U.S. patent application number 12/542247 was filed with the patent office on 2010-02-25 for soluble canola protein isolate production from pmm ("c307").
Invention is credited to Brent E. Green, Martin Schweizer, Kevin I. Segall.
Application Number | 20100048875 12/542247 |
Document ID | / |
Family ID | 41696988 |
Filed Date | 2010-02-25 |
United States Patent
Application |
20100048875 |
Kind Code |
A1 |
Segall; Kevin I. ; et
al. |
February 25, 2010 |
Soluble Canola Protein Isolate Production from PMM ("C307")
Abstract
A soluble canola protein isolate is prepared from canola protein
micellar mass by solubilizing the protein micellar mass in a
calcium salt solution, preferably a calcium chloride solution,
followed by dilution of the resulting canola protein solution.
Following removal of the precipitate phytic acid, the aqueous
canola protein solution is concentrated, optionally diafiltered,
and acidified to a pH of about 2.5 to 4.0 to produce an acidified
clear canola protein solution, which may be concentrated, subjected
to a colour removal step and dried. The canola protein isolate so
formed is soluble, transparent and heat stable in an acid aqueous
environment and also is soluble at natural pH, without
precipitation of protein.
Inventors: |
Segall; Kevin I.; (Winnipeg,
CA) ; Green; Brent E.; (Warren, CA) ;
Schweizer; Martin; (Winnepeg, CA) |
Correspondence
Address: |
SIM & MCBURNEY
330 UNIVERSITY AVENUE, 6TH FLOOR
TORONTO
ON
M5G 1R7
CA
|
Family ID: |
41696988 |
Appl. No.: |
12/542247 |
Filed: |
August 17, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61136208 |
Aug 19, 2008 |
|
|
|
Current U.S.
Class: |
530/377 |
Current CPC
Class: |
A23J 1/14 20130101; C07K
14/415 20130101; A23J 3/14 20130101; A23L 2/66 20130101 |
Class at
Publication: |
530/377 |
International
Class: |
C07K 14/415 20060101
C07K014/415; C07K 1/02 20060101 C07K001/02; C07K 1/14 20060101
C07K001/14 |
Claims
1. A method of forming a canola protein isolate, which comprises:
(a) solubilizing a canola protein micellar mass using an aqueous
calcium salt solution of a concentration of about 1.5 to about 15
wt % (on a per protein basis) to form a canola protein solution
having a protein concentration of about 5 to about 50 wt % (on a
per protein basis), and (b) diluting the canola protein isolate by
about 1 to about 20 fold.
2. The process claimed in claim 1 wherein said calcium salt is
calcium chloride and is used in a concentration of about 2 to about
3 wt % (on a per protein basis).
3. The process claimed in claim 2 wherein said canola protein
solution has a protein concentration of about 15 to about 25 wt
%.
4. The process claimed in claim 1 wherein said canola protein
solution is diluted about 1 to about 3 fold.
5. The process claimed in claim 1 wherein, after the diluting step,
deposited phytic acid is removed to provide a clear diluted aqueous
canola protein solution.
6. The process of claim 5 wherein said clear diluted aqueous canola
protein solution is dried to produce a canola protein isolate
having a protein content of at least about 90 wt % (N.times.6.25)
d.b.
7. The process of claim 5 wherein said clear diluted aqueous canola
protein solution is concentrated to a concentration of about 50 to
about 200 g/L by using a selective membrane technique to provide a
concentrated clear diluted aqueous canola protein solution.
8. The process of claim 7 wherein said clear diluted aqueous canola
protein solution is concentrated to a concentration of about 80 to
150 g/L.
9. The process of claim 7 wherein said concentrated clear diluted
aqueous canola protein solution is subject to diafiltration using
about 2 to about 20 volumes of diafiltration solution to provide a
concentrated and diafiltered clear diluted aqueous canola protein
solution.
10. The process of claim 9 wherein said concentrated clear diluted
aqueous canola protein solution is subjected to diafiltration with
about 5 to about 10 volumes of diafiltration solution.
11. The process of claim 9 wherein an antioxidant is present in the
diafiltration solution during at least part of the diafiltration
step.
12. The process of claim 9 wherein the concentrated and diafiltered
clear diluted aqueous canola protein solution is subjected to a
colour removal step.
13. The process of claim 12 wherein the product of the colour
removal step is dried to produce a canola protein isolate having a
protein content of at least about 90 wt % (N.times.6.25) d.b.
14. The process claimed in claim 5 wherein the pH of the clear
diluted aqueous canola protein solution is adjusted to a value of
about 2.0 to about 4.0 to result in an acidified clear canola
protein solution.
