LI B R.ARY OF THE U N I VER.S ITY OF ILLINOIS NOTICE: Return or renew all Library Materials! The Minimum Fee for each Lost Book is $50.00. The person charging this material is responsible for its return to the library from which it was withdrawn on or before the Latest Date stamped below. Theft, mutilation, and underlining of books are reasons for discipli- nary action and may result in dismissal from the University. To renew call Telephone Center, 333-8400 UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN 995 L16I O-I096 Dextrose in Commercial Ice -Cream Manufacture By W. J. CORBETT and P. H. TRACY Bulletin 452 CONTENTS PACE REVIEW OF LITERATURE 347 PART I: ADAPTABILITY OF DEXTROSE FOR USE IN COMMERCIAL ICE CREAM 348 Comparison of Qualities of Part-Dextrose and All-Sucrose Ice Creams 348 Effect of Time of Adding Dextrose to Mix 357 Comparison of Different Types of Dextrose 358 Use of Dextrose in Counter Freezer Mix 358 Use of Dextrose in Mix When Frozen on Vogt Continuous Freezer. ... 358 PART II: EFFECT OF DEXTROSE ON CERTAIN PHYSICAL AND CHEMICAL PROPERTIES OF THE ICE-CREAM MIX 360 Color 360 Viscosity 363 Acidity 364 Curd Tension 367 Protein Stability 368 PART III: CONSUMER PREFERENCE STUDIES ON QUALITIES OF PART-DEXTROSE AND ALL-SUCROSE ICE CREAMS 368 Ice Creams Judged for Body, Flavor and Sweetness 369 When Hydrous Dextrose Was Given a Sweetening Value of 70. ... 369 When Hydrous Dextrose Was Given a Sweetening Value of 100. . . 371 When Hydrous Dextrose Was Given a Sweetening Value of 83.5. . . 372 When One-Fourth of the Sucrose Was Replaced With Anhydrous Dex- trose Pound for Pound 373 Comparison of Ice Creams for Their Refreshing Qualities 373 SUMMARY 375 CONCLUSIONS 378 LITERATURE CITED 378 APPENDIX 379 ACKNOWLEDGMENT Acknowledgment is made of the cooperation of the Corn Products Refining Com- pany of Argo, Illinois, in the promotion of the studies reported in this bulletin. Urbana, Illinois March, 1939 Publications in the Bulletin series report the results of experiments made by or sponsored by the Experiment Station Dextrose in Commercial Ice-Cream Manufacture By W. J. CORBETT and P. H. TRACY* THE BROWN COLOR and bitter flavor of the corn sugar placed on the market during the prewar period limited its use somewhat in the food industries. Since that time, however, manufacturing methods have been so improved that the sugar pro- duced from corn grain today is far superior to that previously manu- factured, being of a snow-white color and of a pleasing flavor. A description of the modern method of manufacturing dextrose is given in the Appendix on page 379. Most of the investigations heretofore reported on dextrose were made previous to the development of more improved methods of manufacture. The experiments described in this bulletin were made to study the merits of dextrose, as it is now refined, in the manufacture of ice cream. REVIEW OF LITERATURE In 1918 Ayers, Williams, and Johnson 2 * found that a portion of the sucrose in ice cream could be replaced with some grades of dextrose, but not with other grades which imparted a yellow color and a bitter flavor. They reported a sweetness of 80 for dextrose, considering the sweetening value of sucrose to be 100. The same year Frandsen, Rovner, and Luithly 9 * found that 50 percent of the cane sugar used in ice cream could be satisfactorily replaced with dextrose. When the entire amount of cane sugar was replaced with dextrose, the ice cream lacked sweetness and had an unpalatable flavor. Combs 4 * reported in 1926 that ice cream containing dextrose must be frozen, held, and served at lower temperatures than all-sucrose ice cream. Tracy and McCown, 14 * and Combs and Bele 5 * also found a slower heat transmission in the hardening room for dextrose ice cream. Martin 12 * reported in 1927 that dextrose mixes required a longer period of refrigeration in the freezer and caused delayed whipping. Both Combs and Erb 8 * found that dextrose had little or no effect in preventing or delaying the occurrence of sandiness, whereas Anthony J W. J. CORBETT, First Assistant in Dairy Research, and P. H. TRACY, Chief in Dairy Manufactures. *Superior figures with asterisk refer to literature citations, pages 378-379. 347 348 BULLETIN No. 452 [March, and Lund 1 * found that dextrose delayed the occurrence of sandiness to a marked degree, and that lactose was much more soluble in a dextrose-sucrose mixture than in combination with sucrose alone. Combs also suggested that dextrose, because of its greater bulk in relation to its sweetness, could be substituted for a part of the serum solids. From this standpoint, dextrose has found favor with the ice- cream industry, for it made it possible to build up the solids in low-total-solids mixes at little or no additional cost. Mack 11 * in 1935 recommended the replacement of part of the sucrose with dextrose in high- fat and high-total-solids ice creams, to prevent the ice creams from having a crumbly texture and to improve the melting qualities. PART I: ADAPTABILITY OF DEXTROSE FOR USE IN COMMERCIAL ICE CREAM To test the adaptability of dextrose for use in commercial ice cream, all-sucrose ice creams and part-dextrose ice creams were com- pared for sweetness, body and flavor, whipping ability, freezing time, melt down, sandiness, hardness, and dipping losses. The effects of the time of adding dextrose to the mix, of different types of dextrose sugars, and of the use of dextrose in the counter freezer mix and in ice cream frozen on the Vogt continuous freezer were also studied. Unless otherwise stated, the data presented in this bulletin were obtained in tests of mixes in which one- fourth of the sucrose had been replaced with dextrose. These mixes are referred to as dextrose mixes. For the tests in Part I the mixes were prepared in lots of various size from 40-percent cream, skimmilk, skimmilk powder (or sweetened condensed skim, or condensed skim, or condensed whole milk), gelatin, powdered egg yolk, and sugar. Mixes were pasteurized and processed at 150 F. and homogenized at 2,500 pounds pressure. COMPARISON OF QUALITIES OF PART-DEXTROSE AND ALL-SUCROSE ICE CREAMS Sweetening Value At the beginning of this study the authors determined (by organo- leptic tests of water solutions of the various sugars) that on a basis of a sweetening value of 100 for cane sugar hydrous dextrose had a sweetening value of 65 to 70 and anhydrous dextrose had a sweetening value of 70 to 75. However, thru tests described here and thru more 1939] DEXTROSE IN COMMERCIAL ICE CREAM 349 extensive tests described in Part III, it was found that when used in conjunction with sucrose in ice cream dextrose had a sweetening value considerably higher than it had in a water solution. The authors wished to use consumer tests to determine the sweet- ening value of dextrose in ice cream, but before this could be done, it was necessary to test the average consumer's ability to detect differ- ences in sweetness. In order to do this, 123 persons were served ice creams made from 14, 15, and 16 percent cane-sugar mixes and were asked to select the sweetest ice cream. The results were as follows: Sugar content of mix Times selected as sweetest 14 percent 13 15 percent 28 1 6 percent 60 22 consumers could detect no difference After finding that a large percentage of consumers were able to detect differences in the sweetness of ice cream varying 1 to 2 percent in sugar content, the consumer test was then used to determine the sweetening value of dextrose in ice cream. The all-sucrose-sweetened and part-dextrose-sweetened ice-cream samples used for these tests were prepared from the same milk products and were processed and frozen at the same time. Only two ice creams were compared at the same time, and these were served on different-shaped paper plates so they could be distinguished easily. Each consumer was given a form sheet on which his preference could be indicated. The preferences expressed by 1,244 consumers who were served the above ice creams and were asked to compare them for sweetness are given in Table 1. From the first group of 611 consumers it was evident that a sweetening value of 70 for dextrose (the sweetening value of sucrose being considered 100) was too low, because the ice cream in which one- fourth of the sucrose was replaced with 1.43 pounds of dextrose per pound of sucrose omitted, was considered sweeter than the all-sucrose ice cream by a large number of consumers. Further tests showed that hydrous dextrose was not sweet enough to replace sucrose pound for pound, making a sweetening value of 100 for this dextrose too high. When, however, hydrous dextrose was given a sweetening value of 83 and substituted for sucrose at the rate of 1.2 pounds to 1 pound of sucrose, the resulting sweetness was comparable to that of the all- sucrose ice cream. It was also found that sucrose could be replaced with anhydrous dextrose, pound for pound, without a noticeable loss of sweetness in the ice cream. 