Note: Descriptions are shown in the official language in which they were submitted.
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SPECIFICATION
Field of the Invention
The present invention relates to a process for the
shelling (i.e. for the removal of the outer skin, sheath or
hull) of oil- and protein-containing seed kernels, such as
rape or turnip seed, whereby the meat or core of the seed
can be obtained free from fragments of the shell, e.g. for
the pressing or extraction of oil thereform.
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Background of the Invention
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Rape seed and like seed grains have gained an in-
creasingly prominent position as a source of oil and pro-
tein because of the relatively high oil and protein contents
of the meat of these seed grains. It is a common practice
to extract as much oil as possible from the seed grain and
to use the remaining solids as protein concentrate which has
a potential as a source of protein for human ingestion pur-
poses.
Rape seed has hitherto been processed by cleaning
the seed grains, breaking them, rolling the broken product,
conditioning and pressing the oil from the broken product
by rollers. For the maximum oil removal, the pressed cake
is comminuted and is extracted with, for example, hexane
which is able to solubilize remaining oil from the comminuted
pressed cake. The extracting solvent is then removed from
the sclid product by eVaporatioD.
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The resulting solids are used as animal feeds.
A substantial disadvantage of this conventional pro-
cess can be found in the fact that the seed grains are treated
with their shells or sheaths (i.e. the seed-coat fragments).
As a result, the residue of the oil-extraction process con-
tains all of the shell components of the seed grain. These
coat components reduce the physiological food value of the
residue and renders the latter unsuitable for further treat-
ment of the residue to protein concentrates for human con-
sumption. On the other hand, the removal of the coat of theseed grain before the oil-extraction process is fraught with
difficulties because of the relatively small size of the seed
grains, i.e. about 2mm in diameter.
There have been various proposals for removing the
meat or core of the seed grains from the coat. For example,
it has been suggested to remove the coats from the meat by
entraining the seed grains in an airstream and thereby pro-
jecting them at high velocities against baffle surfaces
(cf. Proceedings Fourth International Ra~e Conqress, 1974,
_ _ _ _ 20 p. 637). The production of an air~tream of high velocity,
because of the necessary high throughput of the air for in-
dustrially practical applications, involves high energy con-
-` sumption. Moreover, this process has been found to leave a
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substantial portion of the seed grains with their coats in-
tact so that the product still contains a significant coat
component.
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Object of the Invention
It is the object of the present invention to pro-
vide a process for the removal of shells from oil- and pro-
tein-containing seed grains which permits as completely as
possible a separation of the shells from the meat at low
energy consumption.
Summary of the Invention
This object and others which will become apparent
hereinafter are attained, in accordance with the present in-
vention, by a process which is based upon the surprising
discovery that a defined deformation of the seed grains be-
tween two rigid surfaces can bring about a breaking loose
and total separation of the coat from the meat so as to en-
able separation of the shell components from the meat compon-
ents by a sifting operation. More particularly, the diameter
of the seed grains is reduced, by passing them between two
relatively moving surfaces, to 0.2 to 0.5 times the average
mean diameters of the seed grains and thereafter subjecting
the product to air sifting to separate the coat fragments
from the meat. -
It has been found that a predetermined deformation
of the seed grains, to the extent stated above, splits or
coats the shells and causes them to become released from the
core meat without significantly compressing the core meat so
that the latter can be recovered in its natural parts, namely,
the outer flakes, inner flakes and the germ. The subsequent
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sifting operation thus qives a practically complete separation
of the coat or shell components from the meat so that the oil-
extraction operation can be carried out on practically shell-
free meat and the resulting meat residue can be worked up to
high-value protein concentrates suitable for human consump-
tion. Furthermore, the meat is obtained in a geometric con-
figuration which has been found to be especially suitable for
the oil-extraction operation.
According to a further feature of the invention, the
predetermined deformation of the seed grains is so carried out
that the diameter is reduced to 0.25 to 0.4 times the original
seed grain diameter, preferably to 0.3 to 0.35 times the mean
diameter of the seed grains. This reduction in the diameter
of the seed grains has been found to be sufficient to break
loose the shells from the meat and to do so without pressing
any oil from the meat. The mean normal diameter of rape seed
can be determined readily by sifting and is usually between
2 and 3mm.
The deformation of the seed grains is preferably
effected by passing the seed grains between a pair of rollers
whose spacing, at the regions of closest approach, correspond
to the reduced diameter of the seed grains which is desired
as noted above. The roller assembly, according to the inven-
tion, can have an adjustable gap which can be varied in accor-
; dance with the mean diameter of the seed grains which are
processed therein to effect the desired reduction of the
~ diameter.
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According to the preferred embodiment of theinvention, the seed grains are passed through at least two
pairs of such rollers in succession with the gap between the
rollers of the upstream pair being greater than the gap
between the rollers of the downstream pair. This arrangement
permits the process of the invention to be used for seed grains
with a wide ~ange of dimensions, i.e. permits the desired
diameter reduction to be applied over the total spectrum of the
original seed grain diameters.
According to yet another feature of the invention,
after each passage through a pair of rollers, according to the
; invention, a respective sifting stage is carried out to sep-
arate the coat fragments which have been formed in the previous
deformation stage. This prevents shell fragments from a previous
stage to be pressed into the meat of seed grains which have been
released therein during a subsequent deformation stage.
According to another aspect of the invention, the
deformation of the seed grains is carried out by passing them
between a pair of opposed jaws forming a breaker, the jaws
being oscillated about respective pivot axes so that they
undergo relative oscillatory displacement about the respective
axes. Alternatively, the jaws are relatively displaced perpen- -
dicular to the seed-engaging surfaces of the jaws. Naturally,
the seed-engaging surfaces can be curve~ and can converge in
the direction of movement of the seed grains between these
~aws, the spacing of the ~aws at their distance of closest
approach being equal to the minimum reduced diameter to be
imparted to the seed grains.
