Note: Descriptions are shown in the official language in which they were submitted.
~.~3~
Background of the Invention
Field of the ~nvention
.
This invention relates to a process and apparatus
for the recovery of starch and gluten from a wheat-flour
dough.
Description of the Prior Art
Starch has been traditlonally produced by e~traction
from tubers and also from corn and rice by disintegrating
the tubers or grain and then washing out the starch from
the pulp on screens of various designs. The production of
wheat starch, on the other hand, requires a totally dl.EEerent
process. The reason for thls is the rather special physlca:L
properties of wheat gluten. The gluten tends to swe:Ll dur:Lrlg
the mixing process of wlleat ~lour with water and Eorllls ~
network of a cellular pattern in which the gluten forms the
cell wall and the starch fills the cells. The hydrated or
swollen gluten is very elastic and this property is utilized
when leavening the dough for bread baking. When the yeast
converts some of the starch granules into alcohol, carbon
dioxide is formed and expands the cells. The elastic gluten
walls prevent the gas from escaping and a fluffy and easier
digestible bread can be baked.
While this is obviously a very beneficial feature
of wheat flour in terms of bread production, it is at the
same time one of the most serious problems in the utili~ation
of wheat flour for the productlon of starch. When separatlng
the gluten and starch from the wheat dough, water is used
as the vehicle for washing the starch away from the gluten
nnd in the unwashed dougll, the gluten is dispersed as n very
thln network. While the starch particles have a definlte
size and shape, the gluten has neither of these character-
~ .
- 2 -
~ lD3~
istlcs. Wheat gluten is, however, very stick~, tough and
plastlc in relation to gluten particles from other flour
sources, which property makes it possible ~o collect the wheat
gluten in the form of gluten lumps on a screen while the starch
i8 washed through the screen by means of a washing liquid.
The above characteristics of wheat flour clough
mean that in the separation process two contradictory conditions
must be taken into consideration. Thus, on the one hand, the
washed gluten particles or strands should accumulate as quickly
as possible in order that the gluten losses may be kept small,
while on the other hand, the gluten network must be ruptured
in order that starch granules embedded in thls network will
come into contact wlth the washing liquld. These contradlctory
conditlon~ have necessltated labour consu~llng and very langthy
and expenslve procedures whll~ obtainillg wheat starch oE rathcr
poor quality and yields.
Contlnuous processes have been developed which
involve a quite complete dispersion of the dough in wash
water and the recovery of the gluten on vibrating or rotating
screens having a very fine mesh of 100 microns or finer.
These screens obviously require much cleaning and maintenance
and, due to the large screen area requried, the contact
between products and air is considerable9 this resulting in -~
undue and unhygienic bacterial action and breakdown especially
of the gluten. Moreover, this system requires a comparatively
"hard" type of Plour.
A significant advance in the production oE starch
and gluten from wheat flour dough is the system described ln
Plaven U.S. Patent 3,669,739 issued June 13, 1972. In that
sy~tem a wheat flour dough ls simultaneously mPchanically trented
and spray washed with a starch absorbing liquid, this liquid
~ 3 -
' ' ' '~ ~ ' ' ' ' `' ' '
~11374~
being quickly removed from the recovery reglon so as
to prevent an undue buildup of wash liquid. The dough is
subjected to repeated pinching, shreading and cuttlng actlons
by the disposition and use of improved scrapers, and spreading
members revolving with a rotatable axle extending axially
within a perforated semicircular trough-shaped treatment
zone. The purpose of thls is to break down the gluten net-
work of the dough so that the starch can be washed out and
the starch and reformed gluten lumps recovered in different
regions.
While that system has many advantages, it also has
some qulte severe commerclal dlsadvantages. One of the ma~or
disadvantages is that the lumps of dough are s~lb~ectecl to
repeated and progressive steps of pushlng and movlng, plnching,
cuttlng and shreading operatlons by a plurRllty oE dlEferent
axially spaced and circumferentially offset radially extending
pushing paddles and cutting sabres, the latter members operating
by pinching the dough lumps between the radially outermost
edges thereof and the trough bottom. This pushing and
pinching of the dough against the perforated screen by the
action of the various treatment members tend to cause the dough
to block the screen thereby decreasing the efficiency of the
system.
