Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVED PROCESS FOR SOLUBILIZING GLUTEN
THAT NORMALLY IS CAPABLE OF ABSORBING
WATER WTTHOUT DISSOLUTION
Background of the Invention
Gluten is recognized to be an edible film-forming material that is derived
from cereal grains. Such gluten commonly consists of a water-insoluble complex
protein fraction that is separated from a cereal grain following grinding.
Gluten
commonly is derived from cereal grains such as wheat or corn by known
techniques and is a commercially available article of commerce that finds a
broad
range of applications in the food .and related industries. The separation of
the
gluten commonly is accomplished by physical means from an aqueous suspension
of the ground grain without the introduction of additives, and the resulting
gluten
product is thus a natural food protein of plant origin. The inherent
cohesiveness
and elasticity of gluten provide integrity to various doughs, and facilitate
protective film formation. Such films can serve to improve the appearance of
food products and to retard aging through the blockage of excessive drying to
thereby extend shelf life with the concomitant maintenance of an attractive
product appearance.
Vital wheat gluten is well known and is approved by the U.S. Food and
Drug Administration as Generally Recognized as Safe (GRAS) under 21 C.F.R.
~ 184.1322 for use as a dough strengthener, formulation aid, nutrient
supplement, processing aid, stabilizer and thickener, surface finishing agent
and
texturizing agent at levels not to exceed current manufacturing practice.
CA 02167662 2000-02-15
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See, for instance, "Wheat Gluten, A Natural Protein for the Future-
Today" that is published and presently available from the International Wheat
Gluten Association, 4510 West 89 Street, Prairie Village, KS, 66207, U.S.A.
Additional representative publications that discuss gluten and its end uses
are identified below,
(1) "Edible Films and Coatings from Wheat and Corn Proteins" by
Aristippos Gennadios and Curtis L. Welter, Food Technology, Pages
63 to 69 (October 1990).
(2) "Uses and Functionality of Vital Wheat Gluten", by Ken M.
Magnuson, Cereal Foods World, Pages 179 to 181 (February 1985).
(3) "Acts as Formulation Aid, Processing Aid, Stabilizer, Thickener, and
Surface-Finishing Agent", by Cal Andres, Food Processing, (May
1984).
(4) "A Comparison of Nonmeat Proteins, Sodium Tripolyphosphate and
Processing Temperature Effects on Physical and Sensory Properties of
Frankfurters", by J.T. Keeton, E.A. Foegeding, and C. Patana-
Anake, Journal of Food Science, Vol. 49, Pages 1462 to 1466
(1984).
(5) "Structure & Tolerance a Look at Gluten's Functionality", by Laurie
Green, Bakers Digest, (May 31, 1985).
(6) "World Food Uses of Vital Wheat Gluten", by J.M. Hesser,
Proceedings of the World Con rg ess: Vegetable Protein Utilization in
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Human Foods and Animal Feedstocks, edited by Thomas H.
Applewhite, American Oil Chemists' Society, Champaign, IL,
U.S.A., Pages 116 to 122 (1988).
(7) "Preparation of Vital Wheat Gluten", by G. Grace, Proceedings of
the Wo~ld Congress: Vegetable Protein Utilization in Human Foods
and Animal Feedstocks, edited by Thomas H. Applewhite, American
Oil Chemists' Society, Champaign, IL, U.S.A., Pages 112 to 115
(1988).
It has been recognized that gluten commonly has the ability to absorb
water without dissolution unless an acid, base, enzyme, or solvent (~,
propylene glycol) is employed. See, for instance, U.S. Patent Nos. 3,351,531
and 3,653,925, "Water and Glycerol .as P(asticizers Affect Mechanical and
Water
Vapor Barrier Properties of an Edible Wheat Gluten Film", by Nathalie Gontard,
Stephane Guilbert, and Jean-Louis Cuq, Journal of Food Science, Vol. 58, Pages
206 to 211 (1993), and "Improvement of the Functional Properties of Insoluble
Gluten by Pronase Digestion Followed by Dextran Coagulation", by Akio Kato,
J. Asric. Food Chem., Vol. 39, Pages 1053 to 1056 (1991). Representative
acids and bases that have been suggested to accomplish the dissolution of
gluten
in water include ammonium hydroxide (ammonia), acetic acid, adipic acid,
ascorbic acid, aspartic acid, citric acid, lactic acid, succinic acid,
tartaric acid,
etc. The requirement to introduce such acids and bases in order to solubilize
gluten is inconvenient and may introduce an undesirable component into the
final
product unless a significant effort is made to remove the same. For instance,
such solubilizing agents may be flashed off to at least some degree during
drying. However, this can lead to further complications, such as the pollution
of
the atmosphere, and the possible exposure of workers in the area to a harmful
environment. Accordingly, a need has remained in the prior art for an improved
technique to solubilize gluten.
