August. 1926
I N D U S T R I A L AAVD ENGINEERING CHE*MIXTRY
865
Effect of Milk Salts on the Whipping Ability of Ice Cream Mixes'" By H. H. Sommer and D. M. Young DEPARTMENT OB DAIRY HUSBANDRY, COLLEGE O F AGRICULTURE, UNIVERSITY
HE whipping ability of ice cream mixes in the commercial production of ice cream is an important, subject, not only because of its bearing on the yield of finished ice cream, but also on account of its relation to the body and texture of the product. The effects of the various constituents of the mix, and the effects of various practices in handling the mix are more or less thoroughly known. In observing such effects, however, the industry is accustomed to think in such gross terms as fat, sugar, gelatin, and milk solids-not-fat (commonly called serum solids). The milk solids-not-fat are not considered individually but collectively. Practically, the only occasion for considering any one of them individually has been in connection with the study of a defect in ice cream known as "sandiness," which is due to too high a milk sugar content. The more import8ant constituents of milk solids-not-fat are casein, lactalbumin, lactoglobulin, milk sugar, and the milk salts, consisting of the citrates, phosphates, and chlorides of sodium, potassium, calcium, and magnesium. If dairy products that have undergone slight fermentation are used, we have in addition lactates and a smaller amount of acetates of the above-mentioned bases. It is known that the milk solids-not-fat contribute largely to the whipping ability of the mix. This effect is more specifically due to the milk proteins which they contain. The milk proteins are present in milk and cream, and hence in ice cream mixes, mainly in a colloidal condition. I t is known generally in colloid chemistry that electrolytes have a profound effect on colloids. Specifically, Somnier and Hart3 have shown that even minute quantities of milk. salts have a decided' effect on the milk proteins in the manufacture of evaporated milk. Since the milk salts are known to affect the colloidal condition of milk proteins, it was considered likely that they would also affect the whipping ability of ice cream mixes, which is so largely due to proteins. Accordingly, experiments were undertaken to study the effect of various salts on the whipping ability of ice cream mixes.
T
Experimental
Since it is generally known that bivalent and trivalent ions have the greatest effect on colloids, and it has been found that this generalization held true in the case of evaporated milk,3 the first salts studied were the citrates, phosphates, and calcium salts. Magnesium salts were omitted for the time being because of the relatively small amount present in milk products. I n the first experiment sodium citrate, disodium phosphate, and calcium lactate were used, the amounts chosen so as approximately to double the normal citric acid, phosphorus pentoxide, and calcium oxide content of the ice cream mix. Using cream, milk, skim milk powder, cane sugar, and gelatin, a 200-pound (90.7-kg.) batch of mix was made up so as to contain 12.5 per cent fat, 10 per cent solids-not-fat, 14 per cent sugar, and 0.4 per cent gelatin. After this bat)ch had been mixed and pasteurized a t 145" F. (62.8" C.) for 30 minutes, it was divided into four smaller batches of 50 pounds (22.68 kg.) each. To batch 1, nothing further was added, and this batch served as a control; to batch 2, 1.26 per cent of crystalReceived February 17, 1926. * Published with the approval of the Director of the Wisconsin cultural Experiment Station. 3 J . B i d . C h e m . , 40, 137 (1919). 1
Agri-
OF WISCONSIN,
MADISON, \%'IS.
line disodium phosphate was added; to batch 3, 0.56 per cent of sodium citrate; and to batch 4, 0.97 per cent of calcium lactate. These mixes were then homogenixed a t a pressure of 2000 pounds per square inch (140.6 kg. per sq. cm.), cooled, and aged for 48 hours a t 45" F. (7.2" C.). They were then frozen in a 40-quart (37.85-liter) horizontal Cherry freezer and records made of the overrun a t intervals of one minute. The results are given in Table L4 of S o d i u m Citrate, D i s o d i u m Phosphate. a n d C a l c i u m L a c t a t e on the Overrun in Ice Cream (Per cent overrun) Time in freezer Batch 1 Batch 2 Batch 3 Batch 4 Minutes control phosphate citrate calcium lactate
Table I-Effect
1
2 3 4 5 6 7 8 9 10 11
12 13 14 15 16 17 18
7.0 22.0 42.5 57.0 60.0 60.5 61.5 66.0 71.0 78.0 93.0 99.0
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..I
...
