U.S. patent application number 10/266677 was filed with the patent office on 2003-06-12 for flax protein isolate and production.
Invention is credited to Green, Brent Everett, Martens, Ronald W., Milanova, Radka, Tergesen, Johann Franz.
Application Number | 20030109679 10/266677 |
Document ID | / |
Family ID | 26986057 |
Filed Date | 2003-06-12 |
United States Patent
Application |
20030109679 |
Kind Code |
A1 |
Green, Brent Everett ; et
al. |
June 12, 2003 |
Flax protein isolate and production
Abstract
Flax mid linola oil seed protein isolates are provided. Such
isolates are made by extracting flax and linola oil seed protein
from the oil seed meal, concentrating the aqueous protein solution,
diluting the concentrated protein solution to form protein
micelles, collecting the protein micelles and drying the protein
micellar mass. Further flax protein isolate may be recovered from
the supernatant from the protein micellar formation. The protein
isolates have a protein content of at least about 90 wt %.
(N.times.6.25), preferably at least about 100 wt %, on a dry weight
basis.
Inventors: |
Green, Brent Everett;
(Winnipeg, CA) ; Martens, Ronald W.; (Altona,
CA) ; Tergesen, Johann Franz; (Vancouver, CA)
; Milanova, Radka; (Vancouver, CA) |
Correspondence
Address: |
SIM & MCBURNEY
330 UNIVERSITY AVENUE
6TH FLOOR
TORONTO
ON
M5G 1R7
CA
|
Family ID: |
26986057 |
Appl. No.: |
10/266677 |
Filed: |
October 9, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60327775 |
Oct 10, 2001 |
|
|
|
60333492 |
Nov 28, 2001 |
|
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Current U.S.
Class: |
530/370 |
Current CPC
Class: |
A23J 1/14 20130101; A23J
3/14 20130101; A23J 1/142 20130101 |
Class at
Publication: |
530/370 |
International
Class: |
C07K 014/415 |
Claims
What we claim is:
1. A flax oil seed protein isolate having a protein content of at
least about 90 wt % as determined by kjeldahl nitrogen.times.6.25
(n.times.6.25) on a dry weight basis.
2. The flax oil seed protein isolate of claim 1 wherein said
protein content is at least about 100 wt % (N.times.6.25).
3. The flax seed protein isolate of claim 1 derived from the low
linolenic acid variety of flax linola.
4. The flax seed protein isolate of claim 1 which is substantially
undenatured.
5. The flax seed protein isolate of claim 1 in the form of a wet
protein micellar mass.
6. The flax seed protein isolate of claim 1 in a dry powdered
form.
7. The flax protein isolate of claim 1 in the form of dried
supernatant from the precipitation of flax protein micelles.
8. The flax protein isolate of claim 1 in the form of a dried
combination of concentrated supernatant from the precipitation of
flax protein micelles and precipitation flax protein micelles.
9. A process of preparing a flax protein isolate, which comprises:
(a) extracting a flax oil seed meal to cause solubilization of
protein in said oil seed meal and to form an aqueous protein
solution, (b) separating the aqueous protein solution from the
residual oil seed meal, (c) increasing the protein concentration of
said aqueous protein solution while maintaining the ionic strength
substantially constant by using a selective membrane technique to
provide a concentrated protein solution, (d) diluting said
concentrated protein solution into chilled water to cause the
formation of protein micelles, (e) settling the protein micelles to
form an amorphous, sticky, gelatinous, gluten-like protein micellar
mass, and (f) recovering the micellar mass from supernatant having
a protein content of at least about 90 wt %, as determined by
Kjeldahl nitrogen.times.6.25 on a dry weight basis.
10. The process of claim 9 wherein said extracting of said flax oil
seed meal is effected using an aqueous salt solution having an
ionic strength of at least about 0.10 and a pH of about 4 to about
7.
11. The process of claim 10 wherein said salt solution has an ionic
strength of about 0.15 to about 0.6.
12. The process of claim 10 wherein said salt solution has a pH of
about 5.3 to about 6.2.
13. The process of claim 9 wherein said extracting of said flax oil
seed meal is effected using an aqueous salt solution having an
ionic strength of at least about 0-10 and a pH of about 7 to about
12.
