Novel fibrous product

A process for the preparation of a fibrous natural product comprising agitating an aqueous slurry of ground material from the outer seed coat of a legume, especially yellow or green field peas, to dissolve only water-soluble protein and sugar products, filtering the slurry and drying the solid product thus obtained to provide a novel fibrous natural product. The latter is useful as an additive for edible food products such as bread, muffins and pasta to increase the fibrous content thereof.

This invention relates to novel improved fibrous natural products and more 
particularly it relates to novel improved fibrous natural products which 
are prepared from legumes such as peas and beans. These novel products are 
useful as additives to edible food products such as bread, muffins and 
pasta. 
It is known from Canadian Patent No. 1,111,708, issued Nov. 3, 1981, that a 
fibrous product containing pea fibres can be obtained from the hulls of 
green field peas and such pea fibres have particle sizes in the range 
which pass a 20 mesh screen but do not pass an 80 mesh screen (U.S. 
Standard) Sieve). Particularly preferred pea fibres have particle sizes 
which pass a 20 mesh screen but do not pass a 60 or 40 mesh screen, 
referred to as -20+60 or -20+40, respectively, mesh particles. It is also 
known from Canadian Patent No. 1,048,848, issued Feb. 20, 1979, that a 
related fibrous product containing pea fibres can be obtained from yellow 
field peas. The pea fibres described in this known art were obtained from 
commercially available pea hulls solely by selection of particular 
particle sizes and without any treatment of the hulls. 
We have now found, and herein lies our invention, that the hulls of 
legumes, which we prefer to name as the outer seed coat of legumes, such 
as peas and beans, can be purified by our novel process to provide novel 
improved fibrous natural products. 
We have named or described our novel fibrous natural products obtained from 
the process of our invention as concentrated pea bran when prepared from 
the outer seed coat of peas. 
The invention, as claimed herein, is a process for the preparation of a 
novel improved fibrous natural product which comprises agitating an 
aqueous slurry of ground material from the outerseed coat of a legume to 
dissolve water-soluble products, filtering said slurry and drying the 
solid product thus obtained to provide a novel fibrous natural product. 
According to a further feature of the invention, as claimed herein, we 
provide a process for the preparation of a novel improved fibrous natural 
product which comprises grinding material from the outer seed coat of a 
legume to a requisite particle size, forming an aqueous slurry of the 
ground material and agitating said slurry to dissolve water-soluble 
products, filtering said slurry and drying the solid product to provide a 
novel fibrous natural product. 
In yet a further feature of the invention, as claimed herein, we provide a 
process for the preparation of a novel improved fibrous natural product 
which comprises agitating an aqueous slurry of ground material from the 
outer seed coat of a legume to dissolve water-soluble products, filtering 
said slurry, suspending the solid material in water to form a second 
aqueous slurry and treating said second slurry with an oxidizing or 
bleaching agent, filtering said second slurry and drying the solid product 
to provide a novel fibrous natural product. 
The material to be used as starting material in the process of this 
invention is the outer seed coat of the legume. Legumes which are suitable 
for use in this inventive process are peas and beans such as yellow or 
green field peas, white beans, navy beans and soya beans. The crop, such 
as yellow or green field peas, is usually field dried prior to harvesting 
and during that time the outer seed coat may become contaminated with soil 
and sand and perhaps soil borne bacteria. It is desirable to remove this 
contaminating material in order to provide final products in the form of 
powders having a high level of dietary fibre, being substantially bland in 
flavour and which can be added to food products to increase dietary fibre 
levels without significantly detracting from the flavour or texture of the 
food products. 
The outer seed coat or skin of peas is a preferred starting material. The 
outer seed coat of peas is made up of an outer layer of palisade cells, a 
layer of hourglass cells, smaller parenchyma cells, aleurone cells and, 
finally, compressed layers of endosperm cells. The internal or remaining 
portion of the seed is generally referred to as the meat. 
The raw starting material is generally in the form of whole or complete 
half pea shapes (split hollow spheres or rough hollow hemispheres) of the 
outer seed coat or skins of the pea seed mixed with fragments of spheres 
and pea cotyledon chips or broken powder-like particles. This raw starting 
material is available from manufacturers or processors of split peas who 
process the pea seeds by splitting the seeds to remove the outer seed coat 
or skin and retain only the residual internal portion of the seed in the 
form of split peas (meat). If necessary, the raw starting material may be 
passed over a gravity type separator in order to separate the denser pea 
cotyledon chips and other particles from the lighter, less dense outer 
seed coat pieces. After such a gravitational separation treatment, the 
outer seed coat is low in density, fluffy in texture and fairly light in 
colour. 
