STUDIES ON FRUIT JUICES. 17 



Concentration by freezing. — Concentration to a sirup was easily 

 accomplished. 



Discussion. — The studies on orange juice have not led to results on 

 which a method for its preparation may be based, as no way to 

 successfully retain fresh orange juice flavor has been found. Steriliz- 

 ing the juice injures the flavor, which continues to deteriorate gradually 

 when the juice is kept at ordinary temperatures. In cold storage, 

 however, the flavor is well retained. Certain features of the tech- 

 nology of preparing orange juice have been mastered. Thus, the 

 milk separator may be successfully employed in removing excessive 

 amounts of oil as well as suspended matters from freshly expressed 

 juice. Carbonating and sterilizing the juice in carbon dioxid, as 

 well as cold storage at from 32° to 35° F., permit of satisfactory 

 color retention. Concentration by freezing to a sirup is of promise, 

 but this subject, as well as the use of infusorial earth in filtering, 

 remains to be further worked out experimentally. 



SUMMARY. 



Pressing. 



Satisfactory yields of juice were easily obtained from all of the 

 fruits studied. Lemon and orange juices were best expressed by 

 cutting each fruit into several pieces and then pressing, a method 

 which could be successfully used in pressing pineapples, although 

 the method of pressing the fruit without previous cutting is probably 

 superior. It was found advisable to pass all of the other kinds of 

 fruit pressed without heating through an apple grater to facilitate 

 the outflow of the juice. 



Heating before pressing in the case of black raspberry, blackberry, 

 red currant, black currant, and huckleberry juices resulted in larger 

 yields of juice and the development of more color and a more dis- 

 tinctive flavor than were obtained from cold pressing. Strawberries, 

 red raspberries, cherries, peaches, pineapples, lemons, and oranges 

 were cold pressed. 



Effect of Heating on Distinctive Colors and Flavors. 



Heating the juices sufficiently to sterilize them did not affect 

 injuriously the color of any of the fruit juices, though pineapple, 

 lemon, and orange juices usually darkened somewhat if heated in 

 the presence of dissolved oxygen or if exposed to atmospheric oxygen 

 during the heat treatment. 



The distinctive flavor of the fresh fruit was greatly injured and 

 the familiar cooked strawberry taste appeared when strawberry juice 

 was sterilized by heat. The fresh fruit flavor of orange juice was also 

 distinctly injured when the juice was heated. Although all lost in 

 the quality of freshness, heating did not seriously affect the flavor 



