UNIVERSITY OF CALIFORNIA PUBLICATIONS. COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION. CONTRIBUTION TO THE STUDY OF FERMENTATION. Part I. By E. H. TWIGHT and CHARLES S. ASH. Wine Yeast Culture. BULLETIN No. 159. (Berkeley, June, 1904.) SACRAMENTO w. w. shannon, : : : : SUPERINTENDENT state printing, 1904. BENJAMIN IDE WHEELER, Ph.D., LL.D., President of the University. '<'■''•■ EXPERIMENT STATION STAFF. E. W. HILGARD, Ph.D., LL.D., Director and Chemist. E. J. WICKSON, M.A., Horticulturist. W. A. SETCHELL, Ph.D., Botanist. ELWOOD MEAD, M.S.. C.E., Irrigation Engineer. C. W. WOODWORTH, M.S., Entomologist. R. H. LOUGHRIDGE, Ph.D., Agricultural Geologist and Soil Physicist. (Soils and Alkali.) M. E. JAFFA, M.S., Assistant Chemist. (Foods, Nutrition.) G. W. SHAW, M.A., Ph.D., Assistant Chemist. (Starches, Oils, Beet-Sugar.) GEORGE E. COLBY, M.S., Assistant Chemist. (Fruits, Waters, Insecticides.) RALPH E. SMITH, B.S., Plant Pathologist. A. R. WARD, B.S.A., D.V.M., Veterinarian, Bacteriologist. E. H. TWIGHT, B.Sc, DiplomS E.A.M., Viticulturist. E. W. MAJOR, B.Agr., Animal Industry. A. V. STUBENRAUCH, M.S., Assistant Horticulturist, in charge of Substations. WARREN T. CLARKE, B.S., Assistant Field Entomologist. H. M. HALL, M.S., Assistant Botanist. H. J. QUAYLE, A.B., Assistant Entomologist. GEORGE ROBERTS, M.S., Assistant Chemist, in charge Fertilizer Coniro, C. M. HARING, D.V.M., Assistant Veterinarian and Bacteriologist. C. A. TRIEBEL, Ph.G., Assistant in Agricultural Laboratory. C. A. COLMORE, B.S., Clerk to the Director. EMIL KELLNER, Foreman of Central Station Grounas. JOHN TUOHY, Patron, ) > Tulare Substation, Tulare. JULIUS FORRER, Foreman, ) J. E. McCOMAS, Patron, Pomona, J. W. MILLS, Superintendent, Ontario, }• Southern California Substation. JOHN H. BARBER, Assistant Superintendent, Ontario, A. A. KNOWLTON, Patron, J. H. OOLEY, Workman in charge, ROY JONES, Patron, WM. SHUTT, Foreman, H. O. WOODWORTH, M.S., Foreman of Poultry Station, Petaluma. ! tr y University Forestry Station, Santa Monica. t University Forestry Station, Chico. The Station publications (Reports and Bulletins), so long as avail- able, will be sent to any citizen of the State on application. Contribution to the Study of Fermentation. By E. H. TWIGHT and CHARLES S. ASH. The present bulletin is a report upon the cooperative investigations carried on during the vintage of 1903 by the Agricultural Experiment Station of the University of California and the California Wine Asso- ciation of San Francisco. The Association allowed the use of its large wineries in Sonoma County and built a laboratory in Geyserville 14 by 14 feet for the cultivation of pure yeasts; it also gave the use of its San Francisco laboratory for the analytical work. The object of these experiments was the study of: (1) The influence of temperature on fermentation; (2) The influence of acid (acidity of must) on fermentation; (3) The influence of selected cultivated yeasts on fermentation as compared with the natural (wild) yeasts; (4) The comparative values of the wines derived from these experiments. Considerable work of this nature has already been done in foreign countries, principally in France and Algeria; also at this Station. On the part of the California Wine Association, the observations and analyses reported upon in this bulletin were made by Charles S. Ash, who has charge of its laboratory and who divided his time between its wineries in Sonoma County and its laboratory in San Francisco. Observations were made on 360 fermentations in tanks of 5,000 gallons capacity each, making a total of 1,250,000 gallons of wine, which there- fore puts this work upon a practical basis — and not the result of labora- tory investigation only. It is impossible, in a bulletin of this length, to record all data obtained, so only the most characteristic are herein given. Effect of Temperature on Fermentation. — When the must of grapes is being transformed into wine, a chemical change takes place (C 6 Hi 2 6 = 2 C 2 H 6 -f- 2 C0 2 ), increasing the temperature. In the practical fer- mentation of wine, the temperature varies from 60° to 105° F. The most favorable temperature seems to be about 85° F. When wine was first made in hot countries, it was the ambition of all the savants to produce a yeast that would ferment a large percentage of sugar at a high temperature. These efforts, however, proved to be of little or no value, for it was found that the higher the temperature during fermen- UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION. tation, the greater the amount of acetic, lactic, and other acids formed, and the lower the percentage of alcohol. Volatile Acid. — Kayser, in France, has given the following figures on the increase of volatile acid when fermentation takes place at higher temperatures: 25° C. (77° F.). 