4 MASS. EXPEKIMENT STATION BULLETIN 287 



Fahricus (7), in Iowa, found that frozen strawberries were superior to either 

 canned fruit or strawberry extracts in the manufacture of ice cream. He recom- 

 mended Gandy, Kellogg's Prize, Early Jersey, Giant, and Dunlap as desirable 

 varieties for use in ice cream. The optimum ratio of strawberries to sugar was 

 two to three pounds of fruit to each pound of sugar. He found full-ripe fruit 

 gave a superior flavored ice cream. Storage at temperatures above 25° F. re- 

 sulted in definite quality deterioration. 



Turnbow and Kaf'fetto (IS), also Sommer (15), give general information on 

 fruit ice creams. 



Since the incep|/ion of the frozen-pack method of preserving fruits in the 

 Pacific Northwest about 20 years ago, many papers bearing on the general sub- 

 ject have appeared. Most of these are found in various trade journals and con- 

 tain little actual data. However, the reports by Cruess (2), Joslyn (10, 11), 

 Diehl (6), Wiegand (19), Woodroof (20, 21), Birdseye (1), Lathrop (12), Cul- 

 pepper (3), and others, sum up the available information on the subject. 



The present writers have also published preliminary reports of their findings 

 in the ice cream and fruit products' trade journals (9, 13). 



.--^PART I. FROZEN FRUIT INVESTIGATIONS 

 Experimental Methods 



Approximately 650 one-gallon cans of fruit were frozen packed for these 

 experiments over a three-year period. About one-half of this amount consisted 

 of strawberries; raspberries, cherries and peaches made up the rest. The fruits 

 were all produced in the college orchards, picked when fully ripe, and in prime 

 condition when packed. 



The methods of investigation were varied in order to compensate for the 

 differences among the different fruits studied. However, the same general pro- 

 cedure was followed as closely as possible. All fruit was prepared for packing 

 (hulled, pitted or pared as the case might be) washed in cold water and drained. 

 It was then weighed and the desired quantity of sugar mixed uniformly through 

 the fruit. The fruit was then transferred to one-gallon enamelled, friction-top 

 tin cans, properly labeled, moved into a storage room and held between 0° and 

 5° F. This insured rapid freezing. After a few days in this room (over night is 

 sufficient) the fruit was transferred to another cold storage room held between 

 10° and 15° F. The fruit was removed as needed and melted at room tempera- 

 ture in 15 to 20 hours. After melting, observations were taken on the following 

 points: color of fruit and syrup; flavor of fruit and syrup; proportion of fruit 

 to syrup; size and texture of fruit; and consistency and clarity of syrup. 



The effect of the following factors on the pack was studied: 



1. ^'ariety. 



2. Proportion of fruit to sugar (variation from 20-50 per cent sugar). 



3. Substitution of corn sugar for cane sugar (whole or part). 



4. S.yruj) i)acks. 



5. Freezing without sugar. 



6. Fruit; whole, sliced or crushed. 



7. Vacuum packing. 



8. Standing before freezing. 



9. Thawing and refreezing. 



The melted frozen-packed fruit was used in ice cream in order to study the 

 effect of the factors listed above. Then^fore, an important part of this investi- 

 gation has been a study of the effect of methods of freezing on the properties of 

 fruit ice cream.s. These are described in Part II. 