15. The process claimed in claim 14 wherein the pH of the clear
diluted aqueous canola protein solution is adjusted to a value of
about 2.9 to about 3.2.
16. The process of claim 14 wherein said acidified clear canola
protein solution is dried to produce a canola protein isolate
having a protein content of at least about 90 wt % (N.times.6.25)
d.b.
17. The process of claim 5 wherein said acidified clear canola
protein solution is concentrated to a concentration of about 50 to
about 200 g/L by using a selective membrane technique to provide a
concentrated clear diluted aqueous canola protein solution.
18. The process of claim 17 wherein said acidified clear canola
protein solution is concentrated to a concentration of about 80 to
150 g/L.
19. The process of claim 17 wherein said acidified clear canola
protein solution is subject to diafiltration using about 2 to about
20 volumes of diafiltration solution to provide a concentrated and
diafiltered clear diluted aqueous canola protein solution.
20. The process of claim 19 wherein said acidified clear canola
protein solution is subjected to diafiltration with about 5 to
about 10 volumes of diafiltration solution.
21. The process of claim 19 wherein an antioxidant is present in
the diafiltration solution during at least part of the
diafiltration step.
22. The process of claim 19 wherein the concentrated and
diafiltered clear diluted aqueous canola protein solution is
subjected to a colour removal step.
23. The process of claim 22 wherein the product of the colour
removal step is dried to produce a canola protein isolate having a
protein content of at least about 90 wt % (N.times.6.25) d.b.
24. A canola protein isolate having a protein content of at least
about 90 wt % (N.times.6.25) d.b. and which consists predominantly
of the 7S canola protein and which is soluble and heat stable in an
acidic aqueous environment.
25. The canola protein isolate of claim 24 wherein said acidic
aqueous environment is a beverage having a pH of about 2.5 to about
5.
26. The canola protein isolate of claim 24 having a protein content
of at least about 100 wt % (N.times.6.25) d.b.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application claims priority under 35 USC 119(e) from
U.S. Provisional Patent Application No. 61/136,208 filed Aug. 19,
2008.
FIELD OF INVENTION
[0002] This invention relates to the production of soluble canola
protein isolate.
BACKGROUND TO THE INVENTION
[0003] Canola oil seed protein isolates having protein contents of
at least 100 wt % (N.times.6.25) can be formed from oil seed meal
by a process as described in copending U.S. patent application Ser.
No. 10/137,391 filed May 3, 2002 (U.S. Patent Application
Publication No. 2003-0125526 A1 and WO 02/089597) and U.S. patent
application Ser. No. 10/476,230 filed Jun. 9, 2004 (U.S. Patent
Application Publication No. 2004-0254353 A1), assigned to the
assignee hereof and the disclosures of which are incorporated
herein by reference. The procedure involves a multiple step process
comprising extracting canola oil seed meal using an aqueous salt
solution, separating the resulting aqueous protein solution from
residual oil seed meal, increasing the protein concentration of the
aqueous solution to at least about 200 g/L while maintaining the
ionic strength substantially constant by using a selective membrane
technique, diluting the resulting concentrated protein solution
into chilled water to cause the formation of protein micelles,
settling the protein micelles to form an amorphous, sticky,
gelatinous, gluten-like protein micellar mass (PMM), and recovering
the protein micellar mass from supernatant having a protein content
of at least about 100 wt % (N.times.6.25). As used herein, protein
content is determined on a dry weight basis. The recovered PMM may
be dried.
[0004] In one embodiment of the process, the supernatant from the
PMM settling step is processed to recover canola protein isolate
from the supernatant. This procedure may be effected by initially
concentrating the supernatant using an ultrafiltration membrane and
drying the concentrate. The resulting canola protein isolate has a
protein content of at least about 90 wt %, preferably at least
about 100 wt % (N.times.6.25).
[0005] The procedures described in U.S. patent application Ser. No.
10/137,391 are essentially batch procedures. In copending U.S.
patent application Ser. No. 10/298,678 filed Nov. 19, 2002 (U.S.
Patent Application Publication No. 2004-0039174 A1 and WO
03/043439) and U.S. patent application Ser. No. 10/496,071 filed
Mar. 5, 2005 (U.S. Patent Application Publication No. 2003-0015910
A1), assigned to the assignee hereof and the disclosures of which
are incorporated herein by reference, there is described a
continuous process for making canola protein isolates. In
accordance therewith, canola oil seed meal is continuously mixed
with an aqueous salt solution, the mixture is conveyed through a
pipe while extracting protein from the canola oil seed meal to form
an aqueous protein solution, the aqueous protein solution is
continuously conveyed through a selective membrane operation to
increase the protein content of the aqueous protein solution to at
least about 50 g/L, while maintaining the ionic strength
substantially constant, the resulting concentrated protein solution
is continuously mixed with chilled water to cause the formation of
protein micelles, and the protein micelles are continuously
permitted to settle while the supernatant is continuously
overflowed until the desired amount of PMM has accumulated in the
settling vessel. The PMM is recovered from the settling vessel and
may be dried. The PMM has a protein content of at least about 90 wt
% (N.times.6.25), preferably at least about 100 wt %. The
overflowed supernatant may be processed to recover canola protein
isolate therefrom, as described above.
