaten. Oysters and mussels are very liable to the action of certain bacteria which produce mytilotoxine, CeHisN O2). Tyrotoxine (C7H17NO2) is found in cheese and ice cream, where these foods have undergone a fermenting process by the agency of disease germs. The diphtheria germ, Klebs-Loeffler bacillus produces a toxic poison, so also do the bacilli of cholera, typhoid, tetanus others. Studying over these deductions and chemical changes, we see that combinations are easily upset, atoms from one set of molecules fall dow^n and are taken up by other molecules, forming new sub- stances by these mere changes in arrangement. If we cannot see the exact changes chemically made, we can see the agents at work and we can see how they perform the work. The word ptomaine comes from the Greek word Trrw/ia, which means "cadaver" and was bestowed upon them by Selmi, an Italian BACTERIOLOGY IN CANNING. ii chemist. Delafontaine gives a very interesting explanation of these poisons : ''During the incipient state of putrefaction there are fre- quently produced various compounds, some of which possess in- tensely poisonous properties. They are called ptomaines. They seem to have led some experts into trouble, for the reason that some of them produce symptoms similar to those of various natural poisons such as strychnine, morphine, nicotine, etc. Such poisons have been extracted from cheese, milk, especially in the form of ice creams, and various preparations of meats, such as sausage, smoked meat and fish. ''The action of some of these upon the healthy man very much resembles that of arsenic and other like irritating poisons. Almost every summer, one chemist or another has to investigate cases of poisoning from ice cream, especially resulting^iFom parties or pic- nics, where a number of people are made more or less sick from the effects of eating the compound. The first impulse of victims and friends is to ascribe the trouble to the presence of copper, lead or zinc absorbed by the cream from the freezers. Sometimes the blame is laid at the door of the flavoring extract employed, especially if it chances to be vanilla. But almost invariably the closest chemical analysis fails to sustain the suspicions and leads to the extraction of a ptomaine identical with or closely allied to that sometimes found in cheese. Incidentally it may be stated that on the whole^ the poison-tainted articles exhibit no bad taste or smell, that would act as a warning to the consumer. "As regards some of the symptoms frequently exhibited, they are like those of a very irritating poison. Among other cases, I once was called to examine some meat eaten by fifteen persons who were poisoned. They developed acute inflammation of the stomach and bowels, repeated vomiting and purging, wdth great loss of strength, clammy perspiration and cold extremities. There was nothing in the appearance, taste or smell of the meat to indicate that it was unsound, and yet I could extract from some parts of it a poison which wa's undoubtedly a ptomaine. "Poisoning by ptomaines is by no means uncommon, yet many suspected cases are due only to over indulgence in strongly spiced articles and too much drinking of beer," etc. There is an interesting article also in the Scientific American, which gives some useful information on the subject of ptomaines. It says: "Within the last few days a number of persons in New York City have died from ptomaine poisoning, so that public at- tention is now directed toward the mysterious nature of these 12 BACTERIOLOGY IN CANNING. poisons, which are not generally well understood. 'Ptomaine' is a generic name for alkaloid bodies formed from animal and vegetable tissues during putrefaction and the similar bodies produced by pathogenic bacteria. Very often, perhaps generally, the degenera- tion in the food product is not far enough advanced to offend either the taste or sense of smell ; consequently, suspicion is not excited, and a person eats or drinks something which contains enough of the poison to make a great deal of trouble, if the result is not fatal. We often hear, in the summer, for instance, that persons who at- tend a picnic were stricken with a violent illness, and that the phy- sicians in the neighborhood were kept busy for hours. The fact is developed that only those who ate ice cream were made sick. Some- times it is reported that some one has poisoned the food maliciously, but it is known that the cause of most, if not all, of these distressing experiences was the presence of ptomaines in the milk out of which the ice cream was made. ''It is not an easy task to trace the history of milk back far enough to reveal the precise conditions under which the ptomaines were developed, but it is believed that failure to properly cool the milk immediately after it was taken from the cows, is a partial ex- planation of the evil. Warm weather favors this condition. The ptomaines of ice cream tyrotoxicon are particularly to be dreaded, as well as other poisons, such as mytilotoxin, found in mussels. "It is not pleasant to contemplate that the air we breathe and the water we drink, and a large proportion of our food abounds in bacteria of different kinds. Most of them are, fortunately, harm- less, or should be, if proper precautions are taken. Milk is far from being the only medium for the transference of this poison to human beings. A great variety of solid foods of animal origin are also likely to develop ptomaines. One frequently hears of poisoning by canned goods, such as potted meats or canned salmon, for instance. In some cases a metallic agent, perhaps the solder, is the cause of the trouble, but in the majority of cases the sickness, especially if it is intestinal and painful character, is due to ptomaines. To all ap- pearances, the food may be entirely fit for consumption, and per- haps none of those employed in the canning house may be re- sponsible, but the chances are that unperceived putrefaction has set in and that ptomaines have been produced. ''Fresh fish and oysters are not exempt from the tendency to develop ptomaines. Indeed, fish was one of the first sources from which these poisons were obtained by chemists. The symptoms of these poisons are vomiting, nausea, diarrhoea and retarded respira- BACTERIOLOGY IN CANNING. tion, and in advanced stages, coma. 'There is no known antidote for. this poison, though of course emetics and purgatives should be used where the poison is sus- pected. There are numerous ptomaines in the body, but they are absorbed by the oxygen or expelled by the bowels, liver and lungs. If not, they strike the nerve centers and sickness results. The real cause of many mysterious deaths is ptomaine poisoning, but there are, of course, many mysterious deaths due to other causes. Many cases of ptomaine poisoning do not result seriously at all." CHAPTER III. BACTERIA. MANNER OF PROPOGATING. DESCRIPTION OF VARI- OUS FORMS. CHARACTERISTICS. MOLD FUNGI. The multiplication of bacterial forms vary in different organ- isms, and it may be well to take up the study of these different forms before engaging our attention on the various organisms peculiar to the decomposition of food products. Multiplication by division is a common mode, especially with the spirillum and bacillum. Transverse lines become visible, which increase and become gelatinous. The organism separates at these places and the process begins over again. Under the higher powers of the microscoj>e bright shining spots appear within the protoplasm of the germ cells, which are the new spores or life forms which will, under suitable conditions, increase and break away from the parent cell and develop into full grown cells themselves, and these spots will again appear within their walls, and so the multiplication goes on until the conditions become unfavorable for their nourishment. These favorable conditions depend of course on the amount of ma- terial exposed to their action, and the temperature sufficiently warm for their vegetating power, which for the great numbers- of bacteria must be from 60° to 90° F., but there are some exceptions among the alcoholic ferments where the temperature can fall to 36° or 38^ F. The conditions favorable to the propagation also depend on the compounds formed by their own action on the particular substrata which they are causing to ferment. Sometimes an acid is generated which will kill them, and that acid may be due to their own action. The condition will become favorable, too, when the organisms have performed their work. Other forms may appear and take up the work of disintegration where the first form left oflf, and so after these forms have fulfilled their work, still others may appear on the new 14 BACTERIOIvOGY IN CANNING. mtdium so formed and find it favorable to their peculiar action. Dur- ing the process of germination any particular form of bacillus may change in character from its peculiar form as known under ordi- nary conditions. A rod shaped bacterium may assume the shape of a curved form like the spirillum or thread-like as the leptothrix and round like the coccus. These various forms of the same bac- terium have caused considerable trouble in classification, because they may have the appearance of a different variety or specie. The figure No. 2 will give some idea of the different forms of bacteria. ^ <^ Figure 2. a— GERMINATION OF SPORES, b— BACTERIA WITH ELGEI.I,A. C— SPORE FORMING CEI/I*S. d— ZOOGI.OEA. e— cocci. f— DIPI.0C0CCI. g— STREPTOCOCCI OR CHAINS, SPIRII,I.A AND VIBRIOS. -I.EPTROTHRIX. When germination takes place by spores the appearance of the mother germ darkens and appears granular when a certain point becomes prominent and it swells rapidly, using up the protoplasm of the cell in forming the new growth. Sometimes the former cell will not expand again, but appears to dry up, in which case the life is maintained in the spore which still clings to the mother cell. In a suitable fermentable substance, the spore will germinate, first swelling to unusual size, when the spore within will burst through See Figure 4. BACTERIOLOGY IN CANNING. 15 the wall and there will appear two germs where formerly only one was visible. There are anthrospore and endospore forms of bacteria. The endospore bacteria form their spores on the inside of the plasma or wall of the cell, while the anthrospore bacteria do not. The zoogloea forms of bacteria are peculiar to slimy formations, so that when you observe any fluid of a ropy nature, as sometimes happens with peas, it is this form of bacteria largely the cause of such action, but there are of course other reasons for ropiness in canned peas. These bacteria grow very fast in colonies almost pure naturally. The spore formation of the yeast plant, saccharomyces, is most interesting. The view of these cells budding as seen under a power of 1000 diameters in the microscope, is most interesting because they can be seen so plainly, and their appearance is beautiful. In fact the microscope opens up a new world in the vegetable kingdom and the study is most fascinating. Figure 3. I took a quantity of filtered tomato juice and placed a culture of these alcohol ferments in it, and the next day I transferred a single drop under the cover glass, filling the slight excavation and laying the cover glass over this to prevent to a certain extent the evapora- tion of the liquid. I located a few cells and watched them closely ; I detected shining spots within the cell walls which appeared to be swelling. After a time I was awarded by seeing a slight protuber- ance on one side of a cell which increased rapidly in size, remaining attached to the parent cell. After a time other cells began budding, and then I noticed that the first bud had fully developed and was in its turn showing signs of germination. In a short time it sent out a bud and the mother sent out another one in the opposite direction. In a few hours I again examined the view and the beautiful scene was laid out before me as the following illustration will show. All this occurred in a field not larger than a pin point, and no doubt i6 BACTERIOLOGY IN CANNING. would have been much more abundant in development if the oxygen had not been partially cut off by the cover glass. I then glued the cover glass fast to the glass slide, and in a very short time the glass burst from the pressure of the carbonic acid gas which was being liberated freely. There appeared also other forms of bacterial life from the atmosphere in zoogloeas and the lactic bacteria were also visible, appearing in little short rods. The spores of the saccharomyces, as I stated, began to show themselves within the wall of the cell, and exerted such a pressure in swelling as to push through the wall, and after sending out several buds would turn dark and appear to shrivel up. I met also with cells which sent out buds which, when developed, would break away from them entirely. I examined all these specimens in a tem- perature of 70° to 80° F., which probably accounts for the appear- ance of other forms in the illustration. The true alcohol ferments may be cultivated almost pure at a temperature of 36^ to 40^ F., and while their development is slow, they are able, however, to accom- plish fermentation, without the interference of other organisms which will not vegetate excbpt in higher temperatures. This pecu- liarity of the yeasts make the brewing of beer comparatively easier than the ol3 method where little attention was paid to temperatures. A peculiar film appeared on the tomato juice that I spoke of before, and gradually became thicker and wrinkled in appearance, and the saccharomyces seemed to stop their action and settle down to the bottom of the glass. I examined the fiim under the micro- scope and recognized it as the mycoderma cerevisiae and myco- derma vini, and I found that this film was using up all the free oxygen from the air and so depriving other germs of that very essen- tial element. The cells are various shaped, some round, some long and almost transparent. The spores are easily seen and have a rest- less movement within the walls of the cell. This form is quite com- mon and appears on the surface of many of the fruit juices. fop ^ ^ ^ & p MYCODERMA VINI AND CEREVISIAE. V* OF THK 1^ UNIVERSITY Figure 4 MAGNIFIED X 1000. \ BACTERIOLOGY IN CANNING. 17 The growths of the mold fungi are also interesting, because we can see them with the naked eye to attain the height of an inch sometimes. They have a characteristic plant form and thrive on all liquids of a slightly acid nature, especially fruit juices. The first mold I will describe with reference to its growth, is the pencillium glaucum, which starts from a spore sending out long branches which have the appearance of lengthening out and dividing, like the branches of a bush with joints. When these grow to a certain height the tuft branches produce a large number of conidia, so that the whole surface of a patch of the pencillium glaucum will be covered with millions of these little round cells, each of which is able to start a new plant whenever it falls upon a suitable medium. As a body they present a grayish blue color, and look smaller than the yeast germs. I ^.0^ Figure 6. PENCILLIUM GLANCUS. a— CONIDIA. b — CONIDIA SENDING OUT A BRANCH. C— REPRESENTS THE BRANCHES WITH CONIDIOPHORES AND THESE BEAR- ING NEW CONIDIA OR ROUND CEI.LS WHICH ARE SEED. d— CONIDIOPHORE WITH THE SPORES OF THE CONIDIA, BEFORE THE CEI«I« WAI.I, IS RUPTURED. ASPERGILLUS GLAUCUS. Aspergillus glaucus is a mold fungus, somewhat ?.milar to the pencillium in the manner of its development and production of conidia. Its peculiarity i§ the spiral forms of its ascogonium, which is enveloped by the hyphae. This is a very common variety of mold w^hich grows in abundance in damp places. MUCOR RACEMOSUS. This is a mold fungus which grows at ordinary temperatures on acid surfaces of fruit juices, or in any damp place where a fer- mentable substratum is a base of growth. This fungus grows luxu- i8 BACTERIOLOGY IN CANNING. riantly on bread and attains a considerable height. The branches and sporangia have about the same characteristics in their forma- tion of spores that the two former ones have, that we have studied. In addition, this fungus has the power to propagate by budding, resembhng in many respects the true yeast fungi. The spores are colorless. When mucor racemosus is submerged in a fermentable liquid the sections appear to swell and become large and oval shaped, filled with a highly refractive plasma. They separate at the lines of demarkation and begin budding. The conidia or spores have the same characteristic and resemble the saccharomyces very much. They sometimes germinate in this way when cultivated on a solid substratum. MONILIA CANDIDA. This fungus is a white or grayish colored mold which grows from the spore just the same as the other varieties we have ex- amined, and pear shaped or elliptical spores form on the ends of the branches. It is found on sweet, juicy fruits, and when submerged will produce alcoholic fermentation and will form a white film on the top of fruit juices. ^^/? Figure 7. MAGNIFIED X 1000. a- MONILIA GROWING WHEN SUBMERGED, b— MONILIA CELLS OF A FILM FORMATION. Figure 8. MAGNIFIED X looo. BACII^IvUS I^ACTICI ACIDI-SOUP SUBSTRATUM. CHAPTER IV. BACTERIA COMMONLY FOUND IN DECOMPOSING FRUIT AND VEGE- TABLES. MICROSCOPICAL VIEWS AND DESCRIPTIONS CHAR ACTERISTICS . -—STERILIZATION . It is not my purpose at this time to take up a complete list of the various bacteria found in the many kinds of fruit products, but only a few of the more common varieties, in order that the reader may become familiar with these forms and understand clearly what is meant when we speak of them in the following pages. LACTIC ACID BACTERIA. This form of bacteria as seen under a microscope of looo x appears in short rods slightly contracted in the middle, as will be seen by the representation below. It will resist very high temperatures, and it requires at least 250° F. for ten to fifteen minutes to kill the dry forms. They are the forms which commonly cause milk to turn sour, but are found everywhere in fermenting fruit juices, and act very readily on the milk of corn. The above view was taken of a culture of these germs transferred to a drop of com milk and placed under a microscope. Their action is directly on the sugar contained in the milk and they convert it into lactic acid with no carbonic acid gas when acting alone. They are rarely if ever found acting alone, how- ever, and it is, only by making pure cultures that they may be studied for a short time under the glass. Other forms will make their appearance very soon. This form of bacteria flourishes very rapidly at a temperature of 