CONCORD GRAPE JUICE. 19 



Table 10. — Percentage of alcohol by volume in a particular Concord grape juice at various 



stages of pressing. 



Stage. 



Experi- 

 mcnt 1. 



Experi- 

 ment 2. 



Heated pulp 



First of free run 



Last of free run 



Last of low pressure at 30 tons... 

 Last of high pressure at 110 tons. 

 Composite of juice 



0.08 

 .80 



1.36 

 .86 



2.06 

 .60 



0.09 

 .66 

 1.56 

 1.60 

 2.60 

 .75 



The total time consumed by the pressing period, including the 

 settling period, was 2 hours and 50 minutes. The figures show a 

 normal alcoholic content for the pulp, and an increased alcoholic 

 content as the cheese cools. 



From the tables of composition it is seen that of the 104 samples of 

 juices recorded 44 per cent show 0.10 per cent or less of alcohol by 

 volume; 77 per cent show 0.20 per cent or less of alcohol by volume; 

 83 per cent show 0.30 per cent or less of alcohol by volume; 90 per 

 cent show 0.40 per cent or less of alcohol by volume. The remaining 

 10 per cent of the samples show an alcoholic content ranging from 

 0.40 to 1.07 per cent by volume. 



It is interesting to note that all of the samples showing more than 

 0.40 per cent of alcohol are members of group 2, season 1912. In 

 the manufacture of these juices the settling period was materially 

 longer than that usually allowed. The juices of the seasons 1913 and 

 1914 of the same group, in the preparation of which a shorter settling 

 period was used, show a decidedly lower content of alcohol. It is 

 evident then that the danger period of alcoholic development is con- 

 fined to the time allowed for the pressing of the juice, and that this 

 danger may be reduced to a minimum by reducing the time for this 

 part of the process. 



INTRODUCTION OF WATER DURING MANUFACTURE. 



A small amount of water is introduced into the juice during the 

 process of manufacture. The stages at which the water may enter 

 are (1) washing the grapes, (2) washing the press cloths, (3) washing 

 receptacles, such as kettles, vats, carboys, and vessels. Although 

 a great many experiments were conducted to determine the amounts 

 of water in the finished product due to these additions, no definite 

 results were obtained. 



It is evident that the washing of grapes introduces water into the 

 juice. The amount depends upon -the time the grapes remain in the 

 water, and upon the manner in which the washed grapes are drained. 

 Experiments to determine the amount of water retained by the 

 grapes showed that 2.5 per cent is held, or for 1 ton of grapes about 



