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 tins 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. 