35* C. (95* F.). Yeast No. 2 Yeast No. 8 Yeast No. 9 .0979% Volat, .111.2 .0862 .0780% Volat. .1504 .0824 These figures are not very conclusive, since out of the three examples two have not proven his statement. We have experimented very thor- oughly on the same lines in our laboratory, with more satisfactory results, as given below: At 75° F. At 85° F. At 95° F. At 102* F. Yeast No. 1 Yeast No. 4 .-. .067% Volat. .071 .059 , .062 .065% Volat. .073 .059 .061 .097% Volat. .101 .063 .070 .112% Volat. .119 Yeast No. 5 Yeast No. 6 . .094 .100 This laboratory result was fully confirmed in two cellars in Sonoma County, situated only one and one half miles apart, and handling the same quality and varieties of grapes. We have designated these cellars as "A" and"B": Winery A". B" Average Temperature of Fermentation. 80° F. 95° to 105° F. Average Volatile Acid. .078% .118% Albuminoid*. — Another great objection to fermenting wines at a high temperature is that under these conditions they will not clear readily. This is due to the large amount of nitrogenous matter (albuminoids) retained in the wine, and is exceptionally disastrous in the ease of white wines, on account of their poverty of tannin. A wine with a large percentage of albuminoids is also subject to bacterial diseases. The following table shows the percentage of nitrogen in wines fer- CONTRIBUTION TO THE STUDY OF FERMENTATION. merited at different temperatures, taken from Roos and Chabert, two of the best known authorities on the fermentation of wines in hot countries: Nitrogenous Matter in Winks Fermented at: 25° 0. (77° F.). 30° C. (85° F.). :i.V(\ (15° F.). 4(i° C. (104° F.). No. 1 No. 2 No. 3 .is? .265% .115 .112 •*22% .120 .193 .460% .135 .183 No. 4 .205 Alcohol. — We now come to the most important factor, from an eco- nomical standpoint, in the fermentation of wines: that is, the amount of alcohol produced from a given amount of sugar. Theoretically, 100 parts (100 grms.) of sugar yield: 40.00 Carbon dioxid. 48.40 Alcohol (61% by volume at 15° C). 3.20 Glycerin. .60 Succinic acid. 1.20 Used bv the ferments. The following tables on the above subject give the results of experi- ments conducted in Algeria by Messrs. Roos and Chabert, and they demonstrate that there 1 is a loss in alcohol when wine is fermented at a high temperature : 25° C. (77° F.). 80° C. (85° P.). 35° ('. (95° P.). 40° C. (104° F.). Must No. 1, 17.4% Sugar. Must No. 5, 17.4% " Must No. 8, 19.0% " Must No. 11, 20.3% " 10.0% Alcohol 9.9% 10.9% " 9.7% Alcohol 9.7% " 10.9% " 9.6% 9.2% Alcohol 9.1% " 9.6% 7.2% 7.3% Alcohol 9.3% " 6.1% The results of Messrs. Roos and Chabert are fairly well confirmed* by us, the following experiments having been conducted in the labo- ratory of the California Wine Association: * See Viticultural Report of California Agricultural Experiment Station for 1883-84- 85-86-87, by E. W. Hilgard. UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION. Must No. 1, Carignane, 20% Sugar. 25° C. (77° F.). 30° C. (85° F.). 35° C. (95° F.). 40° C. (104° F.). Alcohol. Sugar. Alcohol. Sugar. Alcohol. Sugar. Alcohol. Sugar. Yeast No. 5 Yeast No. 6 No yeast added 11.3% 11.2 11.0 .100% .105 .105 11.2% 11.3 11.1 .095% .100 .105 10.8% 10.8 10.5 •115% .105 .180 10.4% 10.3 9.9 .200% .195 .220 Must No. 2, Carignane, 21% Sugar. 25° C. (77° F.). 30° C. (85° F.). 35° C. (95° F.). 40° C. (104° F.). Alcohol. Sugar. Alcohol. Sugar. Alcohol. Sugar. Alcohol. Sugar. Yeast No. 5 Yeast No. 6 . 12.1% 12.0 11.9 .105% .100 .115 12.1% 12.1 11.8 .100% .105 .120 11.6% 11.7 11.4 .215% .215 .265 10.9% 11.2 10.6 .290% .285 No yeast added .500 Must No. 3, White, 25% Sugar. 25° C. (77* F.). 30° C. (85° F.). 35° C. (95° F.). 40° C. (104° F.). Alcohol. Sugar. Alcohol. Sugar. Alcohol. Sugar. Alcohol. Sugar. Yeast No. 5. 13.6% 13.4 .200% .210 13.6% 13.6 .215% .200 12.8% 12.6 •415% .450 10.4% 10.8 2.10%* 2.55* Yeast No. 6 * Stuck. Dryness. — And, finally, we come to the question of dryness (low per- centage of sugar remaining after first fermentation). Wines fermented at low temperatures (85 c F. or under) become dry very quickly, running down as low as 0.100 per cent of sugar within two weeks, while wines fermented at higher temperatures sometimes take over a year to reach this condition. We consider this point next in importance to the amount of alcohol obtained, for upon the dryness of a wine largely depend its keeping qualities. A glance over the table already given, showing the amount of alcohol derived and the amount of sugar left unfermented, will make this point readily under- stood. The increase of unfermented sugar at high temperatures is even more constant than the increase of volatile acid under the same conditions. CONTRIBUTION TO THE STUDY OF FERMENTATION. Summary. — Fermentation at low temperatures (85° F. or under) has the following beneficial results : 1. Lower percentage of volatile acid. 2. Lower percentage of albuminoids (easier to clear). 