[0006] Canola seed is known to contain about 10 to about 30 wt %
proteins and several different protein components have been
identified. These proteins include a 12S globulin, known as
cruciferin, a 7S protein and a 2S storage protein, known as napin.
As described in copending U.S. patent application Ser. No.
10/413,371 filed Apr. 15, 2003 (U.S. Patent Application Publication
No. 2004-0034200 A1 and WO 03/088760) and U.S. patent application
Ser. No. 10/510,766 filed Apr. 29, 2005 (U.S. Patent Application
Publication No. 2005-0249828 A1), assigned to the assignee hereof
and the disclosures of which are incorporated herein by reference,
the procedures described above, involving dilution of concentrated
aqueous protein solution to form PMM and processing of supernatant
to recover additional protein, lead to the recovery of isolates of
different protein profiles.
[0007] In this regard, the PMM-derived canola protein isolate has a
protein component composition of about 60 to about 98 wt % of 7S
protein, about 1 to about 15 wt % of 12S protein and 0 to about 25
wt % of 2S protein. The supematant-derived canola protein isolate
has a protein component composition of about 60 to about 95 wt % of
2S protein, about 5 to about 40 wt % of 7S protein and 0 to about 5
wt % of 12S protein. Thus, the PMM-derived canola protein isolate
is predominantly 7S protein and the supematant-derived canola
protein isolate is predominantly 2S protein. As described in the
aforementioned U.S. patent application Ser. No. 10/413,371, the 2S
protein has a molecular mass of about 14,000 daltons, the 7S
protein has a molecular mass of about 145,000 daltons and the 12S
protein has a molecular mass of about 290,000 daltons.
[0008] The PMM-derived canola protein isolate is largely insoluble
in water at natural pH and is more soluble in acid aqueous media,
such as uncarbonated and carbonated beverages, including soft
drinks and sport drinks, but produces solutions of poor clarity. As
such, the PMM-derived canola protein isolate is considered
generally unsuitable for protein fortification of such
beverages.
[0009] Canola is also known as rapeseed or oil seed rape.
SUMMARY OF INVENTION
[0010] We have now found a method for converting PMM into a form
which is soluble and transparent and heat stable in an acidic
aqueous environment and also soluble in water at natural pH. The
resulting canola protein isolate is also low in phytic acid. Heat
stability in solution at low pH, permits thermal processing, such
as hot fill applications. The canola protein isolate is useful in
products for human consumption, such as for the protein
fortification of, in particular, soft drinks and sports drinks, as
well as other aqueous systems, without precipitation of protein.
The canola protein isolate is also useful for non-human food
applications such as pet foods and aquaculture.
[0011] In accordance with one aspect of the present invention,
there is provided a method of forming a canola protein isolate,
which comprises: [0012] (a) solubilizing a canola protein micellar
mass, which may be in a dry or wet form, using about 1.5 to about
15 wt %, preferably about 2 to about 3 wt %, calcium chloride
(CaCl.sub.2) on a per protein basis and sufficient reverse osmosis
RO purified water for an overall protein concentration of about 5
to about 50 wt %, preferably about 15 to about 25 wt %, and [0013]
(b) diluting the resolubilized CaCl.sub.2 treated protein micellar
mass with up to about 20 volumes or more, preferably about 1 to
about 3 volumes of RO water, [0014] (c) optionally removing any
precipitate present, [0015] (d) optionally acidifying the resulting
solution to a pH of about 2.5 to about 4, preferably about 2.9 to
about 3.2, to produce an acidified clear canola protein solution,
and [0016] (e) optionally concentrating the protein solution to
about 5 to about 200 g/L, preferably about 80 to about 150 g/L and
optionally diafiltering with RO water or with saline of
approximately equal pH and conductivity to that of the protein
solution, [0017] (f) optionally subjecting the clear concentrated
canola protein solution to a colour removal step, and [0018] (g)
optionally drying the concentrated canola protein solution.
