Improvements in or relating to Fermentation Processes.
Year: 1899

page_text: Date of Application, 8th Aug., 1899-Accepted, 28th Apr., 1900
COMPLETE SPECIFICATION.
Improvements in or relating to Fermentation Processes.
I, EMILE BARBET, of 167, Rue de Rennes, Paris, France, Engineer, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed to be particularly described and ascertained in and by the following
statement:
-
Aeration is one of the chief features of the activity and multiplication of ferment
cells, provided of course that the must or wort possesses the requisite nutritive
elements. Aeration, however, is not such a simple matter as may be supposed.
When it is desired to aerate a vat of a certain depth it is necessary to put the air
under pressure, and it is blown through a pipe perforated with small holes,
placed at the bottom of the vat. It is not easy to utilise equally all the small
holes of the pipe, and it will always be found that the air tends to issue at one
place in preference to others. Moreover, however small are the holes (and it
they are too small there is risk of them becoming stopped up) it is impossible
to prevent the successive bubbles uniting together and forming spherical bubbles,
the action of which on the liquid is very limited. Thus fifty or perhaps even a
hundred fold more air is injected than is theoretically necessary.
4
The air which acts upon the cells of the barm or yeast is principally dissolved
air. The action of air is entirely different when it can be made to act on the
surface of a thin layer of a liquid culture. A striking demonstration of this is
furnished by the fermentation process with the "Amylomyces Rouxii"; the
tunguses (mucedinea) have very different appearances according as they are
cultivated on the surface or immersed. In another process that of Collette and
Boidin, the submerged fermentation only is attempted, but at the same time a
great deal of air is injected into the mass. This injected air is not capable of
producing in any way the effects of surface culture."
In yeast cells, however, in distinction to the mucedinous culture, the surface
culture is very interesting as this kind or aerobic cultivation renders the cells
much more active, a Pasteur has shewn.
In the present invention it is proposed to carry out this fermentation in thin
layers with considerable access of air and to change the liquid at the surface
exposed to the air by employing the air itself to make the liquid rise by means
of suitable blowing apparatuses.
For the better comprehension of the invention it is described hereinafter
with reference to the accompanying drawings in which
Figure is a view of the apparatus employed in carrying out the invention.
Figures 2 and 3 shew another construction on the same principle but for a
slightly different purpose.
Figure 4 shews a plant of closed and aseptic vats for the continuous fer-
mentation.
Figure 5 shews the apparatus for sterilizing the air.
Let us take first the application of my invention to the manufacture of pure
yeast for distilleries or breweries intended to be used as vat ferments in the
fermentation vessels. I employ a vessel which can be sterilized by steam under
ID 17

page_text: slight pressure and having all the controlling and safety devices which the pro-
cess renders requisite; when the apparatus has been well cleaned and sterilized,
it is supplied by means of successive charges in suitable quantity with sweetened
acidulated and sterilized wort. The wort is cooled whilst protected from any
contamination and introduced aseptically into the apparatus.
In the top part of the apparatus for pure ferment a suitable number of
horizontal copper trays A are placed, which trays have a small indented edge
serving as a lip (Figure 1). These lips are diametrically alternated so as to
compel the liquid to run all along the tray before falling again into the bulk
of the liquid. Each tray is provided with a discharge plug V for cleaning pur-
poses; a threaded inlet hole B is placed suitably in front of each tray, in order
to give access to the plugs and for introducing a water jet. It is necessary to
make the fermenting liquid continuously rise from the bottom of the apparatus
to the aeration trays above. For this purpose a tubular elevator C is constructed
of a number of copper tubes of very small diameter (about 15 millimetres).
Under the lower opening of each tube is placed an injector 1) of sterilized air,
so that there is injected in each tube a succession of air bubbles and rings of
liquid occupying the interior of the tubes. It is obvious that under these
conditions the liquid will rise in the tubes.
The air which accompanies the liquid at the moment of its discharge on to
the upper tray continues to flow along with the liquid over the trays and like
the latter descends from stage to stage and finally passes out at E after having
been made use of as-far as possible.
At the same time it takes with it the carbonic acid.
The circulation of the liquid in the elevating tubes can be utilized for heating
or cooling according to requirements by allowing either hot or cold water to
enter by the cock Fas shewn in Figure 1. An ordinary thermometer or one
with a dial G affords a constant indication of the temperature.
This system of fermentation vats has the great advantage that by producing a
much larger quantity of ferment cells of great activity a smaller quantity of
yeast is needed than in other apparatuses.
Figs. 2 and 3 shew a modification of the same principle for a slightly different
purpose. Instead of having to produce successive quantities of yeast having the
requisite quantity of active cells for the fermentation of a large vessel or brew-
ing vat it may be desired to produce pure concentrated yeast in a laboratory
This apparatus besides being of smaller dimensions should, in the first place, be
so constructed as to facilitate the accumulation and decantation of the yeast in
its lower part from whence it is drawn off with all the usual precautions into
vessels for transport.
In this smaller apparatus the ascent of the liquid is obtained in the same
manner as the preceding by means of air blowing, here, however, the elevating
apparatus C only consists of one tube which may be of glass so that the operator
can better observe the working of the apparatus. The bubbles of sterilised air
reach the bottom of the tube in H. As it is desired to produce not liquid barm
but yeast as solid as possible, the collection in the lower part of yeast cultivated
in the aerobic (the most active) form upon the upper trays must be assured. For
this purpose the trays are in the shape of conical bronze plates A fitted on a
like number of conical central sockets A'. These sockets A are screwed one
above another successively so that the whole forms a kind of tower of plates,
the number, size and depth of which however, can be varied according to circum-
stances. The shape is conical so that the yeast tends to accumulate at the
The surplus, carried off by the liquid, falls from tray to tray through
the openings A² which serve as overflow outlets and reaches the lower reser-
voir I. The lower part K gradually collects this yeast; a pane L permits the
progress of the operation to be observed.
centre.
The liquid is taken up again by a tube M (above the deposit) and the tubular
elevator makes it rise to the upper tray A, and the process continues until the
saccharine it contains is exhausted. It must then be made to fall into I and K.