14. The process of claim 13 wherein said pH is about 7 to about
9.
15. The process of claim 13 wherein, following said extraction
step, the pH of the aqueous protein solution is adjusted to about 4
to about 7 prior to said concentration step.
16. The process of claim 9 wherein said oil seed meal is extracted
by water and subsequent thereto salt is added to the resulting
aqueous protein solution to provide an aqueous protein solution
having an ionic strength of at least about 0.10.
17. The process of claim 9 wherein said aqueous protein solution
has a protein content of about 5 to about 30 g/L.
18. The process of claim 9 wherein said protein concentrating step
is effected to provide a concentrated protein solution having a
concentration of at least about 50 g/L.
19. The process of claim 18 wherein the protein concentration is at
least about 100 g/L.
20. The process of claim 9 wherein said concentrated protein
solution is warmed to a temperature of at least about 20.degree. C.
to decrease the viscosity of the concentrated protein solution but
not beyond a temperature above which the temperature of the
concentrated protein solution does not permit micelle formation
upon dilution.
21. The process of claim 9 wherein said concentrated protein
solution is diluted by about 15 fold or less by adding the
concentrated protein solution into a body of water having the
volume required to achieve the desired degree of dilution.
22. The process of claim 21 wherein said body of water has a
temperature of less than about 10.degree. C.
23. The process of claim 22 wherein said concentrated protein
solution is diluted by about 10 fold or less.
24. The process of claim 9 wherein the recovered protein micellar
mass is dried to a proteinaceous powder.
25. The process of claim 9 wherein supernatant from the settling
step is processed to recover further flax protein isolate.
26. The process of claim 25 wherein the supernatant is concentrated
using a membrane technique and the concentrated supernatant is
dried.
27. The process of claim 25 wherein the supernatant is
concentrated, the concentrated supernatant mixed with the protein
micellar mass and the mixture is dried.
28. The process of claim 9 wherein steps (a) to (f) are effected in
batch operation.
29. The process of claim 9 wherein steps (a) to (f) are effected in
a continuous operation.
30. The process of claim 9 wherein steps (a) to (f) are effected in
a semi-continuous manner.
31. The process of claim 9 wherein said flax oil seed meal is
linola oil seed meal.
Description
BACKGROUND TO RELATED APPLICATIONS.
[0001] This application claims priority under 35 USC 119(e) from
copending U.S. patent applications Ser. Nos. 60/327,775 filed Oct.
10, 2002 and 60/333,492 filed Nov. 28, 2002.
FIELD OF INVENTION
[0002] The present invention relates to a novel protein isolate
derived from any flax oil seed, including the low linolenic acid
variety linola oil seed, and the production thereof.
BACKGROUND OF THE INVENTION
[0003] In U.S. Pat. No 4,285,862 (Murray IA), there is described
the provision of a protein isolate in the form of an amorphous,
viscous, sticky, gluten-like protein mass (PMM), or a dried form of
the mass. The amorphous protein mass is formed settling an aqueous
dispersion of protein micelles consisting of homogeneous
amphiphilic protein moieties The aqueous dispersion is formed by a
procedure described in detail in U.S. Pat. No. 4,208,323 (Muray IB)
wherein protein is extracted from a protein source material using a
food grade salt solution under controlled conditions, the protein
concentration of the resultant extract is increased while
maintaining the same salt concentration, and the concentrated
protein solution is diluted, thereby forming the aqueous dispersion
of protein micelles There is no suggestion in this prior art that
the procedures described therein may be applied or may be modified
to apply to the recovery of a flax protein isolate from flax oil
seed meal.
SUMMARY OF INVENTION
[0004] The present invention provides a protein isolate of any flax
oil seed and a low linolenic acid mutant known as linola oil seed
and a procedure for preparation of the same. A protein isolate is
defined as a protein containing at least about 90 wt % protein at a
Kjeldahl nitrogen conversion rate of N.times.6.25. The term
"protein content" as used herein refers to the quantity of protein
in the protein isolate expressed on a dry weight basis. Such novel
protein isolates and their preparation are not described in the
Murray IA and IB patents.
[0005] Linola oil seed is a mutant of flax oil seed in which the
fatty acid composition has been changed and linolenic acid (Cl8:3)
has been substantially reduced from about 50% in conventional flax
oil seed to about. 2%, through traditional breeding procedures.