It is an object of the invention to provide an improved process to
solubilize gluten in water.
It is an object of the invention to provide an improved process to
solubilize gluten in water that does not require the presence of acids or
bases as
practiced in the prior art to achieve the dissolution of the gluten.
It is an object of the invention to provide an improved process that
facilitates the expeditious dissolution of gluten in water.
It is another object of the invention to provide a process for the
production of a substantially homogeneous aqueous solution of gluten that can
be
utilized to advantage in binding, adhesive, microencapsulation, film-forming,
and/or coating applications.
It is a further object of the invention to provide an improved technique for
the formation of an aqueous solution of gluten suitable for use in the
controlled
uniform introduction of such gluten into association with a variety of food
products where it serves a binding, adhesive, microencapsulation, film-forming
and/or coating function.
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These and other objects and advantages of the claimed invention will be
apparent to those skilled in the relevant art from the following detailed
description and appended claims.
Summary of the Invention
It has been found that an improved process for solubilizing gluten that
normally is capable of absorbing water without dissolution in water ~e.r~.,
vital
wheat gluten or corn gluten) comprises contacting the gluten with agitation
with
water at an elevated temperature having an effective solubilizing
concentration of
pectin (preferably low methoxyl pectin) dissolved therein. The presence of
conventional acids, bases, enzymes, or solvents to facilitate dissolution of
the
gluten as practiced in the prior art is rendered unnecessary.
Description of Preferred Embodiments
The gluten which is solubilized in accordance with the concept of the
present invention is derived from a cereal grain and normally is capable of
absorbing water without dissolution. Representative cereal grains from which
the
gluten can be derived include wheat, and corn. In a preferred embodiment the
gluten is vital wheat gluten. Such vital wheat gluten is commercially
available as
a creamy-tan powder produced from wheat flour by drying freshly washed
gluten. For instance, vital wheat gluten can be obtained from Ogilvie Mills,
Inc., Baker Technology Plaza, 6121 Baker Road, Suite 101, Minnetonka, MN
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55345, U.S.A., under the PROVIM ESP and WHETPRO - 80 trademarks.
Alternatively, corn gluten (zein) is similarly commercially available from
Freeman Industries, Inc., 100 Marbledale Road, Tuckahoe, NY 10707, U.S.A.,
and is amenable for solubilization in accordance with the concept of the
present
invention.
When the gluten is contacted with water in the absence of pH adjustment
as practiced in the prior art, it absorbs water and is essentially insoluble
over
moderate pH ranges. Excess water is repelled and the gluten molecules tend to
associate closely together and to resist dispersion in an aqueous solvent.
In accordance with the concept of the present invention it surprisingly has
been found that gluten can readily be dissolved in water with agitation in the
presence of an effective solubilizing concentration of pectin that is
dissolved in
the aqueous solvent. The pectin component offers the further advantage that it
is
edible and no further effort need be expended for its removal as commonly is
necessary with the acids, bases, enzymes, and solvents utilized to facilitate
gluten
dissolution in the prior art. Any water-soluble pectin may be utilized to
facilitate
the dissolution of gluten when practicing the present invention. The pectin
may
be a low methoxyl pectin having an esterification degree lower than 50
percent,
or a high methoxyl pectin wherein the esterification degree is greater than 50
percent. However, the viscosity of resulting gluten solution commonly will be
influenced by the nature of the specific pectin that is utilized. Also, some
pectins are better able to withstand an increase in viscosity in the presence
of
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other ions (~, calcium ions) as will be apparent to those skilled in the art.
The
low methoxyl pectins are more sensitive to the presence of polyvalent cations
e(-.rg_., Ca++) than high methoxyl pectins and the total soluble solids level
is less
important in determining gelling properties with such pectins. In a preferred
embodiment the pectin is a low methoxyl pectin that optionally may be
amidated.
