Note: Descriptions are shown in the official language in which they were submitted.
~036522 `~ :
. .. . .... . . .
This invention relates -to a hrewiny process for
producing wort and to apparatus for carrying out the process.
Several brewing processes for produclng wort are
already known, in particular for producing beer. These -
processes may be divided in two classes: the first class ;
including brewing processes which employ the so-called
"standard" method and particularly the ba-tch brewing process,
and the second class includiny the continuous processes.
In accordances with these processes, the wort ``
underyoes a given treatment while the crude grains such as
rice, maize, barley and the like undergo another treatment
which includes adding a fraction of mash oE wort or o~ enæyme.s
from an external source. A given sacchariication diayram
is used for each oE the brewiny raw materials, i.e. wort and
crude yrains. To thiæ end, it i.s necessary to ~ncr~as~ the ~;~
temperature rom 45C to 7SC in order to ac-tivate the enzymes.
The tempera;ture is increased in stages, usually three stages.
The first staye occurs at a teinperature close to 45C
and during this staye the proteolysis of the treated product
20 - takes place. At the end of this staye, the temperature is
increased close to 65C and during this second stage the
action of beta-amylase occurs. The temperature is then
increased to close to 75C to induce the action of alpha-
amylase. The whole brewing process up to the saccharification
of the mash which is carried out by increasing the temperature
in stayes and by making use of an intermittently operating
apparatus, lasts from 120 to 140 minutes.
The conventional brewincJ process i.9 appare~ntly yoverrled
by severe operatiny restrictions in particular in respect
of the time-temperature diagram, the milling and the nature o~
the separate treatment oE the crude yrains.
The continuous production of wort, however, yives rise
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to the following a~vantages:
- medium size of vessels, which then ope~ate at full
load, the output being steady and buffer apparatuses which ~
are then sized in accordance with a permanent average ou-tput ..
instead of being sized in accordance with the.peak level of
an equivalent intermittent output;
- ready and more efficient heat regeneration to the
extent to which heat diffuses Ereely xather than being
regenerated intermittently;
-possibility of providing, in a continuous process,
successi.ve steps more suited to the requirements and demands .
of the natural proccsses along the paths Eol.lowed by the
materials;
- :reduct:i.on .in op~:r~tincJ cost.s si.nce thc conventional
~equence o~ intermittent steps and operatic)ns is .replac~d
by a succession o e steady opera-t.ing conditions during the `. :
process, this steadiness requiring fewer interventlons.
}lowever, the continuous process sufEers ~rom the . ~.:
following disadvantage~
- the treatment undergone by the mash is not uniform
because parts or fractions of it pass through the apparatus .~ :
in times or along paths which are different and only the
average conditions to which they are exposed can be controlled. ..
Accordingly, in order to attain the above mentioned ..
advantages, i-t is essential -to compromise between the
. .
requirements of the natural processes and those of the ~ :.
.... .. .
continuous p.rocess. :.
I'his can be done by reducincJ the restrictions which `~ :
are improsed by the natural processes and by reducing the . .:~
i.rregularities within the treatment, the co-existance oE
which is inevitable, so that all of them meet the requirements
imposed by the limits. To this end it has been found: .:
'................................................................................. ; ,. .
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10365;i~Z
- That the natural process requires overheating, for `;,.,
example that due to temperature gradlent in the laminar layer
on the heating side walls, to be reduced in order not to affect .'
the enzymatic potential before termina-tion of the transforma- '.: ' ~'
tions which it. brings about. Through this measure which is :. .
obtaine~ by providing a strong and uniform agitationof the mash ',
and by using a very hiyh ratio of heating surface to volume
of wash in order to reduce the overheatiny to a few degress ;;,
' centriyrade, the brewing process may terminate at the end of ;.'
theextraction and saccharification steps after about one hour. .
- That the brewing process produces a wort having
average characteristics which meet the conditions referred
to above for qulte dlferent "time-temperature" d.iacJrams. It `' .
would seem that the main variable is the total treatrnent time
which controls the total ex.raction depend.incJ on ~he nature
Oe the yrist, the type oE th~ wort,, th~ mash to water ratio, .,
and the particles' si.~e. ....
