Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
209~17
A L~uter Netho~ er Pressu
Desoriptio~
The present invention refers to a method of lautering mash
in a lauter tub for brewing.
The lauter process is one of the most important method steps
in brewing. As is generally known, the wort is obtained in
the lauter process by separating the solid components of the
mash from the liquid ones. The solid components remain on
the bottom of the lauter tub, whereas the wort can then be
removed from the bottom of the tub. The wort which is flow-
ing of~ first is called first wort or original wort. When
this wort has been removed, a considerable amount of extract -
is still contained in the spent grains. In order to obtain
this residual amount, the spent grains are subjected to ex- -
traction by a treatment with hot water. This process is
called sparging. The water which flows off last from the
spent grains contains only a small amount of extract (Glatt-
wasser).
The spent grain ma~s compacts more and more in the course of
lauter process. Hence, a chopping device, which rotatingly
circulates in the lauter tub, is normally used ~or chopping
or lossening the spent grain mass at least at certain inter-
vals.
:
; For some time, it has now been endeavoured to carry out, as
far as possible, the lauter process such that the loosened
spent grain mass comes into contact with the least possible
amount oi oxygen, since it turned out that the quality and
especially also the keeping quality of beers is negatively
in~luenced when an excessive amount of oxygen is introduced
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209~1P~
during the lauter process (cf. the inventor's publication in
"MBAA Technical Quarterly" vol. 23, pages 54 to 61, 1988).
This problem is also discussed in German-Offenlegungsschrift
39 42 980. Said German Offenlegungsschrift especially men-
tions that the atmospheric oxygen normally introduced in the
spent grain mass during the sparging process is disadvanta-
geous, and, in order to reduce this proble~, it is suggested
that the sparge water should be introduced in the spent
grain mass via the support arms of the chopping device. The
aim to be achieved by this measure is that the sparge water
is sprayed close above the spent grain mass whereby the
quantity of the atmospheric oxygen entrained by the sparge
water will be reduced on the whole.
It is the object of the present invention to suggest a
lauter method which has been improved still further in com-
parison with the prior art.
In the case of the method according to the present inven- :
tions, this is achieved by carrying out the lauter process,
at least partially, under excess pressure generated by feed-
ing inert gas.
This execution of the method offers important advantages in
comparison with all hitherto known lauter ~ethods. On the
one hand, squeezing of the spent grain mass will be achieved
by the generation of the excess pressure, ~hich takes place
at least during certain phases of the lauter process, and
this will have the effect that the first wort yield, the so-
called first wort extract, can be increased substantially.
Especially when poor malt qualities are used, in the case of
which the spent grain resistance is comparatively high, an
improvement can be achieved by generating the excess pres-
sure. In addition, shorter lauter times will thus be ob-
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tained because the passage o~ the liquid through the spent
~rain mass is 'lartificially" accelerated. In the final anal-
ysis, the better first wort yield will then also result in a
Glattwasser containing even less extract in the way desired.
5queezing of the spent grain mass is, in pxinciple, already
known. If, however, the squeezing were performed under ex-
cess pressure with the air which i5 normally contained in
the lauter tub, the introduction oP air in the spent grain
mass, which is, in principle, not desired, would even be in-
tensified. Hence, lautering under excess pressure in the
lauter tub has not been carried out so far. However, in view
of the fact that the present invention uses inert gas for
generating the excess pressure, the advantaqes aimed at can
be achieved without any disadvantageous influence on the
quality of the beer. On the contrary, the quality and espe-
cially the keeping quality of the beer is improved still
further because the atmosphere in which the lauter process
takes place is an inert gas atmosphere so that the spent
grain mass will absorb only an insignificant amount of oxy- -
gen or no oxygen at allO
In detail, a large number of variations is obtained ~or the
method according to the present invention.
It may, for example, be advantageous to choose the excess
pressure in response to the spent grain resistance. In view
of the fact that, as is generally known, the spent grain re-
sistance increases in the course of the lauter process and
can be reduced by means of the chopping device at certain
intervals, it may be avantageous to adapt the excess pres~
sure to the spent grain resistance values; in this connec-
tion, a small pressure differencP should be aimed at in each
lndividual case. An automatic closed-loop control can be
provided in this respect as well. For this purpose, it would
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only be necessary to measure, in the manner known, the spent
grain resistance, and to input the result in a controller,
which will influence the excess pressure in a suitable man-
ner by feeding the inert gas into the lauter tub or by per-
mitting it to escape from said lauter tub.
The spent grain resistance can be detected in various ways.