It is to be understood that the sizes of mesh screens referred to 
throughout this specification are to be interpreted as U.S. standard 
screen sizes. Thus, for example, 30 to 60 mesh screen size refers to sieve 
openings of 590 microns to 250 microns, an 80 mesh screen size refers to a 
sieve opening of 177 microns, a 150 mesh screen size refers to a sieve 
opening of 104 microns and a 325 mesh screen size refers to a sieve 
opening of 44 microns. 
In order to increase the surface area of the outer seed coat starting 
material so as to effectively dissolve and remove undesirable components 
during the process, the dry cleaned outer seed coat may be reduced in 
size, for example, by means of a grinder. An air swept pulverizer or 
hammer mill may preferably be used to grind the outer seed coat to a 
powder. The impact of the hammers or beaters affects the components of the 
outer seed coat starting material to different degrees. The pure outer 
seed coat itself is somewhat difficult to grind because of its fibrous 
nature whereas any pea cotyledon chips present are more readily reduced to 
a fine powder. The ground outer seed coat material may then be separated 
by means of a cascading screening system. Initially, the ground outer seed 
coat material may be sifted over vibratory screens or centrifugal screens 
using a 150 mesh screen to separate the finer powder, referred to as pea 
flour, from the larger particle size powder. This pea flour contains 
varying amounts of fibre and protein depending upon the moisture content 
of the outer seed coat starting material and the settings of the grinder. 
This pea flour may be used for treatment according to the process of this 
invention to provide a novel fibrous natural product. 
On the other hand, ground outer seed coat material having different 
particle sizes may also be used in the process of this invention. Thus, 
for example, ground outer seed coat material which passes through a 60 
mesh screen is very suitable for use in the process of this invention. 
Relatively tough cellulosic fibrous material from the outer seed coat 
tends to remain on a 60 mesh screen whereas softer fibres having higher 
contents of hemicellulose, pectins and gums are more readily ground and 
tend to pass through a 60 mesh screen. The actual particle size of the 
outer seed coat starting material may be varied according to the type of 
fibrous natural product which it is desired to produce. The seed coat 
material passing through a 100 mesh screen or a 150 mesh screen, to be 
used as starting material for the process of this invention, the softer 
the fibrous natural product will be which is prepared therefrom and such a 
product tends to be characterized by having a high water absorption. When 
the ground outer seed coat used as starting material is a powder having 
larger particle sizes, such as a powder which passes through a 60 mesh 
screen or a 40 mesh screen, the fibrous natural product obtained therefrom 
tends to be a less soft fibrous product having a lower water absorption 
characteristic. 
It is to be understood, therefore, that ground outer seed coat material to 
be used as starting material in this process may vary over a broad range 
of particle sizes and the particular range of particle size chosen to be 
used will be dependent upon the type of fibrous natural product required. 
Thus, for example, ground outer seed coat material to be used as starting 
material may have particle sizes such that it may pass through any screen 
from about 20 mesh size to about 150 mesh size. Thus, different sizes of 
ground outer seed coat material to be used in this process may be (a) 
passes through 150 mesh screen, (b) passes through 100 mesh screen, (c) 
passes through 20 mesh screen but remains on a 150 mesh screen, (d) passes 
through a 30 to 60 mesh screen, preferably a 40 mesh screen, but remains 
on a 150 mesh screen, (e) passes through a 60 mesh screen but remains on 
an 80 mesh screen, and (f) passes through a 20 mesh screen but remains on 
a 60 mesh screen. 
Any oversized or too large particle size of ground outer seed coat material 
which is considered to be unsuitable for the process of this invention 
recycled and returned to the grinder for regrinding to smaller particle 
size. 
A conveniently sized ground outer seed coat material may be a powder 
passing through a 20 to 60 mesh screen (840 to 250 microns) and remaining 
on a 150 mesh screen (104 microns) or it may be a powder passing through a 
50 mesh screen (297 microns) and remaining on an 80 mesh screen (177 
microns). 
According to the process of this invention, the ground outer seed coat 
material is mixed with an excess of water to provide an aqueous slurry 
which is agitated to dissolve components, such as proteins and sugars, 
present in the ground material. The aqueous slurry used may be of the 
order of from about 2% to about 20% by weight of solid, preferably from 
about 2% to about 10% by weight of solid, and particularly from about 5% 
to about 6% by weight of solid, according to equipment available. 