- That a continuous gr.adual increase of temperature
fro~ the mixing temperature to that o:E the order of 70 to ::
80C, at the end of saccharification gives a result comparable, ; , ,
.. . ..
as far as the eEficiency of the brewing process is concerned,
with that of the brewing process carried out in discrete .` ':.
sta~es and this in~the order of an hour for the washing process. '.'~:
That when malt is first mlxed with all the crude
, ,grains not previously processed at + 100C, saccharification '-
is obtained! at the end of the gradual temperature increase,
. . .
at about 77C and in just over an hour.
- That the extraction and ~ermentabili-ty losses
pecu:l.iar to this practice and made manifest by black colouring
by iodine of the'mash if the temperature is then increased .,
to 100C can be lowered to an economlcally acceptable level ~,,.,, `',
in view of the substantial simp~lifcation of the process and the . . ..
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-" 1036SZZ
apparatus and the possibilities of recovery from the spent
malt, and of recycling, through a very fine milling of the
crude grains which increases the part of thelr volume
accessible, through the surface, to the enzymatic action due
to the wort and through suitable choice of the temperature
at the end of the brewing process.
It should also be noted that the requirement relating
to overheatiny will be met in a more satisfactory manner
with a continuous process where the extension of the apparatus
in the material path direction is such that it assists the `;
surface to volume ratio. ;
As far as the other aspect of the compromise mentioned `;
above is concerned, i.e. the reduction oE the range o~
treatments co-existinc3 in a continuous brewing apparatus ;;
accorcling to the invention, the ollowing m~ans are employed:
- Verticcil c:Lrculation to pr~vent settlincJ from
worseniny disparity of treatment and to obtain as far as
possible a uniform distribution of the net speeds in a cross-
section of the apparatus.
- Use of a reactor having several cells in series
to reduce, by means of statistically defined compensations,
~the "dispersion of the dwelling times to average dwelling
time" ratio to a value lower than that given by a single
cell. r ' '
Configuration and operation of the stirrer chosen
in such a way that this ratio is worsened to the least
possible extent while meeting the requirements to prevent
decantation and to assist heat and mass trans~er, which
requirements justify stirrincJ.
; 30 - Conception of transition between adjacent cells inorder to recluce the "convection exchanc3e to net supply" `;'
ratio in order to reduce the dispersion of the dwelliny times ?,'," ,,
,
','"". ~
i ~ ~ 4 ~
-` 1036S22
and the co-existing treatments in the apparatus.
It has been found that the residual loss of extract
due to the most unfavourable individual,treatments, i.e. those
experienced by parts of fractions of the mash having the
shortest transit or dwelling time throughout the brewing
reactor, could be substantially reduced and attain only a
few percent, even with minimum dwelling times considerably less " ''
than an hour.
Thls remaining loss may b,e advantageously reduced
even further by increasing the averaye dwelliny tirne and/or ,'
by opposing the flow from one chamber to the other in the
direction opposite to the net flow. However, the greater the '-',
output for which the apparatus has been sized the greater , ,,
the ratio of the size oE the cells with respect to that of ,,
the transit oriEice therehetween. ~s a matter oE Eact, the
size oE the particles recluires no!: too smAll a diam~t~r oE ; ``
the transmit orifice. The yr~ater the Elow the yreater the
net speed throuyhout the throttled section and the greater
, ,the turbulence which with a small diameter would tend to
20 ' establish undesired ex~hanges between the cells in the
,
direction opposite to the net flow.
Finally, it should be noted that the generalization
of the recovery devices, particularly those operating on ' '
.
spent grains tends to displace towards an average extraction '
level the economic optima of the primary operations. In
.
'~ particular, duriny~brewing, in view of the recycliny upstream
the pressiny of the liquor obtained throuyh the spent grains,
it may become pro~itable to reduc~ the investment at the
expellses of the extraction level, which is almost'total, up
to now, in the brewing operation.
