Year: 1898

page_text: Date of Application, 24th Oct., 1898-Accepted, 19th Aug., 1899
I, PAUL KROPF, of 56, 5th Avenue, Chicago, State of Illinois, United States
of America, do hereby declare the nature of this invention and in what manner
the same is to be performed to be particularly described and ascertained in and
by the following statement:-
My invention relates to improvements in the process of manufacturing beer
such as is known commercially as Lager beer, and has especial reference to the
treatment of the wort during fermentation.
The object of my invention is to effect the complete operation of making such
beer in from one-third to one-fourth of the time required by the usual processes,
and at the same time to produce a beer which will be free from bacteria, and
possess all of the desirable qualities of the high grade beers.
In the common process of manufacturing beer, which requires from 45 to 60
days, the exact time depending on the quality of beer desired, and whether it is
for immediate use or for export, the following steps are observed; After the
cooked beer wort is cooled down to about 44 degrees F. it is conveyed to the
fermenting vat where the necessary yeast is added to produce the first fermenta-
tion which occupies from eight to twelve days. When it has reached the desired
or proper degree of fermentation, the beer is drawn off into the storage casks for
the second or after fermentation which requires from 30 to 40 days, when the
beer is drawn into the chips cask and kraussened up, or it may be taken directly
to the carbonator and charged with carbonic acid. The object of the first fer-
mentation is to divide the fermentable sugars in the beer wort into alcohol and
carbonic acid. When such division is effected to the proper degree as shown by
the sacharometer, the fermentation is interrupted by withdrawing the beer from
the yeast and turning it into the storage cask for ripening. During the ripening
period, which as above stated requires from 30 to 40 days, a second or after fer-
imentation is effected which separates the floating yeast from the beer, and con-
verts the resin of the hops by oxidation into solids which fall to the bottom and
transforms the alcohol or a portion thereof into aromatic ethers and slowly
eliminates the nitrogenous bodies or albuminous matters. The beer is then ready
for filtering and to be run into the chips casks or the carbonator. It is appa-
rent that the length of time required to produce beer by the old and common
processes increases the contamination by bacteria, and the harmful effect of the
latter can only be avoided by pasteurizing methods. The common processes
involve great expense for storage room and cooling apparatus, which is another
serious objection, which I overcome in the following manner:
The cooked beer wort is cooled down to 44 degrees F. as in the old processes,
and the first fermentation is produced in the usual manner.
When this fermen-
tation has reached the proper stage, as shown by the sacharometer, which occupies
from 10 to 12 days depending on whether high or low fermented beer is wanted,
I pass through the wort, ozonised air from four to six hours, the exact length
of time of such treatment depending on the original specific gravity of the wort.
It will be understood that the time required for this first fermentation varies

page_text: according to the quality of the wort, and the quality of the yeast used, and
therefore the time for introducing the ozonised air must be determined in each
particular case, it being understood that it should be applied during the latter
part of such fermentation. After treating the wort by the ozonized air, I cool
the beer which is then formed, until it is reduced to a temperature of 32 degrees
F. to eliminate the albuminoids, when it is conveyed to the settling tub where
it is kept at such temperature for about 48 hours, when it is ready for filtering
and carbonating. Thus it will be seen that from the wort kettle to the beer
keg, the production of beer by my process does not require more than 14 days
as against 45 to 60 days by the common processes. It will also be seen that by
ozonizing the air which I introduce into the wort I destroy all germs and bac-
teria, and thus produce a much purer beer than is possible by the old processes
involving long exposure to the common air. And not only does my process pro-
duce a purer beer, but the oxidizing qualities of the ozonized air are so effective
that the yeast and the albuminoids are all eliminated during the one fermenta-
tion, and the second or further fermentation is not required. In the few hours
during which I subject the wort to ozonized air, I convert the resins of the hops
and transform the alcohol into aromatic ethers as effectively as in the old process
which requires from 30 to 40 days to effect the same result.
I have found by extensive experimentation, that in order to secure the best
results from my process, I must ozonize the air by subjecting it to a strong
electric current, say of about 25000 volts and that this ozonized air must be
introduced into the wort during the latter part of the first fermentation.
D"
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare, that what
I claim is
1. In the manufacture of beer, fermenting the wort for a period of from eight
to twelve days, and then introducing ozonized air into the wort during the latter
part of such fermentation.
2. In the manufacture of beer, fermenting the wort for a period of from eight
to twelve days, and then introducing ozonized air into the wort for from four to
six hours during the latter part of such fermentation.
3. In the manufacture of beer, fermenting the wort for a period of from eight
to twelve days, and then introducing electrically ozonized air into the wort
during the latter part of such fermentation.
Dated this 94th day of October 1808