20 BULLETIN 656, U. S. DEPARTMENT OF AGRICULTURE. 



6 gallons of water would be introduced. Although only approximate, 

 it is believed that this figure gives a fair representation of the true 

 condition. The content in solids was invariably slightly lower in the 

 case of juice made from grapes which had been washed than in the 

 case of juice from grapes which had not been washed. It was found 

 that about 6 pounds of water was retained in the washed and centri- 

 fuged cloths of standard size for 48 by 48 inch racks. 



Experiments were conducted to determine the amount of water 

 introduced by washing the grapes and washing the press cloths. Runs 

 wherein the grapes were washed, and washed and centrifuged cloths 

 were used, and runs wherein the grapes were not washed and new dry 

 cloths were used, were made. Although a slightly heavier juice was 

 obtained under the latter conditions, the difference was not great 

 enough to allow of definite conclusions. 



Judging from all the experiments and from the chemical compo- 

 sition of the juices, made with and without the use of water, it is 

 believed that about 3 grams of water per 100 cubic centimeters are 

 introduced into the juice during the washing and pressing of the 

 grapes. The amount of water added during the washing of the 

 receptacles is regulated by factory practice. 



CHEMICAL COMPOSITION OF GRAPE JUICE. 



The analyses of the 104 commercial juices taken during the in- 

 vestigations are given in Table 11. This material is divided into six 

 groups, each group representing the juices from one factory. Group 

 1 comprises the samples from the Hudson River district. The first 15 

 samples represent juices made from washed grapes, the remainder those 

 from unwashed grapes. The settling period was about 15 minutes. 

 Groups 2, 3, 4, and 5 comprise the samples from the Chautauqua 

 belt. The grapes of group 2 were washed. During the seasons 1914 

 and 1915 the time allowed for the settling of the cheese before pressing 

 was shortened to about 25 minutes. Groups 3, 4, and 5 are juices 

 made from unwashed grapes. The settling period was about 15 

 minutes. Group 6 comprises the juices made from grapes of the 

 Lake Erie district. For the description of the manufacturing 

 process see page 4. The 1912 samples of group 2 are not included 

 in Table 11, because the alcohol content of this set is abnormally 

 high for a properly prepared grape juice. 



