192 MASS. EXPERIMENT STATION BULLETIN 268 



former for four inontlis was equivalent in flavor to that carried six months 

 at the lower tenii)erature. This is in agreement with previously pub- 

 lished work (1) (-}■). Cream of the quality used in this experiment was 

 still suitable for use as the entire source of fat in ice cream mixes after 

 six months storage. These mixes lacked a full, creamy flavor but carried 

 no noticeable off flavor. 



It was noticed that wlien the frozen cream began to go off in flavor, 

 this deterioration increased rapidly in intensity. In view of this fact, the 

 practice of storing cream for periods longer than six months would be 

 unwise. Storage periods shorter than six months are recommended. 



DISCUSSION OF RESULTS 



No complete explanation can be oft'ered for the slower whipping of 

 frozen cream mixes as conqiared with the fresh cream mixes. It Tiiay be 

 that the higher viscosity and larger fat globules and clumps may not be 

 the cause but may themselves be the result of other changes which also 

 affect the whipping properties of the mixes. 



Applying the protein stability test used by Doan (5), the proteins in 

 frozen cream mixes were found to be less stable than in sweet cream mixes. 

 Between (i and 6.-5 c.c. of 92 per cent ethyl alcohol were required to 

 precipitate the proteins in 5 c.c. samples of frozen cream mixes, sweet 

 cream mixes requiring about 7.5 c.c. Further information indicating that 

 freezing tends to aft'ect proteins has been reported by Anderson and 

 Pierce (6). 



Of the different methods studied for storing frozen cream, freezing 

 with sugar is to be recommended if the cream is to be used in ice cream. 

 The lower viscosity, better whipping properties, and better flavor of 

 frozen sweetened cream mixes over plain frozen cream mixes, more than 

 offset the slight extra cost of storing cream in this way. In an address. 

 Price (7) reported that preliminary investigations indicate that 1-5 per 

 cent sugar is the optimum amount to use in frozen cream. 



Although only a slight improvement was secured by adding gelatin to 

 pasteurized cream before freezing, the results were all in agreement. 

 This was not true with frozen homogenized cream. Here contradictory 

 results occurred, hence the data reported are truly averages rather than 

 indications of a typical set of results. In no case were variations from 

 the control nuirked. 



An examination of the data shows a relationsiiip between the rate of 

 whipping of mixes and the viscosity. With the exception of the frozen 

 gelatinated cream mixes, the more viscous mixes whipped more slowly. 

 There is a tendency for mixes having the smallest fat globules and clumps 

 to whip most rapidly. The frozen gelatinated cream mixes were again 

 the exceptions. Little difference existed in the size of fat globules and 

 clumps between the frozen homogenized cream mixes and their controls. 



The practice followed in some ice cream plants of using frozen cream 

 in combination with fresh sweet cream seems advisable. In this way 

 a better whipping mix results. Also there is less danger of imparting oft" 

 flavors to the finished product. 