80^ to 90° F. It grows on gelatine plates as small, white points, becoming opaque, forming a thick layer. The colonies appear dark yellow in the middle. This is one of the species of bacteria which are found acting on nearly all kinds of food pro- ducts and has considerable resisting power to high temperatures. BUTYRIC ACID BACTERIA. Clostridium butyricum and amylobacter are the putrefactive ferments which cause a great deal of trouble in the canning indus- 20 BACTERIOLOGY IN CANNING. try. This form is one of the most resistant to high temperatures, and develops spores which are hard to kill. These spores are found in dried-up forms clinging to the fresh product, and will begin to de- velop whenever a suitable medium presents itself. These bacteria act on the sugar producing butyric acid, car- bonic acid and hydrogen, and they are anaerobic, producing a very unpleasant taste in fruit juice. It is a motile organism and looks Hke a short straight rod. When these bacteria are ready to form spores they swell up into peculiar shapes, spindle, club shape, lemon shape and elliptical. The spores burst the outer protoplasm and begin de- veloping into a new organism. When colored by iodine the butyric bacteria appear blue. They develop rapidly at blood heat. In gela- tine they form yellow colored colonies. I consider this form of bacteria to be one of the most dangerous forms to be met with in the canning of corn and peas. The full grown bacillus is easily killed at the boiling temperature, but the spores, especially the dried-up forms that have been floating in the air when they find a lodgment in the milk of the corn, are very hard to kill. They are so small in this dried-up form that we can almost conceive of them being able to pass through the juice without becoming wet. After milk has. soured by the action of the lactic bacteria, and the acid is neutral- ized by lime, it will set up butyric fermentation caused by the butyric ferments. This is a spontaneous butyric fermentation from the bacteria in the atmosphere, and will start at a temperature of 70^ to 80^ F. The butyric ferments act very readily on starch, dex- trine, dextrose and sugar cane. These bacteria also play a very im- portant part in the ripening of cheese and give it its peculiar flavor. They have the power of decomposing fermentable substances with- out the aid of free oxygen, and on this account we terrri them anaerobic. The following view will give some idea how they ap- peared in a view taken of fermenting com milk. The rods repre- sent the bacilli and the dots represent the spores. ACETIC ACID BACTERIA. The two well known forms of bacteria which cause acetic acid are the mycoderma aceti and the bacterium Pasteurianum. In 183S Turpin and Kutzing discovered that acetic acid fermentation was caused by micro-organisms, and Pasteur in 1864 confirmed the cor- rectness of their assertion and called the organism mycoderma aceti, but as he was not working with any particular culture, he did not bring out the fact that this acid could be produced by at least one other form, if not more. As he did not employ pure cultures. Figure 9. MAGNIFIED X 1000. BACILIyUS BUTYRICUS. ^t£BE L/8^ Ol' THl SITY Figure lo. MAGNIFIED X looo. BACII.LI BUTYRICI— SHOWING SPORES. BACTERIOLOGY IN CANNING. 21 his methods of making vinegar were not used practically, and in 1879 Hansen classified the germs and obtained pure cultures. The ''quick vinegar process" is employed in the manufacture, where the liquid is divided into drops and given free access to the atmosphere and given free distribution over large surfaces of beech shavings, where the process is taken up and completed by the organisms. The acetic acid germs are characterized by long chains of hour- glass shape, partially bacilli and curved forms. Mycoderma aceti are stained yellow by iodine, while bacteria Pasteuriana are given a blue color by the same stain. No spores have been seen in these bacteria. Figure 11. MYCODERM ACETI AND BACTERIA PASTEURIANA. The bacteria are present in large numbers in various fruit and vegetable juices, and are so common everywhere in the atmosphere that they are among the earliest forms of organic life to appear in the fermentation of food products. BACII«I.US VISCOSUS We will now take up the study of a form of bacteria which plays a great part in the spoiling of canned goods, especially of vegetables like peas, beans, asparagus and corn, causing the whole liquid part to become slimy and ropy so that it can be lifted in long sticky threads. The varieties or species of this slime producing bacteria are given the name of bacilli viscosi. They have the power of resisting high temperatures which, of course, makes sterilization difficult. It is, of course, very necessary to know the characteristics of such forms of bacterial life, their forms, resisting power with refer- ence to heat and antiseptics and their probable source, in order to guard against them as much as possible at the time when the pro- 22 BACTERIOLOGY IN CANNING. duct is exposed to their action. You have, no doubt, seen cans of various kinds of vegetables opened and found the liquid part ropy and slimy, when to all appearances it was clear when filled into the can. This trouble has caused the packers of peas no end of worry, because they have not taken into consideration that much of this trouble was due to this kind of a bacterium. There are some people who put up a great deal of molasses in tin cans, and have a great deal of trouble in preventing fermentation, especially during the hot summer months. The fermentation set up by this organism is very violent, especially when deprived of free oxygen. It forms carbonic acid gas in great pressure, even to the extent of bursting cans tested to with- stand 50 to 75 pounds pressure. Bacilli viscosi make slimy patches in molasses and sets up this fermentation, and on account of its re- sisting power to sterilization, it is hard to keep molasses in tins dur- ing the hot weather, because high temperatures deteriorate the quality of the goods. This organism causes the same trouble in wine and beer, which we sometimes see, become ropy.';:The organism forms in clusters resembling zoogloea as the envelopment in the slime formation holds them in clusters. Pasteur discovered these bead-like chains which set up a viscous fermentation with carbonic acid gas when introduced in wine and beer, and Van Laer found bacilli in rods forming zoogloea, which produced the same viscous fermentation. This fermentation and slime formation is great in proportion to the quantity of nitrogenous matter in the liquid. Ordinarily the cocci appear in pairs surrounded by an envelope of mucilaginous matter. They sometimes grow without the gelatinous envelope, and so ap- pear when cultivated on potato.

?^ University Figure 13 MAGNIFIED X 1000. ONE PART BOUILLON, 99 PARTvS WATER. RANK PUTREFACTION, BOUIL- LON, PRODIGIOvSI. BACTERIOLOGY IN CANNING. 23 The manner of protecting food products from this scavenger and the requirements necessary for steriHzing vegetable and fluids where it finds a lodgment, will be taken up under the process em- ployed in canning and preserving as they will be described in pages to follow, and under those heads we will endeavor to clear up some of the mysteries of spoilage. BACII,I,US PRODIGIOSUS. This is the organism which gives the odor of herring brine or fish to putrefying substances, and is also named bleeding bread, because it is a pigment bearing bacillus of red color, and forms spots when growing on bread, potatoes and onion that resemble blood. It is an egg-shaped germ about uuiui^ of an inch in diame- ter, which is very small. It has no motion and multiplies by divi- sion. It is so minute as to be barely perceptible with a power of 1000 diameters, and Ehrenberg calculated that a cubic inch would con- tain one quadrillion. This organism is very common, nearly always associated with decomposition of vegetable matter in putrefactive stages. One peculiarity about this bacillus is that at blood heat it fails to produce the red pigment and peculiar fish odor, but at 60^ to 70° F., when cultivated on agar, both of these characteristics are evident. The drawing here represented was taken from life. Prodigiosus has the property of converting fermenting sub- stances of a fermentable nature into lactic acid at a temperature oi 80° to 90*^ F., at which temperature it produces no red pigment, so that the whole of its energy is employed in the fermenting pro- cess. When milk is soured and lactic acid is produced, it sometimes has a blue color, which is a pigment in the protoplasm of a bac- terium, similar in many respects to the bacillus prodigiosus. Bacillus prodigiosus is also a germ causing unsoundness in bread and bakers have to guard their dough against this action to pre- vent souring before the baking. In manufacturing tomato catsup and various condiments where chopped onions are used, it is ad- visable to keep them in cool places or use them ag soon after chop- ping as possible, to avoid discoloration and flavor injury from the action of this bacterium. SACCHAROMYCES APICUI^ATUS. This is a lemon-shaped bacterium and is one of the few germs which have a peculiar form easily recognized wherever we meet them. They always appear on the juice of sweet juicy fruits when exposed 24 BACTEPJOLOGY IN CANNING. to the atmosphere. The buds are either lemon shaped or round. The first view I had of these pecuHar forms of organic Hfe was on a substratum of pineapple juice to which had been added a small quantity of sugar, and left exposed to the atmosphere. In a short time a fermentation set in which was not unpleasant to the taste. Examination under the microscope revealed a pure culture of these bacteria, and the scene was one of the prettiest I have ever ex- amined. The little lemon-shaped cells were sending out buds rapidly, and the juice had a flavor of alcohol so similar in many respects to the yeast plant fermentations, but its power to produce alcohol is only about one-sixth of that produced by the yeast saccharomyces cerevisiae. It is found in abundance during fruit seasons on cherries, grapes, plums, gooseberries, pineapples, etc., on the ripe fruits, ready to begin action as soon as the juice is ex- posed. It is always found in the soil under the trees and bushes of such fruits, probably on account of having flourished on fallen fruit and carried down into the ground by rains; remaining alive all through the winter. In the summer time it is carried by wind or dust, and falling upon the fruit still growing, remains until it ripens before setting up fermentation. This characteristic ferment to this kind of fruits, its habits, its habitation, and last its lodgment on the fruit which makes its existence possible, is only an example of almost every other form. Each form will be found in dose proximity to its victim, and nearly all fruits and vegetables and other things will have the dried-up forms either on them or near them, ready when the time comes to resolve the substance again to elementary forms. This is the great scheme of nature to make old things new again, and reduce the matured things of earth to ele- ments to furnish nutriment for the new. ' Although there are many other bacteria which make their ap- pearance in fermentable substances, we have described a few of the more important as having to do with the canning and preserving industries, and they are the principal forms we meet, and if we guard against them, we need have no fears about other forms, ex- cepting, perchance, a bacterium like the bacillus subtilis and the bacillus panificans should make their appearance, in which case the entire method of canning would have to be changed in order to keep the goods from fermenting. So resistant to heat are the spores of these two forms, and I have no doubt other unclassified forms, that they can withstand temperatures of 300° F. for hours, and then de- velop and cause fermentation. So far as I know, these forms have not made their appearance in articles or products which are canned Figure 14 MAGNIFIED X 1000. SACCHAROMYCBS APLCUI.ATUS ON PINEAPPI^E JUICE. Wf.-^ ^ >/\ ^v*"^ Figure 15. MAGNIFIED X 1000. BACII^UUS SUBTII.IS WITH ENDOSPORES X lOOO ON BOUII.I.ON. BACTERIOIvOGY IN CANNING. 25 and preserved. It might be well, however, to give a sketch of these two forms, for fear, perhaps, they might at no distant time find a place among the scavengers of canning products. BACILI^US SUBLII^IS. This bacillus is spore bearing, and the spores appear to be special protoplasmic cells, developed in the parent, surrounded by a thin but very hard membrane, and it is this membrane which pro- tects the life of the spore against the action of heat and antiseptics before development into full grown bacilli. Dry heat, of course, would be less efficacious than moist heatj because the latter if ap- plied in certain ways will soften the membrane and cause the pro- toplasm within to swell, at which time the germ is most susceptible to high temperatures. When moist heat is applied it is noticed that the protoplasm becomes dark and granular, where before it was clear and transparent, and it then begins to swell and gradually will stretch the membrane until it bursts across the middle, which dis- tinguishes this form from the bacillus amylobacter, which bursts its membrane lengthwise. After bursting the membrane it makes its way out and begins to vegetate by lengthening and dividing across the rod form, at which time heat of 160^ F. will kill them. This bacterium makes its appearance in hay infusions that have been boiled, and it is the organism that caused Professor Tyndail so much trouble in trying to sterilize the infusions on account of its great resisting power to heat. It is a motile organism about ^^,^7^ of an inch long and jziffs of an inch in diameter. Its spores are large and easily studied. It multiplies very fast, producing much carbonic acid gas and seems to be peculiar to hay. Owing at times to the close proximity of hay fields to land where the cultivation of canning products is carried on, it would not surprise me at any time to find this organism flourishing in corn, peas, beans, etc., in which case a complete change of processing would become necessary in order to keep these articles from fer- menting. In that case the present sterilizing process would be use- less, and new methods based entirely on bacteriological knowledge would have to take their place. The system referred to will be taken up in detail under another head, and people who desire to be progressive can find a method laid down to form the base of ex- periments that ultimately will insure a superior quality and perfect sterilization. The bacillus panificans is another spore-bearing bacillus which 26 BACTERIOLOGY IN CANNING. is very resistant to the action of high temperatures. The bacilli themselves, like the bacilli subtilis and butyrici, are easily killed at less than boiling temperature, 212^ F., but the seed form, the spores, are very resistant and cannot be killed by continuous boil- ing, notwithstandng any statement made to the contrary. These statements are made by some scientists who claim to have killed the spores in half an hour by boiling, but they either were dealing with other forms or kinds of bacteria, or they never did what they claimed. We know that Tyndall tried this, and we have his word to the contrary, and our own experience with corn and peas, etc., bears him out. I have tried time after time to kill these forms by boiling for eight hours, and every experiment broke down. So the spores of panificans cannot be killed^by boiling. This is the organ- ism which sets up the fermentation of the dough of rye bread, and is peculiar to r}^e. It is a short mptiJe 'rod with threads which in- terlace to form a film when grown "on liquid media. So far as I know these two forms, subtilis and panificans, do not as yet enter into the catalogue of ferments, which cause the troubles in canning and preserving of food products. CHAPTER V. PATHOGENIC BACTERIA. STUDIED BECAUSE OF THE POISONS PRO- DUCED WHEN ACTING ON FOOD PRODUCTS. DIFFERENT KINDS OF THESE BACTERIA STUDIED. THEIR ACTION ON VARIOUS FOOD PRODUCTS DESCRIBED. We have been describing bacteria of non-pathogenic character,, viz : The ordinary forms and organisms which cause fermentation of food products, but which have no connection with the diseases of man. While it is true that ordinary ferments when causing fer- mentation, if taken into the stomach, will cause stomach disorders, and sometimes violent sickness, they must not, however, be con- flicted with organisms which cause specific diseases in man. It is not our purpose in a work of this character to take up a complete history of all known forms of diseases and the organisms which cause them, but simply to study those forms which in atmospheric fermentation find a lodgment in food products of albuminous nature, and by their action on the albumens produce alkaloids and toxic poisons which come under the generic name of ptomaines. In a preceding chapter (page 21) we have taken up the sub- ject of ptomaines and called attention to the very common occur- JSTUBR^ OF TH UNIVERSITY CALIFQ^ # • ^; A > • -4 O \ \ Figure i6. MAGNIFIED X looo. CHOLERA GERMS IN COMMA, S SHAPED AND O SHAPED FORMS. BACTERIOLOGY IN CANNING. 27 rence of poisoning from these alkaloids, and a description of some of the organisms must be interesting. The study of these forms carries the student in bacteriology into a very difficult field, from the fact that the character of these organisms, their mode of action, etc., is removed from the ordinary field of fermentation, and while their action is fermentative in character, they are so frequently found deep in the tissue of the muscles of the sufferer that they become anaerobic in nature, and hard to cultivate in an aerobic state on mediums prepared by artificial means. Many forms, however, occur so abundantly in nature that they can be cultured and studied, and these forms, with possibly one or two exceptions, fall into the line of our study here. COMMA BACCILI.US— CHOI.ORA. The ptomaines, cadaverine, putrescine and choline are without doubt the result of this deadly germ, which has started a fermenta- tion on albuminoids. The comma bacillus was discovered by Dr. Koch to be the cause of Asiatic cholera, and it is due to this bril- liant scientist that the mysteries, doubts and difficulties surrounding, this dreaded pestilence have been cleared up. It was proved that the germs were carried in railways, caravans and ships from Lx)wer Bengal in the delta of the Ganges to all parts of the world, although, this organism is, no doubt, present in every section of the globe. It does not, however, break out into epidemics like those occurring in Asia, except in very rare cases. The section of country men- tioned is the regular hot bed for the disease, and it is epidemic there frequently, owing, no doubt, to imperfect sanitary measures. The comma bacillus belongs to the class of spirilla, or curved bacteria, and usually occurs in slightly curved rods measuring from 1 At to 2 /A of an inch in length and about .5 /* of an inch ia thickness. It occurs sometimes in pairs, sometimes in the shape o£ letter S. Frequently they assume the shape of serpentine threads. The bacillus is identified by placing some of the substance on which they grow on the glass slide under the microscope and allowing a weak solution, methyl violet, to flow between the cover glass and slide, taking up the overflow by blotting paper. With an oil im- mersion lens of 1000 diameters they may be observed alive. They may be easily recognized by their vigorous movement and the stain from the color which they take up. They will grow and multiply rapidly on prepared meat broth kept at blood heat in an incubator, and in time grow larger and form spirilla. 