CONCORD GRAPE JUICE. 9 
From the heating kettles the fruit is dropped to the press room, 
where it is made up into cheeses and pressed. 
PRESSING THE HEATED FRUIT. 
The hot pulp is enveloped in strong, coarse-meshed cloths to 
form layers which are stacked on top of one another. These stacks 
or "cheeses," as they are called, are then subjected to pressure. 
The height of the stacks varies in different factories. It may be 
said, however, that low cheeses are to be preferred to high ones, 
because they allow a better yield of juice on account of the greater 
elasticity of the higher cheeses. 
The presses used in the factories are of two types, the hydraulic or 
power press and the screw or wine press. The number of layers 
varies with the size and power of the press, and the size of the layers 
themselves. As a rule, 10 layers (48 by 48 inches) constitute a cheese. 
While the cheese is being prepared and the number of layers increases, 
the pressure on the cheese grows, thereby increasing the flow of juice. 
This flow of juice is called the free-run juice, since it is the juice 
which is recovered by the weight of the cheese itself without addi- 
tional pressure. This juice is lighter in color than the juice obtained 
after pressure is administered, and is practically the juice from the 
pulp proper. It is materially lower in acid and has less tannin and 
body than the final juice after the pressing process is completed. 
The free run amounts to about 56 per cent of the entire quantity of 
available juice in the fruit. Before the pressure is applied the cheese 
should be allowed to settle. This settling period is of importance, 
as it allows the coarse particles of pulp gradually to shift with the 
flow of juice to the sides of the cloths, followed up by finer material; 
thus a very efficient filter for the juice is provided. If the pressure 
were applied without allowing the cheese to settle, the advantage 
due to the collection of this filtering material and its consequent 
clarifying effect would be sacrificed. Although obviously advanta- 
geous to allow the cheese to settle before applying pressure, it is not 
absolutely necessary. It is evident, however, that the greater the 
amount of suspended matter removed from the juice before it is 
bottled for storage the better will be the precipitation so far as com- 
pactness is concerned, an advantage not to be underestimated be- 
cause of the better conditions for siphoning. Although the time 
allowed for the settling of the cheese varies in the different factories, 
15 minutes is quite sufficient for this operation. This is shown in 
figure 1. The first 10 minutes served to build the cheeses. The 
time of settling was varied to show the effect of time upon the re- 
covery of free-run juice. Table 5 gives the data shown in figure 1. 
39092°— 18— Bull. 656 2 