These modifications were made to provide from The resulting linola
oil seed an edible polyunsaturated oil substantially similar to
sunflower oil in fatty acid composition.
[0006] As far as the applicants are aware, there has not previously
been described the preparation of protein isolates from flax oil
seed or linola oil seed. The applicants arc aware of attempts to
provide flax protein products such as described in U.S. Pat. No.
5,925,401, wherein a flax product containing 35 to 60 wt % flax
protein is provided, well below the protein content required to
qualify as an isolate.
[0007] Accordingly, in one aspect of the present invention, there
is provided a flax oil seed protein isolate having a protein
content of at least about 90 wt %, as determined by Kjeldahl
nitrogen.times.6.25 (N.times.6.25) on a dry weight basis,
preferably a protein content of at least about 100 wt %. The flax
oil seed protein isolate may be derived from linola, a low
linolenic acid variety of flax oil seed. The flax protein isolate
preferably is provided in a substantially undenatured form. The
flax protein isolate may be provided in the form of a wet protein
micellar mass or in a dry powdered form The flax protein isolate
also may be provided in the form of dried supernatant from the
precipitation of flax protein micelles. In addition, the flax
protein micelles may be in the form of a dried combination of
concentrated supernatant from the precipitation of flax protein
micelles and precipitated flax protein micelles.
[0008] In another aspect of the present invention, there is
provided a process of preparing a flax protein isolate, which
comprises (a) extracting a flax oil seed meal to cause
solubilization of protein in said oil seed meal and to form an
aqueous protein solution, (b) separating the aqueous protein
solution from the residual oil seed meal, (c) increasing the
protein concentration of said aqueous protein solution while
maintaining the ionic strength substantially constant by using a
selective membrane technique to provide a concentrated protein
solution, (d) diluting said concentrated protein solution into
chilled water to cause the formation of protein micelles, (e)
settling the protein micelles to form an amorphous, sticky,
gelatinous, gluten-like protein micellar mass, and (f) recovering
the micellar mass from supernatant having a protein content of at
least about 90 wt %, as determined by Kjeldahl nitrogen.times.6.25
on a dry weight basis.
[0009] Supernatant from the settling of the protein micellar mass
may be processed to recover further flax protein isolate. The
supernatant may be concentrated using a membrane technique and the
concentrated supernatant dried Alternatively, the concentrated
supernatant may be mixed with the protein micellar the mixture is
dried.
[0010] The flax protein isolate product in the form of protein
micellar mass is described herein as "gluten-like". This
description is intended to indicate the appearance and feel of the
isolate are similar to those of vital wheat gluten and is not
intended to indicate chemical identity to gluten.
[0011] The flax protein isolate produced according to the process
herein may be used in conventional applications of protein
isolates, such as, protein fortification of processed foods,
emulsification of oils, body formers in baked goods and foaming
agents in products which entrap gases. In addition, the protein
isolate may be formed into protein fibers, useful in meat analogs,
may be used as an egg white substitute or extender in food products
where egg white is used as a binder. The flax protein isolate may
be used as nutritional supplements. Other uses of the flax protein
isolate are in pet foods, animal feed and in industrial and
cosmetic applications and in personal care products.
[0012] Flax oil seed also is referred to as linseed oil seed.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 is a schematic flow sheet of a procedure for
producing a flax oil seed protein isolate in accordance with one
embodiment of the invention.
GENERAL DESCRIPTION OF INVENTION
[0014] The novel protein isolates provided herein are prepared by
following generally the procedure described in U.S. Pat. No.
4,208,323, preferably under the specific conditions described
herein. The process may be effected as a series of batch steps or
as a continuous or semi-continuous process.
[0015] The initial step of the process of providing the flax or
linola protein isolates involves solubilizing proteinaceous
material from flax or linola oil seed meal. The proteinaceous
material recovered from flax or linola seed meal may be the protein
naturally occurring in flax or linola seed or the proteinaceous
material may be a protein modified by genetic manipulation but
possessing. characteristic hydrophobic and polar properties of the
natural protein The flax or linola meal may be any flax or linola
meal resulting from the removal of flax or linola oil from flax or
linola oil seed with varying levels of non-denatured protein,
resulting, for example, from hot hexane extraction or cold oil
extrusion methods. The removal of flux or linola oil from flax or
linola oil seed usually is effected as a separate operation from
the protein isolate recovery procedure described herein.
