STUDIES ON FRUIT JUICES. 13 



Discussion. — The color and flavor, while thus found to be injured 

 but slightly by sterilization, deteriorate greatly on keeping, even 

 though carbonated and kept in cold storage. Only in freezing 

 storage are the color and flavor satisfactorily retained. It is, how- 

 ever, possible to keep red raspberry juice by freezing storage methods. 



PINEAPPLE JUICE. 



Florida-grown red Spanish pineapples were used in all cases. 



Pressing. — High yields of juice were invariably obtained. Juice 

 derived from the peels possessed rather disagreeable soapy flavors. 

 Fresh pineapple juice prepared from crushed unpeeled pineapples 

 was, therefore, less attractive than that from pineapples which were 

 peeled before being pressed. It was found, however, that pine- 

 apples which had not been peeled or previously crushed, but the 

 crowns of which had been removed, might be placed on their sides 

 in cloths on extra heavy racks and pressed. So prepared, the juice 

 was not perceptibly injured by off flavors derived from the peel. 



Effect of heating on flavor. — Although heating the juice caused 

 slight but definite changes in flavor, it did not markedly injure the 

 juice. 



Effect of storage on color and flavor. — Gradual darkening occurred 

 where precautions were not taken to exclude atmospheric oxygen in 

 bottling. This color change was controlled by bottling the juice in 

 carbon dioxid. In addition to this, carbon dioxid imparted an agree- 

 able flavor to the juice, simulating the freshness of the original fruit. 

 When stored at common temperatures, the gradual development of 

 a peculiar taste, designated as a stale flavor, occurred, and much of 

 the rich flavor of the original juice disappeared. The characteristic 

 flavor, however, was sufficiently well retained for recognition of the 

 juice as pineapple. Cold storage at from 32° to 35° F. prevented 

 perceptible losses in flavor during a period of 1\ months. 



Storage at freezing temjjeratures. — During storage at freezing tem- 

 peratures, — 10° C. (14° F.), the color and flavor were well retained. 



Special methods. — A voluminous precipitate formed on heating 

 pineapple juice. A treatment consisting of warming the juice to 

 85° C. and allowing it to stand for one hour was sufficient to com- 

 pletely precipitate the heat-coagulable substances. The bulk of the 

 coagulum was removed by passing the cooled juice through the milk 

 separator. Filtration through paper pulp was thus greatly facili- 

 tated, as clogging of the filter was retarded by the removal of the 

 coagulum. 



Discussion. — It is necessary to take special precautions in the 

 preparation and storage of pineapple juice to prevent deterioration 

 in distinctive color and flavor. Sterilization and the subsequent 

 keeping of the juice free from contact with atmospheric oxygen result 



