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 im 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 retamed 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 