[0016] Protein solubilization is effected most efficiently by using
a salt solution since the presence of the salt enhances the removal
of soluble protein from the oil seed meal. The salt usually is
sodium chloride, although other salts, such as, potassium chloride,
may be used. The salt solution has an ionic strength of at least
about 0.10, preferably at least about 0.15, generally up to about
2.0 to enable solubilization of significant quantities of protein
to be effected. As the ionic strength of the salt solution
increases, the degree of solubilization of protein in the oil seed
meal initially increases until a maximum value is achieved. Any
subsequent increase in ionic strength does not increase the total
protein solubilized. The ionic strength of the food grade salt
solution which causes maximum protein solubilization varies
depending on the salt concerned and the oil seed meal chosen.
[0017] In view of the greater degree of dilution required for
protein precipitation with increasing ionic strengths, it is
usually preferred to utilize an ionic strength value less than
about 1.0 and more preferably a value of about 0.15 to about
0.6.
[0018] In a batch process, the salt solubilization of the protein
is effected at a temperature of above about 0.degree. C. and
preferably up to about 35.degree. C., preferably accompanied by
agitation to decrease the solubilization time, which is usually
about 10 to about 90 minutes. It is preferred to effect the
solubilization to extract substantially the maximum amount of
protein from the oil seed meal, so as to improve product yield. The
upper preferred temperature limit of about 35.degree. C. is chosen
since the process becomes uneconomic at higher temperature levels
in a batch mode.
[0019] In a continuous process, the extraction of the protein from
the flax or linola oil seed meal is carried out in any manner
consistent with effecting a continuous extraction of protein from
the flax or linola oil seed meal. In one embodiment, the flax or
linola oil seed meal is continuously mixed with a salt solution and
the mixture is conveyed through a pipe or conduit having a length
and at a flow rate for a residence time sufficient to effect the
desired extraction in accordance with the parameters described
herein. In such continuous procedure, the salt solubilization step
is effected rapidly, in a time of up to about 10 minutes,
preferably to effect solubilization To extract substantially the
maximum amount of protein from the flax or linola oil seed meal.
The solubilization in the continuous procedure preferably is
effected at elevated temperatures, generally up to about 60.degree.
C.
[0020] The aqueous food grade salt solution and the flax or linola
oil seed meal have a natural pH of about 5 to about 7 to enable a
protein isolate to be formed by the micellar route, as described in
more detail below. The optimal pH value for maximum yield of flax
or linola protein isolate varies depending on the flax or linola
oil seed meal chosen.
[0021] At and close to the limits of the pH range, protein isolate
formation occurs only partly through the micelle route and in lower
yields than attainable elsewhere in the pH range. For these
reasons, pH values of about 5.3 to about 6.2 are preferred.
[0022] The pH of the salt solution may be adjusted to any desired
value within the range of about 4 to about 7 for use in the
extraction step by the use of any convenient acid usually
hydrochloric acid, or alkali, usually sodium hydroxide, as
required.
[0023] Another alternative procedure is to extract the oil seed
meal with the salt solution at a relatively high pH value above 7,
generally up to about 12, preferably about 7 to about 9. Greater
quantities of protein are extracted from the oil seed meal at
higher pH value. The pH of the salt solution, may be adjusted in pH
to the alkaline value by the use of any convenient alkali, such as
aqueous sodium hydroxide solution. Where such alternative is
employed, the aqueous phase resulting from the oil seed meal
extraction step then is separated from the residual canola meal, in
any convenient manner, such as by employing vacuum filtration,
followed by centrifugation and/or filtration to remove residual
meal. The separated residual meal may be dried for disposal.
[0024] The aqueous protein solution resulting from the high pH
extraction step then is pH adjusted to the range to about 4 to
about 7, preferably about 5.3 to about 6.2, as discussed above,
prior to fiber processing as discussed below. Such pH adjustment
may be effected using any convenient acid, such as hydrochloric
acid.
