12 



MASS. EXPERIMENT STATION BULLETIN 302 



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Chart 2. — The Effect of Initial Aging at 68° F. on the Whipping Ahihty of Mixes when the 

 Gelatin Content Was Decreased. 



Effect of an Initial Aging Period at 68° F. on a Gelatin-Free Mix 



A sweet cream mix containing 14 per cent fat, 10 per cent serum solids, 15 

 per cent sugar and no gelatin was processed according to standard procedure 

 as given under experimental methods. One half of the mix was aged for 24 hours 

 at 38° P., and the remaining portion aged at 68° for 4 hours, then at 38° for 20 

 hours. The results (see Table 4, Chart 3, and Plate 4) show that the difference in 

 aging temperature had no significant effect on basic viscosity, melting resistance 

 and appearance, and whipping ability. This indicates that the effects of initial 

 aging at 68°, which were observed in the preceding experiments, were due prima- 

 rily to the gelatin and not to the milk constituents. In all probability the peculiar 

 melting behavior of the ice cream containing no gelatin was due to the presence 

 of foam on the melting surface which retarded the rate of melting. 



The Influence of Composition of Mix on the Magnitude of High Initial Aging 

 Temperature Effects 



In order to study the effect of butterfat and serum solids on the behavior of 

 gelatin when the mix was initially aged at 68° F., the fat and serum solids were 

 varied from 8 to 14 per cent. A butter, skim milk powder, and water mixture was 

 selected for the standard mix in this experiment, as it was found that the physical 

 properties of such a mix could be more readily duplicated from day to day than 



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