It has been found to be advantageous in either of --
the latter cases to impart to at least one of the jaws, an
oscillatory movement parallel to the other.
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The sepalation of the shells from the meat of the
seed grain, following the breàking of the shells, can be
improved still further by subjecting the seed grains prior to
their deformation to a conditioning operation in the appropriate
conditioning apparatus in which the temperature and the water
content of the seeds is ad~usted. In the conditioning apparatus,
the water content should be adjusted to 3.5 to 7~ by weight at
room temperature for best results.
Brlef Description of the Drawing
The above and other objects, features and advan-
tages of the present inventio~ will become more readily apparent
from the following description, reference being made to the
accompanying drawing, in which:
.l is a flow diagram illustrating the process
of the present invention using a single pair of rollers for the
deformation of the seed grains;
F~ 2 is a flow diagram ill~strating an embodi-
ment of the process o~ the invention where two pairs of
deformation rollers are provided in succession, and
FIGS. 3 - 5 show other breaker arrangements in
`~ accordance with the invention.
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Specific DescriPtion
~ In FIG.l of the drawing, there is shown a process-
- flow scheme in which the rape seed has a coating 1 and the core
meat 23 both illustrated diagrammatically for a seed of average
diameter D. The seed is first subjected to conditioning at 3 to
modify its moisture content as has been previously indicated and
is then passed between the two rollers 4 of a roller assembly
having a gap which narrows to the dimension S and which deforms
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the seed by pressing inwardly thereon at 2 diametrically
opposite locations to reduce the diameter D of the seed in
proportion to the mean or average diameter. If this proportion
is selected properly, the coating or shell 1 ruptures and the
core meat falls in its natural components including the outer
leaves or ectoblasts 2a, the inner leaves or hypoblasts 2b, and
the germ 2c. The ecto~last 2a and the hypoblast 2b are approx-
imately of the same geometric configuration.
The ratio V of deformations or diameter reduction in
the rolling gap S with seed of a mean diameter D is given by the
equation: v-8~b. It is essential to the present invention that
V be equal or greater than 0.2 and less than or equal to 0.5.
However, effective results are optimally obtained
when V is equal to or greater than 0.25 but less than or equal
to 0.4. The very best results in accordance with the instant
invention are ob~ained when V is greater than or equal to ~.3
but less than or equal to 0.35i
When the aforedescribed values are maintained, the
natural components ~f the core meat 3 are undamaged during the
rupture of the coating and are not compressed to the po~nt that
there is no oil loss.
: The coating fragments 1 are separated from the
` components of the core meat 2 by a separator 10 which can
operate because of the difference in density of the meat and
the shell fragments,-~ . air separator, or by the larger size
of the coating fragments. In the latter case, a properly dimen-
sioned sieve is all that is necessary. Of course, the rollers 4
rotate in opposite senses so that their seed-engaging juxta-
posed surfaces move downwardly in the direction of movement of
the seed. From the separator 5, the meat components and the
coat fragments are recovered. -
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FIG. 2 shows, somewhat similarly, the process as it
applies to the decoating or shelling of said grains with differ-
ent diameters. In this case, large seeds 6 and small seeds 8 are
subjected to conditioning and are passed through a roller system
comprising two roller pair disposed in succession.
The upstream pair of rollers 7 passes the small seeds
8 while rupturing the coat of the large seeds as shown. Between
the rollers there is provided a separator 10 so that only the
meats of the large grains and the small seed grains pass into the
gap of the downstream pair of rollers 9 where the coating is
broken away from the small grains. All of the meat components
are then collected from the sifter 10 downstream of the roller
pair 9. Naturally, the spacing between the roller 7, greater
than the spacing between the rollers 9 and each of these spacings
should be within the aforementioned range of spacing as degined
by the ratio V given above.
In FIG. 3, there is shown a breaker of a nonrotary
type by means of which the same principle as has been described
above is applied to the removal of the feed coatings of rape seed.
The structure illustrated in FIG. 3 comprises, downstream of the
usual conditioner, a pair of ~ownwardly and mutually convergent
breaking jaws 11 and 12, the jaw 11 being guided for reciprocating
movement in a direction perpendicula~ to the jaw 12 as represented
by the arrow 12. The reciprocating movement can be generated by
- any conventional means, e.g. a crank~ a solenoid, a camshaft or
the like.
Still another breaker ha~ been illustrated in FIG. 4
and comprises a pair of breaker jaws 14 and 15, the latter being
fixed and inclined downwardly from the h~rizontal. The breaker
jaw 14 i3 mounted for pivotal movement about an axis 16 and re-
ceive~ an oscillatory displacement about this axis as has been
represented by the arrow 17.
An especially desirable embodiment of the apparatus of
the present invention is seen in FIG. 5 in which the breaker jaws
18 and 19 are both inclined toward one another and inclined to
the vertical. In this case, the upper jaw 19 is fixed although
it can also be angularly oscillated as represented in FIG. 4.
However, the breaker jaw 18 is here reciprocated horizontally so
that its movement, at the feed-engaging surface, has two compo-
nents, one being perpendicular to the juxtaposed surface of the
jaw 19 while the other components of movement are represented by
the arrows l9a and l9b, respectively.
It will be apparent from FIGS. 3 through 5 that the
breaker jaws can be oriented generally vertically (FIG. 3) or in-
clined to the horizontal lFIGS. 4 and 5) but in every case will
converge toward one another so that their closest spacing corres-
ponds to the spacing S used with the roller dehullers described
in conjunction with FIGS~ 1 and 2.
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