[0025] The concentration of oil seed meal in the food grade salt
solution during the solubilization step may vary widely. Typical
concentration values are about 5 to about 15% w/v.
[0026] The protein extraction step with the aqueous salt solution
has the additional effect of solubilizing fats which may be present
in the canola meal, which then results in the fats being present in
the aqueous phase. It is known that flax or linola oil seed meal
contains significant quantities of a mucilage material which enters
the aqueous flax or linola protein solution, tending to make the
solution somewhat viscous. Such initial relatively high viscosity
tends to inhibit the degree to which the flax or linola protein
solution can subsequently be concentrated, according to the
procedure described below.
[0027] The protein solution resulting from the extraction step
generally has a concentration of about 5 to about 30 g/L,
preferably about 10 to about 25 g/L.
[0028] The aqueous phase resulting from the extraction step then
may be separated from the residual flax or linola oil seed meal, in
any convenient manner, such as by employing vacuum filtration,
followed by centrifugation and/or filtration to remove residual
meal. The separated residual meal may be dried for disposal
[0029] Where the flax or linola seed meal contains significant
quantities of fat, then the defatting steps described in U.S. Pat.
Nos. 5,844,086 and 6,005,076, assigned to then assignee hereof and
the disclosures of which are incorporated herein by reference may
be effected on the separated aqueous protein solution and on the
concentrated aqueous protein solution discussed below.
[0030] As an alternative to extracting the flax or linola oil seed
meal with an aqueous salt solution, such extraction may be made
using water alone, although the utilization of water alone tends to
extract less protein from the flax or linola oil seed meal than the
aqueous salt solution. Where such alternative is employed, then the
salt, in the concentrations discussed above, may be added to the
protein solution after separation from the residual flax or linola
oil seed meal in order to maintain the protein in solution during
the concentration step described below.
[0031] The aqueous protein solution then is concentrated to
increase the protein concentration thereof while maintaining the
ionic strength thereof substantially constant. Such concentration
generally is effected to provide a concentrated protein solution
having a protein concentration of at least about 50 g/L, preferably
at least about 100 g/L.
[0032] The concentration step may be effected in any convenient
manner consistent with batch or continuous operation, such as by
employing any convenient selective membrane technique, such as
ultrafiltration or diafiltration, using membranes, such as
hollow-fibre membranes or spiral-wound membranes, with a suitable
molecular weight cut-off, such as about 2000 to about 50,000
daltons, having regard to differing membrane materials and
configurations, aid, for continuous operation, dimensioned to
permit the desired degree of concentration as the aqueous protein
solution passes through the membranes.
[0033] The concentration step may be effected at any convenient
temperature, generally about 15.degree. to about 60.degree. C., and
for the period of time to effect the desired degree of
concentration The temperature and other conditions used to some
degree depend upon the membrane equipment used to effect the
concentration and the desired protein concentration of the
solution.
[0034] As is well known, ultrafiltration and similar selective
membrane techniques permit low molecular weight species to pass
therethrough while preventing higher molecular weight species from
so doing The low molecular weight species include not only the
ionic species of the food grade salt but also low molecular weight
materials extracted from the source material, such as,
carbohydrates, pigments and anti-nutritional factors, as well as
any low molecular weight forms of the protein. The molecular weight
cut-off of the membrane is usually chosen to ensure retention of a
significant proportion of the protein in the solution, while
permitting contaminants to pass through having regard to the
different membrane materials and configurations.
[0035] Depending on the temperature employed in the concentration
step, the concentrated protein solution may be warmed to a
temperature of at least about 200.degree., and up to about
60.degree. C., preferably about 25.degree. to about 40C., to
decrease the viscosity of the concentrated protein solution to
facilitate performance of the subsequent dilution step and micelle
formation. The concentrated protein solution should not be heated
beyond a temperature above which the temperature of the
concentrated protein solution does not permit micelle formation on
dilution by chilled water. The concentrated protein solution may be
subject to a further defatting operation, if required, as described
in U.S. Pat. Nos. 5,844,086 and 6,005,076.
[0036] The concentrated protein solution resulting from the
concentration step and optional defatting step then is diluted to
effect micelle formation by mixing the concentrated protein
solution with chilled water having the volume required to achieve
the degree of dilution desired. The concentrated protein solution
is diluted by about 15 fold or less, preferably about 10 fold or
less.