28 BACTERIOLOGY IN CANNING. Chemical examination and analyses of this broth will show the presence of the ptomaine poisons mentioned at the beginning of this section. Babes found that at a temperature of blood heat, the bacillus would grow on various kinds of meat, on eggs, vegetables and moistened bread, on cheese, coffee, chocolate and fluid sugars, but only feebly on acid fluids or vegetables, on mustard, onions, wine, beer or distilled water. Wherever there is a large quantity of organic matters, as at the margin of stagnant water, they would thrive. Milk is one of the most dangerous agencies for the growth of the bacilli, and has caused the death of many persons who have used it. The comma bacillus is an aerobic organism, but does not cease to multiply if the supply of oxygen is cut off, but may under this condition be killed readily by germicidal agencies, while in the aerobic state they are very resistant to such agencies. But when the supply of oxygen is cut off it produces a much larger proportion of toxic poisons than when oxygen is present, on account of the necessity of acting on a much larger quantity of albuminous mat- ter in order to get the oxygen necessary to its reproduction. One fact relating to this organism, as well as all other organ- isms we have been considering, is that freezing does not kill them as they seem to pass through a dormant state, and will develop on a suitable medium at favorable temperatures. One experiment by Koch on these bacilli at — lo^ C. did not kill them, and they de- veloped rapidly when placed in favorable conditions. The early ob- servations on ptomaines and sepsines, Pasteur's and Hansen's later observations, led to a search for finding the poisonous properties, or rather results of the action of comma bacilli. Koch prepared cultures of these organisms which were very poisonous, and when given to animals in any way caused their death — "paralytic weak- ness of the lower extremities, coldness of head and legs and pro- longed respiration, leading to death." Pouchet and Villiers were able to obtain substances from the action of the comma bacilli on the dejecta and organs of cholera patients which were characteristic of the organism. Pouchet used chloroform and extracted an extremely toxic poison in the nature of an oily fluid which changed colors in the presence of light and air. His substance gave the characteristic reaction of the alkaloid, the blue reduction color with ferrocyanide and perchloride of iron. Villiers also separated an alkaloid from the dejecta of a cholera patient which, when treated with muriatic acid, formed crvstals, which, when chemically combined with other com- UNIVERSITY CALIFOBii^ Figure 17. MAGNIFIED X 1000. TYPHOID BACItLT IN CI^USTER FOUND IN A GI.AND IN THE INTESTINES. • FROM REAI, MICROSCOPIC VIEW. BACTERIOLOGY IN CANNING. 29 pounds, produced a caustic local action and muscular troubles and an irregular heart action, and finally death. Brieger was able to find several poisons, especially from cultures of the bacillus which were old, which were choline, cadaverine and putrescine. He went into these researches very far; he obtained a toxic poison which, when, injected into animals, produced muscular tremors, cramps and death. He named this new product methyl-guanidine. He also sepa- rated two other toxines characteristic of the cholera bacillus. All these experiments were made with pure cultures of the comma bacillus, and the toxines found were, of course, in much larger pro- portions than when found in natural growths on suitable media- Experiments with these natural growths, however, give practically the same results, proving that the comma bacillus is capable of producing the most deadly ptomaines. One peculiar feature in the study of this deadly organism is that it does not exert a rapid fermentation where other common ferments and non-pathogenic putrefactive organisms, have obtained a hold. Indeed, we can state that these other forms would isolate the comma bacillus and cause it to perish, because certain acids would be produced by their action which would act as antiseptics, to it, and this is true where almost all other pathogenic forms ap- pear outside of the body. Once in a while, however, under favorable conditions, it happens that the cholera germ will begin action first and produce a ptomaine before other common forms would get a hold on the product. In this case, should the substance happen to be a food product of an albuminous nature and taken into the stom- ach at any time after the organism had produced the toxic alkaloid, serious muscular tremors and cramps would result, perhaps ending- in death. TYPHOID BACILLUS. The typhoid fever germ when growing in meat broth and albu- minoids produces a ptomaine which has been isolated by Brieger and called typhotoxin, and it is on this account that .we take up the study of this organism. The bacilli are short, thick rods from Ts-^jijf to TsUs of an inch in length and about one-fourth of their length in thickness. They have slightly rounded ends, and the pro- toplasm is susceptible to color by aniline dyes. They also may be stained by allowing them to stand in a solution of oxalic acid, and after washing will take a methyl blue color. The typhoid germ is found in the kidneys, spleen and intestines of fever patients, in colo- nies or clusters widely separated, which sometimes makes then* JO BACTERIOLOGY IN CANNING. difficult to locate. Cultivated they assume a thread-like appearance, with flagella, which gives them a wavy motion. The germ is able .to flourish in either an aerobic or anaerobic state, exhibiting the same peculiarities as the comma bacilli, in that, when growing in the presence of oxygen they are very resistant to the action of germicides and heat, and produce less toxic poison than when grow- ing in an anaerobic state, requiring the decomposition of more albuminous substance to obtain enough oxygen for their multi- plication. The typhoid bacilli grows rapidly on potato, where they assume typical forms, because the potato is slightly acid, which is a neces- :sary characteristic for their propagation. Unlike many other forms, this germ seems to form an acid poison instead of an alkaloid poison. It develops rapidly in milk .and also in water containing decaying albuminous matter. When cultures of this bacillus were given to animals in food they soon^ died, but was found that the bacteria need not be alive to cause •death. Any substance which had been exposed to their action would also cause death when reaching the intestines, and the cause was traced to toxic and ptomaine poisoning which Brieger proved wrere present in the substances. These organisms are visibly afifected by light and grow htst in dark or shady places. Rays of sunlight or chemical rays are very injurious to their development. This is true of nearly all pathogenic forms, and it would seem to indicate that the rays of light seem to shoot them, to use a military term, and it is hoped that the development and improvement of the X-rays will begin to -open up a new method of destroying these dreadful enemies of man. It is a dreadful thing to contemplate, that there are organisms so minutely formed which can find their way into the body and use the tissue to build up poisons so fatal. We can now see that it is not •so much the germ itself which causes the death of man as it is the poison deposited by the germ deep in the tissue which paralyzes •the muscles^and stops the heart from beating. These organisms also build up the same poisons in the very food we eat when proper conditions present themselves, and were it not for the fact that man is fortified against them, by counteract- ing influences and secretions of the body, we would all fall victims one by one to their deadly action. Nor can we say that we will escape finally, but so long as we know the enemies and can take proper precautions against them, by removing from our midst those decaying things on which they grow, eat and drink pure Figure 18. MAGNIFIED X 1000. TETANUS BACII.I.I. BACTERIOLOGY IN CANNING. 31 food and water, observing every sanitary rule, we can at least keep the enemy in check until age has weakened our energies and we finally have to face the inevitable. Like the plant and the beast, nature will claim us all, our bodies will form the food for this in- significant germ and we will pass away to be dissolved again into elementary forms. What a study it is then, this science of bacteriology. It opens up a new world to us and we are permitted to gaze upon it and behold the scheme of nature giving us object lessons day by day in the tearing down and building up process. Life begetting new life, and new life flourishes on the dead. Seed developing into form, form producing seed, decay of form, and development of seed. This is true of the germ and also of every living thing. TETANUS. The tetanus bacillus produces specific poisons which have been found and isolated, viz : tetanine, tetanotoxin and two other alkaloids resembling strychnine. Tetanus is an infective disease, a wound fever, and known as lockjaw, and is produced by a micro-organism which fincjs its way into a wound and sets up a muscular disease by producing poison- ous alkaloids. This organism is found in the pus of the abscess and in the surrounding tissue. It is a thread shape bacillus with slightly rounded ends. The spores are formed at the end of a short rod and develop at blood temperature after thirty hours. When the spores form on these short rods, which are motile, the bacillus resembles a drum stick. It is a strongly anaerobic organism, as the presence of oxygen interferes with its development, and this fact has made it a difficult matter to obtain pure cultures. Cultivations are made, however, in an atmosphere of hydrogen. Brieger, to whom we owe much of our knowledge of the tox- ines and ptomaines, which are the poisonous alkaloids produced by the pathogenic organisms, found the poisons peculiar to this germ, which he describes as tetanine and tetanotoxin. From the fact that this is an anaerobic organism it is surprising on first thought how it could gain a hold in a wound where oxygen, of course, is present, but when the spores of this organism find a lodg- ment in a wound, where proper precautions have not been taken, the pus and blood corpuscles soon cover them and cut off the oxygen of the air. Here then the conditions are favorable for the development of the tetanus bacillus. Tetanus bacilli, or more properly their spores, are very common and are found everywhere, 32 BACTERIOLOGY IN CANNING. in the soil and around horses, particularly. They seem to be found more numerously around stables, in manure and the soil which has been manured. Vaillard and Vincent made careful observations of the results of the tetanus bacillus, and having separated the poison, found that it acted very similar to snake poison. They found that the bacilli did not produce poison only after acting for quite a time. In the presence of other organisms of putrefactive nature, such as lactic acid bacilli and prodigiosi, they produce the poison much more quickly. This peculiarity of the organism is a striking contrast to the other forms we have been considering, because the acids of the common putrefactive organisms usually have a germi- cidal action on pathogenic forms. Even small quantities of this poison if present in any food will set up the most terrible muscu- lar tremors and cramps, followed by sure death, as there is no known antidote. It is a peculiar fact, however, that we are fortified to some extent against this; organism before the poison is formed in the wound; the blood corpuscles in healthy tissue generally de- stroy it. This organism then is dangerous to man if it happens to find a lodgment in any food product, especially in canned meats and goods of an albuminous nature, where the packages are sealed hermetically, producing anaerobic condition so favorable for its reproduction, and also from the fact that it is able to produce ptomaines more rapidly when acting along with other putrefactive micro-organisms. Stanley in his travels through Africa gives a bit of peculiar and interesting information which we can readily trace to the action of this organism. He found that the savages in certain sections poisoned their arrow points by covering them first with a nutrient juice of a tree, then taking them to a place where drainage had accumulated decomposing substances, they stuck them in the soil,, allowing them to remain for a considerable time. These arrows would set up the most violent muscular contractions, followed by lockjaw and death whenever they found a lodgment in the flesh of their enemies. This poison was, no doubt, caused by the formation of an alkaloid poison by the tetanus bacilli. We are of the opinion that poisons in food products from this peculiar organism do not generally occur in foods that are exposed to the air, but only in hermetically sealed packages. We frequently hear of some one being poisoned, sometimes whole families stricken after having eaten certain kinds of canned meats, and we feel as- sured that this organism produces some of the poisons which cause these complications. It is likely that its action takes place after llBRA^ OF TH ^NIVBKSXTY £tCAUFQ5 :^> oooi X il'iiDva HHl^idHol-saaiH •oooi X aaiaiNOYH •6i 3an3i,.i BACTERIOLOGY IN CANNING. 33 the can has been sealed, before the final sterilizing process, which destroys their life, but not the product of that life. This trouble is due to carelessness, the result of ignorance of the deadly nature of these organisms, and this carelessness is the allowing of too much goods to pile up ahead of the final process. KI^EBS-I^O^FFI^KR. BAC1I,I,US— DIPHTHERIA. The diphtheria, or Klebs-Loefifler bacillus, when growing on suitable media, produces a most virulent ptomaine, which Brieger isolated and used in various experiments upon animals, which caused a poisoning similar to septic, phosphorous and metallic poison. On this account, many cases of poisoning from eating sub- stances like ice cream and certain kinds of meat, fish, etc.. (which were due to a ptomaine, where the action resembled metallic poison- ing), were at first thought to come from the metal packages which contained the foods. As a matter of fact, however, the agent was a bacillus similar, if not identical with the Klebs-Loeffier bacillus. The suspected metals are not so poisonous as many persons im- agine, as they are found in many vegetables. Copper is found in the tomato in some sections, and other vegetables contain metals also. One eminent authority has gone so far as to state that the system is not affected by the presence of metals in small quantities in food products. The poison that does cause the trouble in these food products is an alkaloid produced by micro-organisms, such as the diphtheria bacillus. That this organism produces a most viru- lent poison is undisputed from the fact that the fatality from the specific disease is very great. As has been stated in former pages the chances of these pathogenic forms, for acting on food products, are very rare in comparison to the action of common ferments, but occasionally they get a start, and when they do, we are informed of the fact by the terrible consequences produced on the innocent victims. It is only as a word of warning to packers and preservers that we have taken up this subject, to point out where the danger exists, and to make a few suggestions, which may by careful ob- servation, preclude the possibiHty of these cases of poisoning in the canning business, where even a few cases of this kind causes op- position and prejudice against canned goods generally. Whenever a case of this kind occurs it hurts the entire business, and we must take unusual precautions to guard against them. But to return to our sul)]ect, the Klebs-Loefifler bacilli are rods from 3 fi to 6 fi of an inch in length, slightly swollen at one or both ends, and are colored easily with methyl blue, or by Gram's gentian violet method. 34 BACTERIOLOGY IN CANNING. It is recognized from other bacilli, which may be present, by the deep stain which it takes in contrast to the lighter stains taken by other forms. It is a difficult organism to cultivate in a pure form, as other putrefactive ferments get started first and overgrow the media. It thrives at a very high temperature, and the spore forms will live in the air and on the clothing for a long time. It produces an alkaline poison which loses toxic properties when made acid, and gains back the properties when made alkaline again. Milk is susceptible to the action of this germ, also any food of an albumin- ous nature, but the toxic power is lost in the presence of the com- mon ferments, which nearly always gain a foothold first and pro- duce their acids, which have a tendency to neutralize the ptomaine which it produces. It must not be understood that the varieties we have men- tioned in the foregoing sketches of pathogenic organisms include all the kinds that produce ptomaines. It is undoubtedly true of many others, among which we might mention the anthrax bacilli and organisms which cause septicaemia, but the products of all these forms are very similar in their action, producing severe muscular contractions, cramps, paralysis and death. By studying their nature we may to some extent understand the Ufe history of these forms and the poisons which they create by their action on food pro- ducts. It is this knowledge which will enable us to pack and pre- serve food products and eliminate these forms so that no poisons will be deposited in them. It is a very fortunate thing that their action is confined to food products of an albuminous nature, as this represents only a small proportion of our business. The greater number of packers and preservers confine their preserving to vegetables and fruits, while the greater bulk of albuminous pro- ducts are packed by comparatively few canners. We refer here to packers of beef, fish, oysters, lobsters and soups, and it is to these packers that the history of the ptomaines as here detailed should be very interesting and instructive. The greatest danger in all these varieties comes in warm weather, when the thermometer ranges about blood heat. These products when exposed for only a very short time to the atmosphere offer the most suitable medium for the propagation of putrefactive ferments of all kinds, including, of course, the pathogenic organisms. It is a peculiar fact that the most favorable time for these organisms to gain a foothold is after the first cooking, because it so rapidly develops the spores, or dried- up forms which may find a lodgment there. The heat, of course, is the reason for this and the anaerobic forms will develop rapidly BACTERIOLOGY IN CANNING. 