The present invention in one aspect provides a
brewing process for producing wort in which the mateirals are
~A~ ` 5
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- 1036S;~Z
milled and mixed and at the end of the cycle a separation is
carried out, wherein the materials pass through an apparatus ~;
in an uninterrupted flow and are subjec-ted to a single or .
distinct treatment distributed over several stagesof the
apparatus, for both the grists ofthe malt and -the crude yrains,
which treatment preserves the potential of each enzymatic ;`: ::
fraction by excludiny side wall overheating of the mash, the ~; ;
-treatment eomprisi.ng a proyressive increase of the temperature
and a Eorced agitation whieh opposes settling and assists .;
renewal at the reaction-and exchange sites. .~
The i.nvention also provides apparatus for earryiog . ..
out the proeess aceording to the present invention eomprising a ~; :
eontinuously ope.rat.~ng reaetor having an ax.ial stirr~:r, the ~`
reactor comprls:ing vertieally arranc~ed eells eommunieat.ing in .;.
series ancl eeEeet.in~ the proeess :in stacJes, the eell~ h~ving ..
heating jaekets whieh eover most of their surfaees to reduee :
the temperature yradient in the mash due to heat exehange, these .:.
. . .
jaekets being eapable of being Eed separately or in series by .:
~ one or several hot fluid sourees to obtain differen-t temperatures
20 along the reaetor. `:
The invention wi.ll be further described, by way of
example only, with reference to the aecompanying drawings, in .~-.
which~
: Figure l is a schematic diagram illustrating the
process according to the invention; : .
Fiyure 2 is a schematic view of apparatus Eor
earrying out the proeess aeeordincJ to the invent.ion, .i.n which ~;
erude .grains undercJo a prel.iminary treatment beEo.re .reaehiny
. the malt mash to underyo a :Eitial common treatment, the apparatus ..
eomprisiny two similar reae-tors;
Fiyure 3 is a diagrammatie vertieal eross-seetional .
view of a eontinuous brewing reaetor; and
...,~, .....
.. '; ,
I~A~ 6 -
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1~36S2Z
Figures 4 to 6 are enlarged views showing several .
forms of reactor cells of the type illustrated in Fi~ure 7. '.~
In the process illustrated in Figure l in a first .'
s-tep A mixing water l, malt in the form of.standard ground ... ...
mixture 2 and crude grains in the form of a fine ground mixture
3 are cont1nuously mixed. After mixing, the act1ons of beta- .' .,.
glucanases and'proteases commence at about 40C. The m.ixtur'e .'
is continuously transferred'from A throuyh A pumping assembly ~ ''.
B to a mashing reactor C in which the.treatment is progressively
increased to about 77C. 'The resulting mash is fed to a ',,:' ,
continuously operatiny separation assembly in three steps. The ",',
first step Dl provides the first sweet wort 5, the second step ' ':.
D2 provides the Eirst sparging 6 and the th.ir,d step D3 which
after separation ~rom the sparginy water~ provicles th~ seconcl
sparyiny 7 recyclecl to the step D2. ~Eter this third separatlon
step D3, a li.quor lO is extract~d through a poss.ible treatm~nt
F of the spent grain 8, which may assist mixing at ~. The . ,
sweet wort 5 and the sparging 6 allow wort'9 to be obtained which .'
underyoes A continuous treatment at E. . ' ',
~20 In the convent'ional processes, the malt.and the crude '~,' ''
yrains are treated separately., The treatment for malt comprises , .' ''
1, , .
operati.ons such as mill,ing, water yrist mixture and brewing -.
proper.~ In the apparatus shown in Figure 2, the malt stored in
a silo~71 is first~we1qhed~by means of a platform scale 72 and
:is then forwarded to a mill 74. The mill 74 allows a particle
size of:the malt to be obtained such that it is possible to :'~
adjust the skin size and to'obtain a very high flour output. :.
The ground mixture oE malt is ~ed to tank 76 khrough a condu.it .,.
75~, and water is supplied to the tank 76 vLa a conduit 77.