350 BULLETIN No. 452 [March, TABLE 1. CONSUMER COMPARISON OF SWEETNESS OF ALL-SUCROSE AND DEXTROSE ICE CREAMS* Pounds of dextrose used to replace one pound of sucrose Total number of consumers 1 " Number of consumers expressing opinion indicated Dextrose ice cream sweeter Sucrose ice cream sweeter No differ- ence Hydrous dextrose ice creams 1.43... 611 308 186 117 1.33 57 17 26 14 1.20 167 56 64 47 1.00 284 79 153 52 Anhydrous dextrose ice cream 1.00 125 46 52 27 Unless otherwise stated, "dextrose ice cream" refers to ice cream in which one-fourth of the sucrose was replaced with dextrose. b The consumers included two home-bureau clubs, a faculty women's club, a business men's club, a ladies' social club, dairy manufactures groups, and advanced classes in dairy manufactures and home economics, as well as faculty and office employees in the College of Agriculture. Whipping Ability The whipping ability of fifteen all-sucrose mixes varying in sugar content from 14 to 18 percent was compared with the whipping ability of the same number of mixes in which one- fourth of the sucrose was replaced with dextrose. The rate at which the dextrose was added varied from 1 to 1.43 pounds for each pound of sucrose replaced. The mixes were aged 24 hours and frozen on a 40-quart direct-expansion freezer. Minute overrun and temperature readings were taken. All the mixes were frozen to the same consistency before the refrigeration was turned off. In 40 percent of the tests a longer time was required to remove the heat from the sucrose than from the dextrose mixes (Table 2). In 53.3 percent of the tests it took longer to remove the heat from the dextrose mixes, and in 6.7 percent there was no difference. In 80 percent of the tests more time was required for the sucrose mixes to whip to 100 percent overrun, and in 20 percent the dextrose mixes whipped slower. However, the differences were so slight that they were considered of no practical significance. Minimum and Drawing Temperatures Because it is a monosaccharid, dextrose depresses the freezing point of solutions to a greater extent than does sucrose. It naturally follows, therefore, that ice cream containing dextrose will reach a lower temperature during the freezing process than will that con- 1939] DEXTROSE IN COMMERCIAL ICE CREAM 351 TABLE 2. WHIPPING ABILITY AND MINIMUM AND DRAWING TEMPERATURES OF ALL-SUCROSE AND DEXTROSE ICE CREAM MIXES OF VARYING SUGAR CONTENT Sugar content of mix Time to remove heat from mix Time to whip to 100% overrun b Minimum temperature Drawing temperature Mix A Mix B Sucrose Sucrose Dextrose Mix A MixB Mix A MixB Mix A MixB Mix A MixB perct. perct. perct. F. F. *F. F. 14 10.5 3.5* 2' 50* 2' 53* 3' 10* 3' 7" 23.8 22.8 24.1 22.9 14 10.5 3.5 2' 45' 2' 55* 3' 15" 3' 5" 24.8 23.5 25.2 24.4 14 10.5 3.5 2' 50* 2' 50* 4' 00* 3' 50* 24.55 23.85 25.0 24.3 14 10.5 4.65 2' 50* 3' 15* 4' 10* 3' 45* 24.9 23.8 25.6 24.6 14 10.5 4.20 2' 50* 2' 55* 3' 40* 3' 35" 24.5 23.2 25.0 23.8 14 10.5 4.0 2' 45* 2' 53* 3' 15" 3' 7" 25.6 24.0 25.8 24.2 14 10.5 5.0 2' 43* 2' 38* 4' 12" 3' 52" 24.7 23.2 25.1 23.6 14.5 10.85 5.7 2' 47* 2' 52* 3' 43" 3' 8" 24.1 22.9 24.7 23.3 IS 11.25 4.5 2' 55" 2' 45* 4' 25" 4' 5* 24.4 22.7 25.0 23.3 15 11.25 4.5 2' 55" 2' 45* 4' 25* 6' 15" 24.4 23.0 25.0 24.0 15 11.25 5.6 2' 43* 2' 38* 4' 12" 3' 52" 24.7 23.2 25.1 23.6 15 11.25 3.75 3' 10* 3' 3* 2' 50* 2' 57" 23.9 23.0 24.3 23.1 15 11.25 4.5 2' 55* 2' 52" 2' 20" 2' 8" 23.95 23.2 24.1 23.25 16 12.0 4.0 2' 50* 2' 55" 3' 10" 3' 35* 22.9 22.1 23.3 22.5 18 13.5 4.5 2' 50* 2' 53* 3 40* 3' 37* 22.1 21.1 22.7 21.6 Average 2' 53* 2' 55* 3' 48" 3' 42" 24.2 23.1 24.5 23.5 Anhydrous dextrose. b From time refrigeration was shut off until ice cream reached 100 percent overrun. taining all-sucrose sweetening. The average difference between the minimum temperature of the dextrose and that of the sucrose mixes was 1.1 degrees and the average difference between the drawing tem- peratures was 1 degree (Table 2). The dextrose mixes all registered lower temperatures than did the sucrose mixes. Body and Flavor Scores All the ice creams were scored and criticized for body and flavor 24 or 48 hours after they were frozen. The score card used in the national collegiate judging contest was used in this study. When matched samples were compared (Table 3), the all-sucrose and the dextrose ice creams received the same body score in 42.8 percent of the tests. Each was adjudged superior in 28.6 percent of the tests. The most often expressed criticism of the body of the dextrose ice cream was that it melted quicker in the mouth than did the sucrose. The dextrose ice cream scored below the sucrose ice cream in flavor only once, except in those experiments in which sucrose was replaced with hydrous dextrose pound for pound. Then the resulting ice cream was scored down because it was not so sweet. 352 BULLETIN No. 452 TABLE 3. Bony AND FLAVOR SCORES OF ALL-SUCROSE AND DEXTROSE ICE CREAMS [March, Composition of mix Body score* Flavor score b Fat Sucrose Dextrose Anhydrous dextrose ice creams perct. 12 perct. 14 10.5 perct. 3.5 23.5 23.5 44 44 12 16 12 4.0 23.75 23.75 44 44 12 18 13.5 4.5 24 24 44 44 Hydrous dextrose ice creams 12 14 11.4 4.0 22.5 23 43.5 43.5 12 14 10.5 5.0 23.5 22.5 44 43.5 12 14 10.5 3.5 23.5 23.75 43.5 43 12 14 10.5 3.5 23.75 23.5 42 41.5 12 14 10.5 4.65 23.5 23 43.5 43.5 12 14 10.5 4.25 23 23 44 44 12 14 10.5 4.25 22.5 22.5 42.5 42.5 12 15 11.25 4.5 22.5 23 44 44 12 15 11.25 4.5 23.5 23 44 44 14 14.5 10.85 5.7 23.75 24.25 43.5 43.5 16 15 11.2 5.6 25 25 45 45 Perfect score is 25. b Perfect score is 50, tho 46 is high. Melt Down The proper rapidity of melt down is a rather controversial issue among ice-cream manufacturers. A certain degree of ability to "stand up" is necessary for commercial ice cream that is subjected to careless handling while being served or marketed. Excessive resistance to melting, however, is neither necessary nor desirable, as it detracts from both the eye appeal and the palatability of the ice cream. Melting tests were made on duplicate pint samples of frozen ice 1939] DEXTROSE IN COMMERCIAL ICE CREAM 353 cream either 24 or 48 hours after freezing. The ice cream was hardened in pint Sealrights, which were taken from the hardening room 3 hours before the tests were to be run and the sides and top of the cartons removed. A wire was run thru the middle of each sample to facilitate handling, and then the samples were put back into the hardening room for 3 hours. At the beginning of the tests the samples were placed on glass tumblers inverted on 10-inch .pie tins. The tumblers and pie tins had been previously weighed. At regular inter- vals the ice-cream samples were lifted off the tumblers by means of the wires run thru the middle, and the amount of melted ice cream from each sample was weighed and the percentage loss calculated. The average percentage loss in duplicate samples is given in Table 4. It was found that there was an average of 2 to 3 percent greater melt down with the dextrose ice creams than with the all-sucrose ice creams at the various intervals. Assuming that a desirable melt down is one which is smooth, creamy, even, and free from masses of foamy mix, the dextrose mixes gave as desirable a melt down as did the sucrose mixes. Sandiness Sandiness in ice cream is most troublesome during the winter months when the supplies in dealers' cabinets move slowly. This defect can be avoided for the most part by keeping the concentration of lactose below a certain level. Since dextrose causes a marked differ- ence in crystal behavior in candy, as is generally known, it was desired to study the effect of dextrose on the occurrence of sandiness in ice cream. For this experiment mixes containing 12 percent fat and 12 per- cent serum solids were used. The sugar content varied from 14 to 18 percent. For the most part the results were slightly in favor of the dextrose ice creams (Table 5). That is, when differences were detect- able, slightly more sandiness developed in the all-sucrose ice cream than in the dextrose. All the positive organoleptic tests were checked with the microscope to substantiate the results. Dipping Losses Dipping losses are one of the problems confronting retailers of bulk ice cream. Since the temperature at which the ice cream is dipped has been found to be closely related to dipping losses, it is important that the dipping temperature be lowered if the freezing point of the mix has been lowered. Bierman 3 * at the University of 354 BULLETIN No. 452 [March, TABLE 4. MELT DOWN OF SUCROSE AND DEXTROSE ICE CREAMS Composition of mix Amount melted at intervals indicated Fat Sucrose Dextrose 30' 60' 90' 120' ISO' Anhydrous dextrose ice creams perct. perct. perct. perct. Perct perct. perct. Perct. 