Note: Descriptions are shown in the official language in which they were submitted.
:~:12:~L7~
This invention relates to a method for the separation of
wheat gluten and wheat starch, preferably fron wheat flour.
Besides the traditional Martin process, in which wheat
flour is formed into a dou~h with water, and starch is ex~rac~ed
from the formed dough by washing, methods have been developed in
which starch and gluten are separated from free-flcwing mlxtures of
wheat flour and water.
The so-called continuous batter process, described in
"The Chemistry of Wheat Starch and Gluten and their Conversion
Products" (1965) by J.W. Knight pp. 27-30, involves producing a
free-flowing batter from wheat flour and water in a contin~ous
mixer. After a definite retention time in the mixer the starch is
wash d from the gluten by passing the batter to a pump and supply-
ing simultaneously wash water to the pump. The gluten are isolated
by screening.
According to a variant of the "~esca"-method, described
in "Journal of Food Science" 36 (1971) p. 649-652 a hom~genized mLx-
ture of wheat flour and water is æparated into a starch fraction
and a liquid protein ooncentrate by a centrifugation prooe dure. m e
gluten are not isolated from the protein con oentrate, but the pro-
tain concentrate is dried as a whole~ Supplementary to this method
the gluten may be isolated from the protein con oentrate by
agglomeration at a suitable temperature and holding time Imder
stro~g agitation and separation of the agglomerated gluten, as des-
cribed in British patent speciEication 1,397,370 published June 11,
1975.
, ~ ",
IL2~7~;2
All methods above described comprise diferent sta~es
~i.c. ayglomeration, washing, separation) which are carried
out wi~h di~ferent equipment.
According to the present invention a method is
provided in w]1ich the separation o~ starch and the
agglomeration of gluten from wheat is carried out in one
step by passincJ a mixture containinc3 a wheat protein and
~heat starch and water throuyh a hydrocyclone apparatus.
The recovery o~ wheat gluten is Lacilitated
significantly by this method. Moreover, the use o~ a
hydrocyclone apparatus allows a s~rony reduction of-the
consumption of water which is of great importance in
sol~Ting the waste water problem and in saving eneryy.
Thus accordiny to the present inven-tion there is
provided a method for the separation of whea~ gluten and
wheat starch, characterized in that a mixture containing
wheat protein and wheat starch and water is introduced into
- a hydrocyclone apparatus in which:
a) the yluten ayglomerates in the 71ydrocyclone and is
~ carriea along in agglomerated form in the overf low fraction
.
b) a fraction is separated, at the tappi.ng point,
which contains the bul?; o~ the st:arch.
Preferably wheat flour is us~d for makillg the hatter.
Flour of hard a.; well as soft types o wheat can be used as
start-iny material for the method accordiny to the lnventioll.
The fact that with the new procedure c3rades of wheat
~lour can be used Whi:CIl are not suitable for use in the --r~
existing commercial wheat starch manu~acturiny methods is
of yreat economic advantaye.
7~2
It is also possible to use whole meal f~oM ~-7heat or
other ~orms of proeessinc3 wheat such as e.g. flaked wheat
~nstead of wheat flour.
In ~he followinc~ the method of the invention is descri-
bed by way of example ~ith referenee to wheat flour.
In earryinc3 out the produetion of gluten and starcl
fxom wheat flour aecording to the method of the invention,
wheat flour is rnixed ~ith a suffieient amount of ~ater to
obtain eomplete hydration of the flour and to form a
pumpable batter. The amount of water is about 1.5 tons of
water per ton of wheat flour. The mixinc~ ean be performed
in any suitable apparatus and the prepared batter does not
require a prolonc3ed retention time. An adjustment of the
natural pH of the batter or addition of chemieals- e.g.
to improve hydration of the gluten, is not needed, but may
be practieed under speeial circumstanees.