35 after the cans are sealed if they be not taken immediately to the final process for sterilization. Once more we must sound the warn- ing that all goods, whether vegetable or albuminous in character, should find their way immediately to the retorts after the first heating. Here is where the greatest trouble to all packers occurs; something breaks down about the machinery and the consequence is that many dozens of cans will pile up which have within them the spores of germs deposited from the air or perhaps dinging to the product from the beginning. At so favorable a temperature for the development of these spores, a delay for only a short time is in- imical to the quality. Fermentation begins to set in almost im- mediately, and the most wonderful growths of bacterial forms can take place in a very short time, which will change the very nature of the goods, producing new chemical combinations and some- times very poisonous combinations, as we have seen. We do not pretend to say that this is the only place where ptomaines could be formed in the albuminous products, but it is one of the most dan- gerous places. A great deal depends on the management, that when breakdowns occur, other means of taking care of the goods should be provided at once. It is not policy to limit a business to the exact number of machines necessary to do the work when everything runs smoothly, but to be prepared for emergencies of this kind, which always happen, even in the best managed business, by hav- ing one or two extra machines which can be utilized at such times. We can see where great dangers from ptomaine poisoning might present themselves at earlier stages in the canning process. The canner should be provided with experienced and cautious men, and by that I mean men who have studied up on the subject which we are here presenting. The diseases peculiar to the animals and fish, the meats of which are canned, may deposit ptomaines in the living tissue, as we often read of as occurring in cattle, fowls, pork, etc. The Government understands the full gravity of this question by having inspectors for all meats appointed in different cities. If diseased animals should be slaughtered and the meat of those animals find its way into cans, the possibility of ptomaine poisoning among the consumers of such goods would be great. To the per- sonal knowledge of the writer, schemes have been imposed on the inspectors and meat has been canned which was wholly unfit for food purposes. This was done simply with the one idea to save the cost of the meat, while probably the fearful results were never suspected. Packers who are engaged in canning products of an albuminous nature should be very careful that they are entirely 36 BACTERIOIvOGY IN CANNING. free from anything that would resemble disease in any form. No amount of cooking or pickling will counteract the effect of this poison, it remains because it is a new chemical compound, an alka- loid or an acid. We see the effect of this poison by frequent ac- counts of persons who have eaten smoked fish, mainly halibut and sturgeon, and also fresh sausage which have become poisoned by pathogenic micro-organisms. This subject of ptomaine poisoning is a very recent discovery, and its full import has not been felt until within the last few years, owing, perhaps, to the large increase in the mortaHty of persons using products sealed in hermetical packages. The number of deaths has increased in proportion to the increased packing of goods of this character, and it is with the hope of reducing this mortality that these researches have been given in such minute detail. CHAPTER VI. FERMKNTATION. OBJECT OF STUDY IS TO PREVENT. AI,COHOI,IC FERMENTATION AND THE GERMS WHICH CAUSE IT. PUTRE- FACTION. DISEASE FERMENTATION. PRODUCTS OF FER- MDNTATION. DESCRIPTIVE EXAMPI.ES. ENZYMES. I.ACTIC FERMENTATION. BENEFITS TO PI.ANT AND ANIMAI. JJFE. FERMENTATION DE- FINED IN A BROAD SENSE. In order to understand definitely the action of micro-organ- isms, their Hfe history, functions and products, we must take up the subject of fermentation, not with the same object, however, as brewers and wine makers, but with a view of counteracting the process. The canning and preserving industries are established for the sole purpose of keeping food products Jn a perfectly sterile and healthful condition for food purposes. Alcoholic fermentation' is the kind which is set up by the saccharomyces or yeast plants, of which there are a great variety, but only a few kinds are used in the brewing business, mainly those which produce the greatest amount of alcohol. Then there is the putrefactive fermentation,, caused by various kinds of organisms, chiefly of a lower form than the saccharomyces, and it is their organisms which reduce the de- composing animal and vegetable matter into elementary forms. Then there is the disease fermentation which is set up in the living tissues of man and animals by the pathogenic organisms, and they deposit poisons which produce various diseases and death. BACTERIOLOGY IN CANNING. 37 Taken as a whole, fermentation is the breaking down process, a reduction of the higher forms of Ufe to elementary forms. When^ a fermentable substance is exposed to the atmosphere it is seized upon immediately by various organisms. These are deposited in ' had not expe- rienced so much trouble as Duckwall had encountered in the West, but were able to keep a large per cent, of their cans after five hours' boiling, which process was not successful in the West. The few manufacturers in Maine at that time suddenly had a very rough experience in 1878, when the entire output spoiled, nor were they ever afterwards able to sterilize their cans by the boiling process. Capital had been invested, and the business had been growing rap- idly before, and now everything seemed to be lost. New locations were tried, longer times of boiling were given, but without avail; the corn seemed to have changed into a new product which would not keep. Some manufacturers sent samples to chemists for analy- sis to find out what caused the trouble, but the real cause not being known, they could not give the manufacturers any information of practical value, except that the spoiled corn contained small round globules which were not dissolved by boiUng heat. In the Hght of modern research we cannot but give these chemists due praise, from the fact that Pasteur's germ theory was not generally known at that time and had few believers, even among scientists in Europe, so the reports of the chemists were remarkable from the fact that they were able at all to locate the probable cause. In 1879 a certain manufacturer in Massachusetts adopted a new process. He first boiled the cans, then punctured the cans and finally gave them a cooking for one hour in steam retorts or process kettles at 240° F. This process proved satisfactory for a long time, with only occasional spoilage, due to carelessness in manufacture. We must remember that the manufacturers at this time had no conception of the real cause of the trouble in keeping the corn, but looked upon the matter as a mystery, and whenever a processor found a method of heating the goods in any particular way, by 74 BACTERIOLOGY IN CANNING. which he was more successful than others, he was looked upon as possessing secrets, or information on the subject of keeping goods, and these secrets he tried to conceal with a great deal of mystery. He watched the time of his processes with great exactness, and believed that one minute more or less would cause spoilage. The processors were in great demand, not on account of the actual knowledge they possessed, but on account of what knowledge they seemed to possess. These men had no true knowledge of their busi- ness, and very few of them, even to-day, possess that knowledge, but depend largely upon what they have been told, or upon expe- rience. Experience is a good teacher so long as no new complica- tions occur, but it has been demonstrated from the beginning of the business that these new complications are constantly arising, and old methods of sterilizing are not successful now. The time is now at hand when manufacturers see the folly of depending upon mysteri- ous rules for keeping their goods, and the advanced education in science is letting a flood of light in on the causes of spoilage in the canning and preserving industries. Manufacturers want to know the reasons for processing goods certain lengths of time, and the necessities required for obtaining the best quality, and the rule of thumb does not satisfy them. The time is fast approaching when the demand will be made for men with a scientific as well as a practical knowledge on this subject, so that it now becomes a neces- sity for processors and managers to take up the study of the science of bacteriology and apply that science to their work. The study of this science is a difficult one, because it is a complicated study and so comprehensive that it usually requires the rudiments of a higher education to enable the student to get the full value and meaning of what he reads and sees under the microscope. Then again, there are so many branches of the study that would not have a direct bearing upon this line of business, so that it would require a great deal of study in all directions to enable the student to pick out the points which would be advantageous to this business. These points have been gathered, and the observations made are of par- ticular value, both to the manufacturer and the men who manage the work, and any one who does not desire to make a comprehensive study of this science will find that th^ main points have been pretty well covered in this work. A's, there is a general lack of knowledge on this subject among canners, and a great deal of misrepresentation by certain classes of men who are doing the work of managing and processing, and as there is a great misunderstanding of the principles and char- BACTERIOLOGY IN CANNING. 75 acteristics of bacterial action, this work will be instructive, first to the manufacturer who wishes to become more thoroughly- acquainted with his business; secondly, to the managers and pro- cessors, who will do their work with a definite understanding, and the result will be that we shall have purer, cleaner and more whole- some goods than ever before, and this result accomplished with less loss from spoilage. CHAPTER XII METHODS OF CANNING. The canning of sugar corn is one of the largest industries in the canning business, and the consumption of this one line alone amoimts to more than 30,000 dozen daily, and within the last few years there has been great advancement in methods and cleanliness of carrying on the business, due in a measure to improved machinery for doing the work. The varieties of corn now canned are the "Evergreen" and "F.g\'ptian," which seem to be the favorite seed, because these varie- ties grow well and produce a good yield. Good sound seed are nec- essary to get a good yield and great care should be taken in the selection. Planting should begin as soon as the frost is out of the ground, and in order to get a longer season the planting should be made at intervals for six weeks following, but not later, as the yield is not good. Corn requires good rich ground, properly fer- tilized with bone dust or black manure, in order to get a well-devel-* oped ear and a good yield, and the weeds should be kept down and the soil worked to get good stout stalks. When it comes time to pull the ears, this should be done in the early morning before the sun beats down upon the com, the effect of which is to drive the sugar into the cob. No corn should be car- ried overnight to give a start in the morning, but it is the custom among many canners to do so. It is usually worked up as speedily as possible after it arrives at the factory, and the husking and sort- ing the good sound ears from the worm-eaten ears is the first oper- ation. The unsound ears are trimmed and then the com is passed into the cutting machines, which do the work quickly and better than hand cutters. There are two methods of packing corn, and we will describe both methods, and the cutting machine will prepare the corn for either method, by simply adjusting the knives. 76 BACTERIOLOGY IN CANNING. MOIST PACK. In this method the cutting of the com from the cob resembles the hand cutting, as the whole kernels are removed as nearly whole as possible by the knives at first cutting, leaving very little scraping. After the corn is cut it is passes through a wire-screened machine called a "silker," which removes nearly all silk from the mass. After the silking process the corn is filled into the cans cold, so that the can will cut open full after it is processed. This requires some judgment, because it requires more corn when young than when it is a little old. It is needless to say that the young corn is preferable. Care should be taken not to fill the cans too full of the cold com, as it swells out considerably in the cooking process. The cans are then filled with a weak brine, cleaned and capped, but not tipped. The next process is the "exhaust." The process con- sists in immersing the cans in boiling water, which drives out the air and heats the corn. After exhausting, cans are then tipped and delivered to the steam retorts or process kettles, which are fitted with steam gauges and thermometers, and in these tanks they are given either a steam or a water process under pressure to obtain a higher temperature than boiling. The amount of heat varies with different canners. After this process the cans are taken out and chilled in tubs or tanks filled with cold water, which stops the cook- ing process now going on within the can. This chilling process keeps the corn from tuming dark or scorching. DRY PACK. This method of canning corn is very popular in Maine, and costs more than the other method, but the quality of the pack is better. The knives in the cutting machine are set so that the ker- nels are merely cut in the middle and the remainder is scraped off the cob by the scrapers adjusted in the machine. This part makes a pulp of the corn that is scraped off. After passing through the silker the corn is placed in a "corn cooker," of which there are sev- eral very good ones in general use. Here the grains and pulp are cooked and filled into the cans hot in a very cleanly manner without any slopping. After the cans are filled they are capped and tipped at once, and they are then put into crates and delivered to the steam retorts for the sterilizing process, and the treatment there and after- wards is precisely the same as with the "moist pack." This method, while more expensive, produces a superior qual- ity of corn, and the cans are more solidly packed. Canners cut BACTERIOI.OGY IN CANNING. 77 open some of their goods each day to ascertain if the cans are prop- erly filled and not darkened by carelessness in the final process. WHITENESS. The demands of the trade have been for the canner to produce a whiter color in his com, and so urgent were the demands that the corn which cut open a few shades darker than other brands could not command as high a price. The result has proved very disas- trous to the canner. In order to get his corn as white as possible he shortened his time in the sterilizing process, and in some cases he even reduced the temperature. The consequence was that spoiled corn was prevalent everywhere. Many canners employed chemicals to bleach the corn, commonly sulphite of sodium, which produced the desired color and greatly injured the flavor. The shortening of the process and the lowering of the temperature endan- gered the goods, and the sterilization was accomplished by the use of germicides, such as salicylic acid. Here a new difficulty arose, from the fact that in the presence of iron this antiseptic would show its presence by turning violet or purple in color, and many are the packers who wondered why their corn turned purple. The exposed edges of the tin would furnish enough iron to cause the reaction in the presence of salicylic acid. Other germicides are also used, such as formic aldehyde, benzoic acid, benzoate of sodium, etc., etc., with the effect that while the goods might keep for a long time, yet the germs might not all be killed, and in the course of time would develop, causing the swelling months after ; and in the next place, the flavor was more or less injured by the use of such reagents. Thus a great deal of poor corn flooded the market and injured the trade to the extent that few persons cared to run the risk of buying the article at all. The prices on com fell rapidly, and it could be bought for almost any figure to get rid of it. There were many packers, however, who did not allow the popular clamor for extreme whiteness to influence their better judgment, so they con- tinued in the old way, putting up the article with a view of obtaining the best quality and giving the matter of whiteness only the proper amount of care, which can be exercised in the best methods of can- ning com. It is to these packers that the industry is once more on a proper relation with the trade, and the cry for quality became so strong that the use of bleachers and other reagents is rapidly coming into disfavor, even among former advocates. 