50 MASS. EXPERIMENT STATION BULLETIN 347 



the antioxidant had a very pronounced oat flour flavor, thus showing that too 

 much of the antioxidant had been added. 



Two samples of whole milk powder prepared with and without oat flour by a 

 commercial milk plant were examined. The milk powders were dissolved in water 

 so that the total solids content was equal to that of normal fluid milk. The milk 

 powder containing the antioxidant had a better flavor than did the control. 

 This observation will be checked by determining the peroxide value of the fat. 

 The amount of peroxide oxygen present in a fat serves as an excellent criterion of 

 the degree of oxidation of that fat. 



The effect of an antioxidant in whipped cream was also studied. Oat flour, 

 0.5 percent by weight, and also skim milk extract of oat flour were added to 

 whipping cream before pasteurization. No marked differences were noted in the 

 flavor of the whipped cream after one week's storage at approximately 36° F. 

 It should be mentioned that the cream used in this experiment was of excep- 

 tionally good quality. The experiment will be repeated using a lower grade of 

 cream and also a higher storage temperature for the whipped cream. 



Trials will be made in the near future with other antioxidants of a non-toxic 

 nature. 



Sodium Alginate as a Stabilizer for Ice Cream. (M. J. Mack.) Previous studies 

 have shown sodium alginate to be a satisfactory stabilizer for ice cream. Mixes 

 containing the stabilizer were relatively uniform in viscosity, required no aging 

 before freezing, and whipped readily to the desired overrun. The resultant ice 

 cream was smooth in texture and possessed desirable melting characteristics. 



This project is being continued with the study of another form of sodium 

 alginate which may prove superior to that previously used. 



The Stability of the Fat Emulsion in Cream. (M. J. Mack, in cooperation with 

 Herbert Jenkins, New England Dairies, Inc.) A detailed study was made of the 

 separation of oily droplets of butterfat from cream when used in coffee. This fat 

 separation from cream in coffee is usually referred to as "oiling off". It is con- 

 sidered objectionable by some consumers and many buyers for restaurants and 

 hotels. Therefore the dairyman should handle cream so that the defect will not 

 occur. 



The cause of the oily separation is the partial destruction of the normal emulsion 

 of the fat globules in cream. Any factor or factors which will cause fat globules 

 to coalesce may increase the size of some globules to the extent that they will rise 

 to the surface in hot coffee and be readily apparent. The more important factors 

 involved are as follows: 



1. The separation of milk partially frozen during delivery will produce a cream 

 capable of oily separation in cofifee. 



2. Separating temperatures higher than 90° F., excessive agitation of milk 

 while preheating for separation, and the separation of cream higher in butterfat 

 than 45 percent, decrease the stability of the fat emulsion. 



3. Prolonged holding of cream at the pasteurization temperature increases 

 the amount of destabilized fat in cream. The partial filling of pasteurization vats 

 causes similar undesirable results. Stainless steel or glass-lined steel vats with 

 slow propellor or paddle agitation and a heating medium of 160° F. produced 

 satisfactory results. However, an increase in the speed of agitation or in the 

 temperature of the heating medium, in these same vats, increased the oiling ofT 

 tendency. Coil vats, regardless of the temperature of the heating medium, 

 destabilized the fat emulsion. Heating cream to pasteurization temperatures higher 

 than 145° F. increased the amount of oil separation slightly. Whether cream is 

 agitated slowly or not at all during the holding period apparently made no differ- 

 ence, but rapid agitation caused oiling ofi^. 