3. Greater percentage of alcohol (from 1 to 2 per cent, according to the deviation in temperature above 85° F., which appears to be the point of most perfect fermentation). It is easy to recognize the great losses which accrue in sweet-wine wineries from fermentation at high temperatures, especially if it is the ambition of the wine-maker to ferment them as rapidly as possible. 4. Dryness. Cooling of the Must during Fermentation. — It has been conceded by all authorities that cooling the must is the only practical method of making good dry wines in hot climates. The California Agricultural Experiment Station at Berkeley in the season of 1896 carried on very interesting experiments along these lines, and those interested may find a detailed B A A, Entrance of water. B, Exit of water. Fig. 1. Wine cooler. C, Entrance of warm wine. D, Exit of cooled wine. E, Plan account in Bulletin No. 117, "The Control of the Temperature in Wine Fermentation," by A. P. Hayne. The cooler described in these experi- ments had a small capacity, and though the results w T ere satisfactory, it did not come into general use. However, one of these coolers has been used since that time in one of the small wineries where the experi- ments were conducted. The only argument that can be made against cooling is the expense, and that in very many instances could be reduced to a very low figure, amounting to practically the cost of pumping the must through a coil. At Geyserville this year two coolers were built which cooled a 5000- gallon tank of must twenty degrees in thirty -five minutes; cost of cool- ing estimated at $0.0009, not one tenth of a cent per gallon. These coolers cost $86 apiece. The only other expense was the pumping of the must and cold water through them. Fig. 1 illustrates the contrivance used at Geyserville, which is extremely simple. 8 UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION. Three hundred and twenty feet of 1-J-inch galvanized pipe were arranged in square tiers in a fermenting tank, each arm of this coil measuring eight feet. The warm must was pumped in at the top of the tank and issued from the bottom.' The cold water was pumped in at the bottom and passed from the top. It may be of interest to note that in this case it took about twice the volume of water to cool a given amount of wine. The temperature of the water was 60° F. From our observations at Geyserville, we found that after the must had once been cooled, it fermented out perfectly dry before the tempera- ture again had a chance to rise to the danger point. As all wineries need a large supply of water for washing the tanks? cleaning the machinery, washing the pomace for brandy, etc., a cooler could possibly be built in the reservoir from which the water is dis- tributed. In many instances where wineries are located alongside of a river or an irrigation canal, the cooler could be placed in the river-bed or the ditch. In the building of new wineries, the advantage of such an acquisition should be considered, as the cooling would only cost the pumping of the must through the coil. With cheap oil fuel, this would be nominal. Experiments with Cultivated Yeasts. — Under ordinary conditions, the transformation of fresh grape must into wine is spontaneously pro- duced from the micro-organisms (yeasts) that cover the surface of the grapes at maturity. The principal factor in the vinous fermentation is the elliptic yeast (Saeeharomyees ellipsoidevs). The natural yeasts of some varieties of grapes produced very much better fermentation than others. For example, in California the yeasts of Tanat, Burger, Carignane, Mataro, and Alicante Bouschet are very vigorous, while those of Mondeuse, Malvoisie, Zinfandel, and Mission are, as a rule, quite feeble. As most of our red wines are made from Zinfandels, our atten- tion was first called to this grape. After keeping record of the fermen- tation of all Zinfandels on natural as well as cultivated yeasts, we have come to the following conclusion: Zinfandels, when fermented on their own yeasts (not mixed with any other variety) ferment very rapidly at first, but when they have fer- mented down to about 2 to 5 per cent of sugar, the temperature of the must