12 14 11 34 54 10.5 3.5 17 25 52 12 16 12 33 53 12 4.0 10 38 55 12 18 17 35 55 13.5 4.5 21 42 62 Hydrous dextrose ice creams 12 14 14 41 59 11 4.0 2 14 44 59 12 14 5 38 63 80 10.5 5.0 13 52 72 85 12 14 2 7 32 50 10.5 3.5 7 36 54 12 14 7 35 52 10.5 3.5 8 35 56 12 14 21 37 51 10.5 4.65 21 36 46 12 14 20 48 72 83 10.5 4.25 26 55 78 85 12 15 12 48 77 89 11.25 4.5 8 44 74 88 12 15 15 41 64 78 11.25 4.5 16 40 64 76 14 14.5 7 13 18 32 10.85 5.7 7 . 21 34 59 16 15 7 40 64 80 11.2 5.6 11 46 67 83 Maryland found that a dipping temperature of 8 F. gave the best results for a mix containing 12 percent fat, 10.5 percent serum solids, 15 percent sugar (all sucrose), and .35 percent gelatin. He recom- mended that the dipping temperature be lowered 1 degree for each percent of increase in sugar because of the greater softness of ice cream of higher sugar content. Since dextrose depresses the freezing point of mixes to a greater extent than sucrose does, it naturally follows that somewhat lower dipping temperatures should be maintained for dextrose ice creams than for all-sucrose ice creams. Attempts were made to determine the dipping losses of all-sucrose 1939] DEXTROSE IN COMMERCIAL ICE CREAM 355 TABLE 5. RELATION OF PRESENCE OF DEXTROSE TO DEVELOPMENT OF SANDINESS IN ICE CREAM (Mixes contained 12 percent fat and 12 percent serum solids.) Sugar content of mix Intensity of sandiness under conditions indicated* Sucrose Dextrose -15 toO" F. storage to 10 F. storage 17 days 30 days 17 days 7 days 30 days perct. 14 10.5 perct. 3.5 5 6 No difference detectable 5 4 6 5 No difference detectable 16 12 4.0 3 2 No difference detectable 3 2 4 2 No difference detectable 18 13.5 4.5 4 1 No difference detectable 6 1 3 1 No difference detectable The intensity of sandiness is shown by numbers, 1 being the least sandy and 6 the most sandy. and dextrose ice creams dipped at different temperatures (Table 6). Five-gallon ice-cream cans were filled directly at the freezer with ice cream containing 100 percent overrun. After the ice cream had suffi- cient time to harden in the hardening room, it was placed in electric cabinets where the temperatures were carefully regulated. After the ice cream had been given sufficient time to come to the same tempera- ture as the cabinet, it was dipped into quart packages and the yield calculated. The figures given in Table 6 are averages of duplicate or triplicate tests. When the sucrose ice cream was dipped at the same temperature as the dextrose ice cream (considering only matched pairs dipped at TABLE 6. DIPPING LOSSES OF SUCROSE AND DEXTROSE ICE CREAMS" Composition of mix Losses when dipping was done at: Fat Sucrose Dextrose 0F. 4F. 8F. 12 F. perct. 12 perct. 15 11.25 perct. 5.3 perct. perct. 25 32.5 perct. 27.5 35 perct. 12 14 10.25 3.5 28.75 30 30 31.25 12 14 10.5 4.25 3S" 37.5 14 15 11.25 5.3 30 27.5 31.25 31.25 32.5 35 32.5 35 14 17.5 13 4.5 3l'.2S 35 Ice creams in 5-gallon cans were dipped into quart paper containers. 356 BULLETIN No. 452 [March, the same temperature), the average dipping loss for the sucrose was 29.7 percent and for the dextrose 32.2 percent. Percentage dipping losses at temperatures indicated F. 4 F. 8 F. 12 F. Average Sucrose ice cream 29.37 28.75 30.0 32.5 29.7 Dextrose ice cream 28.75 31.66 35.0 35.0 32.2 However, when the dipping temperature of the dextrose ice cream was 4 degrees lower than that of the sucrose ice cream, the average dipping losses of the two ice creams were comparable. Averages calculated in this manner show a dipping loss of 32.3 percent for the all-sucrose and 31.8 percent for the dextrose ice cream. Percentage dipping losses at temperatures indicated F. 4 F. 8 F. 12 F. Average Sucrose ice cream 29.37 31.75 30.0 32.5 32.3 Dextrose ice cream 30.99 36.66 35.0 35.0 31.8 Hardness It is generally thought that dextrose produces an ice cream which breaks faster on the tongue and is less chewy than all-sucrose ice cream. The dextrose ice cream is also softer because of the greater proportion of unfrozen sirup, which, from the standpoint of refresh- ing qualities, should be an advantage. Reid 13 * found that consumers prefer ice cream that is not too hard. He recommends a serving tem- perature of about 10 F. The device used in these tests for determining the relative hardness of the ice cream was a % 6 -inch hollow brass rod with a tapered steel point % inch long. The total length of the plunger was 32% inches, and it was filled with lead filings until it weighed 510 grams. A millimeter scale was imprinted on the rod. The rod was dropped a distance of 13% inches thru a % 6 -inch tube into a frozen pint sample of ice cream. The penetration of the plunger was then read on the millimeter scale. Readings were made in triplicate and seldom varied more than one millimeter. In general at the lower temperatures, 12 to 8 F., the dextrose ice cream was penetrated only slightly more than the sucrose ice cream (Table 7). At higher temperatures the dextrose ice cream had less resistance than the sucrose ice cream. This would indicate that at the usual serving temperature (about 4 to 6 F.) the con- sistency of dextrose ice cream would more nearly approach that considered desirable by the consumer. 1939} DEXTROSE IN COMMERCIAL ICE CREAM 357 TABLE 7. RELATIVE HARDNESS OF SUCROSE AND DEXTROSE ICE CREAMS Composition of mix Penetration in millimeters at: Fat Sucrose Dextrose -12" F. -8F. 0F. 4F. 8F. 12 F. Anhydrous dextrose ice creams perct. perct. perct. 12 14 13.6 10.5 3.5 15.3 12 16 15.6 12 4.0 16.6 12 18 15.3 13.5 4.5 18 16 15 14 11.25 3.75 15.3 Hydrous dextrose ice creams 12 14 12 31 38 10.5 3.5 14.3 33 47 12 14 11.5 28.3 46 10.5 3.5 13.5 36 54 12 14 11.3 10.5 4.65 15.6 12 14 18 11 4.0 17 12 14 14.5 44 52 10.5 5.0 16 67 85 12 15 13 ... 11.25 4.5 17 12 15 13 3 ... 11.25 4.5 14 3 14 14 14 57 70 10.85 5.7 16.6 80 85 16 15 14 47 69 11.2 5.6 16 68 85 EFFECT OF TIME OF ADDING DEXTROSE TO MIX A series of experiments were performed in which an attempt was made to determine the importance of the time of adding dextrose to the mix. It was found that adding dextrose after pasteurizing and either before or after homogenizing had little or no influence on whipping ability, body or flavor, dipping losses or hardness tests. In one experiment a finely pulverized dextrose sugar was added to the mix in the freezer after the ice cream had been partially frozen. It would be an advantage if the dextrose could be successfully incor- porated at this point so that it would not go into solution and depress the freezing point. This method of adding the dextrose, however, 358 BULLETIN No. 452 [March, caused a supercooling in the freezer and the resulting ice cream had an objectionable powdery body, making the procedure undesirable. COMPARISON OF DIFFERENT TYPES OF DEXTROSE Three dextrose sugars commonly used by the different food indus- tries were used in ice cream to compare their relative merits. These sugars were the regular hydrous dextrose (a granulated refined sugar), anhydrous dextrose (a highly purified granulated sugar), and another highly purified granulated hydrous dextrose made chiefly for the bottling industries. When the above sugars were used in ice cream they gave approxi- mately the same results. Anhydrous dextrose is more expensive per pound than hydrous dextrose, but on a dry-matter basis it is only slightly more expensive, and its use in ice-cream making might well be considered, since sucrose can be replaced with anhydrous dextrose pound for pound. The highly purified hydrous dextrose would be the least practical of the three, because the extra processes required in its manufacture make it more expensive than the regular dextrose, and it gives no better results. USE OF DEXTROSE IN COUNTER FREEZER MIX For this experiment seven batches of ice cream varying in fat con- tent from 12 to 16 percent were frozen on either a 2%- or 5-gallon- capacity counter freezer. The use of dextrose had little or no effect on the time required to remove the heat from the mix, or the time required to whip to 100-percent overrun. The difference between the minimum and the drawing temperatures of the dextrose ice creams and those of the sucrose ice cream was approximately the same as when the mixes were frozen on the larger freezer. It is doubtful if these differences are great enough for the average counter freezer operator to detect them. The University Creamery sold ice-cream mix to a drug store that owned and operated a counter freezer, and during part of the year 1935-36 one-fourth of the sucrose was replaced with dextrose in the mix formula. Thruout this period this store did not notice any difference in either the freezing or the dispensing. USE OF DEXTROSE IN MIX WHEN FROZEN ON VOGT CONTINUOUS FREEZER In the first seven experiments with the continuous freezer a 2-tube 120-gallon capacity Vogt freezer was used in which 50- to 70-gallon batches of mix were frozen. For the last experiment a new 60-gallon 1939] DEXTROSE IN COMMERCIAL ICE CREAM 359 capacity single-tube Vogt freezer was used in which 25-gallon batches were frozen. Mix pressure, refrigeration pressure and temperature, overrun, mix temperature, and drawing temperature were taken at 5-minute intervals thruout the freezing period. In these experiments it was found that the use of dextrose did not affect the refrigeration pressure and temperature, the ability to obtain overrun, or the capacity of the freezer, but lowered the drawing tem- perature an average of 1.2 degrees in the first seven experiments, in which one-fourth of the sucrose was replaced with dextrose, and an average of .2 degree in Experiment 8, in which one-seventh of the sucrose was replaced with dextrose (Table 8). The most serious defect of the Vogt- frozen dextrose ice cream was a heavy, soggy, or sticky body. This ice cream also gave an TABLE 8. DRAWING TEMPERATURES, MELT DOWN, AND BODY SCORES OF SUCROSE AND DEXTROSE ICE CREAMS FROZEN ON VOGT CONTINUOUS FREEZER (Composition of mix: 12.5 percent fat, 10.5 percent serum solids, and .3 percent egg) Exp. No. Composition of mix Average drawing temper- ature Type of melt down Body Sucrose Dextrose Gelatin Score Criticism 1 Perct. 