CONCORD GRAPE JUICE. 5 



difference of opinion as to the merits of these procedures exists. 

 Careful air-ripening, however, mellows the fruit, develops flavor, 

 and admits of a better condition for the process of juice manufacture 

 •than can be attained by using freshly picked fruit. For air-ripening 

 it is of the utmost importance that the boxes of fruit be stacked in a 

 cool place in such a manner that air may circulate freely throughout 

 the stack. This precaution should not be overlooked; otherwise a 

 rise in temperature may cause molding of the fruit. Overfilling the 

 crate should be carefully guarded against to avoid crushing, with 

 resultant souring of the fruit and possible fermentation. With 

 proper care grapes may be kept for several days without particular 

 harm to the fruit. 



A desirable arrangement for a grape-juice factory is one which 

 allows the product to fall from one operation to the next by gravi- 

 tation. In this- way unnecessary pumping is avoided, the metallic 

 surface offered to the pulp or juice is reduced to a minimum, and 

 the work of keeping the juice lines sweet and clean facilitated. 



As to the effect of metals on the quality of the juice, experience 

 has shown that aluminum offers more resistance to the acid of the 

 juice and affects the color less than other base metals. Other metals, 

 such as copper and tin, have been tried. Tin gives the juice a bitter 

 metallic taste and a bluish tinge, and consequently affects the quality 

 materially. Iron also affects the quality of the juice, giving it a 

 purple tinge. It was found that when bottled the product of one 

 of the factories included in this investigation showed a purple ring 

 immediately on the surface. The cause of this ring was traced to 

 the use of iron coils and pipes, which resulted in the formation of 

 iron tannate. 



The gravity plan entails the conveying of the fruit to the highest 

 point in the system; that is, to the first unit in the chain of opera- 

 tions, the crusher. In some factories the fruit is washed in order to 

 remove foreign matter such as dust and leaves before it is crushed. 

 For this purpose the grapes are dumped into a tank of running water, 

 in the bottom of which an endless belt is operated to remove the 

 grapes from the water, and after proper draining convey them to the 

 crusher. 



The process of juice manufacture may be divided into six distinct 

 manipulations : 



1. Crushing and stemming the fruit. 



2. Heating the crushed fruit. 



3. Pressing the heated fruit. 



4. Sterilizing and bottling the juice for storage. 



5. Siphoning the juice. 



6. Bottling and pasteurizing the trade juice. 