[0019] The canola protein isolate provided herein is soluble in an
acidic aqueous environment and is a novel product. Accordingly, in
another aspect of the invention, there is provided a canola protein
isolate having a protein content of at least about 90 wt %
(N.times.6.25) d.b. and which consists predominantly of the 7S
canola protein and which is soluble and heat stable in an acidic
aqueous environment. The acidic aqueous environment may be a
beverage having a pH of about 2.5 to about 5. The canola protein
isolate may have a protein content of at least about 100 wt %
(N.times.6.25) d.b.
[0020] The canola protein isolate produced according to the process
herein may be used in conventional applications of protein
isolates, such as, protein fortification of processed foods and
beverages, emulsification of oils, body formers in baked goods and
foaming agents in products which entrap gases. In addition, the
canola 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 canola
protein isolate may be used as nutritional supplements. Other uses
of the canola protein isolate are in pets foods, animal feed and in
industrial and cosmetic applications and in personal care
products.
[0021] The canola protein micellar mass may be prepared by the
procedures described in above-mentioned U.S. patent applications
Ser. Nos. 10/137,371, 10/476,230, 10/298,678 and 10/496,071.
General Description of Invention
[0022] The initial step of the process of providing the canola
protein micellar mass involves solubilizing proteinaceous material
from canola oil seed meal. The proteinaceous material recovered
from canola seed meal may be the protein naturally occurring in
canola 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 canola meal may be
any canola meal resulting from the removal of canola oil from
canola oil seed with varying levels of non-denatured protein,
resulting, for example, from hot hexane extraction or cold oil
extrusion methods. The removal of canola oil from canola oil seed
usually is effected as a separate operation from the protein
isolate recovery procedure described herein.
[0023] Protein solubilization is effected most efficiently by using
a food grade salt solution since the presence of the salt enhances
the removal of soluble protein from the oil seed meal. Where the
canola protein isolate is intended for non-food uses,
non-food-grade chemicals may be used. 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
0.05, preferably at least about 0.10, 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.
[0024] 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 0.8, and more preferably a value of about 0.1 to about
0.15.
[0025] In a batch process, the salt solubilization of the protein
is effected at a temperature of from about 5.degree. C. to about
75.degree. C., preferably accompanied by agitation to decrease the
solubilization time, which is usually about 10 to about 60 minutes.
It is preferred to effect the solubilization to extract
substantially as much protein from the oil seed meal as is
practicable, so as to provide an overall high product yield.
[0026] The lower temperature limit of about 5.degree. C. is chosen
since solubilization is impractically slow below this temperature
while the upper preferred temperature limit of about 75.degree. C.
is chosen due to the denaturation temperature of some of the
present proteins.
[0027] In a continuous process, the extraction of the protein from
the canola oil seed meal is carried out in any manner consistent
with effecting a continuous extraction of protein from the canola
oil seed meal. In one embodiment, the canola oil seed meal is
continuously mixed with a food grade 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 as much protein from the
canola oil seed meal as is practicable. The solubilization in the
continuous procedure is effected at temperatures between about
10.degree. C. and about 75.degree. C., preferably between about
15.degree. C. and about 35.degree. C.
[0028] The aqueous food grade salt solution generally has a pH of
about 5 to about 6.8, preferably about 5.3 to about 6.2. The pH of
the salt solution may be adjusted to any desired value within the
range of about 5 to about 6.8 for use in the extraction step by the
use of any convenient acid, usually hydrochloric acid, or alkali,
usually sodium hydroxide, as required.
[0029] 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.
[0030] 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.
[0031] The protein solution resulting from the extraction step
generally has a protein concentration of about 5 to about 40 g/L,
preferably about 10 to about 30 g/L.
[0032] The aqueous salt solution may contain an antioxidant. The
antioxidant may be any convenient antioxidant, such as sodium
sulfite or ascorbic acid. The quantity of antioxidant employed may
vary from about 0.01 to about 1 wt % of the solution, preferably
about 0.05 wt %. The antioxidant serves to inhibit oxidation of
phenolics in the protein solution.
[0033] The aqueous phase resulting from the extraction step then
may be separated from the residual canola meal, in any convenient
manner, such as by employing a decanter centrifuge, followed by
disc centrifugation and/or filtration to remove residual meal. The
separated residual meal may be dried for disposal.
[0034] The colour of the final canola protein isolate can be
improved in terms of light colour and less intense yellow by the
mixing of powdered activated carbon or other pigment adsorbing
agent with the separated aqueous protein solution and subsequently
removing the adsorbent, conveniently by filtration, to provide a
protein solution. Diafiltration also may be used for pigment
removal.
[0035] Such pigment removal step may be carried out under any
convenient conditions, generally at the ambient temperature of the
separated aqueous protein solution, employing any suitable pigment
adsorbing agent. For powdered activated carbon, an amount of about
0.025% to about 5% w/v, preferably about 0.05% to about 2% w/v, is
employed.