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... ... ... ... ...
... ...
...
8.5 11.5 13.5 18.0 26.0 33.0 47.5 55.0 60.0 62.5 68.0 76.0 76.0 81.0 81.0 84.0 85.0 84.0
It will be noted that the whipping ability of the mixes containing the sodium citrate and the sodium phosphate was decidedly greater than that of the control, and the whipping ability of the mix containing calcium lactate was decidedly lower than that of the control. A number of experiments have been conducted to study the effect of each of these three salts individually. The results of these experiments thus far have been as follows: 1-Sodium citrate added in amounts up t o 0.3 per cent before aging the mix had little or no effect on the whipping ability of the mix; 0.4 per cent caused a marked increase in the whipping ability of the mixes. 2-The sodium citrate, even in the larger amounts, affected the whipping ability of the mix only when it was added prior t o the aging; if the sodium citrate was added just prior t o the freezing, it showed no effect. 3-Disodium phosphate in amounts up to 0.7 per cent showed little effect on the whipping ability. 4-Calcium lactate in amounts as low as 0.1 per cent showed a noticeable effect in lowering the whipping ability of the mix; 0.5 per cent calcium lactate showed a marked effect.
Table I1 gives the results obtained with 0.4 per cent sodium citrate, and Table I11 those of 0.1 and 0.2 per cent calcium lactate. Table 11-Effect Time in freezer Minutes 1 2 3 4 5 6 7 S 9 10 11
of S o d i u m Citrate on t h e Whipping Ability of Ice Cream Mix (Per cent overrun) --AGED 24 HOURS--&%GED i 2 HOURS-Sodium Sodium Control citrate Control citrate 8.0 18.0 8.0 19.0 24.0 44.5 58.0 58.0 58.0 63.0 67.0 78.0 89.0 98.0
37.0 76.0 102.0 113.0 112.0 110.0 106.0 105.0 105.0
...
23.5 42.0 51.1 55.0 59.0 63.0 71.0 83.0 93.0 100.0
48.0 74.0 91.0 101.0 101.0 100.0 96.0 94.0
... ...
4 The individual experiments reported in this paper have been repeated a number of times. For the sake of brevity only typical experiments are reported.
INDUSTRIAL AND ENGINEERING CHEMISTRY
866 Table 111-Effect Time in freezer Minutes 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
of C a l c i u m L a c t a t e on the Whipping Ability of Ice C r e a m Mix (Per cent overrun) AGED48 HOURS 0.1 per cent 0.2 per cent Control calcium lactate calcium lactate 14.0 6.5 6.0 30.5 14.0 12.5 42.0 19.0 16.0 47.0 24.5 22.0 47.0 33.5 32.0 42.5 48.0 42.0 53.0 54.0 56.0 63.0 66.0 65.0 73.0 70.0 72.0 78.0 77.5 76.0 85.0 82.0 81.0 95.0 84.0 85.0 90.0 89.0 90.0 87.0 90.5 89.0
... ... ...
I n order to determine whether the sodium citrate was operative through its effect on the milk proteins alone, on the gelatin alone, or on both, the experiment reported in Table IV was conducted. Two batches of mix were prepared alike in every respect except that one contained 0.4 per cent gelatin and the other contained no gelatin. These two batches were in turn divided into two groups each, and to one of each group 0.4 per cent sodium citrate was added prior to aging. The mix containing both gelatin and sodium citrate whipped up considerably faster than the others, indicating that the sodium citrate is operative through its effect on both the gelatin and the milk proteins.
Vol. 18: No. 8
of S o d i u m Citrate on t h e Whipping Ability of Ice C r e a m Mix w i t h and w i t h o u t Gelatin (Aged 4s hours) WITH0.5 PER CENT GELATIN -WITHOUT GELATINWithout Time in Without 0.4% 0.4% freezer sodium sodium sodium sodium Minutes citrate citrate citrate citrate 21.0 42.5 37.0 1 19.0 2 42.0 63.0 64.0 64.0 3 61.0 92.5 73.0 81.0 4 72.0 112.0 80.0 Q2.0 5 74.5 120.0 79.0 99.0 6 74.0 117.0 77.0 100.0 7 72.0 120.0 77.0 100.0 8 73.0 123.0 83.0 105.0 127.0 83.0 112.0 9 78.0 10 84.0 130.0 93.0 11 88.0 98.0 12 94.0
Table IV-Effect
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...