rises very high and fermentation stops for a period varying from a few hours to a whole day. Then (in a good year, like 1903) they •become dry. Attached to this report are given some examples of typical Zinfandel fermentations (Figs. 3 and 4). The fermentation is exceptionally irregular, in extreme cases fermenting out as much as 12 per cent of sugar in one day and possibly only 1 per cent the next. In Burgers and Carignanes, the fermentation is uniform all through (Figs. 6 and 7). The must loses approximately the same percentage of CONTRIBUTION TO THE STUDY OF FERMENTATION. iJ sugar the third as the second day, and so on until the fermentation is finished; or they ferment the greatest amount of sugar the second day and gradually decrease. This is the reason why wine-makers like to mix Carignanes (or Burgers) with Zinfandels (Figs. 11, 12, 13). Previous to the vintage, we pursued the following plan: A great many varieties of yeasts were experimented with, pure cultures of all first being made. These pure cultures were obtained by starting from one cell. After they were made they were tested in the same medium and under different conditions in order to select the most vigorous. Our work was carried on with two of these selected yeasts, which we have designated as No. 5 and No. 6. The inoculations from the pure cultures were made into test-tubes full of sterilized must; then from the test-tubes into quart flasks three- fourths full of sterilized must; from the flasks into 10-gallon kegs three-fourths full of sterilized must; and finally into 50-gallon barrels three-fourths full of sterilized must. The transfer from the smaller to the larger vessel was made only when the fermentation was in full swing. In making these transfers, the greatest care was taken to guard against contamination, the casks, bungs, bungholes, etc., being sterilized with steam. When the must in the barrel was at its highest ferment- ing activity, it was dumped into one of the regular fermenting tanks containing freshly-crushed grapes. For each fermenting tank to which cultivated yeast had been added, we filled another tank with the same variety of must and the same percentage of sugar, but fermenting by its own natural yeast, to serve as a check. The fermentation of both tanks was recorded and an account kept of the amount of sugar lost each day, the height of the temperature developed, etc. Some of these records are embodied in this bulletin along with the analyses of the wines fermented with both natural and cultivated yeasts, showing gain (or loss) of the wines fer- mented with cultivated yeasts over those fermented with the natural as regards percentages of alcohol, volatile acid, and unfermented sugar obtained. As there were some three hundred records taken, it would be impossible to discuss them all, so only the most typical are given. 10 UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION. DISCUSSION OF CHARTS. Fig. 2 shows an ideal fermentation; represented as the diagonal of a rectangle. The figures on one side of the diagonal represent the temperatures, and on the other the percentages of sugar in the must. In this diagram the time that has elapsed between the tilling of the tank with must and the completion of the fermentation is four days. Temperature. 69 70 71 72 73 74 75 76 77 78 76 60 81 82 83 84 85 88 8 7 68 24 23 22 21 20 i e 1 8 I 7 1 6 1 6 1 4 I 5 1 2 1 1 ) 9 a 7 6 S 4 5 2 \ \ V \ k \ \ f'Vty v \ \ s v \ V 5 nc1 day \ \ \ \ \ \ \ \ 3 " day \ \ \ \ \ x \ 4""'day Fig. 2. Diagram showing ideal fermentation. CONTRIBUTION TO THE STUDY OF FERMENTATION. 11 Temperature. 70 71 727374 75 76 77 7*768081 82 85 84 858887 88 89 90 91 25 24 25 22 21 20 i ei 1 8 i 7\ l 6 I B| I 4 1 5 1 2 ] 1 1 © e 7 6 5 4 5 2 1 bep .irtt l?"iUl IT 1 s s. 3 16"^ m \ n ,H am \ ^'"pm \ i N s \ s X \ /\ H^a m \ S 1 r \ s \ \3"'am / V '* '" T> ™ \ \ / \ s \ \j \ s s \ •n^pm N V 19' p.m \ i9' h dm s s S^I9 ,H pTn N s «H a-w S \£ > zo* £$1 > *O n pm ^ ,2i sf am \ If p m ,^" rf Am if p.m v ^ vSi'^jn ■JZ"" p.m r'.i ^rtu 23 ,,J am. Fig. 3. Typical Zinfandel fermentations, showing great irregularity. The curves in Fig. 3 show typical Zinfandel fermentations. It can be seen that the fermentation of this variety of grape is very irregular, especially at the end, as previously mentioned (see p. 8). Note that on the 17th of September, p. m., the percentage of sugar in the must was only 10, and on the 18th a. m., the next morning, it had again risen to 15 per cent. This is not an uncommon occurrence, for it occa- sionally happens that there are dried grapes (raisins) among the bunches that are delivered, and when the fermentation sIoavs, the sugar in the raisins has time to dissolve. This condition is a serious obstacle to the wine-maker, especially when the percentage of raisins is large, as was the case in the vintages 1900 and 1901. The same condition is repre- sented on Fig. 4. 