[0036] Where the canola seed meal contains significant quantities
of fat, as described in U.S. Pat. Nos. 5,844,086 and 6,005,076,
assigned to the assignee hereof and the disclosures of which are
incorporated herein by reference, then the defatting steps
described therein may be effected on the separated aqueous protein
solution and on the concentrated aqueous protein solution discussed
below. When the colour improvement step is carried out, such step
may be effected after the first defatting step.
[0037] As an alternative to extracting the 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 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 oil seed meal in order
to maintain the protein in solution during the concentration step
described below. When a first fat removal step is carried out, the
salt generally is added after completion of such operations.
[0038] Another alternative procedure is to extract the oil seed
meal with the food grade salt solution at a relatively high pH
value above about 6.8, generally up to about 9.9. The pH of the
food grade salt solution may be adjusted to the desired alkaline
value by the use of any convenient food-grade alkali, such as
aqueous sodium hydroxide solution. Alternatively, the oil seed meal
may be extracted with the salt solution at a relatively low pH
below about pH 5, generally down to about pH 3. 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
decanter centrifugation, followed by disc centrifugation and/or
filtration to remove residual meal. The separated residual meal may
be dried for disposal.
[0039] The aqueous protein solution resulting from the high or low
pH extraction step then is pH adjusted to the range of about 5 to
about 6.8, preferably about 5.3 to about 6.2, as discussed above,
prior to further processing as discussed below. Such pH adjustment
may be effected using any convenient acid, such as hydrochloric
acid, or alkali, such as sodium hydroxide, as appropriate.
[0040] The aqueous protein solution 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 200 g/L, more preferably at least about 250 g/L.
[0041] 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 3,000 to about 100,000
daltons, preferably about 5,000 to about 10,000 daltons, having
regard to differing membrane materials and configurations, and, for
continuous operation, dimensioned to permit the desired degree of
concentration as the aqueous protein solution passes through the
membranes.
[0042] As is well known, ultrafiltration and similar selective
membrane techniques permit low molecular weight species to pass
through the membrane 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.
[0043] The concentrated protein solution then may be subjected to a
diafiltration step using an aqueous salt solution of the same
molarity and pH as the extraction solution. Such diafiltration may
be effected using from about 2 to about 20 volumes of diafiltration
solution, preferably about 5 to about 10 volumes of diafiltration
solution. In the diafiltration operation, further quantities of
contaminants are removed from the aqueous protein solution by
passage through the membrane with the permeate. The diafiltration
operation may be effected until no significant further quantities
of contaminants and visible colour are present in the permeate.
Such diafiltration may be effected using the same membrane as for
the concentration step. However, if desired, the diafiltration step
may be effected using a separate membrane with a different
molecular weight cut-off, such as a membrane having a molecular
weight cut-off in the range of about 3,000 to about 100,000
daltons, preferably about 5,000 to about 10,000 daltons, having
regard to different membrane materials and configuration.
[0044] An antioxidant may be present in the diafiltration medium
during at least part of the diafiltration step. The antioxidant may
be any convenient antioxidant, such as sodium sulfite or ascorbic
acid. The quantity of antioxidant employed in the diafiltration
medium depends on the materials employed and may vary from about
0.01 to about 1 wt %, preferably about 0.05 wt %. The antioxidant
serves to inhibit oxidation of phenolics present in the
concentrated canola protein isolate solution.
[0045] The concentration step and the diafiltration step may be
effected at any convenient temperature, generally about 20.degree.
to about 60.degree. C., preferably about 20 to about 30.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.
[0046] The concentrated and optionally diafiltered 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.
[0047] The concentrated and optionally diafiltered protein solution
may be subject to a colour removal operation as an alternative to
the colour removal operation described above. Powdered activated
carbon may be used herein as well as granulated activated carbon
(GAC). Another material which may be used as a colour adsorbing
agent is polyvinyl pyrrolidone.
[0048] The colour adsorbing agent treatment step may be carried out
under any convenient conditions, generally at the ambient
temperature of the canola protein solution. For powdered activated
carbon, an amount of about 0.025% to about 5% w/v, preferably about
0.05% to about 2% w/v, may be used. Where polyvinylpyrrolidone is
used as the colour adsorbing agent, an amount of about 0.5% to
about 5% w/v, preferably about 2% to about 3% w/v, may be used. The
colour adsorbing agent may be removed from the canola protein
solution by any convenient means, such as by filtration.
