DEHYDRATION OF FRUITS AND VEGETABLES 5 
tions. Perforated plates are also used in stacks. Several plates, 
each stamped with holes of uniform size, the holes varying in size 
with each plate, are set one above the other, with 6 or more inches 
between plates. They are arranged so that the holes are progres- 
sively smaller from top to bottom. 
An ‘‘approximate-weight” grader may consist of baskets car- 
ried on an endless chain. Traps at intervals along the course of 
the chain are controlled by counterweights of fruits, which represent 
the approximate weight of the desired product in that size. As the 
basket carrying the product reaches a trap that is counterbalanced 
by a lighter weight the trap operates to discharge the product. 
Another grader sorts out easily rolling materials according to 
diameter. As a mechanically-driven cable rolls the materials along 
an opening that increases in width the product falls through and is 
collected according to its size. 
A grader based on the same principle passes the product down a 
chute, the floor of which consists of rollers placed crosswise and at 
increasingly greater distances apart. As the product rolls along the 
chute it is separated in progression according to size. 
PEELING 
Manufacturers show a growing tendency to remove the skin from 
all fruits and vegetables before drying. Because of custom or the 
type of skin, some kinas, notably prunes and apricots, however, are 
never peeled. 
Peeling may be done by hand or by specially designed machines. 
Many types of knives, with straight, curved, or guarded blades, and 
hand-operated cutting machines are obtainable for peeling, trimming, 
coring, and otherwise preparing the material to be dried. Machines 
for peeling and coring apples in one operation are available. 
Friction or rotary mechanical peelers are particularly well suited 
for handling tubers. All peelers of this type depend upon the rasping 
effect of rough surfaces of cement, corundum, etc., forming some part 
of the lining of the peeler, when the product is rotated rapidly within 
the cylinder by a moving bottom. ‘The material is introduced at the 
top and discharged by a side door. ‘These machines are usually 
equipped with water sprays, which wash off the dirt and the par- 
ticles of skin removed by the peeler. 
Two types of peelers are based on the reaction of lye with certain 
tissues under the skins of fruits. In one type the fruit is passed 
through sprays of hot lye solution; in the other it is immersed in the 
lye solution. In the second type (fig. 1) the fruit is placed in a per- 
forated rotating metal cylinder, part of which is submerged in a hot 
lye bath. By means of a worm or other device the product is forced 
through the cylinder and delivered to a corrugated metal cylinder 
rotating on an incline, where cold water sprays remove the loosened 
skin and wash the fruit free of lye. .In another system sometimes 
used (fig. 2) the fruit is placed in a wire basket, which is immersed 
in a tank containing the hot lye solution. This operation is followed 
by washing and rubbing the product free from skins. 
In the lye-peeling machines provision should be made to keep the 
lye bath hot, preferably between 190° and 200° F., as its effectiveness 
is greatly reduced at lower temperatures. The strength of the lye 
bath is between 1 and 3 per cent, depending on the nature and con- 
iO) —— 2. —- ae ae 