12 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION. Temperature. 70 71 72 73 74 75 76 77 78 79 60 81 82 63 64 85 86 8 7 68 89 90 91 25 24 23 22 III 2 ; ie| 1 6, «*| 1 6 15 n| 1 3 I 2 1 t A e 8 7 6 5 4 3 2 1 \ Sept .l6"V»m / / / 17" am A / i? *&* // s rib"ym\ n" p in \ \ V \ \ id^m \ s \ V la 1 * i m "\-t'a"pni X \ J \ \ ^N s 18'" pm V i9"cim Si9"f m 20* am \ f A.« \ 20* pin V *N k nm 21" 7^ K"a ? 2l" p m /| m,« pin Fig. 4. The irregular line starting September 16th shows typical irregular Zinfandel fermentation. The straighter line starting September 17th shows that of second crop. In Fig. 4 the irregular line starting September 16th shows a typical first-crop Zinfandel fermentation; the straighter line that of a second- crop. Note the great improvement in fermentation in the latter, the line showing the reduction of the sugar being nearly straight while 14 per cent is being fermented out. This improvement is due largely to the natural higher acidity of second-crop grapes (see p. 25). CONTRIBUTION TO THE STUDY OF FERMENTATION. 13 Temperature. 70 71 72 73 74 75 76 77 78 79 60 8 t 82 83 84 85 88 8 7 88 89 90 9! 25 24 23 2 2 2 1 20 1 9 I 8 i 7 1 6 1 5 1 A 1 3 1 2 1 1 1 e 8 7 6 5 A 5 2 Sept 2 7"VlT71 > \ V V \ s, \ i I N \ \ W^dm \ \ \23"" pm S r 0*p.m 30" pm Fig. 5. Zinfandel and Carignane fermentation. Fig. 5 shows how the fermentation of Zinfandel grapes is improved by mixing a certain proportion of grapes of a variety known to ferment well (Carignane, in this instance). 14 UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION. Temperature. 71 72 75 74 75 76 77 7« 78 80 8 1 82 85 84 85 88 8 7 88 89 60 91 92 24 25 22 2 I 2 0: IGt ! 8, 1 7| I 6 1 si 1 4 I S| ! 2 1 1 ) 9 8 7 8 5 4 5 2 Vnt 25" pm \ \ J <0ct6'\\m \ u^ ^ \ V > X r r< x ^26^ m. \ \ \ s 8~am S. 26 n pm \ ^ \, s> \ \- -^-p. \ \ \ \ \ \ Sff \ \ \ \ \ \ s X- \ \ \9"« m v 8" a £ \ Vf,. \9'"p.n\ Fig. 6. Typical Carignane fermentations. The good fermenting quality of the Carignane is shown in Fig. 6, the fermentation being through in three days without very great increase in temperature in one instance, and in three and one half days in the other. Note the regularity in loss of sugar. CONTRIBUTION TO THE STUDY OF FERMENTATION. 15 Temperature. 75 76 77 78 78 60 8 1 82 65 64 85 86 6 7 68 80 90 91 92 95 94 95 96 23 22 21 2 0' 19 18, "1 16| 1 5 1 4 1 3 1 2 1 1 1 e 8 7 6 5 4 3 2 1 Oct ^i^m \ i "rim V s\ KiS"pm r> I6"rim Ss Vl6'*cHH N \ \ > V s N N X r_ \ nVtiN. | \ 1.7'Am Fig. 7. Typical Burger fermentations. Typical Burger* fermentations are shown in Fig. 7. Burger is invariably very regular. The must of this variety seldom has over 22 per cent in sugar, while the accidity remains high (.5 to .9). Such a composition is very favorable to a good fermentation (see p. 25). Burger yeast, however, has a good deal to do with the above regularity, as will be shown later by some experiments that are being conducted at present. *It must be remembered that the grape called Burger in California is not the true Burger of the northern grape belt of Europe. Its true origin has net been definitely determined. (See Viticultural Report for 1896, p. 244.) 16 UNIVERSITY OP CALIFORNIA— EXPERIMENT STATION. The following examples show the comparative fermentation of Zin- fandel with its own yeast and Zinfandel with cultivated yeast, the must in both tanks being identical. Out of the nine examples given, seven show a gain in favor of the tank fermented with pure cultivated yeast as a starter. The other two are equal to the natural fermentation. The natural yeast is represented by a solid line; the cultivated yeast by a dotted line. Temperature. 80 81 6263 9466 S6 674869 70 71 72 73 74 75 76 77 76^79 80 8 1 62 65 64 85 86 24 25 22 21 20: i 9 '8; l» 16 16! 1 4 1 3 1 2 1 1 1 e 7 6 5 4 5 2 "0 Sepl \\& n nm ^v pm. A X ^ ?0 M o.m 18" P"\ \ is "Am Strain \ IS" a m \ s >" 'ifm ■s I ^N / x / x . M*1»*_ Jv 'pm N ^ lk ~"? m ZO" am \ \ ^, \ N v \ ;o'* n m ^*3"V»m - -Ty*J™ - X ^ '-> X N . Tl ^ ■ 1 __ 24" pm < ( s 2l ,T, p 2 5" a m \ | Sm1i« Fig. 8. Natural Zinfandel fermentation (solid line) and fermentation with pure yeast (dotted line). Sugar fermented 1st day 2d " 3d " 4th " 5th " 6th " 6} " -- Completed in 6| days Natural With Pure Fermentation. Yeast. o% 4% 1 7 7 7 3 4 5 .- 5 __ 1 __ 4 dav In the fermentation shown in Fig. 8 the tank with cultivated yeast was dry two and a half days before the tank fermenting on its natural yeast, the regularity of fermentation being nearly perfect in the tank with cultivated yeast. CONTRIBUTION TO THE STUDY OF FERMENTATION. 