Improvements in the Manufacture of Bakers' Yeast.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Bakers' Yeast.
I, MORITZ PAUL HATSCHIEK, of 41, Montserrat Road, Putney, in the County
of Surrey, Chemical Engineer, do hereby declare the nature of this invention to
be as follows:
Brewers yeast pressed in the usual way or in a semi-liquid condition, is
washed in about four times its bulk or more of cold or tepid water, to free it
from impurities, like hop-resin etc. if necessary. After the yeast has deposited
in the washing water, the latter is drawn off, and the yeast rendered liquid by
the addition of clean water, heated to the coagulating point and kept at about
that temperature for some time. It may also be heated up to the boiling point,
or if in closed vessels, up to the temperature corresponding to about two atmos-
pheres of pressure, and is then after having heated it more or less as described
submitted to filtration on filter presses or other suitable filters.
To facilitate the hydration of the yeast I may in some cases employ a small
proportion of any suitable acid which can be afterwards neutralized if desired.
The filtrate which is rich in albumen, and especially in the enzymes of the
yeast-plasma, contained in the brewers' yeast, is then mixed with maltose,
dextrose, molasses or other suitable kind of sugar, and this mixture or wort is
cooled down to about 80 to 86 degrees of Fahrenheit and fermented by using
a suitable bakers' yeast as a ferment for starting.
The said filtrate can also be added to any kind of wort prepared for yeast
making, to increase the output of bakers' yeast, or the brewers' yeast can
be directly added to such wort, when mashing up to the usual temperature of
150 to 160° F.: although this latter way of using it, being crude and imperfect,
cannot be recommended.
The said filtrate can also be mixed with an addition of extract of animal or
vegetable matter, rich in albuminous substance, like blood, offal of fish, malt-
combs etc.; or with diastase in the shape of malt-flour or extract, if found con-
venient.
In fermenting the said filtrate or heated and mashed brewers' yeast with a
suitable ferment or leaven, in one or the other kind of wort as before mentioned
with or without the introduction of atmospheric air, and by further treating it
in the usual manner, a strong and sweet bakers' yeast is produced which has
been found to answer well for all purposes of bread making.
Dated this 22nd day of December 1899.
HARRIS & MILLS,
23, Southampton Buildings, London, W.C.,
Agents.

page_text: f
Improvements in the Manufacture of Bakers' Yeast.
I, MORITZ PAUL HATSCHEK, of 41, Montserrat Road, Putney, in the County
of Surrey, Chemical Engineer, 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: -
Brewers' yeast of any description, pressed in the usual way, or in a semiliquid
condition, is dissolved or diluted in a small quantity of water and strained
through a fine sieve and then washed and stirred in four to ten times its bulk or
more of cold or tepid water to free it from impurities like hop resin, slimy
matter, &c. About 4 or 5 ozs. of carbonate of ammonia (or soda or potash) can
be dissolved and added to the washing water per cwt. of yeast, by which means,
as is well known, the beer-yeast is better cleaned and freed from hop resin than
with water alone.
When the beer-yeast has well settled, the washing water is drawn off, and in
case the yeast were not sufficiently well cleaned, the washing could be repeated
a second or even a third time, but then only a smaller addition of carbonate of
ammonia, &c., would be required.
After the beer-yeast has deposited in the washing water, or in the last
washing water when it is washed more than once, the water is drawn off and the
thick yeast is rendered liquid by the addition of about 50 gallons of clean water
per cwt., heated to about 180° F., and preferably kept warm for 12 to 15 hours,
during which time it may sink to between 150° and 130° F. I shall hereinafter
refer to this treatment as the first step in my process.
It may afterwards be heated up to the boiling point or, if in closed vessels,
up to the temperature corresponding with 1 to 3 atmospheres of pressure. I
shall hereinafter refer to this as the second step in my full process.
Then, after having been heated more or less as described, the treated liquid
is submitted to filtration in filter presses or other suitable filters in manner
hereinafter more particularly described.
The object of this second step is to cause the bursting of the yeast-cells, which
will take place after applying from 1 to 3 atmospheres of pressure in excess
of the atmosphere for 15 to 30 minutes and then allowing the steam to escape.
When diffusion only has taken place, which occurs in the first step above
mentioned of my process, the cells of the beer-yeast remain wholly or for the
greater part intact; in this case these cells may be allowed to pass into the
filtrate, and will, under the influence of the seed-yeast, acquire the character of
bakers' yeast in the working vat by the process described later on.
When, on the other hand, the second step of my process is applied, the cells
of the beer-yeast are partially or entirely burst, and in this case the filtration
should be effected through a close material in such a manner as to separate the
whole of the cell walls (cellulose), which can be thrown away as residues or used
as food for cattle or poultry.
Generally speaking I only propose to use the process described as the first step,
but when I wish to obtain a bakers' yeast of exceptional quality I employ the
process described as the second step. The process described as the second step
may be carried out upon dissolved or diluted yeast previously treated according
to the first step, or upon washed diluted yeast which has not otherwise been
treated:
To facilitate the hydration, or rather liquefaction, of the beer-yeast in either
of the steps above mentioned, I may employ a small proportion of any suitable