The slurry may be agitated at a temperature of from about 5.degree. C. to 
about 40.degree. C., preferably from about 15.degree. C. to about 
25.degree. C., more particularly at about 20.degree. C., and for a period 
of from about 2 minutes to about 10 minutes, preferably for from about 6 
to about 8 minutes. It is desirable to avoid agitation of the slurry for 
too long a period in order to avoid dissolving certain soluble components 
present in the fibrous material such as pectins or gums. 
It is also desirable to maintain the aqueous slurry at a pH below about 8.5 
and preferably below about 7.0. The slurry tends to become darker coloured 
on increasing the pH and it is therefore particularly useful to maintain 
the pH within the range of from about 6.0 to about 6.5 when the slurry 
contains ground outer seed coat material from green or yellow peas. The pH 
of the slurry may be adjusted, if desired, by the addition of an 
appropriate amount of a weak acid such as citric acid or phosphoric acid 
to maintain a pH range of from about 6.0 to about 6.5. 
When agitation of the aqueous slurry is complete, the slurry is then 
filtered. A vibratory type screen may be used which may have a 325 mesh 
screen and the solid moist cake retained by the filter is then dried. 
Drying may be effectively carried out by passing the solid moist cake to a 
suitable drier such as a flash type (forced air) drier. The dried material 
thus obtained is a fibrous product which may have a moisture content of 
about 8% with a particle size of from about 150 mesh to about 30 to 50 
mesh. In certain circumstances, it may be desirable to reduce the particle 
size to a maximum of 80 mesh size (177 microns) to reduce the apparent 
texture of the fibrous product. The dried powder may therefore be 
subjected to further grinding, for example, by use of an air swept 
pulverizer. The product thus obtained may then be screened over an 80 mesh 
screen using vibratory or centrifugal type sifters to produce a fairly 
uniform product in the form of a powder. This powder is a fibrous natural 
product which we have named as concentrated pea bran in view of its 
preparation from the outer seed coat of pea seeds. 
As a further valuable feature of the invention we have found that an 
additional processing stage may be included to provide an alternative type 
of novel fibrous natural product which may be desired for certain uses as 
an additive to food products. Thus, after the initial agitation of the 
aqueous slurry and filtering to remove the aqueous filtrate containing 
soluble products, the residual moist solid cake may then be reslurried in 
water and subjected to an oxidation or bleaching treatment. 
This second slurry may conveniently be a 2% to 20% by weight slurry in 
water, preferably from about 2% to about 10% by weight slurry in water, 
and more particularly, from about 5% to about 6% by weight slurry in 
water. 
As a suitable oxidizing or bleaching agent there may be mentioned hydrogen 
peroxide or an alkali metal hypochlorite, such as sodium hypochlorite. The 
oxidizing or bleaching agent may be used at a concentration of from about 
100 parts to about 200 parts per million (ppm). A preferred oxidizing or 
bleaching agent is hydrogen peroxide used at a concentration of about 100 
ppm. Other oxidizing or bleaching agents which may be used are, for 
example, an alkali metal sulphite or bisulphite such as sodium sulphite or 
sodium bisulphite, and sulphur dioxide. Treatment of the aqueous slurry 
with an oxidizing or bleaching agent may be carried out at a temperature 
of from about 15.degree. C. to about 30.degree. C., preferably from about 
20.degree. C. to about 25.degree. C. with a residence time which may be 
from about 5 minutes to about 30 minutes. It is desirable to avoid too 
long a residence time because the aqueous slurry may tend to thicken. A 
preferred oxidizing or bleaching treatment involves agitating the slurry 
at about 25.degree. C. for about 5 minutes. 
As indicated above, it is desirable that the aqueous slurry be maintained 
at a pH below about 8.5 and preferably below about 7.0. A particularly 
useful pH is within the range of from about 6.0 to about 6.5 where using 
an aqueous slurry prepared from the outer seed coat of green or yellow 
peas. Such a pH may be achieved by the addition of a weak acid such as 
citric acid or phosphoric acid to the aqueous slurry. 
When the oxidizing or bleaching treatment is complete, the aqueous slurry 
is filtered, conveniently by use of a centrifuge, such as a decanter 
centrifuge. The moist solid cake thus obtained is then dried, for example, 
by means of a flash type (forced air) drier. The product obtained 
generally has particle sizes of the order of from about 150 mesh to about 
30 to 60 mesh. 
