IMPROVEMENTS IN THE TREATMENT OF BREWERS' YEAST
Year: 1878

page_text: LETTERS PATENT to Arthur Hill Hassall, M.D., and Otto Hehner, F.C.S.,
both of No. 54, Holborn Viaduct, in the City of London, for the Invention of
"IMPROVEMENTS IN THE TREATMENT OF BREWERS' YEAST."
Sealed the 28th March 1879, and dated the 11th October 1878.
PROVISIONAL SPECIFICATION left by the said Arthur Hill Hassall at the
Office of the Commissioners of Patents on the 11th October 1878.
ARTHUR HILL HASSALL, M.D., and OTTO HEHNER, F.C.S., both of No. 54, Holborn
Viaduct, in the City of London. "IMPROVEMENTS IN THE TREATMENT OF BREWERS'
YEAST."
Whereas the brewers are often much inconvenienced in hot weather by the
spoiling of the yeast the inventors have devised the following method of treating
it with a view to preserve in a sweet, sound, and active condition for a time
sufficiently long to meet the requirements of the brewer.
The two principal obstacles to the preservation of brewers' yeast are, first, its
porosity, it being in a semi-liquid state only and permeated by inumerable globules
of carbonic acid gas, which continually escaping allow of a constant and free
admission of the oxygen of the air to all parts of the yeast, whereby chemical
changes are promoted; and second, the rapid generation of acidity in the yeast,
whereby it speedily becomes sour, and is rendered unfit for the use of the brewer.
Bearing these facts in mind the inventors have been led to adopt the following
method for treating the yeast:-
The vessels containing the yeast, usually termed “ stillings," are to be partially
filled with water of as cool a temperature as is procurable, the volume of water
added being of about three times the bulk of the yeast contained in the “stilling.”
The yeast and water are then well stirred, and the yeast allowed to subside for
twenty-four hours, at the end of which time the water is to be drawn off and a
second quantity of water, about half the amount of that first used, is to be added,
ונג ...