14 10.5 14 10.5 14 10.5 14 10.5 14 10.5 14 14 10.5 10.5 14 14 10.5 10.5 13.5 13.5 12.0 12.0 perct. 3~.s' s'.s' 4.65 4! .25 4.25 i'.2S 4.25 4.25 4.25 2.2 2.2 perct. (200 Bloom) .37 .37 .37 .37 .39 .39 .39 .29 .39 .325 .39 .29 .39 .29 .39 .29 .39 .29 (250 Bloom) .2 .3 .2 .3 F. 23.7 23 21.2 20.45 23.9 23 23.9 22.5 22 20.3 24.2 23.7 22.5 22.5 23.7 23.1 22.5 22 21.8 21.9 21.5 21.8 Satisfactory Abnormal, slow Satisfactory Slow, ab- normal Satisfactory Slow, ab- normal Normal Normal Slightly ab- normal Normal Normal Normal Normal Normal 24 24 24 24 24 23.75 24.25 24.5 24.5 23.75 23.75 24 23.5 23 24.5 23 23.5 24 Slightly coarse Sticky Slightly sticky Slightly sticky Slightly sticky Sticky Slightly sticky Satisfactory Satisfactory Sticky Slightly sticky Satisfactory Lacked resistance Lacked resistance Satisfactory Slightly churned, lacked resistance Slightly sticky Satisfactory Lacked resistance Good Good Slightly heavy and soggy 2 3 4 5 6 7 8 Normal Normal Slightly ab- normal Abnormal In Experiment 8 only one-seventh of the sucrose was replaced with dextrose. 360 BULLETIN No. 452 [March, undesirable and abnormal melt down, flattening out and exuding a rather clear serum during the first stages. Later it sloughed off the sides. At the end of two hours it had melted only about two-thirds as much as the control ice cream. Lowering the gelatin (200 Bloom) content from .39 percent to .29 percent in the first seven experiments remedied this defect. In Experiment 8, 250 Bloom gelatin was used and the gelatin content was lowered from .3 percent to .2 percent, which gave a more normal melt down. The exact nature of the abnormal melt down is not entirely known but seems to be closely correlated with protein stability and fat clump- ing. It was found that when the melt down was abnormal, the thin serum which exuded at the beginning was very low in fat and total solids, and the last of the melt down was high in fat and total solids. Alcohol tests showed that the ice creams which gave the abnormal melt down were less stable. In hardness, dipping losses, and flavor scores, the Vogt- frozen ice cream was found to be similar to the batch-frozen ice cream. PART II: EFFECT OF DEXTROSE ON CERTAIN PHYSICAL AND CHEMICAL PROPERTIES OF THE ICE-CREAM MIX Since dextrose contains a functional aldehyde group, it is chemically somewhat more active than sucrose. Therefore it might be expected to react sufficiently with the proteins so that differences could be detected by physical and chemical tests. With this in mind, an attempt was made to determine the effect of dextrose on mix color, viscosity, pH, curd tension, and protein stability. For these tests small experimental mixes were made from 40-per- cent cream, skimmilk, and concentrated skim. The mixes contained 12 percent fat, 10.5 percent serum solids, .35 percent gelatin, and varying amounts of sugar, and were homogenized at 2,500 pounds pressure. Color The color determinations were made thru photometric readings with a Keuffel and Esser color analyzer, using wave lengths ranging from 480 to 630 millimicrons. This procedure compares the color of the mix with the color of magnesium carbonate, which is one of the whitest substances known. The whiter the mix, the closer the color reading approaches 100; the darker the mix, the closer the color reading approaches zero. 1939] DEXTROSE IN COMMERCIAL ICE CREAM 361 TABLE 9. PHOTOMETRIC READINGS OF SUCROSE AND DEXTROSE MIXES PASTEURIZED AT DIFFERENT TEMPERATURES' Wave length Readings taken when mix was pasteurized at: 142 F. 150 F. 160 F. Mixl Mix 2 Mix 3 Mix 4 Mixl Mix 2 Mix 3 Mix 4 Mixl Mix 2 Mix 3 Mix 4 Readings taken on unaged mix 480 58 55 57 55 56.5 59 53.5 55.5 60 57 59 59 510 64 5 62 62 5 65 66 5 66.5 61.5 63 67 62 64 64 540 68.5 67 66.5 67 67 68 64.5 65 67 64 69 69 570 68.5 67 67 67 67.5 68 66 65 65 67 67 67 600 67.5 67.5 66 66 64 57 61 64 67 63 67 67 630 65 65 64 63.5 64 57 62.5 64 67 61.5 67 67 Readings taken after aging mix ten days at 40 F. 480 55 56 57 57 57 57 56 57.5 57 57 56 57.5 510 66 64 64 65.5 65 65 65 65 66 66 66 65 540 . . 71 71 70 67 5 70 68 70 70 70 67.5 70 67 5 570 70 71 71 68 69 68.5 70 67 70 68.5 70 69 600 . . 70 68 70 67 5 68 68 69 67.5 69 67 70 68 630 70 69 68 66 67.5 66 67 66.5 68 67 69 67.5 Mixl: 14 percent sucrose. Mix 2: 12 percent sucrose, 3 percent dextrose. Mix 3: 8 percent sucrose, 8 percent dextrose. Mix 4: 20 percent dextrose. The results of photometric readings of mixes sweetened with sucrose, with a mixture of sucrose and dextrose, and with all dextrose are given in Table 9. The mixes were pasteurized for 30 minutes at 142 F., 150 F., and 160 F. Slightly more color was recorded when dextrose was used, but the differences were not detectable by the naked eye. The dextrose mixes pasteurized at 160 F. showed some- what less color than those pasteurized at lower temperatures. The samples held 10 days showed slightly less color than did the unaged mix. Photometric readings of mixes in which the sugar was added at different stages during the processing are given in Table 10. The mixes were pasteurized at 150 F. The samples in which the sugar was added to the cold milk products and then pasteurized for 30 minutes were the most highly colored. The dextrose mixes were slightly darker than the sucrose mixes, but the color differences were so slight that they could be considered of no importance for all practical purposes. Sugar-and-water solutions were also made up and photometric readings taken to determine whether the increase in color that had been observed in the mixes was due to a dextrose-protein reaction or whether the sugar itself caused an increase in color. In the unheated sugar solutions it was impossible to detect any differences in amount of 362 BULLETIN No. 452 [March, TABLE 10. PHOTOMETRIC READINGS OF MIXES IN WHICH SUGAR WAS ADDED AT DIFFERENT TIMES IN THE PROCESSING* (Mixes were pasteurized 30 minutes at 150 F.) Wave length Readings when sugar was added at time indicated When batch was started When pasteurization tem- perature was reached Just before cooling Mixl Mix 2 Mix 3 Mixl Mix 2 Mix 3 Mixl Mix 2 Mix 3 480 56 63 69 68 67 67.5 55 62 68 67.5 66 66.5 54 59 64.5 65 63 62.5 56.5 64 68.5 68.5 68 66.5 55.5 62.5 68.5 67.5 66.5 66 55 61.5 66 66 64.5 63.5 56 64 69 69 68.5 66 55.5 62.5 68 67.5 66.5 65.5 55 62 66 66 66.5 63.5 510 . . . . 540 570 600 630 Mixl: 14 percent sucrose. Mix 2: 8 percent sucrose, 8 percent dextrose. Mix 3: 20 percent dextrose. color. In the samples which had been heated to 150 F. for 30 minutes there was more color in the dextrose than in either cane or beet sugar solutions (Table 11). The unheated sugar solutions were darker than the heated solutions, probably because heating caused more complete dispersion of the sugar, thus lessening the color. There was as great a difference in the color of the sugar-and- water solutions as in the color of the mixes to which the sugar was added and then heated. This would suggest that the slight difference in TABLE 11. PHOTOMETRIC READINGS OF SUGAR-AND- WATER SOLUTIONS Sugar content of solution Readings taken on wave length indicated 480 510 540 570 600 630 Solutions not heated 14 percent cane 13 13 13 13 13 16 16 15 15 15 16 16 16 16 15 17 17 17 17 17 17 17 17 17 17 17 16 17 17 17 14 percent beet 8 percent cane, 8 percent dextrose 8 percent beet, 8 percent dextrose 20 percent dextrose Solutions heated to 150 F. for 30 minutes 14 percent cane 15.5 16 15 15 14 17.5 18 17 17 15.5 18 18 18 18 15.5 17.5 18.5 19 18 16 18 19 18 19 16 19 20 17 18 15 14 percent beet 8 percent cane, 8 percent dextrose 8 percent beet, 8 percent dextrose 20 percent dextrose 1939] DEXTROSE IN COMMERCIAL ICE CREAM 363 color is not due to a reaction between dextrose and the mix constituents, but to the sugar itself. Viscosity Within reasonable limits the degree of viscosity in a mix has no particular significance. However, from an experimental point of view it is of interest to know to what extent each of the ingredients entering a mix may affect the viscosity. Anything