14 MASS. EXPERIMFA'T STATION BULLETIN 302 



Table 5. Increase in Basic Viscosity and Melting Resistance, and 



Decrease in Overrun of Mixes Initially Aged for 4 Hours at 68° F. 



OVER Those Aged Only at 38° F. 



Composition of Mix Decrease 



Increase in Increase in in Maxj- 



Fat Serum Total Basic Melting Resistance 



mum 



Solids Solids Viscosity Overrun 



Prr cent Percent Percent °A/ Gram.' Melte-i Ice Cream Percent 



8 10 33.5 9.75 20.3 8.0 



10 10 35.5 25.75 30.1 6.0 



12 10 37.5 35.75 50.6 9.0 



14 10 39.5 21.03 82.6 4.0 



10 8 33.5 13.31 59.2 7.0 



10 10 35.5 25.75 30.1 6.0 



10 12 37.5 32.83 22 6 3.0 



10 It 39.5 41.85 — S.9 8.0 



Results Obtained when Varying tfie Percentage of Serum Solids 



This experiment was similar to the preceding, except that in this case the fa I 

 remained constant at 10 per cent, while the serum solids were varied. Increasing 

 the serum solids from 8 to 14 per cent, at 2 per cent intervals, had the following 

 effect on the results of aging at a high initial temperature as compared with 

 aging at 38° F. only. (See Table 5 and Plate 5.) 



1. Magnified the Increase in basic viscosity. 



2. Diminished the increase in melting resistance. 



3. Did not definitely alter the decrease in overrun. 



The ice creams aged at the high initial temperature were again judged superior 

 in body and texture to those aged at a low temperature only. This improvement 

 in body and texture was also magnified as the serum solids were increased. 



The increase in melting resistance, normally caused by high initial temperature, 

 disappeared as the serum solids were increased, due in all probability to the effect 

 of lactose. 



PRACTICAL APPLICATIONS 



Observations on melting appearance made in this study suggest a possible 

 explanation for variations which sometimes occur in the melting behavior of ice 

 cream of uniform composition. Although several causes for excessive retardation 

 of melting and curdled appearance of melting ice cream have been explained in 

 the literature, yet a number of Ice cream manufacturers have trouble in producing 

 a uniform product, even when a standardized formula and processing procedure 

 are used. This fact Indicates that some unknown factors are contributing to the 

 serious defect. In one Instance where the ice cream varied considerably In melting 

 behavior, it was found that the mix was not being cooled after homogenizatlon 

 to a uniformly low temperature each day. In another instance, some years ago, 

 a large ice cream plant was using a surface cooler where tap water was the only 

 cooling medium. After a change was made to cooling with brine, the properties 



