26 MASS. FA'PKRIMENT STATION BULLETIN 293 



(2) As the initial aging temperature is raised from \0°C. (50°F.), this 

 increase in basic viscosity and gel strength reaches a maximum at 20°C. (68°F.), 

 then decreases with further increase of the initial aging temperature. 



(3) Initially aging an ice cream mix at or near the transition temperature 

 of gelatin, 38.03°C (100.5° P.), has no marked effect on basic viscosity and gel 

 strength. 



(4) Initially aging an ice cream mix at temperatures above the transition 

 point of gelatin decreases the basic viscosity and gel strength when compared to 

 rrixes aged at the low temperature 2.2°C. (36°F.) only. 



(5) The magnitude of the basic viscosity and gel strength changes in- 

 creases with an increase in the initial aging temperature period. However, the 

 first two hours produce the greatest change. 



2. The effect of high initial aging temperatures on pure gelatin-water 

 solution was similar to that on gelatin incorporated in an ice cream mix. 



3. Sugar, plasma solids and butter oil had a marked influence on the mag- 

 nitude of the basic viscosity increase due to the use of a high initial aging temp- 

 erature, 20°C. (68°F.). 



4. The observed effects of various initial aging temperatures on the basic 

 viscosity and gel strength of gelatin systems indicate that the colloidal behavior 

 of gelatin is affected by factors which are not generally recognized by current 

 theories. 



5. The observed increase in basic viscosity and gel strength, due to the 

 use of a high initial aging temperature, points the way to a more economical use 

 of gelatin in ice cream. 



The Feasibility of High Aging Temperatures in the Manufacture of 

 Ice Cream. (\V. S. Mueller and J. H. Frandsen.) The object of this study was 

 to determine the feasibility of using an aging temperature of 68° F. A four- 

 hour high aging temperature period was selected as standard procedure. The 

 68° F. aging temperature was used alone and also followed by a low aging temp- 

 erature. Each mix aged at 68° F. was compared to a portion of the same mix 

 which was aged at 38° F. and served as the control. Comparisons were made on 

 the following factors: 



1. Bacterial growth. 



2. Titratable acitlity. 



3. Hydrogen-ion concentration. 



4. Basic viscosity. 



5. Whipping ability. \ 



6. Body and texture. 



7. Melting resistance. 



8. Melting appearance. 



This study was completed during the past year and is now being prepared for 

 publication. 



The following conclusions were drawn : 



(1) When an ice cream mix containing gelatin was aged at 68° F. for a period 

 of 4 hours, either alone or followed by a low aging period, the efficiency ol the gel- 

 atin was increased. 



(2) This increased gelatin efficiency was shown by the improvement in body 

 and texture, increase in melting resistance, and slight retanlalion in rate of whip- 

 ping when compared to an identical mix aged at 38° F. 