A particularly preferred pectin suitable for use in accordance with the
present invention is a low methoxyl amidated pectin extracted from the rind of
citrus fruits that is commercially available from TIC Gums, 4609 R.ichlynn
Drive, Belcamp, MD 21017, U.S.A., under the TIC PRETESTED PECTIN
LM 35 trademark. A preferred high methoxyl pectin is available from the same
source under the TIC PRETESTED PECTIN HM SLOW trademark that offers
considerably slower gelation than the low methoxyl pectin. In this product
some
of the carboxyl groups are esterified with methyl alcohol, while the remaining
carboxylic units exist in the free acid form or as an ammonium salt. The
pectin
choice is influenced by the speed of gelation that is desired in the
contemplated
end use. Sugar sources optionally can be included with the pectin so as to
modify the speed of gelation and the resulting viscosity as will be apparent
to
those skilled in the relevant technology.
When accomplishing the dissolution of gluten in water in accordance with
the concept of the present invention, one need only contact the gluten with
agitation with water at an elevated temperature having an effective
concentration
of pectin dissolved therein. Such agitation can be accomplished by any
_g_
convenient means such as the use of a high shear mixer, homogenizes, etc. The
aqueous solvent conveniently can be provided at an elevated temperature of at
least approximately 40°C. at the time of the dissolution e.~., at a
temperature of
approximately 40 to 60°C. in preferred embodiments).
In accordance with the concept of the present invention, the pectin
commonly is provided in the water in an effective solubilizing concentration
of
approximately 1 to 10 percent by weight of the total solution, and preferably
in a
concentration of approximately 1 to 3 percent by weight of the total solution.
The gluten commonly is dissolved in the water in a concentration of
approximately 1 to 26 percent by weight of the total solution, and preferably
in a
concentration of approximately 19 to 22 percent by weight of the total
solution.
The resulting aqueous solution is substantially homogeneous in nature and
is suitable for use in the controlled uniform introduction of gluten into
association
with a variety of products. Once the solution of the gluten is applied, a
portion
of the aqueous component optionally can be simply removed by volatilization in
order to leave behind a hydrated gluten component that exhibits highly
attractive
binding, adhesive, microencapsulation, film-forming, and/or coating
properties.
For instance, edible protective films can be formed on the surfaces of food
products such as meats, fruits, etc., by spraying or other application
techniques
in order to retard the loss of moisture and to thereby enhance the overall
appearance of the product that is being offered to the consumer. The resulting
solution alternatively may be utilized to introduce the gluten into food
products,
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such as doughs for breads, tortillas, pizzas, and pastas; sausages; breakfast
cereals; nutritional snacks; protein fortified beverages; pet foods, etc.
There are
further non-food applications in cosmetics, pharmaceutical tablet formations,
wallpaper adhesives, etc. Additionally, the resulting solution offers the
potential
for forming a product via the spray drying of the dissolved gluten in
conjunction
with other components where it serves the function of a binding agent and/or
as a
nutritional supplement. For instance, the resulting solution also can be used
in
the microencapsulation of water-soluble or fat-soluble oils or vitamins e(-
._~.,
vitamin A) or other ingredients via spray drying.
The following Examples are presented as specific illustrations of the
invention. It should be understood, however, that the invention is not limited
to
the specific details set forth in the Examples that follow.
EXAMPLE I
Initially 2 grams of low methoxyl amidated pectin commercially available
from TIC Gums, Inc. under the TIC PRETESTED PECTIN LM 35 trademark
are dissolved with stirring in 160 grams of water provided at 40°C. The
pectin
solution is placed in a high shear mixer and agitation is commenced. To the
pectin solution next is gradually added 40 grams of vital wheat gluten
commercially available from Ogilvie Mills, Inc. under the WHETPRO-80
trademark while maintaining the temperature between 40 and 50°C. A
substantially homogeneous solution results within approximately 15 minutes
that
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contains approximately 20 percent by weight of the vital wheat gluten, and
approximately 1 percent by weight of the low methoxyl amidated pectin based
upon the total weight of the solution.
The resulting vital wheat gluten solution is well suited for forming a
protective film upon a food product following the volatilization of a
substantial
portion of the aqueous component.
EXAMPLE II
Example I is repeated with the exception that high methoxyl pectin
available from TIC Gums, Inc. under the TIC PRETESTED PECTIN HM
SLOW trademark is substituted for the low methoxyl amidated pectin.
Substantially the same dissolution results are achieved.
EXAMPLE III
Example I is repeated with the exception that zein corn gluten is
substituted for the vital wheat gluten component. The corn gluten is
commercially available as zein from Freeman Industries, Inc. Substantially the
same dissolution results are achieved.
Although the invention has been described with preferred embodiments, it
is to be understood that variations and modifications may be resorted to as
will
be apparent to those skilled in the art. Such variations and modifications are
to
be considered within the purview and scope of the claims appended hereto.