On the one hand, it is possible to carry out pressure dif-
ference measurements, in the case of which the pressure is
measured above the spent grain mass on the one hand and at
the bottom of the lauter tub, i.e. below the spent grain
mass, on the other, whereupon the values are compared with
each other. The higher the pressure differ~nce, the higher
the spent grain resistance. It is, however, also possible to
datect the spent grain resistance indirectly by measuring
the flow rate in a discharge line, a method which has al-
ready been ~escribed in detail in German-pat. 38 44 389. The
pressure difference measurement as well as the flow rate
measurement provide the desired information on the spent
grain resistance, and, on the basis o~ this information, the
excess pressure can ~hen be adjusted accordingly. The flow
rate measurement proved to be particularly advantageous in
this connection.
It is, of course, not necessary that the inert gas atmos-
phere in the lauter tub contains exclusively inert gas. A
percentage of at least 20 % of inert gas will already pro-
vide a considerable improvement with respect to the aimed-at
result.
The inert gas used can e.g. be nitrogen or also Co2 or a
mixture of these gases. It is also imaginable to feed heli
um, although helium is comparatively expensive. Since it is,
however, possible to circulate the helium in a circuit~ los-
ses can be kept low.
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Moreover, an advantageous effect can already be achieved by
purposeful feedin~ of the inert gas, e.g. in the area close
above the maximum filling level of the lauter tub. The inert
gas, which will then sweep over the surface of the mixture
of water and mash, will form an intermediate layer between
the residual air above said intermediate layer and the liq-
uid so that a direct introduction o~ oxygen will be pre-
vented in this case as well. In this connection, it would
also be imaginable to feed the inert gas during the sparging
process in such a way that it will wash around the spray
nozzles by means o~ which the sparging water is introduced
so that in this case, too, the amount of residual air which
will be entrained in the lauter tub can be reduced.
The pressure value need not be maintained constant through-
out the whole lauter process. It can also be increased or
reduced in the course of the process. Pressure values be~
tween 10 and 100 mb, in particular those between 20 and 50
mb, proved to be suitable pressure values.
~n apparatus for carrying out the method according to the
present invention is characterized by the features that the
lauter tub is constructed such that it is pressure-tight and
is provided with at least one inlet for feeding an inert -
gas. These measures are the precondition under which suit-
able excess pressure values can be generated in the lauter
tub.
In accordance with an additional advantageous embodiment,
the lauter tub has associated therewith a pressure gas stor-
age for storing and recirculating the inert gas. The pres-
ure gas storage can feed the gas into the lauter tub, when
the inlet at thQ lauter tub is opened~ and, when aeration
o~ the lauter tub is required, the presæure gas storage can
previously remove the inert gas via a pump and re-store it
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until the lauter tub will be pressurized again.
The method is applied in an advantageous manner in connec-
tion with a lauter tub provided with a rotatably driven
chopping device. In the case of the method according to the
present invention and in the case of the apparatus according
to the present invention, it is possible to operate the
chopping device again and again or even continuously, with-
out any risk of introducing, by excessive loo~ening of the
spent grain mass, an excessive amount of oxygen into said
spent grain mass because an inert gas atmosphere is produced
in the lauter tub. For making the lauter tub pressure-tight,
a closure flap can, most simply, be arranged in the dis-
charge means of the lauter tub, the opening positions of
said closure flap being adjustable in a variable manner. The
desired closed-loop control or also the desired control of
the pressure can thus be carried out in a very simple man-
ner.
In the following, the present invention will be explained
and described still further on the basis of the embodiment
shown in the drawing.
The only ~igure shows a flow chart of an apparatus according
to the present invention on the basis of which also the exe-
cution of the process will be explained hereinbelow.
In the drawing, reference numeral 1 has been used to gen-
erally designate a lauter tub, which is equipped with a ro-
tatably driveable chopping device 2 in a manner known per
se. The chopping device carries chopping blades 3, which are
effective in the area of spent grain mass 5 depositing on
the bottom 4 of the lauter tub during the lauter process.
How this can be done in detail is disclosed e.g. in German- :
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209~1'7
pat. 38 44 389 so that a comprehensive explanation of these
processes can be dispensed with in the present connection.
The lauter tub is provided with various feed lines and dis-
charge lines in a manner known per se. The feed line 6,
through which the trub to be lautered can be fed, is sche-
matically shown. Reference numeral 7 has been used to des-
ignate the line for feeding the sparge water. The wort can
be removed from the bottom 4 of the lauter tub 1 via the
line 8, which is schematically outlined at this location.
