Improvements in the Manufacture or Production of Yeast.
Year: 1892

page_text: Date of Application, 17th May, 1892-Accepted, 18th June, 1892
Improvements in the Manufacture or Production of Yeast.
We, KARL SCHLAGENHAUFER, Chemist and JACOB BLUMER, Chemist, both
of 256 West 24th Street, New York, 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 :-
This invention has reference to the manufacture or production of yeast, and more
especially compressed yeast, and has for object to produce yeast of the best quality
in a better and cheaper manner than heretofore, and to make its manufacture
independent of the distilling or brewing processes in which yeast has heretofore
been usually obtained.
Yeast is ordinarily made in the following manner :-Starch bearing raw materials
are mashed, whereby their contained starch is gelatinized and dissolved and then
saccharized with the help of malt. The resulting mash or the wort drawn from
the treated substances, is then fermented and the yeast formed in this process is
collected and separated. It is of course necessary to convert as much as possible
of the starch into sugar and it is therefore necessary to deal with large quantities
of sugar and consequently also with large quantities of alcohol produced from it
simultaneously with the yeast. The use of malt requires that the process of
mashing should be conducted at a comparatively low temperature in order that the
diastase in it may act in an advantageous manner, and such as will not allow of
the mash or wort being sterilized. In consequence thereof the fermentation is not
always a pure yeast fermentation, but is very often endangered by secondary
fermentations which cannot be properly controlled.
According to the present invention wort is employed prepared from starch
bearing materials in such a way as to extract all the substances viz. sugar, dextrine,
albuminous matters and mineral salts, necessary to build up the yeast plant, without
in the least changing the starch in the raw materials and without making use of it
at all for the purpose of producing yeast. By not using the starch in the raw
material the subsequent fermentation of unnecessary large amounts of sugar, and
the handling of the alcohol formed therefrom are avoided; for the same reason
the use of malt or diastase is rendered unnecessary because there is no starch
present to be converted into sugar, and therefore the solution or wort obtained need
not be maintained at a comparatively low temperature, but may be heated to any
temperature necessary to effect its sterilization.
The method of manufacturing yeast according to this invention is as follows:-
The cereal or other starch bearing material to be employed is reduced to small
fragments, either dry or wet, by mills, crushing rollers or other suitable appliances.
It is then mixed with a suitable liquid such for example as water, or water and slop
obtained as hereinafter explained or with a diluted solution of an alkali or an acid,
and treated for a suitable time and at a temperature not high enough to gelatinize the
starch or to change it in any way. The most suitable temperature at which to effect
the extraction will be from about 10° to 15° C., and in no case must it be above 50° C.
After the greater part or a sufficient part of the soluble matters that is to say
the sugar, dextrine, nitrogenous substances and mineral salts, have been extracted
from the material treated, the liquid extract is separated from the remaining
material; this may be done by any suitable means such as filter presses, or centri-
fugal machines. In case the extract should be too diluted it may be used to treat
fresh material in place of water or one of the solutions above referred to, and this
may be repeated several times, if necessary, to obtain an extract of the desired
concentration. In thus extracting the starch bearing raw material in a systematic
CO

page_text: manner, it is an easy matter to obtain extracts of 1.020 to 1.040 specific gravity.
It is this extract or solution, containing no starch, since starch is not soluble under
the circumstances, arising during the above described treatment, which is used for
manufacturing yeast according to this invention. It contains only substances
which have heretofore been wasted or were of very little value. The remaining
part of the starch bearing material employed and still containing all the starch of
the original material may be utilized in the manufacture of starch, glucose,
spirit etc. etc., and is not further used in the process of manufacturing yeast
according to this invention. The extract or solution is then placed in a suitable
vessel and heated to from 65° C. to 130° C. in order to sterilize it. In doing this
a part of the albuminous substances in the extract or solution will coagulate, and
the coagulum thus produced must be separated from the clear solution by filtering
or other suitable process, such as by the use of centrifugal machines or by decanting
the clear solution. The coagulum thus separated forms a nutritious food for
animals. The clear wort thus obtained and after being separated from the coagulum
is cooled to about 25° C. to 35° C., and mixed with a small amount of mother yeast,
and fermented. The fermentation must be conducted carefully, the wort being
maintained at a temperature of between 25° C. and 35° C. and agitated by suitable
appliances. When the fermentation of the wort is completed and all the yeast
formed, the liquor is cooled down to about 15° C. and the yeast allowed to settle
to the bottom of the containing vessel. As soon as the liquor appears clear it is
drawn off carefully. The remaining yeast is then washed one or more times with
fresh cold water and is finally pumped into a filter press, in order to obtain the
yeast in a compressed state. The liquor drawn off as above mentioned, contains a
small quantity of alcohol in solution and this is or may be separated by distillation.
The liquor remaining after the distillation of the alcohol is termed slop or swill and
is suitable for feeding animals. In some cases a part of it may be used in place of
water for extracting the soluble part of the original starch bearing material as
hereinbefore mentioned.
We may in some cases combine our method of manufacturing yeast with the
ordinary methods of manufacturing yeast and alcohol. To this end we prepare the
extract from the starch bearing materials in the manner hereinbefore described and
employ it directly, or mixed with water, for mashing other starch bearing raw
materials or starch bearing waste products, care being taken that the sterilizing of
the extract is effected before the addition of the malt necessary for saccharizing the
extract. After the saccharification is completed, the mash or wort is cooled and
fermented in the usual way, thereby forming yeast and alcohol.
In other cases the said extract after being sterilized may be simply added to a
finished mash or wort obtained from other starch bearing materials, the mixture
being then fermented in the usual way, and thus producing yeast and alcohol.
The sterilized extract obtained as described, may also be combined with a mash
or wort obtained from other starch bearing materials, or wort products, at a stage
where the mash or wort is already in course of fermentation.
In all these cases where we combine our extract with a mash or wort obtained in
known ways the yeast and alcohol producing qualities of such mash or wort will
be increased that is to say by using our extract we can save that much of other
mashing material as will correspond to the amount of yeast and alcohol produced
from our extract.
Heretofore the manufacture of compressed yeast has been an essential part of
ordinary distilling and brewing processes but by our invention we make it
independent thereof. In former methods of yeast making the greater part of the
starch in the starch bearing material employed had to be converted into sugar,
while in our process we use raw, that is unmalted grain or starch bearing material
the greater part of which remains and can be utilized in the manufacture of starch
or its derivatives, only the natural soluble portion of the raw material being used
in the production of yeast which has heretofore been usually wasted. While in
former methods the yeast was formed in mashes or wort which were not sterilized,

page_text: and which therefore were apt to be infected with microbes of different kinds, we
produce our yeast in a liquid which is thoroughly sterilized whereby we are able to
obtain an exceptionally pure yeast that can be stored for a considerable time
without undergoing injurious change.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. The manufacture or production of yeast from sterilized extracts by extracting
the soluble matter from raw starch bearing material by means of a suitable liquid
such as herein referred to at such a low temperature that the starch is not
gelatinized or otherwise changed, separating the extract thus obtained from the
solid residue, sterilizing it by heat, fermenting it and thereby forming yeast and
separating the yeast, substantially as herein described.
2. The use of an extract obtained as described in the preceding claim to increase
the yeast and alcohol producing qualities of mashes or wort obtained by any
suitable process, the extract being sterilized by heating at any stage of the process.
previous to fermentation substantially as herein described.
Dated this 16th day of March 1892.
KARL SCHLAGENHAUFER,
By L. W., per F. B.
JACOB BLUMER,
By L. W., per F. B.