Polk County observer. (Monmouth, Polk County, Or.) 1888-1927, 1917-01-26
.PRUNE METHODS GIVEN
o. A. G. REPORT TELLS OF EVAP
ORATOR TYPES.
Processing Softens Prunes and Aids
In Packing But Should Not Be
Used to Add Weight.

There are two main types of evap
orators used for drying fruit; name
ly, steam and hot air. The steam
driers are used only where a very
large output is obtained. 1t is Gus
tomary for most of the orchardists tc
dry their own fruit. Since the or.
chards on the whole are rather small
an inexpensive building is used fol
the process, and the hot air type OF
building is erected. These hot all
driers are of two distinct types
namely, the tunnel, and the stack
There are many types of tunnel drl'
ers. These tunnels consist of grousr
of long, nearly horizontal pipeways,
built over fire pit. They vary in
length from twenty-five to fifty feet
Each tunnel in itself may be COM
plete. or they may all be. connected.
The tendency in the past has been
to have the tunnels too long. In the
newer buildings. however, there are
tunnels from sixteen to twenty-five
feet in length The capacity Of the
drier can be increased more salts
factorily by increasing the number
of tunnels rather than by increasing
the length of the tunnels. The heat
pit is found directly below the tun-
nels. and. as a rule, brick arch fur
naces. or iron stoves. such as are
commonly known as the hop stoves,
are employed. In order to distribute
the heat more uniformly, it is gener-
ally conducted from the furnaces by
long pipes from nine to fifteen inches
in diameter. decreasing the farther
they get away from the source of
heat.
The stack driesis arranged to con-
tain trays which are placed one over
the other. the bottom of the stack be-
ing open. A single stack consists Of
three or four small vertical compart-
ments generally open to each other.
The fruit Is first placed in the top
compartment and after slightly dry
ing is removed and placed in lower
compartment The stack driers turn
out a very good product. but require
maximum amount of labor The
buildings have to be so constructed
that they are very well ventilated
and these ventilatOrs should be of an
adjustable nature so that they can
be opened and closed quickly. Cold
air intakes are also provided. These
should be in below the vent pipes so
as to furnish fresh air rather than
to assist in rapidly sucking out the
warm air. There is a very close re-
lation between ventilation, air cir
and the humidity of the at
Such relationship unfor-
tunately has not been well studied by
the majority Of men operating the
The temperature is gradually in
creased during the drying process,
starting in the neighborhood of one
hundred twenty-five to one hundred
degrees and finishing at
from one hundred sixty to one hun
ired eighty degrees. 1t takes about
hours on the average 10
dry prunes well, the time depending
on the building. ripeness of the fruit.
and atmospheric conditions. The fruit
will generally produce about twenty
pounds of dried fruit to a bushel of
fresh fruit. Before the prunes are
placed over the heat, it is customary
TO wash and grade the fruit. The
more modern buildings now have au-
tomato machinery which does all of
this labor in one process. The prunes
after being sorted, are dipped into
'oiling I've. generally at the strength
Of one pound of I've TO from thirtv
o fifty gallons Of water. This use