[0049] The concentrated and optionally diafiltered protein solution
resulting from the optional colour removal step may be subjected to
pasteurization to reduce the microbial load. Such pasteurization
may be effected under any desired pasteurization conditions.
Generally, the concentrated and optionally diafiltered protein
solution is heated to a temperature of about 550 to about
70.degree. C., preferably about 60.degree. to about 65.degree. C.,
for about 10 to about 15 minutes, preferably about 10 minutes. The
pasteurized concentrated protein solution then may be cooled for
further processing as described below, preferably to a temperature
of about 25.degree. to about 40.degree. C.
[0050] Depending on the temperature employed in the concentration
step and optional diafiltration step and whether or not a
pasteurization step is effected, the concentrated protein solution
may be warmed to a temperature of at least about 20.degree., and up
to about 60.degree. C., preferably about 25.degree. to about
40.degree. C., 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
micelle formation does not occur on dilution by chilled water.
[0051] The concentrated protein solution resulting from the
concentration step, and optional diafiltration step, optional
colour removal step, optional pasteurization 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.
Depending on the proportion of canola protein desired to be
obtained by the micelle route and the proportion from the
supernatant, the degree of dilution of the concentrated protein
solution may be varied. With lower dilution levels, in general, a
greater proportion of the canola protein remains in the aqueous
phase.
[0052] When it is desired to provide the greatest proportion of the
protein by the micelle route, the concentrated protein solution is
diluted by about 5 fold to about 25 fold, preferably by about 10
fold to about 20 fold.
[0053] The chilled water with which the concentrated protein
solution is mixed has a temperature of less than about 15.degree.
C., generally about 1.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.
[0054] 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.
[0055] 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
rate sufficient to achieve the desired degree of dilution of the
concentrated protein solution.
[0056] 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.
[0057] 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.
In lieu of settling by sedimentation, the PMM may be separated
continuously by centrifugation.
[0058] The combination of process parameters of concentrating of
the protein solution to a preferred protein content of at least
about 200 g/L and the use of a dilution factor of about 10 to about
20, result in higher yields, often significantly higher yields, in
terms of recovery of protein in the form of protein micellar mass
from the original meal extract, and much purer isolates in terms of
protein content than achieved using any of the known prior art
protein isolate forming procedures discussed in the aforementioned
U.S. patents.
[0059] By the utilization of a continuous process for the recovery
of canola protein isolate as compared to the batch process, the
initial protein extraction step can be significantly reduced in
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.
[0060] The settled PMM 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 or freeze drying, to a dry form. The dry PMM
has a high protein content, in excess of about 90 wt % protein,
preferably at least about 100 wt % protein (calculated as
N.times.6.25), and is substantially undenatured (as determined by
differential scanning calorimetry). The dry PMM 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
as necessary, which may be below about 1 wt %.
[0061] As described in the aforementioned U.S. patent application
Ser. No. 10/413,371, the PMM consists predominantly of a 7S canola
protein having a protein component composition of about 60 to 98 wt
% of 7S protein, about 1 to about 15 wt % of 12S protein and 0 to
about 25 wt % of 2S protein.
[0062] According to the present invention, the PMM is processed, in
wet or dry form, to provide a clear solution which is either acidic
or of natural pH. The natural pH solution, when dried, produces a
product that can be resolubilized in water at natural pH or can
later be acidified when reconstituted for its intended application
in order to provide a clear acidic solution.
[0063] The PMM is initially solubilized using about 1.5 to about 15
wt %, preferably about 2 to about 3 wt % of a calcium salt on a per
protein basis and sufficient water for an overall protein
concentration of about 5 to about 50 wt %, preferably about 15 to
about 25 wt %. The calcium salt added to the aqueous canola protein
solution may be in any desired form, such as dried powder/flake or
a concentrated aqueous solution thereof The calcium salt
conveniently is calcium chloride, although other calcium salts may
be used.
[0064] After addition of the calcium chloride, the aqueous canola
protein solution is diluted by about 1 to about 20 fold, preferably
about 1 to about 3 fold to reduce the viscosity of the sample.
Deposited calcium phytate present in the sample is removed from the
diluted aqueous canola protein solution, such as by centrifugation
and/or filtration, to yield a clear diluted aqueous canola protein
solution, which may be dried by any convenient procedure, such as
spray drying, to provide a canola protein isolate.
[0065] The pH of the clear diluted aqueous canola protein solution
then is optionally adjusted to a value of about 2.0 to about 4.0,
preferably about 2.9 to about 3.2. The pH adjustment may be
effected in any convenient manner, such as by the addition of
hydrochloric acid. The clear diluted aqueous canola protein
solution remains clear to result in an acidified clear canola
protein solution, which may be dried by any convenient procedure,
such as spray drying, to provide a canola protein isolate.