which could cause a decided increase or decrease in viscosity would likely be considered undesirable by the ice-cream manufacturers, altho slight variations in this respect would be of little consequence. In these tests the viscosity of sucrose and dextrose mixes was measured with a MacMichael viscosimeter. The results of these measurements for mixes heated at varying temperatures for different periods of time are given in Table 12. These mixes were all heated to 142 F. and homogenized. They were then given the additional heat treatment indicated in the table. The additional holding time resulted in nearly all cases in a reduced viscosity, there being little difference in the effect of the two sugars in this respect. Increasing the amount of dextrose increased the viscosity of the mix, which was heated to pasteurizing temperature and cooled immediately, but the viscosity generally grew less the longer the mix was held at the pas- teurization temperature. According to the data in Table 13, dextrose has a tendency to reduce mix viscosity. Tests on pairs of comparable batches showed TABLE 12. VISCOSITY OF SUCROSE AND DEXTROSE MIXES HEATED AT DIFFERENT TEMPERATURES FOR DIFFERENT PERIODS OF TIME" Sugar content of mix Viscosity in degrees MacMichael when mix was held at temperature and for time indicated 142 F. 150 F. 160 F. 0' 30' 60' 0' 30' 60' 0' 30' 60' 14 percent sucrose 98 98 101 103 96 94 90 95 93 90 91 89 99 108 108 100 92 92 94 88 88 92 87 83 99 92 91 97 92 96 90 76 86 86 95 90 12 percent sucrose, 3 percent dextrose 8 percent dextrose, 8 percent sucrose 20 percent dextrose Measured at 45 F. with a No. 30 wire. 364 BULLETIN No. 452 [March, TABLE 13. VISCOSITY OF COMPARABLE BATCHES OF SUCROSE AND DEXTROSE ICE CREAM" Trial Composition of mix Viscosity (degrees MacMichael) Fat Sucrose Dextrose 1 percl. 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12.5 12.5 12.5 12.5 13 13 14 14 16 16 perct. 14 10.5 14 10.5 14 10.5 14 10.5 14 10.5 16 12 18 13.5 15 11.25 14 10.5 13.5 12 13.5 12 14 10.5 14.5 10.85 15 11.25 perct. 5.0 4.2 4.2 4.2 3.5 4.0 4.5 4.5 3.5 2.2 2.2 4.65 5.7 3.75 66.5 40 100 87 88 61 49.5 44 71 88 68 90 86 97 26 40 83 60 21 18.5 31.25 25.75 141 96 82 70 260 249 2 3 4 5t> 6b ?b 8 9 10 11 12 13 14 "Viscosity measured with No. 26 wire. b Sugar added to mixes after the other products had been processed. that in 11 out of 14 trials the viscosity of the dextrose-sucrose mixes was less than that of the all-sucrose mixes. A series of sugar-gelatin-water solutions were also made up and heated at 150 F. for 30 minutes and viscosities determined to see whether or not the dextrose had inhibited the hydration of the gelatin. The data in Table 14 indicate that dextrose did not affect the viscosity of such solutions. Acidity A portable Leeds and Northrup quinhydrone outfit was used for measuring the hydrogen-ion concentration of all-sucrose, part-dex- trose, and all-dextrose mixes. The mixes containing dextrose were 1939} DEXTROSE IN COMMERCIAL ICE CREAM 365 TABLE 14. VISCOSITY OF GELATIN-WATER SOLUTIONS TO WHICH SUCROSE, MIXTURES OF SUCROSE AND DEX- TROSE, OR DEXTROSE, WAS ADDED* (Solutions heated at 150 F. for 30 minutes) Gelatin used Composition of solution Viscosity (degrees MacMichael) Gelatin Sucrose Dextrose A perct. .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 .45 perct. 20 15 10 5 20 15 10 5 20 15 10 5 20 15 10 5 20 15 10 5 perct. 5 10 15 20 5 10 15 20 5 10 15 20 5 10 15 20 5 10 15 20 3.5 7 7 7 7.5 7 4 8 8 8.5 8.5 8 6 9 9 9.25 9 8.5 25 46 47.5 46.5 44.5 45.5 61.5 58 61 57 60 B c D b Di b Viscosity measurements were made with a No. 26 wire. b Viscosity of Gelatins D and Di was measured with a No. 30 wire. Gel- atin Di was the same as D, but gelatin-and-sugar solutions were made up and heated separately and then combined in the correct proportion after the solu- tions had cooled. Viscosity was measured after 24 hours. TABLE IS. EFFECT OF DEXTROSE ON pH OF MIXES* pH of mix pasteurized at temperature indicated Pasteur- izing time 142 F. 150 F. 160 F. Mixl Mix 2 Mix 3 Mix 4 Mixl Mix 2 Mix 3 Mix 4 Mixl Mix 2 Mix 3 Mix 4 minutes . 6.5 6.52 6.47 6.45 6.4 6.35 6.35 6.25 6.4 6.25 6.32 6.25 30 minutes . 6.35 6.34 6.32 6.23 6.4 6.32 6.28 6.20 6.45 6.45 6.40 6.35 60 minutes 6.42 6.45 6.40 6.32 6.35 6.35 6.35 6.25 6.55 6.52 6.50 6.40 Mixl: 14 percent sucrose. Mix 2: 12 percent sucrose, 3 percent dextrose. Mix 3: 8 percent sucrose, 8 percent dextrose. Mix 4: 20 percent dextrose. 366 BULLETIN No. 452 [March, from to .2 lower in pH than the all-sucrose mixes (Table 15). The greatest decrease took place when dextrose was the only sugar used. An experiment was also made to determine the effect on pH of the extent of the heat treatment given the mix. The longer the milk TABLE 16. EFFECT ON pH OF EXTENT OF HEAT TREATMENT GIVEN Mix (Pasteurizing temperature, 150 F.) Sugar content of mix pH of mix after treatment indicated Sugar dissolved in mix at 150 F.; mix cooled immediately Sugar added to cold mix; mix heated to 150 F. and held 30 min. Sugar added to cold mix; mix heated to 150 F. and held 60 min. 14 percent sucrose 6.46 6.41 6.41 6.46 6.42 6.36 6.44 6.35 6.28 8 percent sucrose, 8 percent dextrose 20 percent dextrose TABLE 17. HYDROGEN-!ON CONCENTRATION AND TITRATABLE ACIDITY OF SUCROSE AND DEXTROSE MIXES Composition of mix PH Titratable acidity Fat Serum solids Sucrose Dextrose perct. 12 12 perct. 10.5 10.5 perct. 14 10.5 perct. 5 6.48 6.415 perct. 14 14 10 10 14.5 10.85 5.7 6.51 6.51 16 16 9 9 15 11.2 5.6 6.45 6.405 16 16 9 9 15 11.25 3.75 6.39 6.39 .155 .165 12 12 10.5 10.5 14 10.5 4.2 6.395 6.395 .22 .21 12 12 10.5 10.5 15 11.25 4.5 6.40 6.39 .24 .25 12 12 12 12 14 10.5 3.5 .23 .25 12 12 12 12 16 12 4.0 .23 .24 12 12 12 12 18 13.5 4.5 .24 .24 16 16 9 9 15 11.25 3.75 .17 .18 Average for dext Average for sucrc ose mixes 6.417 6.437 .219 .212 >se mixes 1939] DEXTROSE IN COMMERCIAL ICE CREAM 367 products were heated in combination with the dextrose, the lower the pH (Table 16). The greatest decrease in pH took place when dextrose was used as the sole sweetener. When only part of the sucrose was replaced with dextrose and the mix was pasteurized at 150 F. for 30 minutes, the decrease was slight. A comparison of the acidity of a number of mixes of varying fat and sugar content made up in 100- to 500-pound batches was also made. The part-dextrose mixes tended to be slightly lower in pH and higher in titratable acidity, but the differences were too small to be significant (Table 17). Curd Tension In order to get a more accurate picture of what changes might take place between the dextrose and the milk protein, the curd tension of mixes to which different sugars were added was determined. A modification of the Hill 10 * curd test was used to measure the firmness of the coagulum formed when the ice-cream mix was coagulated with a calcium chlorid plus pepsin solution. The curd tension was measured in grams which represent the force required for a standard star-shaped knife to be pushed thru the coagulated curd. The dextrose was found to exhibit no measurable effect on the curd tension (Table 18). In further studies the sugar was added to the mix at different times: it was added to the cold milk products before the mix was processed; added to the mix before pasteurizing but as soon as the other products had reached pasteurizing temperature ; and added after pasteurizing and just before cooling. The time at which the sugar was added to the mix was found to have no effect on the curd tension. TABLE 18. CURD TENSION OF SUCROSE AND DEXTROSE ICE-CREAM MIXES (Mixes contained 12 percent fat and 10.5 percent serum solids) Sugar content of mix Curd tension when pasteurized at temperature and time indicated 142 F. ISO" F. 160 F. 0' 30' 60' 0' 30' 60' 0' 30' 60' 14 percent sucrose grams 26 23 23 22 24 24 20 22 24 22 23 22 grams 24 22 23 24 28 24 20 26 22 22.5 24 25 grams 20 22 20 22 25 18.5 21 20 18 20 22 22 12 percent sucrose, 3 percent dextrose 8 percent sucrose, 8 percent dextrose 20 percent dextrose 368 BULLETIN No. 452 [March, TABLE 19. PROTEIN STABILITY OF MIXES SWEETENED WITH SUCROSE, SUCROSE AND DEXTROSE, AND DEXTROSE Sugar content of mix Measure of protein stability* when pasteurized at temperature and for time indicated 142 F. 150 F. 160 F. 0' 30' 60' 0' 30' 60' 0' 30' 60' 14 percent sucrose 5.3 5.3 5.1 5.0 5.9 5.2 5.3 5.2 5.2 5.5 5.8 5.0 4 4.2 5.6 4.3 4.8 4.9 4.1 5.0 5.0 4.2 5.5 5.0 4.4 4.5 4.5 4.8 4.7 4.9 4.3 4.5 4.9 4.4 4.4 4.8 12 percent sucrose, 3 percent dextrose 8 percent sucrose, 8 percent dextrose 20 percent dextrose 'Cubic centimeters of alcohol required to start precipitation in a 2-cc sample of mix diluted with an equal amount of distilled water. Protein Stability The alcohol test was used to measure the protein stability of the mix. A 2-cc sample of mix was diluted with an equal amount of dis- tilled water and then 95-percent ethyl alcohol was added until the first signs of precipitation occurred. With this method it is some- times rather difficult to determine the correct end-point, but the method is accurate enough to give the information desired. No correlation was found between the sugar used and the stability of the protein (Table 19). Even when dextrose was used as the sole source of sugar, the alcohol tests were as high as they were when sucrose was used. Adding dextrose and sucrose at different intervals in the processing had no effect on the protein stability of the mixes. PART III: CONSUMER PREFERENCE STUDIES ON QUALITIES OF PART-DEXTROSE AND ALL-SUCROSE ICE CREAMS After it was shown that dextrose could be successfully used in the manufacture of commercial ice cream, and that it had no detri- mental effect upon certain physical and chemical properties of the mix, it remained to determine to what extent ice cream containing dextrose would be acceptable to the consumer. While it is realized that the accuracy of data secured from consumer studies is open to some criticism, such data do help in determining the general likes and dislikes of the consuming public. About 500 people in nine different groups took part in these consumer studies. 