[0037] The chilled water with which the concentrated protein
solution is mixed has a temperature of less than about 15.degree.
C., generally about 3.degree. to about 15.degree. C., preferably
less than about 10.degree. C., since improved yields of protein
isolate in the form of protein micellar mass are attained with
these colder temperatures at the dilution factors used.
[0038] In a batch operation, the batch of concentrated protein
solution is added to a static body of chilled water having the
desired volume, as discussed above. The dilution of the
concentrated protein solution and consequential decrease in ionic
strength causes the formation of a cloud-like mass of highly
associated protein molecules in the form of discrete protein
droplets in micellar form. In the batch procedure, the protein
micelles are allowed to settle in the body of chilled water to form
an aggregated, coalesced, dense, amorphous, sticky gluten-like
protein micellar mass (PMM) The settling may be assisted, such as
by centrifugation. Such induced settling decreases the liquid
content of the protein micellar mass, thereby decreasing the
moisture content generally from about 70% by weight to about 95% by
weight to a value of generally about 50% by weight to about 80% by
weight of the total micellar mass. Decreasing the moisture content
of the micellar mass in this way also decreases the occluded salt
content of the micellar mass, and hence the salt content of dried
isolate.
[0039] Alternatively, the dilution operation may be carried out
continuously by continuously passing the concentrated protein
solution to one inlet of a T-shaped pipe, while the diluting water
is fed to the other inlet of the T-shaped pipe, permitting mixing
in the pipe. The diluting water is fed into the T-shaped pipe at a
race sufficient to achieve the desired degree of dilution.
[0040] The mixing of the concentrated protein solution and the
diluting water in the pipe initiates the formation of protein
micelles and the mixture is continuously fed from the outlet from
the T-shaped pipe into a settling vessel, from which, when full,
supernatant is permitted to overflow. The mixture preferably is fed
into the body of liquid in the settling vessel in a manner which
minimizes turbulence within the body of liquid.
[0041] In the continuous procedure, the protein micelles are
allowed to settle in the settling vessel to form an aggregated,
coalesced, dense, amorphous, sticky, gluten-like protein micellar
mass (PMM) and the procedure is continued until a desired quantity
of the PMM has accumulated in the bottom of the settling vessel,
whereupon the accumulated PMM is removed from the settling
vessel.
[0042] By the utilization of a continuous process for the recovery
of flax or linola protein isolate as compared to the batch process,
the initial protein extraction step can be significantly reduced m
time for the same level of protein extraction and significantly
higher temperatures can be employed in The extraction step. In
addition, in a continuous operation, there is less chance of
contamination than in a batch procedure, leading to higher product
quality and the process can be carried out in more compact
equipment.
[0043] The settled isolate is separated from the residual aqueous
phase or supernatant, such as by decantation of the residual
aqueous phase from the settled mass or by centrifugation The PMM
may be used in the wet form or may be dried, by any convenient
technique, such as spray drying, freeze Hag or vacuum drum drying,
to a dry form. The dry flax or linola protein isolate has a high
protein content, in excess of about 90 wt % protein, preferably at
least about 100 wt % protein (calculated as Kjeldahl N.times.6.25),
and is substantially undenatured (as determined by differential
scanning calorimetry). The dry flax protein isolate isolated from
fatty oil seed meal also has a low residual fat content, when the
procedures of U.S. Pat. Nos. 5,844,086 and 6,005,076 are employed,
which may be below about 1 wt %.
[0044] In accordance with one aspect of the invention, it has now
been found that the supernatant from the PMM formation and settling
step contains significant amounts of flax or linola protein, not
precipitated in the dilution step.