page_text: the mixture is again stirred, and milk of lime, a solution of soda or some other
suitable alkali, is gradually and cautiously added with frequent stirring until the
acid re-action (as shown by a solution of litmus or litmus paper becoming red) is
almost but not quite destroyed. When the litmus paper ceases to become slightly
red but re-tains its blue colour, more alkali has been added than is necessary, the
object being to stop a little of complete neutralization of the acid of the yeast. Next
a solution of salicylic acid or salicylate of soda is to be added in the proportion of
1 ounces to each cwt. of yeast. Other preservatives or antiseptics may be
employed besides salicylic acid, but if salicylate of soda be the one used it may be
combined with the solution containing the alkali, so as to make only the one
operation necessary. The yeast is then once again allowed to subside, the stratum
of supernatent liquid not being removed until the yeast is required for use. The
liquid having been drawn off a mixture in equal proportions of sugar and malt
flour amounting to 5 lbs. per cwt., or a similar mixture of sugar and wheat flour
is added to and intimately mixed with the deposited yeast; this will speedily
begin to feed upon the saccharine and starchy matter, when the yeast will pass
into an active state, as shown by the abundant disengagement of carbonic acid.
If it be desired to communicate very great and unusual activity to the yeast some
soluble phosphate, say, phosphate of potash, may also be added to either of the
above mixtures in the proportions of about 4 oz. to 1 cwt. of yeast.
In some cases the deposited yeast may be used with almost equal advantage
without any addition of saccharine matter.
The water added being comparatively small in quantity, so very much less in
fact than that employed in the washing of yeast with a view to disembitter it, and
the time allowed for subsidence being so great, the activity of the yeast is not
perceptibly effected, it being in every respect as well adapted for the use of
brewers as before it was subjected to the treatment above described.
It has already been stated that the water added should be as cool as possible, and
though not absolutely necessary yet with this view it would be well that the
cistern from which the water is drawn should be under cover and be thoroughly
protected from the heat of the sun. The coolness of the water in exceptionally liot
weather may be still further insured either by placing in the cistern from time to
time a few lumps of ice, or by drawing the water direct from the main by means
of a flexible hose.
Now the mechanical arrangements necessary for the treatment of yeast in the
manner described with the two successive quantities of water need only to be of a
very inexpensive character, and they consist, first, of a flexible hose for partially
filling the "stillings" and of a syphon for removing the supernatent liquid.
The labour attending the addition of the small quantity of saccharine and
starchy matters would be no greater and in fact exactly analogous to that which is
now expended on the stirring and raking of the yeast.
Of course in the construction of new works or breweries very complete
mechanical arrangements might readily be carried out in the placing of the
cisterns, in surrounding "the stillings" with a constant flow of cold water, and in
the' means whereby these are filled and emptied.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Arthur Hill Hassall and Otto Hehner in the Great Seal Patent Office
on the 9th April 1879.
ARTHUR HILL HASSALL, M.D., and OTTO HEUNER, F.C.S., both of 54, Holborn
Viaduct, in the City of London. "IMPROVEMENTS IN THE TREATMENT OF BREWERS'
YEAST."
Whereas the brewers are often much inconvenienced in hot weather by the
spoiling of the yeast the inventors have devised the following method of treating
it with a view to preserve it in a sweet, sound, and active condition for a time
sufficiently long to ineet the requirements of the brewer.
The two principal obstacles to the preservation of brewers' yeast are, first, its
porosity, it being in a semi-liquid state only and permeated by innumerable
globules of carbonic acid gas, which continually escaping allow of a constant and
free admission of the oxygen of the air to all parts of the yeast, whereby chemical
changes are promoted; and second, the rapid generation of acidity in the yeast,
whereby it speedily becomes sour and is rendered unfit for the use of the brower.
Bearing these facts in mind the inventors have been led to adopt the following
method for treating the yeast.
The vessels containing the yeast, usually termed "stillings," are to be partially
filled with water of as cool a temperature as is procurable, the volume of water
added being about three times the bulk of the yeast contained in the "stilling."
The yeast and water are then well stirred and the yeast allowed to subside for 24
hours, at the end of which time the water is to be drawn off and a second quantity of
water, about half the amount of that first used, is to be added; the mixture is again
stirred, and milk of lime, a solution of soda, or some other suitable alkali, is
gradually and cautiously added with frequent stirring until the acid re-action (ns
shown by a solution of litmus or litmus paper) is almost but not quite destroyed.
When the litmus paper ceases to become slightly red but retains its blue colour,
more alkali has been added than is necessary, the object being to stop a little short
of complete neutralisation of the acid of the yeast. Next a solution of salicylic
acid or salicylate of soda is to be added in the proportion of 14 ounce to each ewt.
of yeast. Other preservatives or antiseptics may be employed besides salicylic
acid, but it salicylate of soda be the one used it may be combined with the solution
containing the alkali, so as to make only the one operation necessary. The yeast
is then once again allowed to subside, the stratum of supernatent liquid not being
removed until the yeast is required for use.
The liquid having been drawn off a mixture in equal proportions of sugar and
malt flour amounting to 5lbs. per cwt., or a similar mixture of sugar and wheat
flour, is added to and intimately inixed with the deposited yeast; this will speedily
begin to feed upon the saccharine and starchy matter, when the yeast will pass into
an active state, as shown by the abundant disengagement of carbonic acid.
If it be desired to communicate very great and unusual activity to the yeast some
soluble phosphate, say, phosphate of potash, may also be added to either of the
above mixtures in the proportions of about 4 ozs. to 1 cwt. of yeast.
In some cases the deposited yeast may be used with almost equal advantage
without any addition of saccharine matter.
The water added being comparatively small in quantity, so very much less in
fact than that employed in the washing of yeast, with a view to disembitter it, and
the time allowed for subsidence being so great, the activity of the yeast is not
perceptibly effected, it being in every respect as well adapted for the use of
brewers as before it was subjected to the treatment above described.
It has already been stated that the water added should be as cool as possible, and
though not absolutely necessary yet with this view it would be well that the
cistern from which the water is drawn should be under cover and be thoroughly

page_text: protected from the heat of the sun. The coolness of the water in exceptionally hot
weather may be still further insured, either by placing in the cistern from time to
time a few lumps of ice or by drawing the water direct from the main by means of
a flexible hose.
Now the mechanical arrangements necessary for the treatment of yeast in the
manner described with the two successive quantities of water need only to be of a
very inexpensive character, and they consist, first, of a flexible hose for partially
filling the "stillings," and of a syphon for removing the supernatent liquid. The
labour attending the addition of the small quantity of saccharine and starchy
matters would be no greater and in fact exactly analogous to that which is now
expended on the stirring and raking of the yeast.
Of course in the construction of new works or broweries very complete
mechanical arrangements might readily be carried out, in the placing of the
cisterns, in surrounding the "stillings" with a constant flow of cold water, and in
the means whereby these are filled and emptied.
What we claim is the treatment of brewers' yeast by washing, neutralisation, and
the addition of antiseptic, substantially as described.
Also the said treatment in conjunction or combination with the subsequent
treatment by feeding the yeast, substantially as described.
In witness whereof, I, the said Otto Hehner, have hereunto set my hand
and seal, this Ninth day of April, in the year of our Lord One thousand
eight hundred and seventy-nine.
OTTO HEHNER. (L.S.)