17 Temperature. 70 71 72 73 74 75 76 77 78 76 80 81 82 63 84 85 86 8 7 88 86 90 91 92 93 24 23 22 21 20 10 1 8' 1*1 1 6 1 5 1 4 1 3 1 2 1 1 1 9 8 7 6 5 4 3 2 1 1 5epr) «i,J8*&m. I l£ "V*nT»ff)JTi 1 — 1 7 *l^v 20*0" ^TS^m r *> s / / x / s / N / N . s / s s / V 19" Am I v *> [z£%™ "> -^ 2 2"^™ s Id^jm. v - >Jfl> \ Sent to Cooler S \ 2 3' iJ]L t^ X >i 24'^ io*^ m ^ — >2S'dm ^ 20 ,>l p. ' -' *^6" , am 'Xl'Vim Fig. 9. Natural Zinfandel fermentation (solid line); the same with pure yeast (dotted line). Sugar fermented 1st day 2d 3d 4th 5th 6th 7th " 8th, 9th Completed in Natural With Pure -mentation Yeast. 1% 2% 1 11 1 6 1 4 10 1 4 _. 4 „, 9 days 4 days This chart (Fig. 9) also shows a gain of five days in favor of the tank with cultivated yeast, the regularity of fermentation being also in its favor. The apparent irregularity in the dotted line representing the pure cultivated yeast fermentation on the 19th p. m. was due to the must in the tank being sent through the cooler. 18 UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION. Temperature. 6 6 66 676668 70 71 727374 75 76 77 76^768081 82 83 64 85 8687 68 86 6091 24 23 22 t| 2 0; ! 6 i e ; i 7 ; 1 6 16 1 4 1 3 I 2 1 1 1 8 7 6 6 « 5 2 If 3epl[ J3**,* m i '"a m \ "1^3 "p m ' s | 14'" i4"pin % N. ii j i j i i i i i s . SiV^'k i ' ' " sj\ 1 1 1 1 1 1 i5'"am N v\'*"'p m L s II 1 1 II ! 1 ! JTU« rn ! s \ ~ i v \ 1 1 | "-! x i6'>m | \l5'"^fTl i Ml S s 1 I 1 : s >'?'> ' v i7-*m A it ^ p A ,7>> Si7'am H /i7"pTn fi8"am / J il n8"'am •i8 B, pm Fig. 10. Natural fermentation of Zinfandel (solid line), and with pure yeast (dotted line). Sugar fermented 1st day. 2d " . 3d 4th 5th 6th Natural With Pure Fermentation. Yeast. 6% 3% 8 5 4 5 1 3 3 4 ._ 2 5 days 5$ days Completed in 5 days In this instance (Fig. 10), the natural fermentation was more rapid, being a half day in advance of the tank with the cultivated yeast; but the natural fermentation is quite irregular toward the end. CONTRIBUTION TO THE STUDY OF FERMENTATION. 19 Temperature 70 71 72 73 74 75 76 77 7876 80 8 1 82 83 64 85 88 8 7 88 86 90 61 92 93 94 95 96 97 98 24 23 22 21 20 i e 1 8 17 1 6 1 6 1 A 1 3 1 2 1 1 1 e 8 7 6 5 4 3 2 1 1 kfl — Jf "p.m 19 >pm ^ Ei"p.m . p ZZ"km/ 1 — kzo""*!!! ^~ , - 1 N ! 1 1 • L20"'ATTifrp nv X \ "" -* ^ 'kwSpm > s v2 2. - "'pm i ; ! i •■ ■ H'fiH, In. v^i'^pm > \ | I 23* l.«f» v^JS/'aJn. , > . I i 1 ~~ -.23"^™ | "*« -j?r m\ ] n n i i 1 • •[ V > \ 24'Vm ! _Jj r 1 i \| | 1. J \^24>ir 24'"d.m\ u r\ \ 25'" IE »*a |g Fig. 11. Natural fermentation of Zinfandel and Carignane, mixed (solid line); the same fermented with pure yeast (dotted line). Sugar fermented 1st day " 2d " " 3d " << 4th " a 5th " u 5| '* " (>th " Natural With Pure Fermentation. Yeast. 2% 4% 1 1 5 3 5 4 8 6 3 __ ._ 4 5£days 6 days Completed in 5^ days The result shown in Fig. 11 does not bring out much difference between the two fermentations. The tank with the cultivated yeast is half a day behind, but more regular in the reduction of the sugar toward the end. Notice that in this case there is a mixture of Zinfandel and Carignane. 20 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION. Temperature 70 71 72 75 74 75 76 77 7879 60 8 1 82 65 64 85 88 8 7 88 89 90 91 24 25 22 2 1 20 1 9 i e 1 7 1 6 i 5 I 4 l ; 1 2 1 1 1 9 9 7 6 5 4 5 2 ) p m 23"am 1 - N 23"'pm W - ^ 2 4 "am "V \ ^ -" \ v24**pm \ \ \ N ■^25'am / N • / 25'a^y ' / ^ / \ / / N /25"> m ^.25"'pm \ , - K \ < 26"A m 26" v k . ^Z6> ~- ■" >, 26'" pnt Fig. 12. Natural fermentation Zinfandel and Carignane, mixed (solid line) ; with pure yeast (dotted line). Sugar fermented 1st day 2d "* 3d " Completed in Natural With Pure Fermentation. Yeast. 2% 5% 8 7 11 8 2 2 3£ days 3£ days Here, as shown in Fig-. 12, there is also a mixture of Zinfandel and Carignane, and the fermentation lasts three and one half days in both tanks; but the tank with the eultivated yeast is far more regular. CONTRIBUTION TO THE STUDY OF FERMENTATION, 21 Temperature. 72 73 74 75 76 77 78- 79 80 81 82 83 64 85 88 8 7 88 69 90 91 92 »3 94 95 96 97 98 99 24 23 22 2 r 20 101 1 8, 1*1 16! is; 14 1 3 ! 2 1 1 ] 8 7 6 5 3 2 1 5ept[ ij6 ,h d n. 20'cUn — - --" t V VTjyi pm l< O'Ym. \ \ \ ^I> \ M'lun. l£2"?im \ "*"* -^ \ \ ** ** ,\ \ V \ - •^ ^ 2""p in N N \ \ V k sZ?"V* m 23"" pm Zi" a.m \ v \ X^^'^m. ZS* pm \ \Z4" 1 pm. \ V \ JS'^am ~>24""am. 1 „'• [) I5'\m. •24"pm ^"pmj Fig. 13. The solid line shows natural fermentation of Zinfandel and Carig- nane ; the dotted line shows same fermented with pure yeast. Sugar fermented 1st day. 2d " . Con 3d 4th 4| 5th 6th pleted in Natural With Pure Fermentation. Yeast. 