78 BACTERIOLOGY IN CANNING. SPOILAGE IN CORN. The two methods for canning corn described a few pages back seem to read all right, but these are now in use and in certain locali- ties the canners have been suffering severe losses, both from ''swells" and "sour corn," and ih order to study the causes and nature of these troubles, let us first understand just what is meant by the terms ^'swells" and "sour corn." SWELLS AND SOUR CORN. Swells are the results of pressure made from within the cans by various gases, such as carbonic acid gas, hydrogen, sulphuretted hydrogen, etc., and in the most of cases the cans are sour, although in several instances I have seen sweU.s in which there was no sour- ness produced ; however, these are exceptional and occur only where the fermentation was set up by the alcoholic ferments, such as the saccharomyces, cerevisiae and ellipsoideus, etc. In these swells the odor of alcohol was quite perceptible. These gases, which cause the swelling or bulging out of the ends of the cans, are the evidence of fermentation which is set up sometimes by a single variety of bacteria, but more often by quite a number of different varieties, such as the prodigiosi, amylobacter, butyrici, etc., which are found swarming in the anaerobic state within the can. The presence of these bacterial forms may be explained in this way : Either there is a small leak in the can, or else the sterilizing process was inadequate to kill off the spores which developed afterwards. Sometimes, where the leak is very large, the cans may not show by bulging out the ends, in which case the escaping fluids will be seen oozing from the hole through which the gases are also making their escape. If swells occur from leaks, there need be no alarm, but if a single can is found which swells without the presence of a leak, there is a rea- sonable doubt about the goods being properly sterilized. Often there has considerable time elapsed before swells make their appear- ance, in which case it is evident that the goods were nearly, though not perfectly, sterilized. If only a single spore remains alive, it may develop sooner or later, and if it does, the can will soon swarm with its kind. It thus happens sometimes that goods will appear all right for quite a time, and then after being agitated will swell. In this case it is a fact that some forms have not been killed and have been lying in a dormant condition, perhaps on the surface of the contents, so that when the can is agitated and the spore is sub- merged, the fermentation will be certain as a result of its develop- OF THE ^J UNIVERSITY . :^ Figure 20 MAGNIFIED X 1000. MOIyD FUNGI. MONILIO CANDIDA AND ASPERGII.I.US GROWING WHEN SUB- MERGED IN CORN JUICE. DEVEI.OPMENT OE BUDS FROM CONIDIA. BACTERIOLOGY IN CANNING. 79 ment. This frequently happens when the conidia of mold find a lodgment and are not killed by the heat. We have seen the house- wife fill the fruit cans and seal them hot, and after a time have seen the mold grow on the surface, especially if the package happened to be glass. So long as the cans so filled remained in a quiet state, the contents would be perfectly sweet, but just as soon as the can was shaken sufficiently to submerge the mold film, fermentation and spoilage would result, because the mold would break up the sugar to obtain oxygen for its development, and thus resemble an alcoholic ferment. Thus we see that goods do not necessarily swell in a short time after the final process, but it is usually the case if the final process does not sterilize the contents perfectly. Whenever the process is shortened and antiseptics are used, unless they be used in liberal quantities, there is danger of fermentation and swells in some future time. If the heating does not kill the germs and the reliance is placed upon the antiseptic, unless that antiseptic is very powerful, the spores are not killed. The effect of the chemical is a reaction on the oxygen which makes it unfit for the development of those spores. After a tiipe, however, there may be a loss of power in the chemical, in which case the dormant spore will develop and the swelling of the can will result "Sour corn" is a term often misused, but its real meaning is that the corn within a can, which has all the appearance of being good on the outside, is found on opening to be sour and nauseating to the taste. Cans of sour corn will never under any circumstances swell, otherwise they would come under the heading of swells. I have opened hundreds of cans of sour corn and placed the juice under the microscope to see if there was any bacterial life. I have located the dead germs, but when transplanted to nutrient media I have never been convinced that any Hfe existed, and when growth did appear, I was convinced after hundreds of experiments that they came from the air, and that the germs found in sour corn were dead. I found that some cans which did not show a swelled appearance at the time did contain various living forms, but when these cans were put in an incubator they would swell. The accom- panying plate will show one view that I obtained from a can of this kind of corn. This example comes under the head of swells, and is not sour corn, properly so-called. This is, of course, a view somewhat at variance with that recently given out by men who claim to have studied the subject, but their errors were made by not making a proper distinction between swells and sour corn. 8o BACTERIOLOGY IN CANNING. Sour corn, then, is a trouble which we must locate in another part of the process of canning. It could not be due to any imper- fection in the final process of sterilization, for in that case we could be able to induce a violent fermentation by incubation. But in the case of sour corn incubation has no effect. One thing may be observed at this point, however, and that is, that when these sour cans are placed in warm water they will bulge out slightly, but on cooling will draw in again. In order to explain this phenomenon we will undertake to locate the place where the souring occurred. You will bear in mind that the canners who have been losers from this trouble complain that a certain portion only of their pack sufifered in this way. Some say, "I lost about lo per cent, of my pack ;" others say, "One quarter of my pack soured and the balance was good." These strange phenomena seem to throw a shroud of mystery around the trouble, but the strangeness of it all dis- appears when the light of understanding is turned on the causes. The cause of sour corn is fermentation which takes place before the final process or sterilizing process. I want to impress this thought upon my readers, and the reasons for the statement. If the corn is not perfectly heated in the cooker and completely used out of it, so that none will remain at blood temperature in the cooker for any length of time, and if the cans are not quickly capped, tipped and taken to the final process, there is danger of sour corn. I have examined corn which came from the cooker in a house that was having trouble with sour corn, and I found that the corn was some- times allowed to stand in the cooker for quite a while, waiting on the filling; that when the filling of the cans was going on faster than the capping facilities, some of this corn proved to be in active fermen- tation when being filled into the cans. I found also the same thing going on in the cans which sometimes accumulated ahead of the capping machines. The firm which was having the trouble had their capping machines get out of order frequently, and when this would happen the com would get sour in the can, so that when it was sealed it enclosed an active fermentation and much gas. The presence of this gas will explain why the ends bulged out when the cans were afterwards placed in warm water. After the process the corn absorbed the gases which were sealed up in the can, and when heat was applied again these gases expanded, but in a short time would be absorbed again on cooling. All this can be readily seen and understood if the juice is examined under different condi- tions with the microscope, using a lens of looo diameters. This study of sour corn under the microscope is very interest- THE I.ARGE GERMS ARE SACCHAROMYCES. THE SMALLER CELLS ARE MVCODERMA VINI SUBMERGED. ft* — - V*. ^' ,.: ^ » .* . • '-• - "-"C ■ 1 * ' !>•• -4* Mo' X "' ^^ -^y ■ ^ ;V. v? -I'l - " '■■ *\ .0 . *. - -•^ ,>»o •. «*> '^si - » :i ' VoV -^'S: .... .... b»o 00 •. _ • K' '"^ ♦> oCP» »?o • "V '^ "Xo Oo» •%/ o o o\,o» ■ \ 7 Figure 21. MAGNIFIED X 1000. THE CLUSTERS ARE AMYLOBACTER AND LACTIC MICROCOCCI THE SMALL RED DUMBELL MICROCOCCI ARE BLEEDING BRAST CALLED PRODI- GIOSI. THE INTERIOR OF THE SACCHAROMYCES REPRESENTS THE SPORES IMBEDED IN THE PROTO- PLASM. CHAINS ARE MYCO- DERMA ACETI. BACTERIOLOGY IN CANNING. ing, as the various ferments described in the former part of this work, viz: Prodigiosus, butyricus, lactic bacillus, amylobacter, mold, yeasts or saccharomyces, and an infinite number of various other forms which we have not classified nor described, are seen, and we can become familiar with their destructive power. STERILIZATION. In order to determine just what degree of heat would be neces- sary to kill all the bacteria in a can, I subjected numbers of cans to various temperatures and these experiments were made both with corn in the regular canning — that is, just after it came from the cooker — and also with cans which I inoculated with various ferments and molds. These experiments are very interesting and will give the experimenter a splendid idea of the requirements necessary to keep corn. The following diagram will give some idea of what occurred with each experiment : Can Corn Time of Boiling Result Time Tem. 3 cans 3 •• I '' 6 " 6 " 6 '• 6 " 6 " 1 hour 2 hours o 4 i; ft " 7 " 8 " 9 " lO " All spoiled <( (< II II II II 4 •• 2 kept 11 erceptible discoloration. The scorching is caused by the tin being struck with cold air, and energy thus set free scorches the corn. Ice is always coldest when melting ; metal is always hottest when cooling, especially when cold air strikes it. The blacksmith will tell you how much easier it is to get burned by iron which is chilling in the air than by a very white heat. One sticks to the flesh and the other repels it. A PERFECT STERIW^ING PROCESS. From what we have studied on the subject there are two or three very important conclusions we can draw with reference to the very resistant forms of bacteria and the method of killing these forms without injuring the quality of the goods to be processed. We know of at least one form that we cannot kill at 250° F., and for all we can tell there may be others. I am speaking now of the spores or undeveloped seeds, and dried-up forms which have not begun to vegetate. We have seen that when Winslow began his experiments he was able to sterilize corn at the boiling tempera- ture when he applied that temperature for four or five hours. For some unaccountable reason to us none of the resistant forms of bacteria seem to have troubled him; if they had the spores would certainly have been just as destructive to his corn as it is to ours. 86 BACTERIOLOGY IN CANNING. It may have been that these forms had not begun to attack sugar corn at that time, it having been cultivated' in this country only for a short time. It is likely that the putrefactive bacteria which at this date are so hard to kill had been growing and developing on vegetables and decomposing matter of an entirely different character, so that they had to habituate themselves to this new product. This is not an uncommon observation, taken of bacterial life, as we frequently see this phenomenon in cultures on prepared media, where certain organisms start very slowly on one kind of substance, and then reproductions will flourish much more rapidly than the parent germs, because they have adapted themselves to the particular composition of that substance. But to proceed : After the boiling process had failed, and packers were losing all the com they canned, a temperature of 240° F., with ten pounds steam pres- sure, was substituted and the time of cooking was reduced to about one hour. This process has been working successfully up to within the last ten or fifteen years, and in some localities is still successful, owing, perhaps, to latitudes where these organisms occur in smaller numbers in the atmosphere. But the fact is, this process has ceased to give general satisfaction, and a still higher temperature of 250^ F., fifteen pounds steam pressure for fifty-five minutes, is now declared to be a perfectly safe method of sterilization. Looking at this matter from a historical standpoint, we would not be surprised if the time would come when even this extraordinary heat would prove inefficient. As we know that the bacillus subtilis, which is common in infusions of hay undergoing fermentation, we would not be surprised if this organism should habituate itself in com. We must admit that if we should have to contend with the spores of this organism, whose proved resistance is over 300° F. that the heat we are now applying would have no effect whatever. I per- sonally have never experimented to find out just what temperature would be necessary to kill these spores, but we can rely on the evi- dence of so eminent a scientist as Professor Tyndall, who admitted his inability to kill them by continuous heat at 300^ F. for hours, not only in one experiment, but in hundreds. With this evidence before us we are inclined to think that Klein and others erred when they said that these spores could be killed by ten minutes' boiling at 120° C. This is not probably the only organism in the world which is so resistant to heat, and it is well for us to look ahead for a perfect sterilizing process, so that when the time comes when we are unable to keep goods by our present methods, we may have a perfectly reliable method to adopt. Nor do I think that we should wait until we are forced by losses, but we ought to begin. BACTERIOLOGY IN CANNING. 87 at once to experiment and devise practical ways of carrying on this jperfect system. We have been referring to the system discovered by Professor Tyndall, which is based on truly scientific principles and is called discontinuous heating. In order to understand this process and its effect on micro-organisms we must refer back to what we have studied on the vegetation of germs from spores. These small refrac- tile bodies that are called spores are surrounded by two coats or coverings which, like asbestos, in their power of resisting heat, preserve the life within, except when extraordinary temperatures are used to destroy it. For an example we would refer to the mus- tard seed, which, in its dry state, protects the life within through four minutes* boiling. When these spores are placed in a suitable nutrient medium they begin to soften and expand, and the coatings give away like the bursting of a grain of corn when it sprouts, and the life witEin the spore begins to expand and is soon surrounded with a soft protoplasm so delicate and sensitive as to perish when even an ordinary boiling temperature is used against it. Just like the sprout from the grain of corn, the developing bacillus is sensi- tive to the heat. It is during this vegetative period that we can overcome the action of bacteria easiest. If we boil our cans of com for a half hour the first time and chill them to 40^ or 50^ F., and keep them at this temperature for a few hours, many of the spores will begin to expand without causing any fermentation, so that if we heat them again for half an hour so as to allow the can to receive 212^ F. throughout its con- tents, all these developing spores will perish. After chilling and storing again, some more of the spores will develop, which will be killed in the next heating, and on the third or fourth heating they will have all perished, leaving the contents of the can sterile, and the corn will be almost as fresh as the green product and its white- ness never before equaled. To the practical canner this system of sterilizing would seem to be almost out of the question on account of the extra expense connected with it, but I will say that the extra expense may be entirely overbalanced by the prices such an article would bring on the market. As I stated before, the time may come when this system wilf be the only safe method of sterilization, and when that time does come, those packers who have studied this method and experimented along this line will get all the best trade and prices which will repay them for the extra expense. In order to carry on this work successfully, a cooHng system similar in many respects to that employed by brewers will have to 88 BACTERIOLOGY IN CANNING. be used — a number of cooling cdlars chilled with ammonia pipes to keep the temperature down to between 40^ F. and 50° F. If the number of boiling processes were four, of course three chill-rooms would be necessary, and also four sets of boiling or sterilizing tanks. It would also be necessary to have quite a large supply of cold water in order to chill the cans after each boiling process. When you think of corn being kept by the boiling process for a length of time not longer than two hours, and realize what fine flavor and white color it would possess, surely the experiment will be worth the while for those packers who are progressive and want to pro- duce the best quality. While speaking of quality, I want to say that the market never has enough really fine quality to supply its demands. It has a great deal more poor quality than it demands, and one case of poor corn is a worse drug on the market than ten cases of good com at higher prices. The American people demand a good quality, and if they cannot afford to pay the price, they buy poor goods which they do not relish, and consequently do not consume. It is a trait of the American people that they will have the best quality even if it costs a little more money. I believe our packers ought seriously to consfder this method and experiiment along this line, and thus be prepared for emergencies, which the history of this business demon- strates will surely come. Referring to the present methods of pack- ing corn, a few suggestions along the line of care would seem to be in order. As packers will no doubt proceed with the higher temperatures for the present, a few remarks on management will be beneficial. Corn should be pulled early in the morning of the day of de- livery, before the rays of the sun drive the sugar into the cob from the kernals. No corn should lay overnight in the sheds, as fer- mentation begins rapidly, and a great deal of the natural sugar is lost by standing. All cobs and waste should be removed from the vicinity of the buildings, so that the atmosphere may not become burdened more than ordinarily with the spores of bacteria, which would surely be developed on said cobs and waste. From the fact that sp>ores peculiar to the micro-organisms which feed on corn are present in the shocks and on the grains of com, it is a very neces- sary thing that after cutting the corn should be cooked as soon as possible to retard their action. After being cooked the corn should be filled into the cans hot and thus find their way to the final process as soon as possible to avoid sour corn, which disease occurs right at this point. The heating which the corn receives in the BACTERIOLOGY IN CANNING. 