It is the object of the present invention to over-
come the above disadvantages of the prior art systems.
Summary of Invention
This ob~ect is achieved according to the present
inventlon by treatlng the wheat flour dough in such a manner
that fresh dough surfaces available for contactlng wash water
are created continuously be repeated cuttlng or sliclng the
dough at a locatlon remote from the screen or perforate member.
-- 4 -
,
-
~3~
In this way, pressing of the dough against the screen as
required by the prior art processes is substantially avoided
and the attendant disadvantages, especlally the tendency of
the screen to become blocked by material being treated, is
greatly reduced or even eliminated.
Detailed Description of the Invention
The apparatus of the present lnvention has the
usual basic features including a trough-like vessel having
a substantially semicircular, at least partly perforated bottom,
dough treatment members mounted on a rotatable shaft extending
longltudinally within the vessel, means for addlng washing
liquid to the vessel, means for withdrawing this washlng
liquid together wlth extracted starch via tho perforat:Lons,
means for introducing dough in one cnd oE the vasse:l and
means for discharging gluten at the opposite end. This
apparatus is characterized by improved treatment members
in the form of rotatable radial blades having angularly
inclined faces adapted to lift and advance the dough while
substantially avoiding pressing of the dou~h against the
perforated bottom. These blades are further characteri~ed
by having sharpened leading edges which are adapted to co-
operate with fixed cutter bars extending transversely across
the vessel. Thus, the dough is lifted by the rotatable blades
and is sliced or cut by a scissors action between the rotatable
blades and cutter bars to expose a fresh surface for contact
with the washing liquld. Mreover, some lumps of dough
which have been ralsed by the rotatable blades may slide
down the sharpened leading edges thereof towards the shaft
and as a consequence are sliced e~en Eurther by the comblned
action of their own weight and the said sharpened edges.
.
~374~74
This arrangement very clearly avolds the prior art
problems of the dough being pressed against the perforated
bottom, thereby clogging the perforations. Any system
which relies upon a kind of shredding action for cutting
and exposing new surfaces of dough for starch removal will
result in some degree of pressing of the dough against the
perforated bo~tom and the resultant clogging of the holes.
It has been found that this problem can be avoided only by
having the rotatable blades relatively well spaced from the
perforated bottom and contouring the faces of these blades
solely to lift and advance the dough. The present invention
provides substantially no shredding action and a clean cutting
action occurs remote from the perforated bottom at the fixed
cutter blade and along the length of the rotating bLndcs.
This cutting actlon has the eEEect o exposing a vcry ~ub-
stantial area of dough for contact wlth the wash llquid to remove
addltional starch. By providing this very distinct cutting
actlon, the worklng of the dough especlally agalnst the
perforate member is decreased to a minimum whlle the exposure
of fresh surfaces for removal of starch is maximized.
The present invention also includes a novel process
for separating and recovering starch and gluten from wheat
flour dough. According to this process, a substantially
continuous flow of wheat flour dough is introduced into one
end of an elongated treating zone having a substantially
semicircular, at least partly perforated bottom. Within
this zone the dough ls sub~ected to repeated and progressive
steps of llfting, cuttlng and moving operatlons by a plurallty
of rotating radlal blades having angularly disposed Eaces
to lift and advance the dough while substantially avoiding
pressing of the dough against the perfor~ted bottom. The
- 6 -
' '.: .' :
, . . ~ .
cutting action is provided by means of sharp leading edges
on the blades which co-operate with fixed cutter bars so
that as the dough is being lifted and advanced, it is also
being sliced or cut by a scissors action between the rotating
blades and fixed cutter bars to expose a fresh surface.
The rotating blades also provide fresh surfaces via
a knife action brought about by raised lumps of dough returning
to the trough by sliding along the sharp leading edges of the
rotating blades during which the lumps are sliced by the
combination of the sharpened edges and their own weight.