'30 The malt gri.st and water are mixed in the tank 76. This mixing
is carried out at a temperature which assists the activity of '.
beta-ylucanases and proteases. The water grist mixture, i.e. the ~:
_ 7 _
.3
io365~Z ,~
mash, is pumped by a pump~12 through a conduit l.1. The pump 12 '.
feeds -the mash through a conduit 13 to a continuously operati1l~ ~.',,'
brewing reactor 15 which will be described below and which is '-''. ,.:
illustrated in Figure 3. ~. . :
At the same time, the crude grains undergo,a separa-te ,'~
treatment. The crude grains which may comprise maize, rice, '', .
barley and the like reach,the part of the apparatus indicate'd ,~ ''': .
by re:Eerence numeral 78, and then are weighed by a plat~orm ,,, ~,'
scale 79 and ~all lnto a mixiny tank 80. ~ixing wa-ter is ' .,;,
supplied to the tank 80 through a conduit 81, and a fraction '-.. `': '
of the malt mash 83 from the reactor 15 is also supplied to ,~
the tank 80 through the conduit 82 throuc3h either the pipe 69',.~ ...
or :the pipe 70. The resulti.ng mixture comprisiny the ground . :'
mixture.oE -the crude grains, mixiny water and a Eraction oE '
malt mash is pumped by a pump 85 Erom the tank 80 throucJh
conduit 84 and supplied through a conduit 86 to a sccond
continuously operating brewiny reactor 15l which is substantially .,'
the same'as the reactor 15. In particular the second reactor ,;''',;
15 has a stirrer 51`opera.ted by a motor 5~. ' , .
The mash of crude grains.leaves the reactor 15l ,,~
through a conduit 87, fl.ows through a heat exchanger 88, and '.'.. .:.
,, .
flows throuyh a conduit 89 back to the mixiny tank 76. . ....... '~.
A by-pass 90 is provlded in the conduit 89. Thus the mash of .. ,: .
crude grains from the heat exchanger 88 can,also be injected ' ''.
into the~malt reactor 15 at different temperatures ranging ",.
from 35C to 80C in accordance with the enzymati.c state of the
malt and the desired composition oE the wort, the i'nlets to the , '~
reactor 15 being through the pipes 69 or 70. `. ',
The mixture of malt mash and crude grains Erom the , ':
mixing tank 76 1s pumped into the reactor 15 and discharged .,: ,,
through a.conduit 16 to be Eed to filtration apparatus 18 in ',
.which the continuous separation operation takes. place and wort l9 ~,', ;~ .
is obtained.
~ 8 - ',',
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. ...
1036SZZ
, According to the known processes, the mash of crude -'. .
. .
grains is mi,xed with a low proportion of malt mash of the ordcr
of 5 to 25~, which allows a certain enzyma-tic activity to occur
which is absent in the crude grains. Moreover, this mash of
~ . ...
crude grains undergoes a temperature increase by stages. The ,:~:
first stage ranges from 75~ to 85 and is called liquifaction .''. :
or gelatinization, and the second s-tage occurs at 100C and .~.
partly hydrolyses the starch-water mixture. ,~ `
~owev~r, the temperature increase may be.progressively
10 , increased by means of the reactor 151. The mash of hydrolysed .
crude grains.may'be cooled to a temperature of from 35C to ' .... '
50C and remixed with the ground mixture of malt to which water .'
has been added. ~t temperatures of from 35C to 50C the ' .
,activity of the beta-glucanases and certain proteas~s ta]ces ~:.
place.
It shou.ld be noted that .Eor both th~ t.r~atment oE th~ ''
malt mash and the separate.treatment of the mash of the crude~::
grains, lt is possible,to provide a different progre.ssive ~. '
temperature increase of the temperature stage system applied ';
in conventional brewing~methods. Thus, in the case of the malt'',
mash the progressive temperature increase in the reactor'15 is`'
from about 30C;to about 80C, and in the case of the mash of .
crude~grains the~progressive temperature increase in the
~: . second reactor 15 is from about 30 to about 100C. These
increases may be in the form of a straight line or of a number,.
of.curves which are calculated from data of the degrada-tion oE~.
~: ' the protein materials and the carbohydrates compounds.