89 cooker destroys all, or nearly all, developed bacilli, but if there should be a lapse of twenty or thirty minutes, those forms that were not killed would create considerable acid by their action on the sugar. Now if the can should be sealed in this acid condition, the result would be sour com. I believe I have made this subject so clear that no doubt can hereafter exist as to the causes of this trouble. After rushing the cans to the final process the tempera- ture, with dry steam, should be gradually raised to 250° F., with only a little exhaust, but enough to insure perfect circulation. If for any reason there should happen to be five or six inches of water in the bottom, from a clogging of the exhaust or otherwise, the cans would not be perfectly sterilized, even though the thermometer should register 250° F. throughout the process. The circulation in this case would entirely be cut off from the bottom row, and for several rows of the cooking would be very imperfect and the swelling of these cans would be a certainty. The upper courses of cans would likely keep all right, from the circulation of steam due to the pet-cock under the thermometer exhausting though only slightly. The danger, however, to the whole lot would be very great if for any reason the exhaust at the bottom of the kettle should become clogged. I have mentioned this feature of processing be- cause I have seen the trouble happen, and the only remedy is to have a good, careful man in charge of this work, who would know from the actions of the kettle when anything of this nature occurs. After attaining a temperature of 250° F. with a liberal exhaust, the escape of steam maybe lessened by closing the exhaust all but about one turn, and the temperature regulated entirely by the steam valve for fifty-five minutes. When the time is up, turn off the steam and allow it to run down gradually to about 220° F.,when the cans should be immediately flooded with cold water before the lid is opened. An inch and a half water exhaust in the bottom must be opened at once and an overflow outlet near the top also. The diagram on the next page will also show how to operate these appliances. The water line runs along back of the kettles and should be a two-inch fine if possible. The connection to the kettle from this line should be made with a hose controlled by two valves, one at the top to prevent back pressure on the hose when the steam is on, and the other at the supply end. When the lid is raised the hose will bend, and this gives a direct connection of water through the lid for this purpose, viz : A spray, which is done by passing the pipe through the lid and then having an ell on this, then a short piece of pipe with an inverted ell, so as to throw the water against the lid, and thus spray the cans completely from the top. See 90 BACTERIOLOGY IN CANNING. diagram W. Keep the water running until it overflows from the overflow pipe, when the cans will, no doubt, be chilled sufficiently to prevent darkening in color. This chilling process is a most satis- factory and successful means of preserving the color of com which, under other circumstances, is darkened considerably when the cold air strikes the can on opening the kettle. The high temperature 0V£R FLOW RIPE EXHAUST does darken the corn just a little, but by using this chilling system a whiter corn will be obtained than by other methods where only 240° F. was used. CORN TURNING BLACK IN SPOT. This disease of corn has been the cause of much loss ta packers, and from the nature of the trouble considerable mystery is attached to it. Within the last few years packers have been puz~ zled to find, on opening cans of corn, black spots here and there among the grains. " Those who had been using chemicals for pre- serving the com, and bleaches to whiten it, naturally attributed the BACTERIOLOGY IN CANNING. 91 trouble to them, but when the same thing repeated itself when no chemical nor bleachers were used, the solution of the problem be- came very compHcated. Black spots are of two kinds, and the causes are two, viz : A bacterium called black torula, and the action of chemicals and tin. The first cause, black torulae, are bacteria of a black color and the product of their fermentation is black. The action of these ferments can often be s^en right in the corn field where the ear has become bruised and exposed to the air, when a dirty tar-black substance will be seen to cover the kernels. It is the same organism that sets up the black rot in tomatoes and fruits. If these germs find access to the com, they will form small colonies throughout the contents of the can and the spots will form if any delays occur between the cooker and the final process. The germs themselves are easily killed in the process, but their product will remain in the can. When the cause is due to the presence of these germs, the spots will be observed throughout the contents of the can and not alone around the outside edges. When the black spots have a purple tinge, they art due to the presence of salicylic acid which has had a reaction on the exposed edges of the tin. When the spots occur only next to the tin and are black, they rr^ay be accounted as coming from an action of the acid on the steel, due to a poor tin-plating. There are two processes of plating steel : one is a palm oil process, the other is an acid process, where the tin taken by the sheet which has been immersed in acid and then passed through rollers to squeeze the surplus tin off. Some mills leave only a shadow of plate on the steel, using as low as a pound and a-half of tin to plate a box of steel sheets. Under a magnifying glass this plating will appear porous and the steel is exposed to the action of the natural acid of the canned product. The acid starts on the steel, and of course the black spots will make their appearance. There should never be less than three pounds of tin used to the box and this tin should be applied to the steel in such a manner as to entirely cover it. The acid which is used as a flux is also dangerous to corn, and these difficulties due to poor tin-plate can all be obviated by a chemi- cal quantitative and qualitative analysis. The spots caused by black torulae can be prevented by the oft-repeated instructions: "To make the greatest possible speed with the product from the time it comes in until it reaches the sterilizing process." The motto should be in the packing of corn : "From the field to the finished can in the shortest possible time." 92 BACTERIOLOGY IN CANNING. PBAS. Early June peas are planted from selected seed about April 15, and marrowfats about June i. The yield per acre varies, but averages about fifty bushels per acre, producing about thirty dozen of two- pound cans. They should be picked in the early morning, and this should be done with all products which are canned, with no excep- tion; and the reason is^ that the product is fresher and will be sweeter if gathered before the hot sun beats down and drives back the sweetness into other parts of the plant. By numerous experi- ments this fact has been demonstrated, that during the night the sugar will follow the sap and the sun's rays will drive a great deal of it back again. When peas are raised for canning they should be planted on ground close to the factory, so that they may be canned as quickly as possible after they are gathered. When they are raised in con- siderable quantities on level ground the vines are mowed just like grain and taken to the viner, which is a machine representing by its work the great genius of its makers and is one of the most won- derful inventions of the age. The vines are thrown into this machine and the clean peas are taken from the end free from bruises and clean to a remarkable degree. After the hulling they are taken to a machine which separates the four or five sizes desired, which is probably the most important feature of canning peas. When the cans are cut open the contents must be uniform and the size must correspond to the wording of the label. According to the size as well as the quality, the prices are graded in the market, and it is needless to say that the smaller sizes bring more money. After the peas are graded they are taken to the "blanchers" and scalded to get rid of the mucilaginous matter which covers the skin. The outside of peas offers a very fertile medium to the bacil- lus viscosus, which will set up fermentation if they be allowed to stand. The blanching process cleans and heats the peas through, after which they are filled into cans sometimes by hand, but pre- ferably by machinery built for the purpose. These machines are made to graduate the quantity of peas for each can. It is a very important matter, this filling of the cans, in order that the cans may open with clear liquid, for if too many peas are put into the can the cooking will burst them and the liquid will not be clear. Right here I want to say that no packer should trust his goods to any machine without inspecting each step of the process. Machines are built to fill, brine and cap goods all in one opera- BACTERIOLOGY IN CANNING. 93 tion. This should never be done unless the goods can be inspected between each process. No machine does perfect work, however well it may be planned and built, and the man who trusts entirely to machinery without experienced help to inspect each process, is liable to have loss on account of poor quality, the result of imper- fections. It is a far wiser plan to have separate machines for each process, and where peas are filled by machinery they should be inspected and doubtful cans weighed. After filling, brining and sealing, with as much dispatch as possible, the cans are ready for the last and most important part of the work, the sterilizing and cooking process, which is done at a temperature of 240° F., with a time depending entirely on the nature of the peas. If the peas are young and tender, which should be the case if the business has received the proper care, this tem- perature maintained for fifteen minutes will both sterilize and suf- ficiently cook them without any danger of bursting the peas. Young peas will take this temperature in a very short time, as they are not very resistant to heat, like corn. Experiments go to show that 240° F. will be registered throughout the can in about ten minutes and all organisms which are peculiar to peas, the most common of which is the bacillus viscosus, will be destroyed. Mar- rowfats and old peas require about double the time that the young peas are given. The peculiar, slimy and ropy appearance sometimes seen in peas is, like sour corn, due to the bacterial action between the blanching and sterilizing process, and this must be always the case where the cans are allowed to stand, due to overcrowding or un- necessary delays or breakdowns. The packer must understand that there must positively be no delays here, he must have reserve machines to avoid this in any line of goods he is packing. Of course, if the sterilizing process is not sufficient, the can will swell, and if too long the peas will be overcooked and the liquid will be muddy. So great care must be exercised to get just the happy medium. Care must be exercised all along the line, and no packer should be without a competent manager, who is up on all these points. I might go even further and say that the packer should in the near future demand that his superintendent should have some knowledge of bacteria before trusting his capital to men without the proper knowledge to prevent loss. Under no circum- stances should peas be colored, either by artificial coloring matter or by heating them in copper. If there is a demand for very green peas, be brave enough to say No. If peas are vined at the proper time, and speed and care used throughout the system, no color will 94 BACTERIOLOGY IN CANNING. be necessary. They will open green enough in appearance and will be entirely free from poisons. There is nothing which can bring discredit upon a business quicker than adulterations, and while the public demands that the product shall be a good color, by all means give it to them, but do not resort to artificial means. What the consumer wants, is not so much the color, but the standard. If the standard is good the color will be all right, and this is why the consumer wants the good color, because naturally it is associated with good quality. Canners have a great deal to contend with to please the trade, but in order to win for the industry the confidence and respect of the people, two things must be observed — honest goods and cleanliness of the work. It is with the hope that many of the evil effects of the violation of these two points will be remedied that this work is given to the canner. We will uphold only honest methods, and to be exempt from spoiling, due to bacterial action, you must be very clean in the work. TOMATOES. It is not the purpose of the writer to give formulae for packing the various kinds of goods, only so far as the keeping qualities are concerned, because each packer has his own ideas of how he wishes to pack his goods ; but the principle of keeping those goods are not always apparent. Some packers do not exhaust their tomatoes, merely fill, seal and process ; others leave the vents open and then tip the cans before processing; others steam the filled cans before capping in steam boxes. In point of flavor the first method, no doubt, gives the best results, but the tomatoes must be rushed through quickly from the time of scalding to the sterilizing process, as fermentation begins very quickly after scalding. The scalding of tomatoes is a very important feature of tomato canning. This should be done when the water is boiling and jump- ing, then ft will scald the peel without heating the tomato to the center. If the water be not boiling hard, the tomato will be partially cooked and heated through before the skin will loosen. Frequently it will be noticed that a great deal of meat will come ofif with the skin, when the water was not at the proper temperature. If the tomatoes leave the scalder whole and firm, the skin will be easily removed and fermentation will not begin so soon. If the tomatoes be filled into cans promptly and processed at 240° F. for ten minutes, the sterilization will be all right, but the cans will not draw in as Figure 22 MAGNIFIED X icoo. TOMATO JUICE FERMENTING. SACCHAROMYCKS, BUTYRICUS, PRODIGIOSUS AND I.ACTiC BACII.1. LI BR^ UNIVERSITY Figure 23 MAGNIFIED X 1000. TOMATO JUICE FERMENTING. A — IvS A CHAIN MYCODERMA ACETl. Same as No. r at 2.20. BACTERIOLOGY IN CANNING. 95 rapidly as in the other system, where the cans were exhausted. If properly sterilized, however, the goods will keep and the cans may be snapped back to their natural shape by the boys who pile them. The tomatoes packed in this manner are very superior in quality and flavor, but require good management and dispatch in handling throughout, in order to prevent sour tomatoes, which, like sour corn, are most disagreeable in taste. A very common method of packing tomatoes is in the use of steam boxes, where whole truck loads are pushed into them and allowed to steam for about ten minutes before capping. There is great danger in this method, especially if allowed to accumulate ahead of the capping machine, and two views taken of the juice which was thus exposed for over half an hour will be interesting. Fermentation started almost as soon as the cans left the steam boxes, and I made an examination about fifteen minutes after, and again in twenty minutes after that, and the development in that short time was marvelous. By comparing Fig. 22 with Fig. 23 the propagation may be observed in the case of each cell. The great danger in allowing these tomatoes, which have been heated, to stand for any length of time is clearly seen by the micro- scopic views we have taken. We know that the result would be sour tomatoes if the cans should be processed while this fer- mentation is going on, for the acids formed would be sealed up, and also whatever gases were present when the cans were sealed. Packers have often noticed that tomatoes would sometimes spoil if moved about from one place to another. This is probably due to the presence of mold conidia on the surface of the juice in the can, due to imperfect sterilization or perchance a slight leak when the fungus has started to grow on the surface, having been drawn into the can through the leak. As long as the fluid is not shaken the fungus will grow on the surface without causing any fermentation, and also keeping back any other forms which might happen to find a lodgment on the surface ; but if the can be moved and shaken, the swelling is only a matter of a very short time, as fermentation will commence at once, with perfect resemblance to true alcoholic fermentation. The reason that tomatoes will spoil when agitated is nearly always due to mold conidia, and when they are heated and filled into cans at home, the air space will contain enough spores to start the growth of a pencillium on the surface. If the cans are carried to a dark, cool place and not disturbed, they will not spoil, but if shaken will ferment rapidly. Tomatoes are used not only for canning, but in the preparation 96 BACTERIOLOGY IN CANNING. of table condiments, such as soup, catsup, chili sauce, chutney, etc., and it may truly be said that the tomato is the most popular vegetable grown for food. SWEET TOMATO CATSUP, CHILI SAUCE, CHUTNEY. The tomato is a very perishable vegetable, easily attacked by bacteria, very susceptible to the growth of mold, on account of its sweet acid juice which forms a very large per cent, of its make-up. It is this juice which makes it so valuable for catsup purposes. The juice and meat of the tomato are forced through a screen and a com- mercial article called tomato pulp is preserved and sold for making catsup. On account of the very fermentable nature of tomatoes, this pulp is hard to keep, except in hermetically sealed packages, which must be sterilized. On account of its being a good medium for the growth of the molds, such as aspergillus glaucus, pencillium mucor, racemosus, mycoderma vini and monilia Candida, this pulp can- not be put up in hermetical packages without spoiling, unless these packages be given a sterilizing after sealing. It has been a very common method to add an antiseptic to tomatoes while cooking, and thus preserved, the juice could be sealed up hermetically and would keep fairly well, although not perfectly, as the antiseptic could not be used in quantities of sufficient power to destroy germs without injuring both the flavor of the goods and the health of the consumer. Salicylic acid, which is a very powerful and tasteless germicide, has been used for this purpose, but the laws of several States have been made so stringent against its use on account of complica- tions which made their appearance in some persons affected with heart trouble. By the use of this and other germicides, it was easy to barrel up the juice of tomatoes which could be kept and made up into catsup whenever it was wanted. This tomato juice is made into catsup, which in its turn must be kept from the action of bacteria by some germicidal reagent, because it cannot, according to present methods of bottling, be made to keep, nor can it be sterilized because the cork would not keep out the germs. On cooling a vacuum of such power is pro- duced that air is sucked in through and around the cork, and this air may have in it the spores of bacteria which will begin fermen- tation in the goods at once, unless it is armed against the attack with a powerful antiseptic. Another reason why catsup and chili sauce are usually given BACTERIOLOGY IN CANNING. 