STUDIES ON FEUIT JUICES. 7 



juices in carboys, therefore, requires further study. It is not 

 improbable that a method of sealing in which no air space remains 

 in the carboy, or in which no oxygen is present in the gases above 

 the juice surface, would result in the complete arrest of the develop- 

 ment of molds. 



SPECIAL METHODS OF PREPARATION. 



As has been stated, the methods of handling just described can be 

 successfully applied to but a limited number of those juices tried, 

 namely, black raspberry, blackberry, black currant, sour cherry, and 

 peach. In the case of strawberry, apple, and other juices which are 

 greatly injured in distinctive flavor by being heated, it is possible to 

 retain the flavor satisfactorily by keeping the juice in freezing storage 

 at a temperature of 14° F. Although certain juices, as pineapple and 

 orange, are not greatly injured in flavor by sterilization, they change 

 in flavor and color upon being kept at ordinary temperatures after 

 sterilization. Keeping such juices in cold storage at from 32° to 36° 

 F. causes satisfactory retention of the color and flavor. Another 

 cold-storage method of general application to fruit juices, and one 

 particularly valuable for fruit juices the distinctive characters of 

 which are injured by heat, is the method of concentrating by freezing. 



Juices of oranges, lemons, and pineapples darken greatly in color if 

 sterilized and subsequently kept in contact with atmospheric oxygen. 

 Satisfactory color retention can here be had by sterilizing and keep- 

 ing the juices free from atmospheric oxygen, which is most conven- 

 iently effected by carbonating slightly and sterilizing them in carbon 

 dioxid. 



APPLICATION OF COLD STORAGE TO FRUIT JUICES. 



Storage of Raw Juices at 32° to 35° F. 



Apple juice, cooled quickly after pressing to 32° F., and stored at 

 this temperature, will keep for from 6 weeks to 3 months before it 

 ferments sufficiently to be considered hard or sour. 1 Unpublished 

 experiments on the keeping of raw orange juice at from 32°to35°F. 

 show that its flavor deteriorates quite rapidly. An unfavorable 

 feature of storage of raw fruit juices at from 32° to 35° F. is the 

 development of molds at juice surfaces. It is not improbable that 

 simple measures for the suppression of the mold growths could be 

 successfully used, as, for example, keeping the containers entirely 

 filled, or keeping the juice surfaces well blanketed with a layer of 

 carbon dioxid, or possibly using ultraviolet light. It seems probable, 

 however, that cold storage of freshly expressed juices at from 32° to 

 35° F. is of but limited application, as the activities of microorgan- 

 isms are not sufficiently held in check. 



1 U. S. Dept. Agri., Bureau of Chemistry Cir. 48. 