[0066] The acidified clear canola protein solution or optionally
natural pH solution is optionally concentrated to a concentration
of about 50 to about 200 g/L, preferably about 80 to about 150 g/L,
by using a selective membrane technique, such as described above
for the concentration step during PMM formation.
[0067] The concentrated clear canola protein solution then may be
subjected to a diafiltration step using water, acidified water or
saline at the same pH and same or lower conductivity than the
protein solution. Such diafiltration may be effected using from
about 2 to about 20 volumes of diafiltration solution, preferably
about 5 to about 10 volumes of diafiltration solution. In the
diafiltration operation, further quantities of contaminants are
removed from the aqueous solution by passage through the membrane
with the permeate. The diafiltration operation may be effected
until no significant further quantities of contaminants and visible
colour are present in the permeate. Such diafiltration may be
effected using the same membrane as for the concentration step.
However, if desired, the diafiltration may be effected using a
separate membrane, such as a membrane having a molecular weight
cut-off in the range of about 3,000 to about daltons, preferably
about 5,000 to about 10,000 daltons, having regard to different
membrane materials and configuration.
[0068] An antioxidant may be present in the diafiltration solution
during at least part of the diafiltration step. The antioxidant may
be any convenient antioxidant, such as sodium sulfite or ascorbic
acid. The quantity of antioxidant employed in the diafiltration
medium depends on the materials employed and may vary from about
0.01 to about 1 wt %, preferably about 0.05 wt %. The antioxidant
serves to inhibit oxidation of phenolics present in the
concentrated canola protein isolate solution.
[0069] The resulting clear concentrated canola protein solution may
be subjected to an optional colour removal step, such as that
effected on the concentrated canola protein solution in the
PMM-forming operation, using granulated activated carbon.
[0070] The concentrated optionally decolourized canola protein
solution may be dried by any convenient procedure, such as by spray
drying. The dry canola protein isolate has a high protein content,
in excess of about 90 wt % protein, preferably at least about 100
wt % (N.times.6.25) d.b.
[0071] The canola protein isolate produced herein contains both
albumin and globulin fractions and is soluble in an acidic aqueous
environment, making the isolate ideal for incorporation into
beverages, both carbonated and uncarbonated, to provide protein
fortification thereto. Such beverages have a wide range of acidic
pH values, ranging from about 2.5 to about 5. The canola protein
isolate provided herein may be added to such beverages in any
convenient quantity to provide protein fortification to such
beverages, for example, at least about 5 g of the canola protein
isolate per 12 fluid ounce quantity. The added canola protein
isolate fully dissolves in the beverage and does not impair the
clarity of the beverage, even after thermal processing. The canola
protein isolate may be blended with dried beverage prior to
reconstitution of the beverage by dissolution in water.
EXAMPLES
Example 1
[0072] This Example describes the preparation of a canola protein
micellar mass from canola oil seed meal.
[0073] `a` kg of canola meal was added to `b` L of `c` M NaCl
solution at ambient temperature and agitated for 30 minutes to
provide an aqueous protein solution. The residual canola meal was
removed and the resulting protein solution was partially clarified
by centrifugation to produce `d` L of partially clarified protein
solution having a protein content of `e` % by weight. The partially
clarified protein solution was then filtered to further clarify
resulting in a solution of volume `f` having a protein content of
`g` by weight.
[0074] A `h` L aliquot of the protein extract solution was reduced
to `i` kg by concentration on a polyethersulfone (PES) membrane
having a molecular weight cutoff of `j` daltons. The resulting
concentrated protein solution had a protein content of `k` % by
weight.
[0075] The concentrated solution at `l` .degree. C. was diluted `m`
fold into cold RO water having a temperature `n` .degree. C. A
white cloud formed immediately and was allowed to settle. The upper
diluting water was removed and the precipitated, viscous, sticky
mass (PMM) was recovered by centrifugation in a yield of `o` wt %
of the filtered protein solution. The parameters `a` to `o` are set
forth in the following Table I:
TABLE-US-00001 TABLE I t BW-SD084-E28-08A BW-SA082-G14-08
BW-SD087-G21-08A a 60 20 20 b 600 200 200 c 0.15 0.15 0.15 d 511
160 174 e 1.78 1.56 1.46 f 540 180 181 g 1.51 1.34 1.31 h 540 180
181 i 32.68 8.28 8.28 j 100,000 100,000 100,000 k 18.64 22.29 22.86
l 30 29.8 30 m 1:15 1:15 1:15 n 2.2 1.5 2.4 o 3.4 51.5 30.0
Example 2
[0076] This Example describes the processing of the product from
Example 1 into a canola protein isolate soluble in aqueous acid
media.
