STUDIES ON FRUIT JUICES. 9 



through a glass or block tin delivery tube reaching nearly to the 

 bottom. When the desired temperature has been reached, the flow 

 of carbon dioxid is momentarily increased, the delivery tube being 

 withdrawn at the same time and a paraffined cork stopper, taken 

 from scalding water, instantly inserted. 



In Bottles. 



The juice is cooled to refrigerator temperatures in a cask and a 

 current of carbon dioxid passed through until the product tastes 

 distinctly of the dissolved gas. It is then transferred to the bottles. 

 The air above the surface of the juices in the bottles is displaced by 

 a rapid current of carbon dioxid after which the cork is instantly 

 forced into position, tied in place and the bottles and contents given 

 the necessary heat treatment. By thus lightly carbonating, excessive 

 pressures due to carbon dioxid are not developed on heating. 



The principal effect of thus excluding atmospheric oxygen by 

 carbon dioxid is the satisfactory retention in color observed in citrus 

 and pineapple juices. The products are at the same time improved 

 in palatability by the presence of carbon dioxid. 



EXPERIMENTAL WORK. 



A condensed summary of the experimental work with the different 

 fruit juices taken from the laboratory notes follows. Except where 

 noted to the contrary, the conclusions are based on the work of three 

 or more successive seasons. 



STRAWBERRY JUICE. 



Locally-grown berries, variety Gandy, were used in most instances. 



Pressing. — To secure good yields it was necessary to grind before 

 pressing, the pressure being applied very gradually to allow time for 

 drainage. The yields ranged from 63 to 88.06 per cent. 



Sterilization. — The juices were sterilized without injury to color, 

 but with marked injury to fresh fruit flavor. A cooked strawberry 

 taste developed. 



Keeping after sterilization. — Color and flavor changed greatly on 

 keeping the juice in common storage, even in carbon dioxid. The 

 beautiful, bright, red colors faded to dull brownish-red tones, and 

 all distinctive flavor of strawberry disappeared, except for a slight 

 cooked strawberry aroma. Disagreeable flavors developed upon 

 prolonged storage at common temperatures. 



Keeping in freezing storage and concentration by freezing. — Raw 

 strawberry juice retained well its original color and flavor in freezing 

 storage at — 10° C. (14° F.) for nearly 8 months. The juice could be 

 concentrated easily by freezing, but -when partly concentrated be- 

 came gelatinous, the juice and ice separating with difficulty. 

 91345°— Bull. 241—15 2 