0% 2% 9 2 3 9 4 6 ._ 2 4 _•_ 1 __ 6 days ■ih days In this fermentation of Zinfandel and Carignane, mixed (Fig. 13), the pure yeast has gained half a day on the natural yeast and is also more regular. 22 UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION. Temperature. 80 81 82 83 8465 66 87 9869 70 71 72 737475 76 77 7879 80 81 82 83 8 4 85 8887 88 89 24 23 22 2 || 20 ] g i 8 l 7 1 6 i s i 4 I 3 : 2 ; 1 1 9 3 7 6 5 4 5 2 5 V-jn 2 9'"pm 29'^m 1 30' ,,_ / 1 rf3fl "^m / 1 M<] **• £ — ?*m~ ~^ __ ^^n ~ '*> w> pN! \ X \ S L s s Sn 3"am ! \s$."*d m 1 i . \\ 1 s 1 W'r 1 1 ' 1 i'* ? m V »„ i 1 i i i V ■>«> \ y^ m I 7n^ "^v- \ V I- II 4^>\ l" 1 Fig. 14. Natural fermentation of Carignane and Malvoisie, mixed (solid line); with pure yeast (dotted line). Sugar fermented 1st day. 2d " . 3d 4th 5th Completed in Natural Fermentation. 2°/ 2 With Pure Yeast. 1% 2 4 9 7 5 5 days 6 3 5 days The fermentation of a mixture of Carignane and Malvoisie is shown in Fig. 14. The good fermenting quality of the Carignane shows in the regularity of the fermentation under natural conditions. There is, however, a slight gain of half a day in favor of the cultivated yeast. CONTRIBUTION TO THE STUDY OF FERMENTATION. 23 Temperature. 53 9465 86 97 8969 70 7| 727374 75 79 77 78798081 82 63 64 85 898788 89 90 91 9J 24 23 22 2 1 20 1 9 1 8 1 7 1 6 1 5 1 4 1 3 1 2 ) 1 1 9 9 7 « 5 ■4 3 2 1 5ept JO'M m 3o* K pm J Jo"^' m r 1 3o** p m > \ Octi'Vm^ ^ ^s s i n " a in \ \ ^""a m \ N , "NJ^ptl I j \ 1 1 . <*,■*»*" -„ \ i 1 ! ! I f\ V '-- „ | r ~7 3" am - ■O'^m i ! t V- y pm i V 1 \ # >3"«piJ\i i / \ /'-♦"•pm. ^pjN Fio. 15. Natural fermentation of Carignane and Malvoisie, mixed (solid line): the same fermented with pure yeast (dotted line). .Sugar fermented 1st day 2d 3d 4th 4i 5th Completed in 4| days Natural With Pure ermentation Yeast. 2% 3°/ 1 3 6 6 8 £ 5 ._ ._ 2 4| days b\ days The results in these two tanks of Carignane and Malvoisie, mixed (Fig. 15), were identical, both fermentations finishing at the same time. 24 UNIVERSITY OF CALIFORNIA— EXPERIMENT STATION. Temperature. 70 7| 72 73 7« 75 76 77 78 7© 80 8 1 82 83 84 85 86 8 7 88 89 90 61 92 93,94 24 25 22 21 20 I 8 1 8. 1 7, 1 6 1 5 1 4 1 3 1 2 ! 1 10 9 e 7 6 5 4 5 2 1 Oct r 5 "Vim U "VllTl i5'"pm. "1 -fits I5' fc pnr» > \ N s V V \ s. s i6'a m s k K N X k 16'" pm x \ N N x v s, 7 "am. N l6'"pm 1 \ l7 "r ) V \ < \ 18'"^ m. N \ I7"dm1 l9"rtTTl ; ^ H» Fig. 16. Natural fermentation of Mataro and Carignane, mixed (solid line); same fermented with pure yeast (dotted line). Sugar fermented 1st day 2d " 3d 4th 4£ Completed in Natural Fermentation. 1% 3 With Pure Yeast. 3% 6 7 5 11 2 4 4£ days 3 days With two varieties, such as Mataro and Carignane, that ferment well (Fig. 16), we have a regular and rapid fermentation, but the tank with the cultivated yeast is much more regular and one and one half days ahead. CONTRIBUTION TO THE STUDY OF FERMENTATION. 25 Analyses of Wines resulting from Various Fermentations Recorded on Charts. — From an observation of the analyses of the wines resulting from the fermentations recorded on Figs. 8, 9, 10, 11, 12, and 13, it will be seen that the percentage of alcohol in the wines fermented with cultivated yeast is either greater than or about the same (with the exception of No. 13) as in the wines fermented on their natural yeasts. The volatile acid and the percentage of unfermented sugar are in all cases lower in the wines fermented on cultivated yeast. Analyses of Wines resulting from Fermentation with or without Addition of Cultivated Yeast. Corresponding to Charts. Chart No. Tank No. Fermentation. Alcohol. Per Cent by Volume. Volatile Acid. Grs. per 100 c.c. Reducing Sugar. Grs. per 100 c.c. * 1 314 294 Natural Yeast No. 6 12.0 12.3 .084 -.065 .265 .090 9 1 292 291 Natural Yeast No. 6 10.9 10.9 .133 .052 .110 .075 10 ) 173 272 Natural Yeast No. 5 11.9 11.8 .096 .080 .205 .100 a 1 307 177 Natural Yeast No. 5 12.3 11.8 .094 .080 .170 .120 12 j 307 313 Natural Yeast No. 5 12.3 12.3 .094 .085 .170 .110 13 ] 172 171 Natural Yeast No. 6 11.9 12.4 .096 .093 .205 .175 Correction of the Acidity of the Must. — It has frequently been stated that when the must is deficient in free acid, the fermentation is slower, and sometimes the wine does not pull through. Roos and Chabert, Bouffard, Casalis, and Coste-Floret in France are among the authori- ties who have demonstrated the importance of correcting the acidity of the vintage. It appears that 0.7 to 0.8 per cent is about the normal amount of acidity needed in the fermentation of dry red wine. When the acidity falls below, it is a common practice in Italy and