[0077] `a` kg of the PMM from batch `b` having a protein content of
approximately `c` wt % was resolubilized in `d` L of `e` M saline
to provide a solution with a protein content of `f` %.
[0078] The conductivity of this solution was then raised to `g` mS
by the addition of CaCl.sub.2 from a concentrated solution prepared
by dissolving 77 wt % flake CaCl.sub.2 in RO water.
[0079] This `h` L of solution was then diluted `i` in `j` L of room
temperature RO water. Upon diluting, no pellet formed but the
solution was quite cloudy. The greenish coloured precipitate was
removed by centrifugation and filtration to produce `k` L of clear
solution having a protein content of `l` wt %.
[0080] The clarified protein solution was then adjusted to pH `m`
with HCl. A PES membrane with a molecular weight cutoff of 10,000
Daltons was used to concentrate the pH 3 adjusted filtrate to
approximately `n` wt % protein in a volume of `o` L.
[0081] A `p` L aliquot of retentate was run through a 300 ml GAC
column to determine if the GAC provided any colour or taste
improvements. The GAC treated material was then spray dried to
provide a dry product with a protein content of `q` %
(N.times.6.25) d.b. The product was given the designation `b`
C307C.
[0082] The remaining `r` L of retentate was spray dried to provide
dry product with a protein content of `s` % (N.times.6.25) d.b. The
product was given the designation `b` C307. The parameters `a` to
`s` are set forth in the following Table II:
TABLE-US-00002 TABLE II b BW-SD084-E28-08A a 3 c 41 d 3 e 0.15 f
17.77 g 22.5 h 6 i 1:10 j 60 k 70 l 1.45 m 3 n 7.5 o 11 p 1 q
105.12 r 10 s 105.58
Example 3
[0083] This Example describes an alternate method of processing the
product from Example 1 into a canola protein isolate soluble in
aqueous acid media.
[0084] `a` kg of PMM from batch `b` was resolubilized with `c` wt %
(on a per protein basis) CaCl.sub.2 and `d` L RO water to make a
`e` kg protein solution having a `f` wt % protein content. The
resolubilized PMM was diluted with `g` volume(s) of room
temperature RO water. A greenish coloured precipitate was removed
by centrifugation. The resulting `h` kg of centrate having a
protein content of `i` wt % was then adjusted to a pH of `j` with
HCL. The acidified clarified protein solution was then passed
through `k` L of granular activated carbon having the same pH and
conductivity as the protein solution at a rate of `l` BV/hr.
[0085] The GAC treated solution having a protein content of `m` and
mass of `n` kg was then spray dried to produce a dry product with a
protein content of `o`% (N.times.6.25) d.b. The product was
designated `b` C307C. The parameters `a` to `o` are set forth in
the following Table III:
TABLE-US-00003 TABLE III a 1.58 b BW-SA082-G14-08A c 2.5 d 2.21 e
3.1 f 21.05 g 1 h 5.8 i 10.02 j 2.90 k 1.5 l 5 m 6.36 n 8.4 o
102.76
Example 4
[0086] This Example describes a method of processing the product
from Example 1 into a natural pH canola protein isolate that can be
used as is or acidified prior to application to produce a clear
solution.
[0087] `a` kg of PMM from batch `b` was resolubilized with `c` wt %
(on a per protein basis) CaCl.sub.2 and `d` L RO water to make a
`e` kg protein solution having a `f` wt % protein content. The
resolubilized PMM was diluted with `g` volume(s) of room
temperature RO water. A greenish coloured precipitate formed and
was removed by centrifugation. The resulting `h` kg of centrate
having a protein content of `i` wt % was then passed through `j` L
of granular activated carbon having the same pH and conductivity as
the protein solution at a rate of `k` BV/hr.
[0088] The GAC treated solution having a protein content of `l` and
mass of `m` kg was then spray dried to produce a dry product with a
protein content of `n` % (N.times.6.25) d.b. The product was
designated `b` C307C. The parameters `a` to `n` are set forth in
the following Table IV:
TABLE-US-00004 TABLE IV a 1.57 b BW-SD087-G21-08A c 2.5 d 1.96 e
3.53 f 18.14 g 1 h 6.7 i 8.63 j 1.7 k 5 l 7.88 m 6.2 n 102.80
SUMMARY OF DISCLOSURE
[0089] In summary of this disclosure, the present invention
provides a novel method for forming a canola protein isolate which
is soluble and transparent and heat stable in an acidic aqueous
environment and soluble in a natural pH aqueous environment from a
canola protein micellar mass. Modifications are possible within the
scope of the invention.
* * * * *