The pumpable batter is, witllout any further interstaye,
introduced into the hydrocyclone apparatus, in which a
spontaneous agglomeration o~ the gluten to threads and
elots takes plaee. The phenomenon that the gluten agglomerates
in the hydrocyclone is unexpected and amazing. Moreover, i-t
i.s surprising that the gluten a~ylomerates, which may he
~everal ern long, do no-t in~luence the per~ormanee o~ th~
hydrocyclone. No blockiny or ehokiny o~ t.he hydrocyelolles
occu ~: s .
~2~7~2
5--
It further turns out that -the cJluten agglomerates
~ formed can easily be separated from the overflo~ of the
hydrocyclones ~y screening.
In the hydrocyclone apparatus a heavy fraction is
separated from the batter. This heavy fraction, which
contains the bulk of staxeh (prime c~rade starch or A-starch)
and the bulk of the fibre, leaves the hydrocyclone
apparatus at the tapping point. The aqueous miYture of
prime grade starch and fibre is subsequently subjected to
a screeninc3 procedure ln order to separate the starch
from the fibre. In order to obtain a still purer grade
starch, the hydrocyclone apparatus may also comprise an
hydrocyc]one washing section. Fresh ~ater is supplied to the
last washing stage of this washing section.Other methods of
purification e.g. washing with water in separators or
eentrifuges are also suitable. The pure starch suspension
therel~y ob~ained ~ay be further eoncentrated, dewatered and
dried.
The light fraction separated in the hydrocyclone
~o apparatus contains besides agglomerated gluten the
remainincJ eomponents o-E the wheat flour, e.g. starch
(second yrade starch or B-starch), the rest of the fibre
and disssolved rnal:exials. The agglomerated gluten is
sep~rated from this licJh~ raction discllarcled as the over~lo~
o~ the hydrocyelolle appara~us and is ~herea~er driecl. Thi.s
sepaxation can he accompli.shed hy screeni.llc3. The screens Qr
si.eves used, havinc3 an aperture in the ranCJe of from
0.3 mm to 2.0 mm, need not meet particu]ar requirements
because tlle acJcllomexated c31u~en can be screened easily. The
7~
--6--
screenin~ is advan~ageousl~ performed i.n an ori~inal
rotating gluten ~asher irl which a further a~glomeration of
the glu~en take.s place to the well-known lumps o stii~
consistency.
Tlle liquid passing the screen contains the second
~rade s-tarch and the soluble makerial. The second grade
starch is recovered thererom e.g. by centrifugi.ng or
decanting. That the over1O~ of the hydrocyc.l.orle apparat.us
may al.so con~ain some prime grade starch. This prime grade
starch can ~e recovel^ed after screening t:he agglomerated
gluten ~y passing the undersize`stream through a number of
hydrocyclones. The underflow of these cyelones, containing
the prime grade starch, is recirculated to the washing
section of the hydrocyclone apparatus. The over~low contains
second grade starch and soluble material.
In order to effect a better separation of the staxch
and protein in the practical operation of the method of the
invention it is preferred to recirculate a part of the
gluten-free overflow from the hydrocyclone apparatus for
preparation of the batter. Recircula~ion in combination ~ith
a suitable number of hydrocyclones stages for countercurrent
wasl~ (J makes possible a reduc-tion of the consumptioll o
water to ].ess than about 3 m of wat:cr per ton of ~heat
flour.
Further :;mprovement of -tl;~ performance of.the
separcltion is ob~.a.ined by raisi?ly the temperature i.n the
hydrocyclones above 30C and preferably to a range of 30C
to 50C. When the overflow .is recirculated a raise in
l2~ 2
temper~ture occurs. Additional methcls of raising the temperature
are the introduction of pre-heated fresh water or of steam into the
hydrocyclone apparatus.
