STUDIES ON FRUIT JUICES. 19 



Orange juice also underwent a marked darkening in color when 

 kept at room temperatures after being sterilized. The color was 

 fairly well retained when atmospheric oxygen was excluded by 

 sterilizing the juice and subsequently keeping it in vacuum or in 

 carbon dioxid, and the change in color was well controlled by keep- 

 ing the juice at low temperatures. The flavor of sterilized orange 

 juice, already slightly injured by the heating necessary for sterili- 

 zation, underwent further changes when kept at room temperatures. 

 It was found that by keeping the juice in cold storage at from 32° 

 to 35° F. the flavor was well retained for long periods. 



Keeping in Freezing Storage and Concentration by Freezing. 



The distinctive colors and flavors of all fruit juices kept in freezing 

 storage at about —10° C. (14° F.) were found to remain practically 

 unchanged during many months, except that a peculiar coagulation 

 of much of the coloring matter appeared in the juice of the black 

 raspberry. It was possible to concentrate fruit juices to sirups by 

 freezing out the water as ice and centrifugalizing. Characteristic 

 colors and flavors were well retained on concentrating. 



Filtering. 



Infusorial earth greatly promotes the filtering of fruit juices, as it 

 retards greatly the clogging of the filter. 



CONCLUSION. 



Juices of red and black currants, blackberries, black raspberries, 

 sour cherries, and peaches may easily be successfully prepared on 

 the large scale by the methods used for the preparation of grape 

 juice, as they retain their characteristic properties well on being 

 sterilized and stored away. Strawberry juice and red raspberry 

 juice are not suited for preparation on the large scale because of 

 the readiness with which the distinctive colors and flavors change. 

 Huckleberry juice is somewhat characterless. Pineapple juice 

 requires special methods for its successful preparation not necessary 

 in case of the other juices. Its preparation on the commercial scale, 

 however, is of marked promise. 



Satisfactory methods for the preparation of lemon and orange 

 juices have not been developed. The peculiar change in flavor of 

 lemon juice stored after sterilization, even at low temperatures, is an 

 obstacle to be overcome before the preparation of the juice on the 

 large scale can be considered advisable. The problem of preparing 

 orange juice is not without promise. It is not unlikely that highly 

 specialized methods in which cold storage will play a prominent, if 

 not dominating, part will be required. 



WASHINGTON ; GOVERNMENT PRINTING OFFICE : 1915 



