18 MASS. EXPERIMENT STATION BULLETIN 287 



PART II. STUDIES OF FRUIT ICE CREAMS AND ICES 



Experimental 



The fruit available from tlic studies reported in Part I was utilized in ice 

 cream to determine the effect of methods of packing on flavor and other char- 

 acteristics. Other factors invesftgated in the making of fruit ice creams were: 



1. Comparison of fresh afid frozen fruits. 



2. Effect of the percentage of fruit. 



3. Time of adding fruit during freezing. 



4. Effect of fruit on rate of freezing and i)roperties of the ice cream. 



5. Addition of vanilla and fruit extracts. 



6. Causes of off-flavor in fruit ice creams. 



Since strawberry/ is the most popular fruit ice cream, a principal part of the 

 study was devoted*^ to it. Raspberry, cherry, pineapple, and peach ice creams 

 and ices were ahp investigated following the same general procedure used for 

 strawberry. The' experimental work with strawberry ice cream is discussed in 

 detail. Properties and observations peculiar to other fruit ice creams are then 

 discussed briefly. This is followed by a discussion of fruit ices. 



All fruit ice creams contained 15 per cent by weight of the fruit being studied, 

 unless a statement is made to the contrary. Freezing data were secured by tak- 

 ing the temperature of the mix in the freezer and the percentage of overrun at 

 minute intervals throughout the freezing process. The ice cream was held at 

 hardening-room temperatures (0-5° F.) for a few days before it was judged. 

 The judges were students and members of the college staff, mostly not specialists 

 in dairying and therefore representing fairly well the general consuming public. 

 A three to one preference was assumed to be significant. 



The ice cream mix used averaged 14.5 per cent fat, 10 per cent serum solids, 

 15 per cent sugar, and 0.35 per cent gelatin. It was pasteurized at 150-155° F., 

 held 30 minutes, and homogenized at 3,000 pounds pressure at the pasteuriza- 

 tion temperature. The mix was aged from 5 to 24 hours before freezing. A 40- 

 quart brine freezer was used, with brine varying from -5 to 2° F. in temperature. 

 All samples of ice cream for judging were drawn from the freezer at the same 

 temperature and at an overrun of 85-90 per cent, and were hardened for a few 

 days before examination. 



Acidity readings were determined by titrating a 9-gram sample with one-tenth 

 normal sodium hydroxide with phenolpthalein as indicator. Hydrogen ion 

 determinations were made electrometrically, using a Leeds-Northru]) jiotcnti- 

 ometer with the quinhy drone electrode at 77° F. 



Strawberry Ice Cream ^ 



Desirable Varieties for Use in Ice Cream 



A comparison of the conuuon New England varieties of strawberries over 

 three fruit crops was made. On the basis of the trials,, the strawberry varieties 

 studied may be grouped as follows in respect to their comparative value for 

 flavoring ice cream (see also Table I) : 



Excellent: Howard Supreme and King Edward. 



Very good: Marshall, Howard 17, First (Quality. 



Fairly good: Aberdeen, Boquet, Beacon, Bliss, Commonwealth, Progressive. 



Somewhat lacking in flavor: Marvel, Meteor, Mastadon, Sample, Senator 

 Dunlap, Stevens Late Champion, Bun and Heritage. 



Differences were in evidence among varieties from year to year which would 

 indicate that among the leading varieties, seasonal effects, ripeness of fruit, etc., 



I 