The continuously opera-tinc~ brewing reactor 15 shown;.
in Figure 3 is vertically arranged and may compri,se several
sections. The first section forms the bottom 21 of the reactor
and includes an inlet pipe 14 for -the mash. The upper part of
the first section 21 comprises a flange 22 which is applied
':~
'' 1~36~
:. against a lower flange 23 on the second section 24. A toroidal ' : ,:'
. .
seal 25 ensures ti~htness between the flanges 22 and 23, the .,
latter be.ing held by fixing elements 26. The upper part of . :~
the second section 24 comprises a second flange 27 on which a ~ .
guide flange 28 is placed and serves as connecting element ' .,, ,:.
~. .: ..
between the flange 27 of the second section and a lower flange . . .
29 of.the third section 30. Toroidal seals 31 and 32 ensure ,' .,~
tiyhtness between the 1anyes 27 and 28, and between the ' '
flanges 2~ and 29. ~ixing elements 33 connect the second and '.
the third sections 24 and 30.
. The upper part of the third section 30 comprises a
second flange 34 provided with a toroidal seal 35 on which a . ,.
second gulde flange 36 is placed. Between the guide flange 36 ,.
an~ a lower flange 37 of a fourth secti.on 38 is p.rovided a ;
seal 39, and fixing elements 40 connect the thirdi s~ction 30
and the fourth section 38. '.rhe upper,part o~ the fourth , `' '
section 38 comprises a :Elange 41 which i5 connected through
fixing elements 42 to a flange 43 integral with a fifth :'
section 44, a toroidal seal 45 ensuring tightness be-tween the ' .
flanges 41 .and 43.
A fifth section 44 which forms the lid of the reactor
lS includes an outlet conduit 16. The lid includes turning '',. '~
seals 46 through whlch seals and the guide flanges 28 and 36 :
~: ~ having guiding bearings 47 passes a shaft 50 of a stirrer 51 ~, :
i ~ .
~ ~ ~ having blades.52. The shaft 50 is coupled to a driv.ing motor .
: ' 54 by means of a coupling 53. , ~ :
The sections 2~, 30, 38 comprise a series of brewing ~.. "
cells 55 to ensure, from the hydrodynamic poin-t o.E view,
, favorable decomposition conditions in severAl stages of the
30process. ...
The,reactor is heated by a plurality oE thermostatic
heating pockets 56, 57 connected to each okher by sections as ' ' -
-- 10
0365ZZ
illustrated in Figure 3; the pockets 56, 57 may be for example ,.:"
of triangu'lar s.ection to allow the heatin~ surface to be . '-.
increased. A heatlng syste~ is obtained the heat gradient of
which between the heating side wall 58, 59 and the mash lS very :'''
small. This allows the enzymatic potential of the mash to be :- .
preserved, i.e. the quality and quantity of the enzymes can be ''
preserved. This temperature variation between the heating
fluid and the substrate cloes not exceed a few deyrees centigrade.
. The pockets 56, 57 have pipes 60. .Thus, for the
second section 24, the heatiny fluid can enter through pipe 60,
flow throuyh the pockets of successive cells by means of ' ~.
connections 61 between the pockets 56, and discharge through
a pipe 62 leading to the supply tank (not shown) supplying
heatiny fluid. Similarly, Eor the th.ircl section 30, the heating
fluid can enter through a pipe 63, flow through con,nections 6~
and discharge through a pipe 65. ,l1he in~et o~ the ~ourth . ..
section 38 is formed by a pipe 66 and its outlet by a pipe 67,
connections 68 ensuring the transfer of the heatiny fluid.from
one pocket to another. Pipes,69, 70 are provicled at different
locations.in the reactcjr 15 and allow mash to be removed or
supplied,:for example in accordance with the recluirements of :
~ a mash............................................................... -,
: Heating may be provided for each section 24, 30, 38 '~
: thereby ensuring a progressively increasing temperature of ,~
the mash. Thus, section 24 is at a temperature between 35 ancl ~-
::: ',.
50C its upper part:being a-t 50C and its lower part being at .~.
