252 MASS. EXPERIMENT STATION BULLETIN 271 



DEPARTMENT OF DAIRY INDUSTRY 

 J. H. Frandsen in Charge 



A Study of Packaged Ice Cream. (K. E. Wrigiit). This project has 

 been continued throughout most of the year, and the results have been 

 tabulated and published as Bulletin 269. 



The Effect of Initial Cooling Temperatures on Gelatin in the Aging 

 of the Ice Cream Mix. (K. E. Wright). "Work so far completed on tliis 

 project indicates that much of the texture benefits resulting from aging 

 an ice cream mix are associated with the viscosity imparted by gelatin, 

 and that high initial temperature in the aging period favored the develop- 

 ment of greater viscosity. It was also determined that the maximum 

 viscosity was found to be imparted when the mix was allowed to cool from 

 80°-100° F. to lO" F. without agitation, and that the whipping property 

 was decreased as the viscosity increased. 



This work as far as completed indicates tliat the results of aging an ice 

 cream mix are dependent upon the factors affecting crystallization of the 

 gelatin portion of the product. 



Factors Affecting the Aging Time of Ice Cream Mix. (K. E. Wright). 

 Work so far completed would indicate that the solidification of fat in tlie 

 aging of the mix is a minor factor and tliat the adsorption is probablj' 

 the important factor. 



Only 50 per cent of the benefits of aging in a 24'-hour period are ob- 

 tained during the first 4 hours, and the rate of adsorption or whip improve- 

 ment appears to depend on the amount of emidsifying agent available, i.e., 

 a butter mix improves more slowly than a cream mix or one containing egg 

 yolk. A fairly satisfactory relation was found between the surface ten- 

 sion and the ease of whipping. In all cases a decrease in surface tension 

 was noted after a 24-hour aging period. Cream mixes were found to have 

 less surface tension than butter mixes. Buttermilk was found to have 

 a lower surface tension than skiTnmilk, and the addition of buttermilk to 

 a butter mix lowered the surface tension of the mix and improved its 

 whipping property. 



Extractions of egg yolk with various fat solvents indicated that the 

 .solvent altered the emulsifying agent. An ice cream freezer was developed 

 which was found to be very useful for experimental freezing and is an 

 improvement over the commercial freezer because of its smaller capacity. 

 Chemical study of the emuLsifying ingredients of ice cream mixes is being 

 continued along with cataphoretic measurenients of the effects of the in- 

 gredients whicli aid cmulsification. 



A Study of Frozen Sweet Cream for Use in Ice Cream. (M. J. Mack). 

 This project has been active the last two years and full report is published 

 in Bulletin 268. 



The Utilization of Frozen Fruits in Ice Cream. (M. J. Mack). This 

 study is being conducted in cooperation with the Department of Horti- 

 cultural Manufactures. The third crop of such fruits as strawberries, 

 raspberries, cherries, and peaches is now being studied. This year the 

 fruit has been packed with cane sugar in fruit to sugar ratios of 2:1 and 

 3:1, with sugar syrup, with invert sugar, and in partial vacuum. Fruits 

 preserved in these different ways are being compared in order to deter- 

 u'ine their relative merits for use in ice cream. 