The separation of gluten and starch from wheat flour
according to the method of the invention can be carried out by
means of m~lti-stage hydrocyclone apparatus as e.g. used in the
co m starch industry. Special re~uirements are not needed for
these appara~us: a multi-stage hydrocyclone apparatus consisting
of 3 hydrocyclone stages for clarifying the overflow and a multi-
stage section of about 9 stages for washing in countercurrent with
fresh water will be suitable. me hydrocyclone stages consist of
one or a number of multihydrocyclones, e.g. as described in Dutch
patent application 75,02097, laid open to the public August 24,
1975.
'~le connection in series of the hydrocyclone stages can
be accomplished in several ways e.g. as described in Die Starke 15
(1963) p. 371-373. An example of hydrocyclone apparatus which is
also useful for the method of the invention is described ln U~lited
States patent specification 3,890,888, published June 24, 1975.
me hydrocyclones throughout the apparatus preferably
have a diameter of the cylindrical part of 10 - 15 mm. The pres-
sure drop across the hydrocyclones is about 3 - 6 bar.
'me following example serves to illustrate the method of
the invention by the em~bodiment accordiny to the accompanyiny draw-
ing. Other embodiments are h~wever possible.
.~ ,,
.~..,
~.~.Z iL~
--8--
EX~MPI.~ '
.Wheat flour from silo (A) is mixed in a mixer (B)
~ith the sieved overflow from hydrocyelone apparatus (D) and/
or ~ith ma~e~up water to form a pumpable bat-ter. The weight
ratio of the f.l;our ~o the sieved overflow is in the range of
a~out 1 : 1.5. The batt,er is introduced into hydroeyclone
apparatus (D) by means of pump ~.'Hydrocyclone apparatus (D~
eonsists of 12 hydroeyclone stages of which the 3 upper
stages function as clarifying stages (Dl) and the remaining
9 stages function as washing st,ages (D2). The batter mi~ed
with the underflow of the hydroeyelone section and the
overflow of t,he ~ashing hydrocyelone section, is supplied
by means of a pump (E) to the first ~ashiny ll~Tdrocyc].one
stage. At this stage the batter is divided into an overflow
fraction containing light eomponents and an under10w
fraction containiny heavy components. This division is
repeated at each subsequent washillg hydrocyclone stage.
wash
Fresh.water of a temperature of 40C is int:roduced at V .;nt.o
the supply eonduit of t,he last washing hydrocyclone stage,
~hich discharges at the tapping point an a~ueous starch
20 , suspension eontaining fihre. The fibre is removed at-. III
after ~lbration by means o~ a screenincJ apparatus (F). The
pure/ Eibre-free starell su.spension leav.illg at ~V i.s
eoneentrated, ancl s~.arcll is recovered in known manner, by
means of a vaeuum ~.ilter ancl pneumat1.e drying. The protein
eontent o~,the stareh is 0.3'-~i on dry hasis. The overflow
~rom the washincJ section (D2), COnsiStinCJ o~ water, ~luten,
small st,arch gL^anllles and clissolved eomponent-s, is eonduc-ted
by means o pump (G) in~o the three-s~age section ~Dl).
.~ ,
9_ .
The agcJlomerated gluten is carxied alonc3 in the overflow
. of this section and is screenecl from the over~low by means
of the rotatlng gluten ~7asher apparatus (I~ ith a mesh si~e
of 0.5 mm. The yluten leaving at I are dried pnewnatically
to a gluten product containing appro~imately ~0~ protein
on dry basis (fac-tor 5.7).
The fraction passing screening apparatus rotating
gluten washer (H) is divided into t~o parts. One part is
used for the preparation of the batter of wheat flour
whereas the other part leaving at I is evaporated and dried
after recovery of the second grade starch.
. The hydrocyclone apparatus functions under the followi.ng
conditions: The dia~eter of the cylindrical part of
hydrocyclones in all mu]tihydrocyclone stages is 10 mm. The
pressure drop across the hydrocyclone is 3.5 bar. The
quantity of fresh water supplied in the refining stage amounts
to about 2.5 m3 water per ton of ~heat flour.
