Improvements in the Manufacture of Yeast.
Year: 1895

page_text: Date of Application, 19th Sept., 1895-Accepted, 18th Jan., 1856
CUBILETE SPECIFICATION.
Improvements in the Manufacture of Yeast.
I, HARTOG ELION, of 76, Westzudijk, Rotterdam, in the Kingdom of The
Netherlands, Doctor of Chemistry, 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 relates to the manufacture of yeast, chiefly pressed or bakers'
yeast, from molasses and sugar syrups, such as are produced in the manufacture
and refining of sugar.
This invention is based on the discovery that, with the exception of phosphoric
acid, all the elements needed for the increase and growth of yeast are present in
molasses and sugar syrups in sufficient quantity and in suitable condition to become
assimilated by the yeast cells or yeast organisms; on the discovery that by the
mere addition of phosphoric acid and an appropriate dilution with water, molasses
or sugar syrups are rendered fit for the propagation and development of yeast ;
and on the discovery that a valuable (marketable) yeast can be obtained from such
dark-coloured material provided (if) a clear solution of the molasses or of the
sugar syrup is prepared, in such a way that dark-coloured floating or suspended
substances, which have a prejudicial effect on the colour and the utilisation of the
yeast are removed from the solution.
In carrying out this invention, it is immaterial under what conditions, in what
manner and at what time the required quantity of phosphoric acid is added, if only.
present in the liquid when the propagation of the yeast takes place. It will
moreover be understood that the phosphoric acid may be added in a combined
state; as, for instance, in the form of salts, etc.
The quantity of phosphoric acid required is determined by the quantity of
yeast that may be expected to be produced. Supposing that the molasses will
yield up to 20 per cent. of yeast; and that the yeast will contain 1 per cent. of
anhydrous phosphoric acid (P,O,), the yeast obtained from 100 kilogrammes of
molasses will assimilate in this case 0-2 kilogrammes of P₂Os, consequently the
addition of twice or thrice that quantity, viz. 04 or 0.6 kilogrammes of P,O,, on
100 kilogrammes of molasses will be more than sufficient.
Should the reaction of the liquid be alkaline it is advantageous to acidify it
slightly in the ordinary way, as, for example, by means of sulphuric acid. It is
also expedient to sterilise the liquid by boiling it.
The clear solution can be prepared by filtration with the aid of any filter
capable of yielding a bright solution, or by any other means adapted to accomplish
the same result.
For the manufacture of yeast from molasses, etc., according to this invention, a
more diluted liquid is required than in cases where a single fermentation of the
liquid, without increase of yeast, is desired. The degree of dilution will depend
on the character or quality of the molasses or sugar syrups employed, and cannot
be determined by any fixed standard; but whilst it is possible and usual to ferment
such liquids containing 25 to 33 kilogrammes of molasses diluted to 100 litres, the
appropriate concentration for the increase of yeast will be no stronger than about
16 or 17 kilogrammes of molasses diluted to 100 litres.
To the clear diluted solution, the required quantity of yeast is added, the
propagation and development of fresh yeast being brought about according to
well-known principles.

page_text: In working according to my improved method, the yeast resulting from one
operation may be employed for a following operation; a fraction only of the
collected yeast being necessary for this purpose. An addition of about 0.2 kilo-
grammes of yeast to 100 litres of the liquid (about 12 kilogrammes to
100 kilogrammes of molasses) will suffice.
In working according to my improved method, no micro-organisms, besides
yeast, are employed; none, for example, which produce lactic acid and which
have heretofore been generally employed in the manufacture of bakers' yeast.
Consequently the yeast produced according to my method differs from bakers'
yeast by the very small proportion of foreign micro-organisms which the former
contains.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I claim :-
The improved manufacture of yeast substantially as herein described from a
solution of molasses or sugar syrup containing the required quantity of phosphoric
acid or to which such acid has been added either in the free state or in the
combined state (salts, etc.) by preparing a clear solution (freed from suspended
dark substances) of appropriate dilution, adding the required quantity of yeast
and causing the increase of yeast in the said solution according to well-known
principles, without the use of other micro-organisms for instance those which
produce lactic acid, etc..