212 MASS. EXPERIMENT STATION BULLETIN 280 



or sugar syrup (a 40 per cent syrup being most satisfactory), either plain or vac- 

 uum packed. Any of these methods are satisfactory for storing fruits for fruit 

 ice cream. The condition of fruit when packed, and the variety, seem to be as 

 important as the method of packing if the fruit is to be utilized in ice cream. 



About 15 per cent of frozen fruit has been found to be desirable for flavoring 

 strawberry, cherry, pineapple, banana, and other fruit ice creams. About 20 

 per cent is necessary for peach, and from 10 to 12 per cent for raspberry. The 

 fruit should be added to the freezer immediately after the freezing process is 

 started if a short freezing time is to be realized and the maximum of flavor is to 

 be secured. No previous preparation of the fruit, as grinding or slicing, is neces- 

 sary for the smaller fruits as the dasher of the freezer will break up the fruit. 

 Fruit ice creams should be drawn from the freezer at about 23°F. 



Frozen strawberries, raspberries, peaches, nectarines, plums, cranberries, and 

 pineapples have been found to be as satsifactory as the fresh fruit for making 

 ices or sherbets. From 15 to 20 per cent of fruit has been found to be necessary. 

 However,* the acidity of the finished product must be increased by adding either 

 citric or tartaric acid. The acidity content should be 0.6 to 0.8 of 1 per cent. 



Titration with O.IN sodium hydroxide solution, with phenolphthalein as 

 indicator, has been found to be a satisfactory commercial test for acidity in ices 

 and sherbets. Since many ices are colored pink, it would seem that the end 

 point could not be secured with phenolphthalein as the indicator. However, 

 the solution becomes almost colorless before the end point is reached, so that 

 the color change at the end point is easily observed. 



A Study of Ice Creams High in Fat Content. (M. J. Mack). In New 

 England during the past 5 years, many small ice cream concerns have organized 

 for a specialized type of business. They sell only ice creams of high fat content 

 and do only a retail business, usuallj^ through attractive road-side stores. 



The majority of these dealers buy a prepared basic mix through one of a 

 small number of concerns specializing in this type of product. Obviously, it 

 would be more economical if the dealer were to prepare his own mix as well as 

 freeze it. However, difficulties arise in the preparation of a basic mix of this 

 composition. Therefore, this project has been started with the objective of 

 securing information concerning ice creams of this composition. No published 

 work on this subject is availiable. 



From the data now available, it is apparent that ice creams of a higher fat 

 content than 18 per cent should contain no more serum solids than are furnished 

 by the milk and cream used in their manufacture. As the fat content increases, 

 the homogenization pressure must be decreased. A pressure of 800 to 1000 

 pounds is sufficient for an ice cream containing 20 per cent fat. Sufficient stabil- 

 ity is secured from the fat and gelatin. Aging for 24 hours seems more beneficial 

 than with ice creams of lower fat content. A high drawing temperature of about 

 25.5° F. must be maintained if the freezing time and yield are to be satisfactory. 



To date it has been very difficult to introduce frozen cream or butter as the 

 source of fat, for an extremely viscous product results. As the study progresses 

 it is hoped that this and other problems pertaining to the manufacture of high 

 fat ice creams can be successfully met. 



A Study of the Effect of Various Initial Aging Temperatures on the 

 Behavior of Gelatin in Ice Cream. (W. S. Mueller). The continuation of 

 this study during the past j^ear has definitely shown that aging an ice cream 

 mix containing gelatin for 4 hours at 68° F. results in an increased efficiency of 

 the gelatin. Of the various initial aging temperatures tried, which ranged from 