page_text: mineral or vegetable acid (say, 1% of hydrochloric or 4% of sulphuric acid, &c.),
which can be afterwards neutralized if desired.
The filtrate obtained by either the first or second steps, which is rich in
albumen contained in the brewers' yeast, is then mixed with maltose, dextrose,
molasses, or other suitable kinds of sugar, and this mixture or wort is cooled
down to about 83° to 86° F. and fermented or set into action by using a suitable
bakers' yeast as a ferment for starting the growth of new yeast of the same
nature and of a similar character.
A wort can be prepared by adding to one cwt. of the filtrate of beer-yeast,
sufficient pure water to make a bulk of from 120 to 150 gallons and from 40
to 50 lbs. of sugar; the said proportions may however be somewhat varied without
increasing or diminishing the result to any considerable extent.
The above description refers to the manufacture of bakers' yeast, for which
purpose but small proportions of sugar are sufficient to form the walls of new
yeast cells, and in the present case the contents of these yeast cells are built up
from the constituents of the filtrate gained by the treatment of beer-yeast herein-
before described.
The wort, consisting of the filtrate of beer-yeast and the added water and
sugar, can be made in one bulk, but it is preferable to prepare it in three or
four portions and to add them to each other in the working vat at intervals
of about three hours.
The seed-yeast, or so-called ferment, is put into the working vat with one
fourth or one third of the wort to start with, and purified atmospheric air is
then pumped or driven by blowers into the wort in the ordinary way through
roses or pipes provided with small holes near the bottom of the vat. For every
1,000 gallons of wort, about 5,000 gallons of pure air should be driven into the
working vat during one hour's time, and this is to be continued until the growth
of yeast is finished and the wort exhausted, which is the case after 9 to 10 hours
from the time of starting.
During the whole time of working the temperature of about 839 to 86° F.
should be maintained and deviations from the same avoided.
The driving or forcing of large quantities of air into the wort is done to facili-
tate the growth of yeast-cells by supplying them with plenty of oxygen, and at
the same time to hinder the originating of alcoholic fermentation, which would
result in a waste of sugar.
As soon as the operation is finished the wort is cooled down to about 70° F.,
either by passing it through or over a refrigerator or by adding the necessary
quantity of cold water. Then the yeast is left for about 12 to 18 hours to
settle at the. bottom of the vat, and as soon as this has been accomplished, the
clear wort or wash is drawn off, and the deposited yeast is then strained or
sifted and well washed in pure cold water.
The washing, and afterwards the pressing and the packing, of the new
bakers' yeast are done in the usual manner.
As in the aforesaid treatment of the brewers' yeast high temperatures are
used, by which it becomes completely sterilized, the bakers' yeast produced from
it is to be considered as practically free from infection.
Nevertheless, and especially in warm weather, slight additions, say of about 1
part in 10,000 to 20,000 parts, of the usual disinfectants, like salicylic, sulphurous
or formic acid, etc., may be used in the wort or afterwards in the washing water,
to prevent infection through the water or from the surrounding atmospheric air.
The filtrate of the beer-yeast prepared in the aforesaid manner according to
the first or second steps, can also be added to any kind of wort suitable for making
bakers' yeast to increase the output of the latter, or the brewers' yeast can be
directly added to such wort during the process of mashing malt or grain or both
up to the usual temperature of 150° to 160° F., although this latter way of
using it, being crude and imperfect, cannot be recommended.
In working or fermenting the said filtrate prepared by the first or second

page_text: steps, or heated and mashed brewers' yeast referred to in the next preceding
paragraph, with a suitable ferment or leaven, in any suitable kind of wort as
before mentioned, with or without the introduction of atmospheric air, and by
further treating it in the usual manner as described, a strong and sweet bakers'
yeast is produced which has been found to answer well for all purposes of making
bread, rolls, etc.
In the foregoing description I have described the various steps in the order
in which it is, speaking generally, convenient to take them, but it will of course
be obvious that the order may to some extent be varied if desired. For example,.
it it quite possible to take the above-named second step, when my full process
is employed, before taking the above-named first step, as the order in which
these two operations should be carried out, and the time allowed for liquefaction
and diffusion, are in the main a question of convenience of manipulation.
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 bakers' yeast, the use of brewers' yeast treated as
herein before described in the preparation of, or in addition to, a wort, and the
addition to such wort of a suitable proportion of bakers' yeast to act as a ferment-
ing or working agent thereon, substantially as herein set forth.
2. The preparation of brewers' yeast for use in the manner hereinbefore
described for the manufacture of bakers' yeast, by diluting the same, heating it
to such a temperature and for such a length of time as to cause diffusion of the
contents of the yeast-cells through the walls of the latter whilst leaving the
cells or the greater part of them intact, and subsequently filtering the same in
such a way as to allow the yeast-cells to pass into the filtrate, substantially as
herein described.
3. The preparation of brewers' yeast for use in the manner herein before
described for the manufacture of bakers' yeast, by diluting the same, heating
it to about 180° F. and keeping it warm for about 12 to 15 hours and afterwards
heating it to the higher temperature above mentioned, by which the yeast-cells
are burst, and subsequently filtering the same so as to remove the walls of the
cells from the filtrate, substantially as herein described.
4. The process of manufacturing bakers' yeast which consists in mixing a
filtrate rich in albumen obtained from brewers' yeast with a saccharine solution,
cooling the mixture or wort thus obtained to about 83° to 86° F., adding to
such mixture or wort a seed-yeast or ferment consisting of a suitable bakers'
yeast, and keeping the mixture at a temperature of about 830 to 86° F. during
the whole time of working, substantially as herein described.
Dated this 20th day of September 1900.
HARRIS & MILLS,
23, Southampton Buildings, London, W.C.,
Agents.