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Conclusion
This preliminary report points out the importance of the milk salts as a factor in determining the whipping ability of ice cream mixes, a factor that had hitherto been overlooked. These results indicate an explanation for variations in the whipping ability of mixes that are otherwise uniform in their composition, variations which always have been very puzzling and up to the present time inexplicable. Work in this field is being continued by the authors to determine what other salts have such an effect, the manner in which the salts exert this effect, and the application of the results to commercial practice. The possibility of affecting an economy in the manufacture of ice cream by the use of sodium citrate is being considered.
Catalytic Removal of Oxygen from Gas Mixtures Containing Hydrogen' By J. A. Almquist and E. D. Crittenden FIXEDNITROGEN RESEARCH LABORATORY, WASHINGTON. D. C.
LTHOUGH absorption methods for the removal of free oxygen from gas mixtures are known, it is often more convenient to effect its removal by causing its catalytic combination with hydrogen to form water. This is particularly true in working with the large volumes of gas for the commercial synthesis of ammonia. For the preparation of hydrogen-nitrogen mixtures for this purpose, byproduct nitrogen resulting from the production of oxygen by the fractionation of air may be used to advantage where it is available. Such nitrogen contains oxygen in amounts which will be dependent in general upon the degree of purity sought for the oxygen. The concentration of oxygen in such waste nitrogen is too low to permit free combustion with hydrogen, but the reaction can be made to go readily in the presence of suitable catalysts. Among the readily available catalyst materials for water synthesis, copper appears to be the most promising and, therefore, a brief study has been made of the effectiveness of various forms of this metal.
A
Experimental
The catalysts tested were (1) copper shot, (2) copper reduced from Baker and Adamson C. P. granular copper oxide, (3) copper reduced from fused copper oxide which was prepared by E. C. White of this laboratory by heating copper in an oxidizing atmosphere with an oxyhydrogen flame. All the catalysts were 10 to 14 mesh. The reduction of the copper oxides was started a t 310' C. in 3Hz:Nz and allowed to continue without further application of heat. After reduction had ceased under these conditions, the temperature was maintained a t 310' C. until reduction was complete. 1
Received April 16, 1926.
In making the oxygen removal tests, purified 3H2:Ns gas and oxygen, after passing through calibrated flowmeters, were mixed and entered the catalyst contained in a glass reaction tube mounted in a constant temperature vapor bath. After leaving the catalyst, the gas passed in succession through a water trap, concentrated sulfuric acid, fused potassium hydroxide, and phosphorus pentoxide. All or an aliquot part of this dry effluent gas was then analyzed for free oxygen by passage over platinized asbestos mounted in a constant-temperaturevapor bath (310' C.) and collecting the water formed in a weighed U-tube containing phosphorus pentoxide. Before beginning each test the entire system was flushed with 3Hz:Nz,and blank tests were made on the oxygen content, which gave results of 0.001 to 0.003 per cent 0 2 by volume. The activity of the platinized asbestos in the analyzing system was also checked a t intervals by admitting a known quantity of oxygen in 3Hz:Nz directly to the platinum catalyst and weighing the water formed. The results for various rates of flow are given in Table I. of Oxygen f r o m 3Ha:Nn b y Copper Catalysts Temperature Space VOLUME, PERCENT 0 2 Material C. velocity Inlet gas Exit gas Copper shot 310 12,000 0.89 0.105 444 12,000 3.05 0.006 ( 60,000 2.00 0.01 4 on 0.009 0,059 2.00 120,000 310 Copper oxide (Baker and 4.00 0.034 Adamson) 0.083 2.00 180,000 4.00 0.081 0.006 2.00 60,000 4.00 0.006 0.016 2.00 120,000 4.00 0.011 310 Copper oxide (fused) 0.029 2.00 180,000 4.00 0.016 0.075 2.00 240,000 Table I-Removal
I
I