During the travel through the treatlng zone the dough
is also constlnuously belng contacted wl~h a wash llquld for
washing out and removlng stnrch erom the dougll, whlch wasll watar
then exits through the bo~om perforatlons. 1~ is, of course,
most important to keep the perforations open so that the wash
liquid can discharge without accumulating in the treating zone.
Thus, if gluten lumps are moved along the treating zone while
submerged in water, they will not have sufficient absorption
power to catch and merge with small gluten particles suspended
in the wash liquid.
Descrlption of the Preferred Embodiments
Certain preferred embodiments of the invention
are illustrated by the attached drawings, in which:
Figure l is a general perspective view of the
device of the invention;
Figure 2 is an end elevation ln partial sectlon;
Figure 3 is a plan view with portions of the cover
removed;
Figure ~ is a plan view showing A complete
commercial installation,
Figure S is a side elevation of an industrial
installation;
and
Figure 6 is a perspective vlew of n rotntable blade.
_ 7
~3~7~
As will be seen from the drawings, the device
primarily comprises elongated substantially cylindrical vessels
or units 10 mounted in pairs with a common collecting trough or
pan 11 for each pair of vessels 10. The vessels are supported
by outer frames formed by lower horizontal frame members 13
and upper horizontal frame members 14 fixed between vertical
posts 12. Between the pairs of vessels is a central support
frame formed by horizontal frame members 15 and 16 fixed between
vertical tubular members 21.
Each vessel or unit 10 is in the form of a series
of modules in end-to-end relationship and separated by low
partition walls or dams. As shown ln Figure 5, each vessel
10 is made up of four modules lOa, lOb, LOc, and l()d o~ eclual
length. The support Erame ls also construclte~l ln mocluLo~
corresponding in length with the vessel ~lodule6,
The troughs or pans 11 are formed from stainless
steel sheeting, each having lower incline panels 17 merging
at a central outlet 18. The pans for vessel modules lOb,
lOc, and lOd extend the ful~ length of each vessel module,
while for the first vessel module lOa the pan extends only
under the second half of the vessel module. The first half
of vessel module lOa is the dough receiving portion and does
not have a perforated bottom. Extending upwardly from the
lower panels 17 are removable side wall panels 19 which are
hung from and held in place by panel hooks 20. The lower
extremities of these side wall panels are retrained behind
Prame members 13. Thus, it will be seen that these sicle wall
panels 19 can be very quickly and easily removed for cleaning
purposes.
-- 8 --
~37~7~a
A light gauge stainless steel panel 23 is wrapped around each
upper central frame member 16 with the lower end edges of the
panel 23 being welded to lower central frame member 15. This
forms a pair of vertical panels extending longitudinally between
vertical tubes 21 and forming back splash panels. Also in
this central region are a pair of locking bars 24.
Each unit or vessel 10 has a semicircular perforated
bottom 25. This perforated bottom is made up oE stainless
steel panels of the modular length. Each panel conveniently
has a thickness of about 0.03 inch and the perforations can
convenlently be of 0.025 inch diameter with a spacing of 0.05
inch. The units lO are constructed with a series oE
longitudinally spaced semiclrcular T-sh<lped rlbs 2~ sllp~orted
at thelr outer ends by Erame me~ crs l~l and at ~hel.r Lnner
ends by frame member 15, wlth relnforclng tubes 27 runnlng
longitudinally between the ribs 26 for further stiffening. These
rlbs and reinforcing tubes are flxed ln posltlon and the
perforated stalnless steel panels are then mounted on top of
the semicircular ribs and cemented in position to form the
semicircular bottom. Thus, if any portion of the device becomes
badly fouled or a perforated panel is damaged, a side wall
panel 19 can be very quickly removed allowing access to the
adjacen~ perforated bottom panel which can also be very quickly
serviced or replaced by a new panel. This provides a great
saving in down tlme of the devlce.