1939] DEXTROSE IN COMMERCIAL ICE CREAM 369 ICE CREAMS JUDGED FOR BODY, FLAVOR AND SWEETNESS The ice-cream samples were prepared in the same way as those for the consumer tests described in Part I. Most of the ice cream was frozen to 100-percent overrun and served from gallon containers; the remainder was frozen to 80-percent overrun and served in bricks. A reproduction of the questionnaire which was filled out by the consumers is given below. Experiment No 1. Did you notice any difference in the flavor of the ice creams? If so, which flavor did you prefer and why? 2. Did you notice any difference in the body of the ice creams? If so, which ice cream did you think had the best body? 3. Did you notice any difference in the sweetness of the two ice creams? If so, which had the sweeter taste? 4. Were you hungry at the time of the judging? 5. Do you enjoy eating ice cream? Occupation Sex. When Hydrous Dextrose Was Given a Sweetening Value of 70 In this experiment one- fourth of the sucrose was replaced with hydrous dextrose at the rate of 1.43 pounds of dextrose per pound of sucrose, giving the corn sugar a sweetening value of 70 compared with a sweetening value of 100 for the cane sugar. The ice creams were of the following compositions: (1) 12 percent fat, 10.5 percent serum solids, 14 percent sugar, .35 percent gelatin, and .3 percent dried egg yolk; (2) 14 percent fat, 10 percent serum solids, 14.5 percent sugar, .33 percent gelatin, and .30 percent dried egg yolk; (3) 16 percent fat, 9 percent serum solids, 15 percent sugar, .30 percent gelatin, and .30 percent dried egg yolk. The mixes were frozen on a 40-quart direct- expansion batch freezer. The dextrose ice cream was found to be comparable to the sucrose ice cream in body and flavor but was considered much sweeter (Table 20). The most common criticisms, or reasons for preferences, are given in Table 21. Many of the consumers thought that the dextrose ice cream tasted richer or creamier than the sucrose ice cream. It is probable that the slightly different type of body produced by the dex- trose could account for the seemingly richer flavor. The data in Tables 20 and 21 show quite conclusively that when dextrose is used to replace a fourth of the sucrose, a sweetening value of 70 for dextrose is too low. 370 BULLETIN No. 452 [March, TABLE 20. CONSUMER COMPARISON OF PART-DEXTROSE AND ALL-SUCROSE ICE CREAMS FOR BODY, FLAVOR, AND SWEETNESS, WHEN ONE-FOURTH OF SUCROSE WAS REPLACED WITH HYDROUS DEXTROSE GIVEN A SWEETENING VALUE OF 70 Kind of sweetening Number preferring quality indicated Number choosing ice cream as sweeter Number finding no difference in quality indicated Body Flavor Body Flavor Sweetness 12 percent fat in mix Sucrose 146 161 118 144 83 172 48 93 100 Dextrose 14 percent fat in mix 63 22 37 25 36 33 10 33 23 Dextrose 16 percent fat in mix Sucrose 106 103 87 85 77 103 33 70 62 All mixes Sucrose 315 286 242 254 196 308 91 196 185 Dextrose TABLE 21. CONSUMER COMMENTS ON PART-DEXTROSE (HYDRATE) AND ALL- SUCROSE ICE CREAMS WHEN DEXTROSE WAS GIVEN A SWEETENING VALUE OF 70 Reason for preference 12 percent fat 14 percent fat 16 percent fat Sucrose Dextrose Sucrose Dextrose Sucrose Dextrose Number of persons basing preference on reason indicated Not so sweet 17 8 5 9 7 8 3 14 5 28 49 19 3 1 10 2 8 2 5 1 1 10 4 2 6 16 11 7 8 10 5 6 9 5 15 23 4 11 4 5 12 Sweeter Richer or creamier Not so rich Smoother body Better texture and body Firmer body Better flavor 1939] DEXTROSE IN COMMERCIAL ICE CREAM 371 TABLE 22. CONSUMER COMPARISON OF PART-DEXTROSE AND ALL-SUCROSE ICE CREAMS FOR BODY, FLAVOR, AND SWEETNESS, WHEN ONE-FOURTH OF SUCROSE WAS REPLACED WITH HYDROUS DEXTROSE GIVEN A SWEETENING VALUE OF 100 Kind of sweetening Number preferring Quality indicated Number choosing ice cream as sweeter Number finding no difference in quality indicated Body Flavor Body Flavor Sweetness Sucrose 104 146 125 87 153 79 34 72 52 Dextrose When Hydrous Dextrose Was Given a Sweetening Value of 100 The ice cream used for this test contained 12 percent fat, 11.5 percent serum solids, 14 percent sugar, .37 percent gelatin, and .30 percent dried egg yolk. The mix was frozen on a Vogt continuous freezer having a capacity of 120 gallons an hour. The body of the dextrose ice cream was considered sticky by the authors, and the cane- sugar ice cream was considered sweeter than the dextrose. The majority of consumers also found the sucrose ice cream sweeter (Table 22), indicating that in sweetening value a pound of hydrous dextrose is not equivalent to a pound of sucrose. The flavor of the sucrose ice cream was preferred by about as many consumers as judged that ice cream sweeter than the dextrose. It is interesting to note the decided preference for the body of the dextrose ice cream altho the authors had criticized it as slightly heavy and sticky. The most numerous comments on the body and flavor of the two ice creams are given in Table 23. TABLE 23. CONSUMER COMMENTS ON PART-DEXTROSE (HYDRATE) AND ALL-SUCROSE ICE CREAMS WHEN DEXTROSE WAS GIVEN A SWEETENING VALUE OF 100 (Both sucrose and dextrose mixes contained 12 percent fat) Reason for preference Sucrose Dextrose Number of persons basing prefer- ence on reason indicated 31 10 5 24 9 14 6 14 7 21 14 Not so sweet Smoother body Body not so heavy or gummy Better flavor 372 BULLETIN No. 452 [March, When Hydrous Dextrose Was Given a Sweetening Value of 83.5 Since the consumer tests indicated that the dextrose ice cream was much sweeter than the all-sucrose ice cream when one-fourth of the sucrose was replaced by dextrose at the rate of 1.43 pounds of dextrose per pound of sucrose, and not so sweet as the sucrose ice cream when the dextrose replaced the sucrose pound for pound, TABLE 24. CONSUMER COMPARISON OF PART-DEXTROSE AND ALL-SUCROSE ICE CREAMS FOR BODY, FLAVOR, AND SWEETNESS, WHEN ONE-FOURTH OF SUCROSE WAS REPLACED WITH HYDROUS DEXTROSE GIVEN A SWEETENING VALUE OF 83.5 Kind of sweetening and gelatin content Number of consumers preferring quality indicated Number of consumers choosing ice cream as sweeter Number of consumers finding no difference in quality indicated Body Flavor Body Flavor Sweetness Sucrose, .39 percent gelatin Dextrose, .325 percent gelatin . . SO 19 31 22 30 24 9 25 24 Sucrose, .39 percent gelatin Dextrose, .29 percent gelatin. . . 54 25 42 20 34 32 10 27 23 another experiment was made in which 1.2 pounds of dextrose was used to replace one pound of sucrose, this amount being the median derived from the sweetening values given to dextrose in the two pre- ceding experiments. The sucrose mix contained 12.5 percent fat, 10.75 percent serum solids, 14 percent sugar, .39 percent gelatin, and .30 percent dried egg yolk. For the dextrose ice creams the fat and serum solids were the same as for the all-sucrose mix, but the gelatin con- tent was lowered to .325 percent and to .29 percent, as it had been previously shown (Part I) that a reduction of the gelatin content in the mix would prevent or lessen the heaviness or stickiness in the body of the Vogt-frozen dextrose ice creams. These ice creams were also frozen on a Vogt continuous freezer. The authors were of the opinion that the all-sucrose ice cream had a slightly sticky body, but that the dextrose ice cream was free from that defect. However, the body of the sucrose ice cream was much preferred by the consumers, and this may have influenced their preference for the flavor of that ice cream also. The fact that the opinions on sweetness were about evenly divided indicates that a sweetening value of 83.5 for dextrose (compared with 100 for sucrose) is quite close to its actual value. 