54 MASS. EXPERIMENT STATION BULLETIN 378 



pearance are undoubtedly caused by factors which affect the stability 

 of the proteins, but this explanation does not seem to be true when the 

 defects are slight. 



A number of factors, in addition to those already mentioned, have been 

 found to affect the appearance of melting ice cream, such as the com- 

 position of the mix. High butter fat content, low sugar concentration, 

 and an excessive amount of stabilizer may all contribute to the difficulty. 

 The kind of stabilizer used is also important, since stabilizers vary in 

 their effect on the melting characteristics of ice cream. Fast freezing 

 and hardening are both necessary in order to secure a smooth melting 

 appearance. Dipped ice cream has a more desirable melting appearance 

 than packaged ice cream, which siiows tliat the percentage of overrun is 

 also involved. 



Ice cream which has desirable melting characteristics can be secured 

 by the use of good ingredients, properly proportioned. The homogeniza- 

 tion temperature and pressure must be satisfactory for the composition of 

 the ice cream, and rapid freezing and hardening are also essential. 



A Study of the Efficiency and Practicability of the Paper Milk Bottle. 



(J. H. Frandsen and M. A. Widland.) As far as the study went, no off- 

 flavors seemed to lie due to the paper bottles. 



A Comparison of the Electropure and Vat Methods of Pasteurization. 



(Leo D. Lipman, J. H. Frandsen, and H. G. Lindquist.) .Split batches 

 of raw milk were pasteurized in (a) the Electropure at 162° F. for 16 

 seconds and in (b) a spray vat at 143° for 30 minutes. Preliminary con- 

 clusions from this study are: 



1. The reduction in the vitamin C content of milk was less rapid in 

 Electropure-pasteurized milk than in raw or vat-pasteurized milks. 



2. The Electropure method gave better (i.e. lower) phosphatase re- 

 sults than the vat method. 



3. Pasteurization by both methods decreased the cream volume. While 

 the Electropure method tended to give a greater cream volume than 

 the vat method, the difference was so small that no definite conclusions 

 can be drawn as to which of the two methods of pasteurization results in 

 a lesser decrease in cream volume. 



4. There was no significant dift'erence in efficiency of bacterial reduc- 

 tion between the vat and Electropure methods of pasteurization. 



5. Electropure-pasteurized milk became oxidized less rapidly, less 

 frequently, and to a lesser degree than vat-pasteurized milk. A cooked 

 flavor was found more often and was more pronounced in vat-pasteurized 

 milk than in Electropure-pasteurized milk. 