In accordance with the present invention, the lauter tub is
constructed such that it is able to resist an excess pres-
sure of up to approx. 1 bar above atmospheric pressure. At
the discharge means 9 of the lauter tub, an adjustable valva
flap 10 is provided, which is fully closed or adapted to be
adjusted to various opening positions. The positions of this
valve flap can be adjusted via a central control and regu-
lating unit 11. In addition, the lauter tub 1 can have con-
nected thereto a pump 12, which is connected to a pressure
gas storage 13 for inert gas. This pressure gas storage
opens into the trub feed line 6. ~hen the pressure feed line
6 is closed at its free end (not shown), pressure can be
introduced into the interior of the lauter tub 1 via said
line.
The lauter tub has additionally arranged thereon two pres-
sure sensors 14 and 15, which permit a determination of the
spent grain resistance. The result of this measurement is
also proce~sed in the control and regulating unit 11.
An alternative possibility of detecting the spent grain
resistance is also indicated in the drawin~. In the case of
this alternative possibility, a flowmeter 21 is arranged in
a discharge line 20, said flowmeter permitting a detection
o~ the variations of the rate of flow per unit time in re-
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sponse to time. This result can then also be inputted into
the control and regulating unit 11, where it can then be
used for internal pressure control.
Instead of the valve flap 10 shown in the drawing, a con-
stant closure of the flap 10 is imaginable as well; in this
case, pressure control can be effected via the relief valve
22, which is shown as an alternative possibility.
In the following, one of the possibilities of executing the
lauter process according to the present invention will be
described.
For the purpose of lautering, the mash is first pumped via
the line 16 from the mash tub, which is not shown, into the -
lauter tub 1. When this process has been finished, the spent
grain mass will deposit on the bottom 4 of the lautsr tub,
whereas the first wort will accumulate above the spent grain
mass. The lauter tub can now be closed in a pressure-tight
manner via the flap 10. When the lauter tub has been closed
in a pressure-tight manner (in the course of this process
also the valves in the other feed lines and discharge lines
are closed), the air contained in the lauter t~b can first
be sucked off via the pump 12, i.e. at least a partial vac-
uum can be produced. By opening valves, which are not shown
in detail, it will then be possible to feed the inert gas
compressed in the pre~sure gas storage 13 Prom said storage
i~to the lauter tub so that a pressure of up to 1 bar excess
pressure will be generated in said lauter tub. This excess
pressure has the effect that the first or original wort ac-
cu~ulating above the spent grain mass can be obtained more
rapidly and that, at the end, part oP the residual first
wort is squeezed out of the spent grains. A higher yield of
first wort will thus be achieved. After the removal of the
first wort via line 8, air is prevented from being intro-
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duced in the spent grain mass together with the sparge water
fed via line 7, since an excess pressure, generated by an
inert gas atmosphere, has already developed in the interior
of the lauter tub. It follows that the introduction of an
excessive amount of air into the wort and into the spent
grain mass, respectively, is prevented throughout the whole
lauter process.
During the lauter process, the spent grain resistance can
be measured continuously. Depending on this spent grain re-
sistance, the chopping device can, in a manner known per se,
be raised or lowered, or it can be caused to perform a rota-
tional movement. Moreover, said spent grain resistance can
also be used for controlling via suitable signal lines 17
and 18, respectively, the pressure in the lauter tub such
that said spent grain resistance will be minimized.
The pressure gas storage can have provided therein inert gas
in the form of N2 or C02 or also helium. A mixture of this
gases is imaginable as well. In view of the fact that, after
termination of the lauter process, when aeration of the
lauter tub is required, the pump 12 permits the inert gas to
be removed from the lauter tub and to be then restored in
the pressure gas storage 13 with the aid of a compressor -
means which is not shown either, the inert gas can be used
in a circuit so that no inert gas will be "wasted".
The generation of an excess pressure by means of the inert
gas can take place throughout the whole lauter process; it
can, however, ~ust as well su~ice to work with an excess
pressure only during specific phases, e.g. during the phase
in which sparge water is supplied, during the phase in which
the first wort is obtained, or also between these phases.
A plurality of advantages are achieved by generating the ex-
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cess pressure in the lauter tub, these ad~antages being e.g.
an increase in the amount of the first wort extract, no oxi-
dation of the wort nox the resultant deterioration in quali-
ty, less Glattwasser, clearer wort and, finally, also the
possibility of using finer bruised grain. ~oreover, more
brewing operations are carried out per unit time, since the
time required for the lauter process can be reduced. Final-
ly, the method is also advantageous in the case of poor
malt qualities with high spent grain resistances, since the
squeezing of the spent grains under excess pressure permits
even in these cases acceptable first wort yields.
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