page_text: It will be noticed that in the interior of the cylinder there are three vertical
rods (Figure 3) placed at 120 degrees apart, on which are fixed as many
catches o as there are plates. The rods can rotate 90°, so as to lay all the catches
flat against the side. In this position the tower of plates, the lowest one of
which rests on the cam p on the cross shaft P can be taken away or replaced.
After having replaced the plates the catches are turned as shewn in Figures 2
and 3. The whole has been so arranged that there is a space of some millimetres
between each plate and its catch.
To empty the plates a half turn is given to the eccentric p by means of the
outside handle Q. The whole series of sockets A' are lowered while the plates
supported by the catches o are detached from their sockets, and let all their con-
tents flow away. In order to make the shaft of the sockets A¹ descend a kind of
finger is attached to P which strikes on the spur of the eccentric and pulls it.
down. Meanwhile the elevator is worked at full speed so that the liquid washes
away the yeast deposited on the plates and conducts it to the bottom K.
In order, now, to remove the yeast, suitable cans are well washed and sterilized
in a stove; the opening of these cans is provided with a rubber tube sterilized
and corked with a pinch of bone black and a bit of wadding. The discharge
cock is immersed in a small basin of sterilized water or formol: the basin S is
rapidly lowered, and the rubber tube of the can is immediately placed on R
which is opened. If by chance this cock should be stopped up, a sudden admission
of air through through the cock T which is an extension of the former will effect
the removal of the obstruction.
When all the yeast is drawn off the fermented liquid is taken out of the
apparatus to be distilled. Water for washing is then introduced until the
apparatus appears clean, and finally it is re-charged with fresh liquid which is
boiled in the apparatus itself so as to sterilize it. The plates are put back in
place by raising the eccentric p. The cooling is effected by sprinkling the
exterior of the cylinder with water; a thermometer G indicates the temperature
favourable for propagation. If it is necessary afterwards to modify the tem-
perature the worm U is used by passing through it either hot or cold water
according to need.
The apparatus is provided with elaborate aseptic precautions; for instance, the
cocks are immersed in water containing formaline, likewise the shaft P passes
For a continuous
through a double stuffing box with a basin of sterilized water.
manufacture, instead of sterilizing the wort each time in the apparatus itself,
which destroys the yeast attached to the plates or the sides, the wort is placed
in a special basin and afterwards cooled aseptically with the necessary pre-
cautions.
The other details of construction explain themselves; the bars W W (Fig. 2)
serve as handles for taking out the set of plates; the bronze rod X is a guiding
rod for keeping the device quite vertical and rigid. With regard to the sterilized
air we will treat of that shortly.
a manufacturing
The same principle can be applied to distillery vats on
5 scale. The wort can be aerated in the vats to effect the fermentation, the
upper part of the vat being provided at a slight depth with a large flat semi-
circular plate. The wort at the bottom is raised by a sterilised air elevator and
spreads in a sheet over the semicircular plate where it becomes aerated regularly
and not excessively. This plate is the seat of an abundant production of active
O ferment cells which will quicken the sluggish fermentation and give the
maximum yield without necessitating the propagation of a great quantity of
yeast. In other words the vat will effect a certain prolificacy in order to pro-
duce the number of cells which are indispensable. If we arrange the elevators
to make the wort return not to the vat whence it has been drawn but to the
5 following vat, and if a series of closed and aseptic vats is thus arranged, it is
obvious that a continuous fermentation process is produced. A suitable quantity