[0045] In such procedure, the supernatant from the dilution step,
following removal of the PMM, may be concentrated to increase the
protein concentration thereof Such concentration is effected using
any convenient selective membrane technique, such as
ultrafiltration, using membranes with a suitable molecular weight
cut-off permitting low molecular weight species, including the food
grade salt and other non-proteinaceous low molecular weight
materials extracted from the source material, to pass through the
membrane, while retaining flax protein in the solution
Ultrafiltration membranes having a molecular weight cut-off of
about 3000 to 10,000 daltons having regard to differing membranes
and configurations, may be used Concentration of the supernatant in
this way also reduces the volume of liquid required to be dried to
recover the protein, and hence the energy required for drying. The
supernatant generally is concentrated to a protein content of about
100 to 400 g/L, preferably about 200 to about 300 g/L, prior to
drying
[0046] The concentrated supernatant may be dried by any convenient
technique, such as spray drying, freeze drying or vacuum d dying,
to a dry form to provide a further flax protein isolate. Such
farther flax protein isolate has a high protein content, usually in
excess of about 90 wt % protein (calculated as Kjeldahl
N.times.6.25) and is substantially undenatured (as determined by
differential scanning calorimetry) If desired, the wet PMM may be
combined with the concentrated supernatant prior to drying the
combined protein streams by any convenient technique to provide a
combined flax protein isolate. The combined flax protein isolate
has a high protein content, in excess of about 90 wt % (calculated
as Kjeldahl N.times.6.25) and is substantially undenatured (as
determined by differential scanning calorimetry).
[0047] In another alternative procedure, a portion only of the
concentrated supernatant may be mixed with at least part of the PMM
and the resulting mixture dried The remainder of the concentrated
supernatant may be dried as any of the remainder of the PMM.
Further, dried PMM and dried supernatant also may be dry mixed in
any desired relative proportions.
[0048] By operating in this manner, a number of flax protein
isolates may be recovered, in the form of dried PMM, dried
supernatant and dried mixtures of various proportions by weight of
PMM and supernatant, generally from about 5:95 to about 95:5 by
weight, which may be desirable for attaining differing functional
and nutritional properties.
[0049] As an alternative to dilution of the concentrated protein
solution into chilled water and processing of the resulting
precipitate and supernatant as described above, protein may be
recovered from the concentrated protein solution by dialyzing the
concentrated protein solution to reduce the salt content thereof
The reduction of the salt content of the concentrated protein
solution results in the formation of protein micelles in the
dialysis tubing. Following dialysis, the protein micelles may be
permitted to settle, collected and dried, as discussed above. The
supernatant from the protein micelle settling step may be
processed, as discussed above, to recover further protein
therefrom. Alternatively, the contents of the dialysis tubing may
be directly dried. The latter alternative procedure is useful where
small laboratory scale quantities of protein are desired.
[0050] An alternative procedure for production of the flax protein
isolate is to utilize an iso-electric precipitation procedure. In
such a procedure, extraction of the oil seed meal is effected under
alkaline conditions, following which the pit of the protein
solution is adjusted to a lower value, particularly the pH of the
iso-electric point of the targeted protein, at which pH value the
protein has a neutral change and precipitates out of solution. The
precipitates may be washed to remove contaminants by resuspending
the precipitate in water and reprecipitating the protein.
DESCRIPTION OF PREFERRED EMBODIMENT
[0051] Referring to FIG. 1, there is illustrated schematically a
flow sheet of a batch process carried out in accordance with one
embodiment to the invention. Flax oil seed meal, which may be
linola oil seed meal, and aqueous extraction medium are fed by line
10 to an extraction vessel 12 wherein the oil seed meal is
extracted and an aqueous protein solution is formed. The slurry of
aqueous protein solution and residual oil seed meal is passed by
line 14 to a vacuum filter belt 16 for separation of the residual
oil seed meal which is removed by line 18. The aqueous protein
solution then is passed by line 20 to a clarification operation 22
wherein the aqueous protein solution is centrifuged and filtered to
remove fines, which are recovered by line 24.
[0052] The clarified aqueous protein solution is pumped by line 26
through ultrafiltration membrane 28 to produce a concentrated
protein solution as the retentate in line 30 with the permeate
being recovered by line 32. The concentrated protein solution is
passed into a precipitation vessel 34 containing cold water fed by
line 36 Protein micellar mass formed in the precipitation vessel 34
is removed by line 38 and passed through a spray dryer 40 to
provide dry flax protein isolate 42.
[0053] Supernatant from the precipitation vessel 34 is removed by
line 44 and pumped through ultrafiltration membranes 46 to produce
a concentrated protein solution as the retentate in line 48 with
the permeate being removed by line 50. The concentrated protein
solution is passed through a spray dryer 52 to provide further dry
flax protein isolate 54.
