12 BULLETIN 241, U. S. DEPARTMENT OF AGEICULTUEE. 



BLACK RASPBERRY JUICE. 



Locally-grown berries of the Doolittle and Kansas varieties were 

 used. 



Pressing. — Upon being pressed without previous heating, yields of 

 from 61.8 to 75 per cent of juice were obtained. Yields as high as 

 76. 1 8 per cent were secured by hot pressing. Pressure must be applied 

 very gradually for satisfactory yields. 



Sterilization. — The juices were not injured perceptibly in flavor or 

 in color by sterilization. 



Keeping after sterilization. — Juices prepared by either hot or cold 

 pressing retained their color and flavor, which were practically 

 unchanged for prolonged periods at common temperatures. Special 

 measures, such as keeping at low temperatures or sterilizing in carbon 

 dioxid, are therefore not necessary. 



Concentration by freezing. — Upon concentrating black raspberry 

 juice by freezing, a peculiar coagulum formed, consisting apparently 

 of flocculated coloring matter. Concentrating by freezing as applied 

 to black raspberries did not appear to be of particular value, in view 

 of the excellent color and flavor retention of the juice when sterilized 

 and kept at room temperature. 



Discussion. — Juices can thus easily be prepared from black rasp- 

 berries by crushing and then pressing them with or without previous 

 heating. The characteristic color and flavor of black raspberry juice 

 are excellently well retained upon sterilizing it and keeping it after 

 sterilization at ordinary temperatures for prolonged intervals, even 

 as long as several years. The sterilized juice is rather acid, requiring 

 the addition of sugar to make it palatable. 



RED RASPBERRY JUICE. 



Locally-grown berries of the Miller, Brandywine, and Cuthbert 

 varieties were used. 



Pressing. — High yields of juice, ranging from 71.9 to 82.3 per cent, 

 were easily obtained by crushing and pressing the berries. It was 

 necessary to press slowly and to use double press cloths. 



Sterilization. — Although red raspberry juices underwent a distinct 

 change in flavor on heating, the palatability of the juice was not 

 greatly injured. 



Keeping after sterilization. — The color faded and disappeared and 

 the flavor changed greatly, even during storage periods of 6 months. 

 Bottling the juice in carbon dioxid and keeping it in cold storage at 

 from 3'2° to 35° F. after sterilization had no apparent effect in retard- 

 ing these changes in color and flavor. 



Keeping raw juice in freezing storage. — The color and flavor were 

 excellently well retained. 



Concentration by freezing. — The color and flavor were well retained. 

 Highly colored, richly flavored, very acid juices were obtained. 