The top portions of the vessels lO have Eurther
semiLclrcular T-cross sectlon ribs 2~ w:Lth one 90 segement
of the top portion belng enclosed by an arcuate s~ainless
steel panel 29. An lnspectlon window is also provlded ln
the upper portlon and this lnspectlon wlndow has a protective
screen 30 and a plastlc cover 31. The cover ls held ln
posltion by means of clamp members 32 and 32a.
7g~7~L ~
Extending along the length of the top of each
vessel 10 is a header tube 33 with downwardly directed
orlfices. Wash water is sprayed into vessel 10 through this
header. At ~he top of header 33 are a series of upwardly
extending tubular connectors 34 which connect to flexible
tubing for feeding in the wash water. This wash water may either
be fresh water or water which is collected from the pans 11. For
instance, the water collected from the pans of modules lOc
and lOd may be sprayed into the top of vessel modules lOb and
lOc.
The vessels 10 are divided into a series of compart-
ments separated by low dams. These dams include radially
positioned low partition walls 35 mounted between adJacent
vessel modules and partltlon walls 35a mounted at thc middla
of each vessel module. The dams extencl upwardly from the
bottom of the vessel to a height of about two-thirds of the
radius of the vessel.
Bearing members 36 are mounted at the ends of the
modules directly above the dam members 35 and these bearings
support for rotation a square tubular shaft 37. Mounted on ;
this shaft 37 are a series of blade members 38. Also mounted
within the vessels lO are a series of fixed blades 39 for
co-operation with the rotatable blades 38. The blades 39 are
mounted at their ends in blade holding bars 40 and each blade
39 has a pair of cutting edges 41.
Each rotatable blade 38 has a flat front face 43
and a star-shaped central cut-out 42 for keying o~er the
square shaft 37. These blades are spaced along the shaft
by means oE square spacers which slide over the square shaft
37. Thus, each modular length of the unit is assembled by
sliding a series of blades 38 and square tubular spacers 47
-- 10 --
.: ' .' ., -' : . .
.. . . .. . . . .
7gL7~
onto a modular length of square shaft 37 and placing this
in a vessel module.
Each blade 38 has a pair of diametrically opposed
radial arms and each arm has a sharpened leading edge 44 of
concave profile terminating in a projecting tip 4S. The blades
also have curvilinear trailing flange portions 46 which curve in
a direction generally away from the flat face as shown. The
combination of the curved cutting edge 44, the projecting tips
45 and the curved flanges 46 all work together to lift and cut
the dough while substantially avoiding any pressing of the
against the perforated bottom panels 25 and at the same
time adva~cing the dough forwardly through the vessel over
each dam 35.
It has also been found to be advantageous Lf n
propellor shaped paddle 57 1~ pofJit:Loned ad~acent each dam
35. These paddles trail slightly the cutter blades and serve
to deflect dough raised by the immediately adjacent cutter
blade over the dam. These are mounted on the shaft in the
same manner as the blades 38.
A backwashing header 50 may also be mounted for
travel longitudinally along beneath the adjacent pair of
vessels 10. This header has a pair of arcuate tubular members
51 with upwardly directed spray nozzles 52. These two tubes
51 are connec~ed at their inner ends to a T-member 53 and
this connects to a vertical tubular connector 54 onto which
is connected a flexible sanitary hose 55. For travel along
beneath the perforated bottom panels, the header tubes 51 are
supported on horizontally extending shafts 56.
Backwashing of the perforated panels 25 can also
very conveniently be done by slmply removing the sidc panels
19 and spraying the perEorated panels manually wlth hoses.
.. . . ~
As shown in Figure 4, a Lypical commercial installation
comprises two pairs of vessels 10. Platforms 58 are provided
for servicing and maintaining the vessels, with access stairs
59. The number 60 indicates the location for feeding dough
; into each pair of vessels.
A detailed description of the operation of the system
has not been given since this will be readily evident those
; skilled in the art. Thus, the means for feeding in dough,
discharging gluten, circulating liquid, etc., are all well
known in the art.
'
~ ,
.
- 12 -
.. . . . . . .
'`. ' ' .: ' ' . , : .
., , ~