35C. The section 30 has a temperature between 50C and 65C,
its upper part being at 65C and its lower pa.rt being at S0,C.
Sec.tion 38 has a temperature between 65C and 80C, its upper
part being at 80C ancl its lower part being at 65C. This ,
results in the mash undergoing a proyressive temperature
increase from about 30C to about 80C in a -time interv~l of .;-
..
0365ZZ
an hour. `
The above described process and apparatus havc the
following advantage: ;
In the apparatus which comprises series communicating
cells through which a mechanically stirred fluid continuously
flows, transfer from one cell to the next is often the result
-,:
of convection movements in the two directions (see Figure 7).
This phenomenon is sometimes calIed "back-mixing" and is ~;
particularly effective when agitation is intense and when flow
between cells is not unduly restricted.
This phenomenon has, however some disadvantages~
-Levelling of various elements of the transformation
potential.ity of the treated materials (for instance, tendency
of the liquid extract rate to become uniform alonq the reactpr)
-Loss o~ a part oE the advan~age theorectically
attainable by employincJ series-connected cells: the contractlon
in the distribution of the dwelling times (at the various
thermal and biochemical stages) is a minimum only in the ideal
case, and this results in a lower homogeneity in the succession
of transformatlon conditions experienced by the mash and thus
in a part of the latter undergoing treatments quite different
~. .
~ from the optimum treatment which can be imposed only as an
- ;,., ~ -: .
! - ' "
-Owing to uncontrolled forward and backward movements
superimposed on the net output, enzymatic fractions undergo
; harmful overheating bèfore they -terminate the intended bio-
chemical transformations.
Xt has been suggested that brewi.ng in three temper-
:, ,
ature stages does not correspond to an acute need, indeed the
complex enzymatic transformations distributed along the sequence
o the temperatures undergone during brewing leads to sub-
stantially equivalent results for a large variety of heat
.'.'~
- 12 -
'!. . , ~
~7 ~
-~" 103~;SZZ
diagrams possible in a given time interval.
This leads to successful continuous production
despite the disadvantages mentioned above, b~t it is apparent ~:
that the efficlency suffers from an excessive dispersion of
the treatments imposed on the various elementary volumes of
mash, particularly i~ the successive exchanges therebetween
ean only partially attenuate the consequences of this ::.
dispersion. . ': .
rrhis dispersion ean be maintained within aeceptable
limits,by redueing the baekmixing throuyh one or more of the
following means:
-Restraining the passage from eaeh eell to the nbxt
(the eonstruetion ean be modi~ied to allow the sti,rrer to be
suitably mountecl).
-Reduction o.f stirrincJ intensity to a min:imum.
-~nstalling a means b~tw~en the cells to a~sist flow
in. the direetion imposed on the reaetor, even exelucling the'
passage in the opposite direetion.
, The ~assac3e 91 from each ee].l 551 to the next eell
552 is restrained and agitation is reduced to a minimum. It is
also possible to install between the eells 551~ 552 a-t~the
passa~ge 91 a means which assists the flow in the direetion .::
: imposed on the reaetor 15 even by exeluding the passage in the ,:
op.posite clirection. "'
.
~ ~As shown in F,igure 4, this means may comprise a screw
: . or a helix 92 mounted.on the shaft 50 of the stirrer 51. This
.
..
serew or helix 92 creates a pumping.ef:feet whieh may be adjusted
aeeordiny to the output o~ the reactor 15.
~s shown in ~igure 5, the means may alte.rnatively
30 comprise a non-return valve 93 arranged between,the.eells 551~ ''
552. 'rhe valve 93 may comprise a 1exible dise or membrane 94, :~
for example of rubbe.r, having a eentral opening 95 for reeeiving ',
.
-.13 - ,.,
FA :
036SZZ
. .
the shaft 50 of the stirrer 51. The flexible disc or membrane
94 rests on the periphery of an electro-magnet 91 and is hel~ ~ ~in position by a ring 96 integral with the shaft 50. When the ` ~ -mash is forced in the direction of the arrow A, the disc or - -
membrane 94 is flexed thereby allowing the mash to flow only - -
in one direction. When the mash flows in the opposite direction -
lt pushes the disc or membrane 94 against the periphery of the
passage 91 thereby cutting off -the flow.
