The Athena press. [volume] (Athena, Umatilla County, Or.) 18??-1942, 1911-08-11
THE CHEMISTRY OF THE HOP.

BY II. v. Tartar, Oregon Agricultural
College.
The large amount of hops grown
in this state makes the chemistry OF
the hop of interest both to the local
experiment station chemist as we'll as
as the hopgrower. The annual pro-
duction of the hop crop of this state
approximates 10000 bales annually,
while the total consumption of hops
in the United States, according to
one writer, amounts to 45,000,000
pounds. Again, in the adoption OF
proper standards for judging the quail
ity of hops the chemical composition
must be given considerable consider
alton. Since the cone is the portion
of the plant used commercially, only
this portion will be considered in
what follows.
Many researches have been carried
out by different chemists on the COM
position of the hop cone, the earliest
investigations dating as far back as
1920. During recent years much
work has been done on this subject
and the results obtained have not
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The different investigators seem to
be agreed, however, that the principal
constituents of the hop cone are a
volatile oil, wax, hard resin, two
soft bitter resins, an alkaloid and a
tannin.
If hops are placed in still with
water and the mixture boiled, oily
drops will be seen coming over with
the distillate. AS the process con-
tinues and larger quantity of ma
terial collects it will be noted that
| it has light green color. This oily
hop and although it amounts to only
hop and altogether it amounts to only
one-half of l per cent, it is the con-
stituent which gives to the hop it's
fragrant odor 1t is a greenish, mo-
bile liquid and is very aromatic. 1t
is composed of three or four differ
ent bodies, some of which are known
chemically as terpenes, being closely
related in composition to ordinary
turpentine.
A wax was isolated from the hop
in 1862 by German chemist. He
| found the substance to be white,
waxy material, closely allied in ma
ture to beeswaX and other wakes. An
examination showed the hop wax to
be chemical compound, known as
myricyl palmitate The amount of
this substance present in the hop
amounts to approximately 0.40 per
cent 1t is a tasteless, inert sub
stance which is apparently of no
value in the practical uses of the
hop.
From the investigations made it ap,
pears that there are three distinct
resinous substances in the hop cone
and for convenience two are deslg.
mated as soft resins" while the third
is called the hard resin" When the
cone is extracted with ordinary ether,
all three of these resins are dis.
solved. If the ether be evaporated
from the extract obtained, however
and the resulting residue be treated
with light petroleum spirit, only the
soft resins pass into solution, while
the hard resin is left behind as 6
light green amorphous residue. ,a-
The hard resin is almost tasteless
Chemical experiments indicate tina
it is probably mixture of differen
substances and no definite results
have been obtained as to it's actua
! composition. So far as is known /
has no value in the practical uses o
the hop. The amount of hard resfr
seems to increase with the age o.
the hop and also with the use of higf
temperatures in drying.
For convenience the soft resins are
designated as the alpha and the
"beta.' According to the present
belief these substances are the con
stituents which impart to the hoE
cone the major part of its actual com
mercial value. Collectively they are
known as the chop bitter" or "bit'
ter principle" and many consider the
amount of soft resins as one of the
prime factors in judging the quality
of the hop. Analyses made in this
laboratory show that Oregon hops
contain from 13 to IS per cent OF
these materials. In the pure state
the soft resins are both crystalline
substances, which, although only
sparingly soluble in water, are read
lily soluble in alcohol. They impart
to their solutions an intensely bitter
taste. The beta" resin is colorless
while the alpha is of a beautiful
golden yellow color. When in solu
ton both act as weak acids toward
alkalies and for this reason they are
often termed the 'hop-bitter acids
They also possess certain definite an
tiseptic properties.
Hops have long been assumed to
contain an alkaloid. A German chem
ist several years ago succeeded 1r
isolating substance giving the gen
eral reaction of an alkaloid. Subse
quent investigators repeated this in
vestigation with negative results. Re
Gently, however, an alkaloid has beer
isolated which is said to closely re
semble morphine in it's properties
Practically nothing of real definite
nature is known regarding this sub
stance and it is evidently present II
very small quantity.
A tannin is present in the bract'
and stems of the hop cone which car
be extracted with hot water. WheI
isolated it is a reddish brown powder
possessing an astringent taste. Wha
the actual value of the hop tannin II
lin the commercial uses OF the hop II
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