When it is desired to reduce the particle size to obtain a more uniform 
size of product, the dried material may be ground by using, for example, 
an air swept pulverizer. This grinding produces a powder which may then be 
screened over 80 mesh screens (177 microns) using vibratory or centrifugal 
type sifters. The generally uniform powdered product is a novel fibrous 
natural product which we describe as a concentrated pea bran and which is 
useful as an additive in a variety of food products where natural fibre is 
required.

The invention is illustrated by, but not limited by, the following Examples 
describing the process and the products of the invention. 
EXAMPLE 1 
One thousand pounds of cleaned outer seed coat from yellow field peas are 
ground in a Jacobson hammer mill equipped with air conveyance for product 
removal. The powder is sifted across a 150 mesh screen using a Kason 
centrifugal sifter. The fine fraction passing through the 150 mesh screen 
is a variety of pea flour with a protein content of approximately 22% and 
a crude fibre content of approximately 11%. The fine pea flour amounts to 
approximately 170 pounds. This pea flour is subjected to a process as 
described at the end of this Example. 
The remaining powder retained on 150 mesh is sifted over a 40 mesh screen 
in a similar type of rotary or centrifugal sifter. The material that 
passes through 40 mesh is gathered for further processing. The material 
retained on 40 mesh is returned to the grinder or hammer mill for further 
size reduction. Approximately 750 pounds of material passes through the 40 
mesh and 80 pounds is recycled to the grinder. 
The 750 pounds of powder passing through the 40 mesh screen is mixed with 
14,250 pounds of water to form a slurry in water containing 5% w/w solids. 
This slurry, having a pH of 6.8, is agitated and held for an average 
residence time of 7 minutes at a temperature of 20.degree. C. 
The slurry is then pumped to a Sweco brand vibratory screen fitted with a 
325 mesh screen. Dissolved components are washed through the screen while 
the fibre fraction is collected as a solid wet filter cake. This solid 
cake of fibrous material weighs about 3,000 pounds and has a solids 
content of approximately 20%, i.e., it contains about 600 pounds of solid 
material. 
The solid cake is passed to a flash type (forced air) drier. The solid cake 
is dried to a moisture content of 8% and then ground in an air swept 
pulverizer. The moisture content is thereby reduced to 5% and the powder 
is then sifted over a Kason type centrifugal sifter with an 80 mesh 
screen. The oversized particles are recirculated to the feed entry to the 
flash type (forced air) drier where they provide some additional 
friability to the new feed cake entering the drier. The 550 pounds of 
powder that passes through the 80 mesh screen is a novel fibrous natural 
product which we describe as "concentrated pea bran" and which is useful 
as an additive to a variety of food products. 
The pea flour (approximately 170 pounds) is formed into an aqueous 5% w/w 
slurry and subjected to a similar type of treatment as indicated above. 
There is thus obtained a fibrous natural product (80 to 100 pounds) as a 
dried powdered product which is a concentrated pea bran. 
EXAMPLE 2 
The process of Example 1 is repeated to the stage where there is obtained 
the solid wet cake of washed fibre weighing about 3,000 pounds and having 
a solids content of approximately 20%. An additional processing stage is 
then carried out as follows: 
This washed fibrous material weighing about 3,000 pounds and containing 
about 600 pounds of solid material is added to 3,000 pounds of water 
containing phosphoric acid to provide a slurry of about 10% w/w having a 
pH of 6.5. To this slurry is added 100 parts per million (ppm) of hydrogen 
peroxide and the slurry is agitated and maintained at 25.degree. C. for 5 
minutes. The slurry is then centrifuged in a Sharples decanter centrifuge. 
The liquid supernatant is stored for future use at the beginning of this 
process and the 1,375 pounds of solid cake having a solids content of 40% 
is passed to a flash type (forced air) drier. 
The solid cake is dried to a moisture content of 8% and then ground in an 
air swept pulverizer. The moisture content is thereby reduced to 5% and 
the powder is then sifted over a Kason type centrifugal sifter with an 80 
mesh screen. The oversized particles are recirculated to the feed entry to 
the flash type (forced air) drier where they provide some additional 
friability to the new feed cake entering the drier. The 550 pounds of 
powder that passes through the 80 mesh screen is a novel fibrous product 
which we describe as "concentrated pea bran" and which is useful as an 
additive to a variety of food products.