[0054] As an alternative, the concentrated protein solution in line
48 may be passed by line 56 to mix with the protein micellar mass
before the mixture then is dried in spray dryer 40.
EXAMPLES
Example 1
[0055] This Example illustrates the recovery of linola protein from
linola oil seed.
[0056] Linola oil seed was cold pressed and the oil recovered. 16.8
kg of crushed meal was added to 335 L of 0.15 M NaCl solution (5%
w/v extraction concentration at 13.degree. C.) and the mixture
agitated for 60 mins, followed by a 60 min. settling period. 190 L
of extract was decanted and filtered through 20 .mu.m filter pads
to provide 180 L of an aqueous protein solution having a protein
content of 6 g/L.
[0057] The aqueous solution was reduced in volume to 11 L by
concentration on an ultrafiltration system using 30,000 daltons
molecular weight cut-off The resulting concentrated solution had a
protein content of 6 g/L, which represented a yield of 51 wt % of
the protein originally extracted from the linola meal.
[0058] The concentrated protein solution at a temperature of
300.degree. C. was added to water at 4.degree. C. at a dilution
ratio of 1:10. A white cloud formed immediately and was allowed to
settle for 16 hours. 93 L of supernatant was decanted leaving 12 L
of precipitated, viscous, sticky protein mass (PMM). An aliquot of
PMM was freeze dried to determine protein content. The freeze dried
PMM was found to have a protein content of 92 wt % (N.times.6.25)
db. The overall yield of protein from the protein extracted from
the linola meal was 27 wt %.
Example 2
[0059] This Example illustrates the recovery of flax protein from
flax oil seed meal.
[0060] 17.5 kg of commercial flax oil seed meal was added to 350 L
of 0.5M NaCl solution (5% w/v) at 20.degree. C. and the mixture was
agitated for 60 minutes followed by 60 minutes settling time. The
resulting protein extract solution had a protein concentration of
8.5 g/L. A further 17.5 kg batch of commercial flax oil seed meal
was processed in the same way and the resulting protein extract
solution had a protein concentration of 7.9 g/L. The two extract
solutions were decanted and filtered using 20 .mu.m filter pads in
a filter press and the filtrates combined.
[0061] The filtered aqueous protein solution then was concentrated
on an ultrafiltration system using 5,000 daltons molecular weight
cut-off to provide 11 L of a concentrated aqueous protein solution
having a protein content of 120 L.
[0062] The concentrated protein solution at a temperature 31
.degree. C. was added to tap water at 4.degree. C. at a dilution
ratio of 1:10 A white cloud formed immediately and was allowed to
settle for 16 hours at 40.degree. C. 105 L of supernatant was
decanted leaving 10 L of precipitated, viscous, sticky protein mass
(PMM). The PMM was centrifuged at 10,000 g for five minutes to
provide a dense white mass, which then was freeze dried
[0063] 178 g of dried protein isolate was recovered, corresponding
to an overall yield of protein extracted from the flax oil seed
meal of 6 wt %. The freeze dried PMM was found to have a protein
content of 109 wt % (N.times.6.25) d.b.
Example 3
[0064] This Example illustrates the effect of pH on linola
extraction.
[0065] Linola oil seed meal was extracted in a 5% w/v solution with
the extraction pH adjusted with either NaOH or HCl to the derived
pH levels of 4, 5, 6, 7, 8, 9, 10, 11 and 12 All extractions were
performed at room temperature and effected in an orbital shaker for
30 minutes at 230 RPM. Following the mixing period, the spent meal
was separated from the extract and samples taken for protein
content analysis.
[0066] The results obtained are set forth in the following Table
I:
1 TABLE I Extraction pH Extraction Protein 12 0.942% 11 0.708% 10
0.522% 9 0.616% 8 0.514% 7 0.330% 6 0.264% 5 0.165% 4 0.188%
[0067] As may be seen, the extractions are higher pH yielded more
protein than the lower pH extractions. Extractions at pH 5.0 and
4.0 were quite cloudy in appearance, indicating some
precipitation.
SUMMARY OF DISCLOSURE
[0068] In summary of this disclosure, the present invention
provides novel flax and linola protein isolates and procedures for
their preparation. Modifications are possible within the scope of
the invention.
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