France to raise the acid strength to this standard by adding tartaric acid to the crushed grapes. This is considered a lawful operation, for if the addi- tion be properly made, it does not add anything to the wine that would be injurious to health, nor does it increase the volume; most of the acid is precipitated with the lees. During the vintage we made numerous investigations on the effect of various percentages of acidity on the fermentation of must, and clearly demonstrated that when the acidity was deficient, the fermentation suf- fered. In such cases we increased the acidity to the European standard, with good results. Different varieties of grapes need different acidi- ties, but probably 0.65 to 0.75 per cent for white grapes and 0.70 to 0.80 26 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. per cent for reds is sufficient for California wine. We expect to con- tinue this investigation, with experimental data, this coining vintage. (See Figs. 4 and 7.) The Addition of Sulfurous Acid or Sulfites to White Wine. — We made some investigations on the principle of Andrieu for the handling of white grapes. His theory is to stop the natural fermentation of the must by adding sulfurous acid (sulfur fumes or a metallic sulfite). The fermentation being checked for a period of from twenty-four to forty-eight hours, the dirt settles and a comparatively clean must can be drawn off. The clean must is then inoculated with a pure cultivated yeast trained to ferment in the presence of as great or a greater percentage of sulfurous acid than has been added to the must. The advantage of this method is supposed to be the improvement of the wine, as it is fermented in a comparatively clean state. Very satis- factory results have been obtained by this method in the treatment of grapes that have been damaged by mildew or early rains. We have not sufficient data to offer any conclusions this year, but the method seems very promising. Further investigations will be made the coming vintage. Points Noted on Comparison of Fermentations with and without Culti- vated Yeasts. — 1. Fermentation with cultivated yeasts is more regular. 2. Start of fermentation with cultivated yeasts is more rapid. 3. Period of fermentation is about the same in both. 4. Temperature is the same. 5. The correction of the acidity in the must to 0.7 or 0.8 per cent with tartaric acid greatly assists the fermentation of dry wines. REPORTS AND BULLETINS AVAILABLE FOR DISTRIBUTION, REPORTS. 1896. Report of the Viticultural Work during the seasons 1887-9'], with data regarding the Vintages of 1894-95. 1897. Resistant Vines, their Selection, Adaptation, and Grafting. Appendix to Viticultural Report for 1896. 1898. Partial Report of Work of Agricultural Experiment Station for the years 1895-96 and 1896-97. 1900. Report of the Agricultural Experiment Station for the year 1897-98. 1902. Report of the Agricultural Experiment Station for 1898-1901. BULLETINS. No. 121. The Conservation of Soil Moisture and Economy in the Use of Irrigation 125. Australian Saltbush. [Water. 127. Bench-Grafting Resistant Vines. 128. Nature, Value, and Utilization of Alkali Lands. 129. Report of the Condition of Olive Culture in California. 131. The Phylloxera of the Vine. 132. Feeding of Farm Animals. 133. Tolerance of Alkali by Various Cultures. 134. Report of Condition of Vineyards in Portions of Santa Clara Valley. 135. The Potato- Worm in California. 136. Erinose of the Vine. 137. Pickling Ripe and Green Olives. 138. Citrus Fruit Culture. 139. Orange and Lemon Rot. 140. Lands of the Colorado Delta in Salton Basin, and Supplement. 141. Deciduous Fruits at Paso Robles. 142. Grasshoppers in California. 143. California Peach-Tree Borer. 144. The Peach- Worm. 145. The Red Spider of Citrus Trees. 146. New Methods of Grafting and Budding Vines. 147. Culture Work of the Substations. 148. Resistant Vines and their Hybrids. 149. California Sugar Industry. 150. The Value of Oak Leaves for Forage. 151. Arsenical Insecticides. 152. Fumigation Dosage. 153. Spraying with Distillates. 154. Sulfur Sprays for Red Spider. 155. Directions for Spraying for the Codling-Moth. 156. Fowl Cholera. 157. Commercial Fertilizers. 158. California Olive Oil ; its Manufacture. CIRCULARS. No. 1. Texas Fever. No. 8. Laboratory Method of Water 2. Blackleg. Analysis. 3. Hog Cholera. 9. Asparagus Rust. 4. Anthrax. 10. Reading Course in Economic 5. Contagious Abortion in Cows. Entomology. 6. Methods of Physical and Chem- 11. Fumigation Practice. ical Soil Analysis. 12. Silk Culture. 7. Remedies for Insects. Copies may be had by application to the Director of the Experiment Station, Berkeley, California.