97 some antiseptic to keep them is the fact that when once opened these articles would either have to be consumed the same day or else kept on ice to prevent fermentation. I have sealed catsup and boiled it for an hour and then covered the cork with sealing wax, but it would almost in- variably spoil unless some germicide were used to make the oxygen in the contents unfit for bacterial food. I made an examination of some catsup I had tried to preserve without antiseptics, and the result was a formation of mold on the surface. Indeed, I have found that molds are the chief obstacles in the manufacture of pulp, catsup and chili sauce without antiseptics, nor can their action always be prevented by the use of antiseptics unless used in very large quantities. The frequent losses to manufacturers in these lines will verify the truth of the statement. During very warm days after rains, sometimes the molds will develop so rapidly on the tomatoes that they can- not be used up before the fungus becomes visible to the naked eye. The conidia are very resistant to heat and it is sometimes very hard to preserve catsup, chili sauce, etc., during such times, even with the aid of germicides. Looking over the business as carried on; that is, by the use of antiseptics to keep the goods, I cannot but say that it is risky, because a quantity sufficient for the killing of ferments cannot be used without injuring the flavor of the goods and endangering the health of the consumer. Owing to the non-expansion of glass, bottles cannot be sterilized so readily as tins, so that the keeping of catsup, chili sauce, etc., becomes a problem. The manufacture of tomato catsup from unfermented material is a very great industry at this time, and the form- ulae in use by great concerns are proprietary and should not become public property. As different concerns have their own peculiar methods, which they consider better than others, any formula which might be suggested would be open to criticism, and it is not the purpose of this work to take up the different ingredients which go to make up any particular food product, but simply to point out the dangers from bacterial action and give the necessary precautions to prevent loss. It is my impression that tomato catsup and chili sauce. 98 BACTERIOLOGY IN CANNING. also chutney, can be put up without the use of antiseptics, which would no doubt give a better flavor to those condi- ments, but we must not overlook the fact that the consumer will have to be careful and keep these products in a cool place to prevent fermentation. When a good method of sterilizing these goods in glass is discovered, the dangers which beset the manufacturers who use antiseptics will be obviated to a great degree. It is argued, in opposing the use of antiseptics in food products, that because nearly everything now prepared for table use is preserved chemically, so much may be taken from different articles of food at a single meal as to inter- fere with the natural peptonization of that food in the stom- ach during the process of digestion under the influences of saliva, gastric juice, bile and pancreatic juice. This ar- gument has such force that laws have been passed in sev- eral States and European countries prohibiting the sale of such goods altogether, and in a few instances only when the packages are labeled ^'compounds," or '^chemically pre- served." It is hard to draw the line, however, because there are several articles which are preserved by antisep- tics to which no reasonable man could object. Smoked meats are preserved from the creosote taken from the smoke, and we find that the honey bee preserves its honey by injecting formic acid. I am inclined to think that in a general way antiseptics of certain kinds are not injurious to man, but I do think that there ought to be limitations only in the use of chemi- cals to such goods as cannot be kept free from the action of the bacteria. For instance, in a chemical analysis of a great many varieties of canned goods by Government chemists, they discovered the presence of salicylic acid in nearly all. Every thinking man will agree that this is unnecessary for keeping goods packed in tin, because the simple sterilizing process was all that was required to keep canned goods. Salicylic acid was used in corn so that the corn might be whiter, because a shorter process would keep it when the germicide was present. It is the abuse of privileges which brings down the wrath of the law upon all. While I think that it is possible to keep the most of goods without the use of antiseptics, I am not ready to con- Figure 24 MAGNIFIED X 1000. PENCILLIUM, ASPERGli:.I,US, GI^AUCUS AND SOME OF THE CONIDIA. V^ OF THB r aNIVERSITY BACTERIOLOGY IN CANNING. 99 demn their use in some cases, for it is vastly more injurious to the human stomach to receive foods which are undergo- ing fermentation than to receive foods which are free from that fermentation, even if they are preserved by small quan- tities of harmless germicides. The disorder to the stomach would be infinitely greater in the former case. I have seen thirty grains of salicylic acid taken daily for a whole month without any perceptible inconvenience to the man, and, indeed, we might go still farther and state that foods chemically preserved are sometimes very bene- ficial to sufferers from stomach troubles, as they retard the action of foreign ferments and allow the peptonizing pro- cess to go undisturbed. Foods which cannot ordinarily be sterilized and kept are better if preserved with some harm- less antiseptic, and we might include under this head toma- to catsup, chili sauce and chutney, because after they are opened they become exposed to bacterial action, and the an- tiseptics would prevent this for quite a time at least. CREAM OF TOMATO SOUP. The canning of this article is quite extensive and the formulae are proprietary, but from the milk used in the man- ufacture the loss occasioned is sometimes alarming. In this article, as well as other products where milk is used,the dan- ger from lactic fermentation caused by the bacilli lactici acidi and bacilli cyanogeni, which give the blue color to milk, is very great. When these organisms get a start the loss is generally complete, nor is their action perceptible until too late to save the goods. There is no swelling or bulging of the cans to indicate that they are at work, and it is only when their work has progressed far enough to be noticeable that it can be detected except by chemical analysis for lactic acid. These germs break the sugar into lactic acid without any other chemical change, and on account of the usual boiling process they are generally the only forms left, and conse- quently in almost all cases the work is accomplished by pure cultures. The boiling or sterilizing process will kill off all the ordinary forms of bacteria and only these will remain because of their great resisting power. Some packers have resorted to the use of germicides to keep this soup, because it appeared that it was not possible to sterilize it, but such is not the case; it may be sterilized in a short time under proper pre- 100 BACTERIOLOGY IN CANNING. cautions by two methods, either the discontinuous process or 130° C. for fifty minutes. The organisms which cause this trouble are non-motile, and you would never suspect the terrible damage they were doing unless you knew the character of the organism. OYSTERS. 'Che oyster beds in Chesapeake Bay cover hundreds of thousands of acres, and the dredging gives business to over fifteen hundred vessels and eleven thousand people, while those directly and indirectly interested are about one hun- dred and fifty thousand. The packing of oysters begins in October and runs through the winter, finally ending about the last of March. The oysters in shells are brought in fresh and steamed in steam cans, after which they are shucked, washed an4 filled into boxes by weight regulated by law. The cans are hot dipped, capped and given a heavy process of from ten to fifteen minutes at 240° F. The only place where considerable care must be exer- cised in the packing of oysters is after they are shelled. If exposed to the atmosphere for any length of time, bacteria of a pathogenic nature may find a lodgment, and, if allowed to begin their action, will produce ptomaines. There is dan- ger to a certain extent also with the oysters in the shell be- fore steaming if they be not fresh and cold. No diseased oysters should be used, none that may be slightly tainted, for if these poisons are once deposited, or, more properly, produced, the results will be damaging in the extreme, may even cause the death of the consumer. The word of warning given here is not ill-timed; there have been cases where packers of oysters have put up oys- ters which ought to have been buried and we frequently read of whole families stricken with terrible cramps and sickness as a result of eating contaminated canned goods. This is damaging to the business in general, and this warn- ing should be sufficient to keep any man from willfully can- ning oysters or anything else which may have become con- taminated. MEATS AND FISH IN GENERAL. There are many ways in preserving and canning these articles which have caused the growth of various mammoth BACTERIOLOGY IN CANNING. 101 establishments to produce a supply sufficient for the de- mand. The canning of beef, sausage, clams, lobster, salmon, sardines, etc., represents millions of invested capital, to say nothing of the various other methods of preserving by dry- ing, smoking, pickling, etc. The canning of meats and fish of every description is easily done, and there will be no difficulty if they are fresh and rushed through rapidly after the first heating and given a heavy process, varying with different kinds of meat. Only the ordinary precautions are necessary as described in the sterilizing processes of other goods. Probably no line of canned goods has caused so much trouble as the canning of meats and fish. There have been hundreds ot cases where people have been stricken down and died from eating canned goods of this kind, because of the presence of ptomaines. Meat is very susceptible, and fish even more so, to the action of pathogenic germs. Even meat canned from animals suffering with some disease may contain these tox-albumenoids, and it sometimes happens that unscrupulous persons will try to evade the law and will persist in canning meat which they know ought to be condemned, I know, personally, of one man who was ar- rested time and time again for trying to can meat which was wholly unfit for food. The dangers attending these cases are very great, and anyone who does try to evade the law should be dealt with in a very summary manner. During the process of canning meats and fish, the dan- gers from ptomaines is very great unless everything is done with dispatch. The juice of meats is probably the most nu- tritious medium for the spontaneous growth of micro-or- ganisms. Not only common putrefactive germs will begin action, but even pathogenic bacteria will thrive remarkably well and most rapidly, too, in a favorable temperature. Meat should always be kept very cold, which is an unfavor- able condition for the propagation of bacteria. One fact must stand out clearly to packers of meats and fish: **No amount of processing and no quantity of antisep- tic will dispose of ptomaines after they have been pro- duced." Another method of preserving meat so that bacteria will not attack it is by salting. Salt, when used in sufficient quantities, will make the conditions unfavorable for the 102 BACTERIOLOGY IN CANNING. propagation of bacteria. This method is carried on exten- sively by pork packers and fish packers, and the market for this class of goods is very large. Another method of preserving meat is by smoking. This is also carried on with fish, such as herring, sturgeon, hali- but and cod. The preserving of smoked meats and fish is the result of the creosote taken from the smoke by the meat. This creosote, together with the salt, makes the meat a poor medium for the propagation of bacteria. The danger from ptomaines in these smoked meats and fish is very great from any carelessness in handling the raw pro- duct. There was a time only a few years ago when the deaths caused from eating smoked sturgeon were numreous and for a long time the article was tabooed. Another method of preserving meat and fish for a con- siderable time is by cold temperatures. Bacteria will not develop at the freezing point, and the great pork houses and fish depots are employing this method all the time in preserving their products, so that the consumer may get pure, fresh meat and fish. The danglers in this line come from allowing the tem- peratures to raise during the handling and shipping of the product. Meat and fish will spoil very rapidly if the tem- perature is thus allowed to raise only a few degrees. By long exposure to the atmosphere in the cold state, the spore of putrefying germs, both pathogenic and non-pathogenic, have found their way into the meat, but will not develop so long as the temperature is freezing, but when the tempera- ture does increase, through carelessness in handling, bacte- rial action begins at once, and perchance some forms may produce those poisonous alkaloids. Even if they are frozen again, the poison will remain, and we have read of many cases of poisoning from this source, principally where saus- ages were eaten. Freezing is a method of keeping many kinds of goods milk, butter, eggs, cream, lard, etc., also vegetables. Milk is a very dangerous medium for bacterial action, and no amount of after freezing will eliminate any poisons which may have been produced when it was warm. How frequent are the cases of tyrotoxicon poisoning from eating ice cream? The cause was the production of this tyrotoxi- con or other ptomaines by such germs of cholera, tetanus, BACTERIOLOGY IN CANNING. 103 typhoid or diphtheria bacilli, which may have started to de- velop on the fat of the milk; that is, the cream, when it was warm. Many dairies are very filthy in their methods, and they sometimes adulterate their milk with water from ques- tionable sources. This water may be alive with disease germs which will find a most excellent nutrient medium in the warm milk. It is here, most probably, that the poi- son is produced in the cream, and the effects cannot be realized until the cream is eaten. I have no doubt that we should hear of many more cases of this kind of poisoning than we do if it were not for the fact that so small a quantity of cream is used ordinarily at meal time, so that if the poison does exist the quantity which may be taken in the small amount of cream used in coffee might not be noticed nor cause any trouble, but it is generally seen by its alarming effects where larger quanti- ties are eaten in the frozen form of ice cream. Sugar is a great preservative in the manufacture of pre- serves where the amount used is far in excess of the nitro- genous elements. In this form it is very thick and does not yield readily to bacterial action, as the amount of nitrogen- ous matter which goes to make up the protoplasm of a cell is not easily taken up because the fluid is too thick. Mold, however, will grow on things which are sugar- cured and exposed, but not so well where the substratum is thinner and more acid in nature. Preserves which are put in bulk are usually covered with some kind of parchment which has been bathed in an antiseptic solution of sulphur dioxide or something similar. If preserves are put up with a thin syrup, it is necessary to follow the usual rules of sterilization by hermetically sealing and submitting to boiling. Drying and evaporating are two methods of preserving founded on the principle of depriving the cells of bacteria of the necessary liquid protoplasm for vegetative purposes. Spores of all kind& may lodge on dried fruits and evapor- ated products, but they cannot grow because there is no moisture to swell the cells. The enemies of these products are worms. PICKLES, KRAUT, ETC. These products differ from almost all other products in that they demand a certain amount of natural fermenta- 104 BACTERIOLOGY IN CANNING. tion before they are ready for consumption. The formulae for producing the best quality are, of course, proprietary, and differ with different concerns. The peculiar fermentation is brought about by adding enough salt to them, so that only certain kinds of bacteria will propagate. Too much salt will limit the needed fer- mentation, and too little salt will expose the products to the action of foreign ferments. The secret comes in using only the required per cent, in order to facilitate the action of one kind and at the same time make the medium unfit for the development of other kinds, which would produce dis- eases, known as soft pickles, spoiled kraut, discolored onions, etc. Probably the greatest enemies to these products are the different types of mold. A great deal depends upon the season, location, water, and temperature in producing ^the best quality. SOUPS. The methods employed to produce the fine canned soups vary with the different concerns who manufacture them, and the formulae are proprietary, but there are some trou- bles experienced which can be cleared up by the application of bacteriology. One of the most common troubles experienced is bitter- ness. The cans do not swell, but the soup tastes so bitter that it cannot be eaten. I was present when one concern had a great deal of this kind of trouble, and the cause seemed very mysterious. Every ingredient was examined for purity and seemed all right, but a few days after the soup would be intensely bitter and was a total loss. The cause was finally and very unjustly blamed on the cans. The manufacturer had been using a certain gasoline flux for soldering, and, while it was slightly bitter, it was not the real cause, as it would have required at least a table- spoonful in each can to have produced such bitterness as was present in the goods. At the time, I had not begun the subject of bacteriology, and the trouble seemed as much a mystery to me as to anyone else, but I never was satisfied with the theory of the flux as the cause, because other goods which went into these cans did not have the unpleasant taste. The method employed by this firm was to get in large quantities of very poor meat, some of which was entirely BACTERIOLOGY IN CANNING. 