| Popis: |
Summary 1.Whey separation was observed in samples containing as little as 0.1 per cent of the vegetable stabilizer after 96 hours of storage at 42°–46° F. 2.Using normal amounts of the stabilizer, i.e. , from 0.3 per cent to 0.5 per cent, and under the conditions of the experiment, a whey separation of approximately 50 per cent was noted after four days' storage. 3.Pasteurization of the mix was carried out at temperatures of 145° F., 165° F. and 175° F. for 30 minutes. The use of higher temperatures for pasteurization caused less whey separation. After 96 hours of storage the samples pasteurized at 145° F. showed 26 per cent separation, and those pasteurized at 175° F. showed an average of 4.7 per cent whey separation. The higher temperatures also retarded the rapidity with which the whey separation appeared. 4.Drying of the powdered stabilizer at 100° C. and under 20 inches of vacuum for as long as one hour did not affect its property of causing whey separation. 5.Heating a water suspension of the stabilizer to 205° F. for two hours retarded the rate and diminished the total amount of whey separation appearing in the mix when the stabilizer was used. It was, however, not reduced to the extent expected. An average of about 18 per cent of whey was observed after 96 hours of storage. 6.Pasteurization of the milk products to 165° F. or 175° F. for 30 minutes before adding the stabilizer, brought about a reduction in the whey separation which was not greatly different from the results obtained by pasteurization of the products plus the stabilizer at similar temperatures. 7.The greatest reduction in whey separation was obtained when the milk products used in the mix, i.e. , milk, cream, and skimmilk powder, were heated to 205° for one hour before the stabilizer was stirred in at 145° F. By this method the separation of whey was negligible after 72 hours of storage, and showed an average of less than one per cent after 96 hours. 8.The percentage of serum solids in the ice cream mix had no effect on the whey separation. 9.A mix having a low percentage of fat seemed to favor the separation of whey more than a 12 or 14 per cent fat mix. 10.Incomplete cooling of the mix had no influence on the whey separation provided the mix was cooled to about 65° F. after pasteurization. |