1939] DEXTROSE IN COMMERCIAL ICE CREAM 373 TABLE 25. CONSUMER COMPARISON OF PART-DEXTROSE AND ALL-SUCROSE ICE CREAMS FOR BODY, FLAVOR, AND SWEETNESS, WHEN ONE-FOURTH OF SUCROSE WAS REPLACED POUND FOR POUND WITH ANHYDROUS DEXTROSE Kind of sweetening Number preferring quality indicated Number choosing ice cream as sweeter Number finding no difference in quality indicated Body Flavor Body Flavor Sweetness Sucrose 57 40 41 48 52 46 28 36 27 Dextrose When One-Fourth of the Sucrose Was Replaced With Anhydrous Dextrose Pound for Pound Anhydrous dextrose differs from the regular dextrose in that it is slightly more refined and is moisture- free. These qualities should raise its sweetening value above that of the regular dextrose. To determine the correct sweetening value of anhydrous dextrose anci to measure consumer preferences, a mix was prepared containing 16 percent fat, 9 percent serum solids, 15 percent sugar, .30 percent gelatin, and .30 percent dried egg yolk. In the dextrose ice cream one- fourth of the sucrose was replaced with anhydrous dextrose pound for pound. The ice creams were frozen on a 40-quart direct-expansion batch freezer. These ice creams were given similar scores by the authors. The consumer tests (Table 25) show that in sweetness and flavor anhy- drous dextrose is comparable to sucrose. The body of the cane-sugar ice cream was preferred by the greater number of consumers. COMPARISON OF ICE CREAMS FOR THEIR REFRESHING QUALITIES The dextrose-sweetened ice cream seemed to the authors to have a slightly shorter texture, to melt down faster on the tongue, and to be slightly less chewy than ice cream sweetened entirely with sucrose. These qualities should make the dextrose more cooling or refreshing. In order to test this hypothesis, mixes were prepared containing 12 percent fat, 10.75 percent serum solids, 14 percent sugar, .35 percent gelatin, and .30 percent dried egg yolk. Data were also obtained on mixes of 16 percent fat, 9 percent serum solids, 15 percent sugar, .30 percent gelatin, and .30 percent dried egg yolk. In the dextrose mixes one-fourth of the sucrose was replaced with anhydrous dextrose pound for pound. 374 BULLETIN No. 452 [March, TABLE 26. CONSUMER OPINIONS CONCERNING REFRESHING QUALITIES OF SUCROSE AND DEXTROSE ICE CREAMS Sucrose Dextrose No difference 16 percent fat in mix Number preferring ice cream indicated 41 33 75 43 11 51 Number judging ice cream most refreshing 12 percent fat in mix Number preferring ice cream indicated 72 44 29 25 15 47 Number judging ice cream most refreshing The ice creams were frozen on a 40-quart direct-expansion batch freezer and were served on very warm days. They were given similar scores by the authors. The following type of questionnaire was used for the consumer tests. Questionnaire: Which of the ice creams do you prefer? What are the reasons for your choice? Do you notice any difference in the refreshing qualities of the ice creams? If so, which one do you consider most refreshing? Do you consider the regular commercial ice cream on the market satis- factory from the standpoint of refreshment? Occupation Sex Consumers did not find much difference between the dextrose- TABLE 27. CONSUMER COMMENTS ON PART-DEXTROSE (ANHYDRATE) AND ALL- SUCROSE ICE CREAMS WHEN DEXTROSE WAS GIVEN A SWEETENING VALUE OF 100 Reason for preference 12 percent fat in mix 16 percent fat in mix Sucrose Dextrose Sucrose Dextrose Number basing preference on reason indicated Sweeter 25 9 9 17 9 1 17 4 9 3 3 1 7 8 3 10 3 9 5 7 25 5 17 13 16 6 24 Not so sweet Richer and creamier Smoother body Better body and texture Firmer body Better flavor 1939] DEXTROSE IN COMMERCIAL ICE CREAM 375 sweetened and the all-sucrose sweetened ice creams from the stand- point of their refreshing qualities. When the mix contained 16 percent fat, dextrose was preferred to the all-cane-sugar ice cream (Table 26). Consumers thought it was sweeter, richer, and creamier than the all-sucrose ice cream, and that it had better flavor, body, and texture (Table 27). This decision was reversed when the mix contained only 12 percent fat. SUMMARY Studies were made of the adaptability of dextrose for use in commercial ice cream. In most of the tests one- fourth of the sucrose was replaced with dextrose in the dextrose mixes. The part-dextrose- sweetened ice creams and the all-sucrose-sweetened ice creams were compared for sweetness, body and flavor, sandiness, whipping ability, melt down, hardness, and dipping losses. The time of adding dextrose to the mix, different types of dextrose sugars, and the effect of freez- ing dextrose mixes in the counter freezer and the Vogt continuous freezer were also studied. In addition, the effect of dextrose upon certain physical and chemical properties of the mix was determined, and consumer tests of the various ice creams were made. Sweetening Value. In water solution dextrose had a sweetening value of approximately 65 to 75, compared with 100 for cane sugar, but its sweetening value was greater than this when it was used in conjunction with sucrose in ice cream. Consumer tests showed that when one-fourth of the sucrose for an ice-cream mix was replaced with dextrose, one pound of hydrous dextrose was equivalent in sweetness to .83 pound of sucrose, and that anhydrous dextrose could replace cane or beet sugar pound for pound. Whipping Ability. Dextrose-sucrose mixes frozen on 10-, 12-, 20-, and 40-quart direct-expansion batch freezers whipped to 100 percent overrun in about the same time as did all-sucrose mixes. Minimum and Drawing Temperatures. The time required to remove the heat from both mixes was practically the same. The average drawing temperature of the dextrose ice cream was 1 degree Fahrenheit lower than that of the all-sucrose ice cream when frozen in the batch freezer and 1.2 degrees lower when frozen in the Vogt freezer. Flavor, Body, Melt Down, and Sandiness. When used to replace one-fourth of the sucrose, dextrose had little or no effect on flavor or body scores. The dextrose ice cream melted down slightly more 376 BULLETIN No. 452 [March, rapidly than the all-sucrose ice creams, tho the percentage loss in weight at 60 to 90 minutes was rarely more than 2 to 5 percent greater. When dextrose was used to replace one- fourth of the sucrose in high-serum-solids mixes, there was a slight delay in the development of sandiness. Dipping Losses. Owing to differences in hardness, dipping losses for dextrose ice cream were slightly higher than for sucrose ice cream when the dipping was done at the same temperature; but when the dipping temperature for the dextrose ice cream was lowered approxi- mately 1 degree for each percent of dextrose, the dipping loss was comparable to that of the sucrose ice cream. Hardness. Tests run at 12 to F. showed no difference in hardness between the dextrose and sucrose ice creams, but at higher temperatures the dextrose ice cream became less resistant than the sucrose ice cream. Time of Adding Dextrose. The time at which, during the proc- essing of the mix, the dextrose was added made no difference in the freezing and whipping processes. Adding a finely pulverized dextrose to the mix at the freezer during the freezing process produced super- cooling in the freezer and caused a powdery body in the ice cream. Effect of Different Types of Dextrose. In a comparison of hydrous dextrose, anhydrous dextrose, and a highly purified hydrous dextrose, comparable results were obtained when the sugars were used in the mix on the same dry-matter basis. Types of Freezers. Approximately the same results were obtained with the dextrose mixes frozen in the 2%- and 5-gallon counter freezers as were obtained with the larger batch freezers. When dex- trose was used in mix frozen on the Vogt continuous freezer, the drawing temperature was lowered, but neither mix pressure nor the ability to obtain overrun was affected. However, the ice cream contain- ing dextrose had a sticky body. This difficulty was overcome by a reduction of the gelatin content. Color. In the study of the effect of dextrose on certain chemical and physical properties of the mix, it was noted that dextrose mixes had slightly more color, as determined by the color analyzer, but that there was not enough difference to be perceptible to the eye. Replacing one-fourth of the sucrose with dextrose had practically the same effect on color as replacing all the sucrose with dextrose. The time at which the sugar was added to the batch had only a slight effect on the amount of color in the mix. Adding the sugar immediately before cooling produced the least color increase in the mix. 1939] DEXTROSE IN COMMERCIAL ICE CREAM 377 Viscosity. Dextrose had no effect on the viscosity of sugar- gelatin-water solutions, but usually lowered the viscosity of the ice- cream mix processed in the usual way. When the sugars were added after the milk products had been pasteurized and homogenized, the dextrose mixes gave a slightly higher viscosity. pH. Dextrose generally lowered the pH slightly, depending on the time and temperature of pasteurizing and the percentage of dex- trose in the mix. The maximum decrease observed in this study was .2 in pH. When one- fourth of