105 too poor for any purpose. It was meat which could not be sold in any other way, and the proper care for preserving it on ice had not been exercised. This meat was cut up and placed in large kettles full of water which were brought to a simmer and kept thus for eight to ten hours. The juices thus extracted would be spiced and flavored, then canned, sealed and processed at 240° F. for seventy minutes, which was a sufficient heat to sterilize cans. The trouble came in the meat, which had been exposed to the action of a certain variety of bacteria belonging to the putrefactive class. I examined meat under the same conditions afterwards and found that all the bitter products were produced before the meat entered the kettles. The bacterium which caused the trouble I am unable to name, but am of the opinion that it belongs to the class of viscous ferments. It was a rod of from 2 to 4 ft in length and 1 /i in thickness which formed colonies in spots resem- bling the typhoid bacilli and were surrounded by an envel- ope of mucilaginous nature which gave a clammy and sticky sensation to the touch. The bitter product resembled that of aloes. The bitterness was so pronounced that all utensila used in the manufacture would contain more or less of it, and when the cream of tomato soup was made in the same kettles, it, too, became bitter and deepened the mystery of the causes at the time. It is almost needless to say, that in the first place the meat was not the proper quality, and in the second place there was not sufficient care taken for preventing bacterial action, so necessary to avoid these complications. SUMMING UP. We have taken up the study of such forms of bacteria as^ are commonly met with in the destruction of food products, but we have not studied all the different forms, but only those which are best known and which have served the pur- pose of teaching us just what they are, what they look like under the microscope, and how they act under different conditions. We have taken up the most important branches of can- ning and preserving, being careful not to lay down any iron-clad rules or formulae, but with a view of simply apply- ing our knowledge in bacteriology in a practical manner to 106 BACTERIOLOGY IN CANNING. obtain the best results with a minimum loss. By studying the applications of this science as applied to those branches, it will make the way clear for the application to any kind of canning and to any kind of product. We have learned that bacteria are the causes of all spoilage, that they come from the air, that they demand certain temperatures to destroy them. We have learned how they develop and on what they particularly thrive, under what conditions and in what temperatures. The mysteries have been cleared up to a great extent and the necessary precautions have been carefully laid down for preventing loss. To the man who intends to take up this science and study it with a view of applying its principles to his busi- ness, the work that we have taken up in these pages will open up the way and give him a pretty good foundation. I would recommend that every packer and preserver should fit up a room in a suitable part of his factory, with a microscope and all the necessary attachments, also tubes, flasks, plates, an incubator, etc., and there begin to learn for himself just what kinds of bacteria are peculiar to any product he intends to pack, and observe their action and note their resistancy to heat, and the action of different germicidal agents on them. The value of a practical knowl- edge of this science cannot be underestimated, and the points which do not seem clear to him in the text will be clearly demonstrated by actual observation. We cannot foretell what new sterilizing agents may be introduced in the future, but we have every reason to be- lieve that electricity will sooner or later be the best power for the purpose. We have considerable evidence that the X-rays are germicidal. Just how these rays affect bacteria we cannot say, but we would compare the rays to shot from a gun. These rays have great penetration and are so fine and close together that they seem to shoot through even wood, and we can imagine that bacteria will be shot by them and affected in such a way as to stop their vegetation. It is a fact that even the leucocytes of the blood, which are the white corpuscles, are destroyed when the powerful X-rays are turned upon living tissue. There have been cases where flesh has become perfectly dead after being ex- posed to high power. BACTERIOLOGY IN CANNING. 107 The time may come in the future when a machine may be contrived that will send the rays through canned goods in such a manner as to kill all bacterial life within the can and the product would remain as fresh as when put into the can. As I stated before, we cannot tell what improvements may come, but we know that the scientists are working and experimenting along this line to destroy disease germs, and if the canner and preserver keeps pace with them by keep- ing up his studies in this direction, he may be able to adopt for himself the very latest discoveries, and he may apply the principles in his own work. I speak of electricity as a possible power to accomplish sterilization and this idea is held by a great many who are using it in their laboratories. I have experimented a great deal with both straight and alternating currents of various voltage and am convinced that the action of the electric fluid on the carbon in the molecular construction of any goods is such as to make it poor food for bacteria, but have not been able up to the present time to prevent scorching. I have taken the positive and negative wires and fast- ened platinum strips to the ends, and, being careful not to let them come in contact with each other, I have placed one end in the centre of a jar of fruit juice and then made a cir- cuit around this with the other wire. Of course both strips would heat white hot during the experiment, but the cur- rent would pass through the goods and its action was such as to make the juice unfit for any bacterial life excepting mold on the surface. I merely state this to show that electricity has some germicidal action, but on account of the crudeness of the experiments and the lack of definite knowledge on this sub- ject, it has no real value at present further than to give us an idea. For the present, then, we are simply confined to those methods of sterilization which have been discovered and tried successfully by the most eminent scientists of our time. We can continue to study and apply the principles, and our knowledge will always be a safeguard against any severe loss. If these pages have cleared away any of the clouds of mystery surrounding the troubles of canning and preserv- ing, and have opened up the ways and means to prevent loss, the writer will feel fully repaid for the long hours of tedious study devoted to the work. FINIS. STERILIZATION IN CANNING. by edward w. duckwall, Author of ^'Bacteriology Applied to the Canning and Preserving of Food Products." The primary meaning of Sterilization is barrenness, and has a suggestion that the application of heat is necessary to accomplish that result. We use the term in canning to de- signate the final cooking process which is commonly believed to kill all life within the can. The life here meant is bac- terial and vegetable life. There are many peculiarities about the sterilizing process. The question is often asked, why is it that peaches, pears, cherries, apricots, etc., will keep, when given a process of 250° F. for one or two minutes, and tomatoes, corn, and peas will invariably spoil, especially corn, which requires almost an hour ? Why are the bacteria in cold pack tomatoes killed when processed fol* fifteen minutes at 250° F. and those in hot pack corn will not be killed in that time, when the spores of the very same germs are found in both ? Why will some goods keep when processed in open bath, while other goods will not keep except they undergo a process for a much longer time at a higher temperature ? If we take four sound cans of corn and tomatoes and punch a hole in each, the vacuum will draw in about one cubic inch of air or perhaps less; and if we reseal and give them a light ex- haust, then process in the open bath for thirty minutes, the corn will spoil, while the tomatoes will keep. Why is this ? Surely the tomatoes received as many varieties of bacteria through the puncture as did the corn, yet the one will keep and the other will spoil. In order to answer these questions, it is necessary to un- derstand the nature of bacteria and the requirements neces- sary for their propagation. We know that certain varieties of these microscopical plants require certain kinds of food for their propagation, which may not be suited to other BACTERIOLOGY IN CANNING. 109 varieties. We find this to be true in the higher vegetable kingdom; if we visit the sandy wastes of Arizona and New Mexico we will find the cactus growing under conditions that would consume the delicate Rose and beautiful Lily of the Valley; if we visit Alaska and Greenland we will find the evergreens flourishing under conditions that would freeze the palm and orange trees of Florida; we find moss growing on rocks where potatoes could hardly find a lodge- ment. So we may look for certain characteristics of this kind in bacterial life. We find a certain class of germs flourish and propagate on sugar combined with moist nitrogenous matter. These germs will convert the sweet juices of fruits or any other sweet infusions into alcohol, succenic acid, glycerine, car- bonic acid gas, etc. Some will convert the sugar into acids at once, but usually another class of bacteria which feeds upon the alcohol which has been generated by the Saccha- romyces from the sugar, and those bacteria convert the alcohol into lactic, acetic, malic, or butyric acids, etc., ac- cording to the particular nature and kind of bacteria they happen to be. Then there are still other varieties which take the fruit acids and feed upon them, converting them into more simple or fatty acids. For example, if we take some of the milk of sweet corn and inoculate it with a pure culture of Saccharomyces or yeast and keep the infusion at a temperature of 34° F. (as this is the only class of ferments which will propagate at so low a temperature), the sugar in the corn will be converted into alcohol, etc.; then if we inoculate further with the Lac- tic Acid Germs, Bacilli Lactici Acidi, and increase the tem- perature to 85° or 90° F., the alcohol will be converted into lactic acid, and if any sugar remains, acetic, malic, or bu- tyric acid may be a result of some germ acting on the lactic acid, but usually the conditions are more complicated than this, and when we increase the temperature from 34° to 90° F. it is a favorable time for any number or the different va- rieties of bacteria to thrive, and thus we would be able to observe the work of breaking down, begun by various fer- mentive and putrefactive agents. The chemist could, after a couple of days, find any fatty acid known, as a result of the combined bacterial action. Peaches, pears and cherries and succulent fruits are sus- BACTERIOLOGY IN CANNING. 110 ceptible to the action of a variety of bacteria, prominently Saccharomyces Apiculatus Cerevisise and Pasteurianus, which have very little resisting power against heat, so as soon as the temperature reaches a certain degree they per- ish, but not so with many other varieties present. These may in the course of time succumb to the starving process or the antiseptic influence of the fruit juices, but so far as the heat is concerned they are able to live through it, but unable to develop into mature forms from their spores, be- cause the medium or substratum is unfit for their food. If perchance, however, the first variety should survive an in- sufficient cooking and should set up a fermentation, then these other varieties might find a suitable medium in the products of that fermentation, but experience has taught us and the microscope reveals to us that the material and con- ditions are not suitable for their development and when the Saccharomyces, etc., have perished by the heat, so they remain dormant or the fruit acids kill them ultimately. Bacteria spores are not the only forms of life which may sustain a light process. Strange as it may seem, the seeds of some of these fruits will grow, if planted even after the cans have been processed. I have seen tomato vines grow from the seeds in cans that had been processed the year previous, also a cherry tree grown from a seed thus. Now there is a trouble often experienced by canners which seems unaccountable to many and is commonly ex- perienced with canned fruits, such as cherries, peaches, pears, etc., viz: Spring Bottoms. This class of goods, as we have seen, is given only a light process, and we also learn that the fruit life is not always killed by that process. All fruits have some of the peculiarities of bacterial life them- selves. We can look upon them, large as they are, as being endowed with some of the same natural characteristics of the Saccharomyces, in that they lose sugar and set free an equal weight of alcohol and carbonic acid gas. Pasteur is authority for this, and he proved it abso- lutely by experiments, ascertaining by weight the loss of sugar and the relative production of alcohol and carbonic acid gas. Spoilage is liable, of course, after the alcohol is pro- duced, because this is a food for the spores of germs which have been dormant in the cans up to this time. They will Ill BACTERIOLOGY IN CANNING. immediately seize upon this for development and spoiled goods will result. It is of course a very material advantage to the canner to preserve as much as possible of the fruit flavor and this may be done only by cooking as little as possible, but if he is troubled with Springs, it is evident that the pro- cess has been too light to kill the fruit life. It is also a well-known fact among canners, that if their products are not canned with dispatch and processed before any fermentation takes place, there is liability of spoilage, unless the process be increased. Sometimes the goods will spoil from this cause after a very much longer process at a higher temperature. The reason is the same, fermentation started and new products were formed by that fermentation which furnished food for a much more resist- ant class of bacteria. The necessity of using only sound fruits in a light pro- cess now becomes clear. If any rotten or diseased portions find their way into the cans, of course the products of that bacterial action go in also, and they are food for that class of spores whose heat-resisting powers are always menacing the canner and preserver. Going a step in this direction, we might say something along the line of cleanliness in the work of canning and in the preparation of the food products to be preserved. Cer- tainly, if foreign substances find their way into the goods, there will be cans here and there in the pile of finished stock that will spoil, most unaccountably to the manager, who had apparently treated all alike. A very small particle of foreign matter will cause a can to spoil sometimes, because it may contain nutrient food for spores of bacteria which would ordinarily remain dormant in the regular process of uncontaminated stock. Many interesting experiments may be made profitable along this line. Take a can of tomatoes and add a small quantity of milk, give it the regular to- mato process, and then after a couple of weeks open it, and you will find it disagreeably sour, perhaps in less time than that. Then try a little corn with tomatoes after the same manner and see the result. The canner should never add any foreign substance to his goods without first ascertain- ing what properties it contains that might furnish food for the spores of bacteria which in his ordinary process are dor- mant. BACTERIOLOGY IN CANNING. 113 There is a widely circulated belief among canners that the green parts and cores of certain fruits and vegetables will cause spoilage unless they be removed, and while it is no doubt an advisable proceeding from a standpoint of hav- ing best quality, yet those things have very little to do with spoilage. If the green parts be cooked tender, they will keep just as well as the ripe; the only difference, if any, will be a little more cooking. Sterilization, then, is a misapplied term, and is only real when all life is absolutely killed within the can. To say that any package is perfectly sterilized means that a heat not less than 250° F., continued for at least one hour, has been given it, and there is some doubt if even this is sufficient in some cases. However, with due care goods will keep with varying temperatures, although we cannot say that they are perfectly sterilized. — The Trade, Decem- ber 2, 1898. ~ OF THE ' y university "SIcaufob^ A number of special articles on Bacteria, Sour Corn, etc., will be found in the copies of The Trade of 1898. THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW AN INITIAL FINE OF 25 CENTS WILL BE ASSESSED FOR FAILURE TO RETURN THIS BOOK ON THE DATE DUE. THE PENALTY WILL INCREASE TO SO CENTS ON THE FOURTH DAY AND TO $1.00 ON THE SEVENTH DAY OVERDUE. ^PR 101935 ■m^ %^ SEP 20 1940 \9W=* t^ »\, LIBKAW f Un ^P>> 1 6 1960 PECD LP AFH i6 19o0 SENTrONILL OCT t 6 1 995 U. C. BERKELEY LD 21-100m-8 '34 YC 18(16 i^'Soyo