Since brewing involves exchanges between liyuid and
particles suspended therein, it is necessary to prevent settling
which would tend to have a harmful effect on the conditions
under which this exchange takes place and could also overfill ;
the reactor. i ~,
In addition to assisting heat transEer and also mass
trans~er between particles and liquid, the ayitation tends to
prevent settling.
This, however, inv~lves the following disadvantages:
-reduction in the particle size prevents further
separation;
-backmixing is increased by increasing agitation.
- These disadvantages may be overcome by the following
means: ~ ,
Confinlng the size dlstribution of the particles by
providing dry milling in several passages and screening and
recycling between the passages. In this manner, by bringing
the size of the fines which generate the filtration close to -
that of the coarse particles, which impose a detrimental strong
agitation in other respects, the disadvan-tag~s reE~rred to
above are reducecl.
-Adoption of a configuration which prevents filling
up with minimum agitation: cells 551~ 552 may for example be
shaped in the form of a pear so that the centrifugal movements
- 14 -
.;. ~ .
~Al `"':~
- ~0365Z2
yenerated by the stirrer 51 are deflected upwards. In addition,
blades 52 may be provided in each cell 551~ 552 in the zone 97
where a stagnant deposit of particles would tend to occur (see
Figure 6).
The movement of the liquid within the reactor consists
of a imposed flow and turbulent movement. The particle.s follow
the movement of the liquid and move close to each other to a
given extent, although this movement is less the heavier the
particles and the shorter the duration oE the turbulence.
The movement of the particles also comprises a slow
- component downwards settliny, and the consequences of this may
be reduced by the agitation and through a suitable choice of
the grain size and the cross-section of the reactor. This gives
the particles a dwellincJ tirne in the reactor longer than that
of the liquid and this .is more so the heavier the particles
and the loncJer the treatment t.ime they recluire.
~ t i.s preferred to proceed as Eollows as far as the
duration and completion of the brewing extraction are concerned:
-Circulating the mash of the reac-tor upwards from
below.
-Obtaining a balance between the~parameters which
assi~st settling and those which oppose it so that there occurs
a residual settling without causing total stagnation of the
heavlest particles.
-The efficiency of the brewing operation and that of
the separation downstream thereof is found to be sensitive to
the initial solid/liquid ratio. However, the finished wort is
subject to a minimum density constralnt. The optimum distri-
bution of the total water between that fed to the inlet and
that used to wash the spent malt may differ from that required
in a batch process; it may also diEEer in a continuous process
depending upon whether the cirFuIation is upwards or downwards
- 15 -
~` ~036S;~Z
`' in the reactor, particularly when the circulation is downwards ''
while employing a finer milling, a more dilute mash and less
washing water than in a conventional brewin~-for a wort of
given density.
It is advantageous to recycle the last sponging .
liquor either at the stage preceding the separation or during ~ ,
brewing. When this recycling is carried out during brewing, it '~
may take place -towards the end of the proteolysis operation, ', " '
giving rise to the following advantages: ,'
-Dilution of the mash favorable to amylolysis when ,,
the,same is likely to be harmful to the proteolysis which would
better occur in a thick mash. ' j~
-F,ffect of shifting the pll in a direction favorable ,'',~,
to amylolysis th~ requirements of which differ ~rom those of
the proteolysis. ~;" " ,
-Contribution t'o the temper~tur~ increa~e oE the mash "' ,
in the reactor. . ..
-Minimum disturbance of the ex,traction poten-tial by
feeding'the sponging liquor when the mash has attained a ~; ' ,;
density of the same or~,er as that of these liquors. `'
It has been found that part of the tr~ansformations
. .
due to proteases and beta-glucanases could be advantageously
carried out in the mixer upstream of -the reactor at an average ,, ~
temperature of from 35 to 45C in this apparatus. ,~ ;
~,- :
.
'`~'.
~, .
. . ~ .
- 16 -
~A :
-,....