the sucrose was replaced with dextrose there was an average decrease of .02 in pH. Protein Stability and Curd Tension. Dextrose had no measurable effect on the protein stability or on the curd tension of the ice- cream mix. Consumer Preferences. When one-fourth of the sucrose was replaced with hydrous dextrose at the rate of 1.43 pounds of dextrose per pound of sucrose omitted, the dextrose ice cream was comparable to the sucrose ice cream in body and flavor but was considered much sweeter by most judges. When one-fourth of the sucrose was replaced with hydrous dextrose pound for pound and the ice cream frozen on the Vogt freezer, the body of the dextrose ice cream was much preferred to the body of the all-sucrose ice cream. In flavor and sweetness the all-sucrose ice cream was preferred. When one- fourth of the sucrose was replaced with hydrous dex- trose at the rate of 1.2 pounds of dextrose per pound of sucrose omitted, and the mixes were frozen on a Vogt continuous freezer, the body and flavor of the all-sucrose ice creams were preferred by a ma- jority of the consumers. In these tests the gelatin content of the dex- trose mixes was reduced below that of the all-sucrose ice cream so as to prevent the dextrose ice cream from having a sticky body. These ice creams were rated by the consumers as comparable in sweetness. When one-fourth of the sucrose was replaced with anhydrous dextrose pound for pound, dextrose ice cream in the opinion of con- sumers was comparable in flavor and sweetness with the all-sucrose ice cream. In this test the body of the all-sucrose ice cream was preferred by the greater number of consumers. In the test of refreshing qualities the consumers preferred the all- sucrose ice cream when the mix contained 12 percent fat, and pre- ferred the part-dextrose ice cream when the mix contained 16 percent fat. 378 BULLETIN No. 452 [March, CONCLUSIONS The following conclusions apply to ice creams sweetened with sucrose as compared with those in which one-fourth of the sucrose is replaced with dextrose. 1. Consumer tests show that hydrous dextrose has a sweetening value which is 83 percent as effective as sucrose in ice creams, and anhydrous dextrose has a value equal to sucrose. 2. The use of dextrose in ice cream does not affect the time to freeze and whip the mix. 3. When 25 percent of the sucrose is replaced with dextrose the drawing temperature will be approximately one degree lower. 4. Dextrose imparts as desirable flavor and body to batch- frozen ice cream as does sucrose. When dextrose ice cream is frozen on the Vogt continuous freezer, the stabilizer content must be reduced in order to avoid a sticky body. 5. Dextrose ice cream melts slightly faster at room temperature, which possibly accounts for the greater refreshing qualities of high- fat ice creams having one- fourth of the sucrose replaced with dextrose. 6. Dipping the dextrose ice cream at lower temperatures than the sucrose ice cream helps to minimize dipping losses. 7. Dextrose imparts slightly more color to the mix, slightly lowers the pH, and decreases mix viscosity. LITERATURE CITED 1. ANTHONY, R. S. and LUND, A. A. Repressing sandiness in ice cream by the use of corn sugar. Ice Cream Trade Jour. 27, No. 10, 60-62. 1931. 2. AYERS, S. H., WILLIAMS, O. E., and JOHNSON, W. T., Jr. Sugar substi- tutes in the ice cream mix. Ice Cream Trade Jour. 14, No. 4, 29-30. 1918. 3. BIERMAN, H. R. The effect of overrun, temperature and composition on the dipping losses of ice cream. Md. Agr. Exp. Sta. Bui. 293. 1927. 4. COMBS, W. B. How corn sugar in an ice cream mix affects the harden- ing process. Ice Cream Trade Jour. 23, No. 1. 1927. 5. and BELE, FRANK. Cerelose in ice cream. Ice Cream Rev. 10, No. 4, 66, 106-112. 1926. 6. Improving quality with corn sugar. Ice Cream Rev. 10, No. 5, 132-140. 1926. 7. CORN INDUSTRIES RESEARCH FOUNDATION. Corn in industry. 1936. 8. ERB, J. H. Controlling sandiness in ice cream by using a combination of sugars. Ice Cream Trade Jour. 27, No. 8, 35. 1931. 9. FRANDSEN, J. H., ROVNER, J. W., and LUITHLY, J. Sugar-saving substitutes in ice cream. Neb. Agr. Exp. Sta. Bui. 168, 1918. 1939] DEXTROSE IN COMMERCIAL ICE CREAM 379 10. HILL, R. L. A decade and a half of soft-curd milk studies. Utah Agr. Exp. Sta. Circ. 101. 1933. 11. MACK, M. J. Defects of high solids mixes and their cure. Ice Cream Field 27, No. 3, 24-27. 1935. 12. MARTIN, W. H. How much sugar? What kind? Ice Cream Trade Jour. 23, No. 3, 44-45. 1927. 13. REID, W. H. E. and ARBUCKLE, W. S. Some factors affecting the serving and dipping temperatures of ice cream. Jour. Dairy Sci. 20, No. 7, 456. 1937. 14. TRACY, P. H. and McCowN, C. Y. A study of factors related to the hardening of ice cream. Jour, of Dairy Sci. 17, No. 1, 47-60. 1934. APPENDIX Modern Method of Manufacturing Dextrose The initial step in the manufacture of dextrose from corn grain is the efficient separation of the grain into the following portions: that which is water soluble, the germ, the hull or fiber, the starch, and the gluten. The shelled corn is soaked in warm water from 30 to 60 hours in large cylin- drical tanks called steeps. The softened grain is then ground between two close-set plates revolving in opposite directions. The grain of corn is cracked or torn to pieces without injury to the germ, after which it passes into deep rectangular tanks called germ separators. There the germ con- taining the oil floats on the surface because it is lighter in specific gravity than the rest of the cracked grain, which settles, is drawn off the bottom of the separator, and is sent to the Buhr Mills. The grinding in this mill completely separates all particles of hull from the starch and gluten. This finely ground mixture is then passed over a silk sieve thru which the starch and gluten pass with the water and are separated from the hull and fiber. The mixture of starch and gluten which passes thru the silk sieves is sent to the starch tables which are slightly inclined wooden troughs about 2 feet wide and 120 feet long. The starch, being heavier than the gluten, settles out on these tables in a solid cake, while the gluten flows over the end of the table with the water. The starch deposited on the table is removed by flushing with fresh water, which again puts the starch in suspension. This starch suspension is filtered several times to remove all impurities, after which it is diluted to a Baume of about 13. The suspension is then acidulated with hydrochloric acid and cooked under pressure in bronze tanks at a temperature of approximately 275 F. This cooking is continued until all the starch is converted into dextrose, after which the excess acid is neutralized with sodium carbonate. The sirup is then filtered and finally run thru bone charcoal to remove the last traces of sediment and color. After the final filtration over the bone charcoal, the clarified liquor is condensed in vacuum evaporators until it has a Baume of 40 to 50. The concentrated sugar liquor is conducted into large cylindrical crystallizers, where it is slowly agitated for 90 to 100 hours, during which time the crystallization takes place. The heavy liquor containing the 380 BULLETIN No. 452 crystals of pure dextrose is then run into centrifugal machines which separate the crystals from the uncrystallized liquor. While still in the centrifugal the crystals are washed with pure water until nothing remains but the crystallized dextrose. It is then taken to the rotary air dryers where the excess moisture is removed, after which it is screened and bagged. Hydrous dextrose contains approximately 92 percent dry matter. Anhydrous dextrose is made by redissolving hydrous dextrose and re- crystallizing as above. By this method a product of higher purity is obtained and the finished crystals are dried until they are practically free from moisture. Dextrose is a different type of sugar from cane sugar, being a mono- saccharid whereas sucrose is a disaccharid. Dextrose crystallizes more slowly than cane sugar, and it may form different types of crystals. It is slightly less sweet than cane sugar and exerts greater osmotic pressure. It is used extensively in the different food industries, especially in. the bread, cake, confectionery, carbonated beverage, and dairy manufacturing trades. Its use in ice cream has been advocated on the basis that it prevents oversweetness, 7 * produces a creamier texture, and adds to the sensation of coolness that is expected in ice cream. As to nutritional value, dextrose is more easily and quickly assimilated by the body than is cane sugar, which must be converted into dextrose and fructose before assimilation can take place. The medical profession in general advocates the use of dextrose in infant feeding, for counteracting insulin shock in diabetes, in the treatment of obesity, and to keep the supply of blood sugar at the proper level for people whose work or play requires unusual exertion. 50SO 3-39 15816 NIVERSITY OF ILLINOIS-URBANA