page_text: 18 placed in each vat for controlling the progress of the operations. The
efficient control includes the regulation both of the supply of saccharine wort, or
the degree of aeration, in, such, a manner as to ensure the total exhaustion of
the sugar (Figure 4). The fermentation will consequently be much less volu
minous and entirely after Pasteur's method. In this manner a theoretic..yield
may almost be attained.
In order to effect more certainly the exhaustion and also; for economising in
the installation we reserve the right of making these, closed, vats...the ante
chamber, so to speak, of the actual fermentation vats Y. There should, be
three or four vats Y and a varying number of aseptic vats 7 so as to finish the
process of fermentation in the large vats Y and to form there a sufficient stock
for the distilling. Thus the size and cost of the aseptic vats Z can be reduced
and an industrially perfect system of continuous fermentation realised.
I will now describe the method of sterilising the air intended for the puré
yeast and for the fermentation vats.
The apparatus for sterilising air (see Figure 5) is composed essentially of a filter
of wadding 1 located in the centre of a steel receptacle 2, capable of supporting the
full pressure of the steam generators and which corresponds to the ordinary
sterilising vessels. Instead of having to remove this filter periodically to stove
it, the filter is permanently fixed in its steriliser. is the entrance for steam
and 4 the discharge cock for the condensed water. By putting full steam pres-
sure into 2 for a sufficiently long time without letting air circulate in the
filter, all the portions of the wadding will gradually reach the temperature of
150° to 160° Centigrade (according to the pressure) and the filter will be com-
pletely purified. It will then be capable of sterilising the compressed air by
simple filtration. To insure a perfect uniformity of the high temperature
throughout the cotton wadding a very small passage of air may be allowed, this
air having been previously heated in the tube 5. The air, which is allowed to
enter in small quantities through the cock 6, circulates in the tube 5 then through
the wadding filter 1, and when it passes out at 7 it should shew a temperature
of at least 150° C. by the thermometer 8. It will then be perfectly certain
that the wadding is completely sterilised.
The steam is then stopped, 6 is opened further and the air is sterilised as
usual by filtration.
Before passing into the filter the air is passed through a primary filter 9 where
it is deprived of the major portion of its germs and dust. This arrangement
has the advantage of preventing the filter 1 from becoming dirty, and also allows
of the wadding being changed much less frequently. The casing 2 can be used
for permanently heating the air. It is only necessary to pass a small jet of
steain into the casing 2 to warm the air, and use the warm air fór heating the
yeast instead of employing a strong steam jet which has the drawback of
killing many of the cells and diluting the wort. Or steam can be freely applied
all the time for adding the sterilising action of a very high temperature
to that of the filtering, and then afterwards the temperature of the air is cooled
by water before it enters into the wort.
With regard to the details of the construction it may be mentioned that the
layers of wadding are very easily replaced. A perforated false bottom serves as
support, and then a series of small copper diaphragms regulate the layers of
wadding. Finally, at the top, the last diaphragm is provided with a sort of
central perforated pipe which abuts against the lid and a slight pressure is thus
given to the wadding preventing the direct passage of the air.
In this manner all precautions are taken for preventing contamination by
air. The cock 6 is placed in front of the passage to the wadding so that it does
not interfere with the sterilising of the air. '
Like the sterilising apparatus 2, the filter 9 is secured to the wall by a flat:
iron band.
The small apparatus (see Figure 2) intended for laboratory purposes for

page_text: making pure yeast, differs but little from the foregoing. Its modifications pro-
vide for not having steam under pressure at disposal; consequently the sterili-
sation is effected by a gas jet.
The filter 2 is placed in the course of the combustion gases from the Bunsen
burners 10, but it is preserved from direct contact with the. Hame so as not to
singe the wadding.
The flame first strikes the coiled air tube of the apparatus which at this spot
makes three turns: higher up the burning gases lose their high temperature
by contact with the coils of tube for the cold air. In this manner a systematic
heating of the air is attained. When this is effected the gases pass through
the openings 11 to surround the sides of the filter and pass out through the flue.
The other details may easily be understood by reference to the drawings.
In order to make yeast, the previous process of sterilisation by means of the
filter is performed as has just been described until the thermometer marks 150°
Centigrade. Then the filter is allowed to cool by passing through it a suitable
current of air which is afterwards injected into the fermented wort. Both in
the laboratory apparatus as also in that for manufacturing purposes the air
drawn in must be permanently maintained at a given temperature.
I reserve the right of varying the proportions above set forth as well as
details of execution according to requirements as may appear desirable for the
purpose proposed and explained above.
Having now particularly described and ascertained the nature of my sand
invention and in what manner the same is to be performed I declare that what
I claim is: -
1. Improvements in fermentation apparatuses either for industrial or laboratory
purposes, characterised by the cultivation of aerated wort by causing the wort
to ascend into the trays, by means of aerating and elevating tubes, substantially
as described.
2. In the fermentation apparatus set forth in Claim 1, the sterilisation of the
air by means of easily purified filters of cotton wool, each filter being per-
manently located in its sterilising stove, substantially as described.
3. The application of the aerobic process to the culture of pure yeast and its
extension to the vats themselves so as to effect continuous fermentation under
almost absolutely pure conditions, substantially as described.
Dated the 8th day of August 1899
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.