Wheat Gluten in Food and Non-Food Systems

WHEAT GLUTEN
Research
Department
r TECHNICAL BULLETIN
Editor: Gur Ranhotra
I Volume XVI, Issue 6 I June, 1994
WHEAT GLUTEN IN FOOD AND NON-FOOD
SYSTEMS
Clodualdo C. Maningat, Ph.D., Sukh Bassi, Ph.D.
Midwest Grain Products, Inc.
Atchison, KS 66002
and
J.M. Hesser
International Wheat Gluten Association
Prairie Village, KS 66207
INTRODUCTION formance in a variety of products.
Wheat gluten (WG) is the natural water-insoluble pro- The uses of WG are wide-ranging and, during the last
tein portion of wheat endosperm which, during wet decade, its utilization has intensified. This bulletin
processing of wheat flour, is separated in the form of a reviews the current, and possible future, uses of WG in
protein-lipid-starch complex. Commercial WG has a food and non-food areas.
mean composition of 72.5% protein (77.5% on dry
basis), 5.7% total fat, 6.4% moisture and 0.7% ash;
GLUTEN USAGE WORLDWIDE
carbohydrates, mainly starches, are the other major Although the uses of WG can vary from country to
component. The major protein fractions of WG consist country, baking represents the predominant usage of
of gliadin and glutenin which differ in their solubility WG, accounting for 63% of total usage worldwide (Figproperties
and molecular weight. Wheat gliadins consist ure 1). In the European Economic Community, flour
of about 50 different single-chained proteins with mole- fortification ranks close second to baking usage with pet
cular weights of 30,000-100,000 daltons (1). When iso- food application ranking third. The second leading use
lated, gliadins are very sticky, which apparently is re- of WG worldwide and in North America and Australia is
sponsible for the cohesion property of WG. By contrast, in pet foods. Baking, imitation meats/fish, and procglutenin
proteins are multi-chained, polymerized by di- essed foods are the major uses of WG in Japan. In
sulfide bonds, and larger in size with molecular weight Japan, WG is also used for the preparation of bread
of about 3,000,OOO daltons. Upon isolation, glutenins known as “Fu” bread, for the production of monosodiexhibit
resiliency but neither cohesion nor extensibility um glutamate as a seasoning agent, and for the preparand,
therefore, appear to give WG its elastic properties. ation of gluten hydrolyzate for use as an extender for
Wheat gluten is unique among cereal and other plant
proteins because of its capacity to form a cohesive and
viscoelastic mass suitable for breadmaking. The viscoelasticity
appears to be because the gluten proteins are
water compatible and, thus, will swell and interact (1).
As water is taken up by WG, it goes through a glass
transition where it changes from a hard glassy material
to one that is rubbery and elastic. WG is also unique in
its ability to impart wheat flour doughs the property to
retain leavening gases. Other unique properties of WG,
as summarized by Bushuk and McRitchie (2), are: appropriate
balance in the content of gliadin and glutenin,
unusually high content of the amino acid glutamine,
and extreme polydispersity of its molecular weight.
These unique properties define gluten’s superior per-
soy sauce called “Sho-yu” (3). WG also plays an important
role in the vegetarian food for the 309 million Buddhists
worldwide and the 100 million Chinese Buddhists
in which Chinese-style meat analogs have been made
from WG by hand or simple extrusion (4).
COMMERCIAL PRODUCTION
OF WHEAT GLUTEN
There are several processes for industrial production
of WG, and they are named after the company or the
person who developed or patented the process (5).
These processes include: Martin, Batter, Hydrocyclone,
Pillsbury Hydromilling, Raisio/Alfa-Laval, Modified
“Fesca”, Alkali, and Far-Mar-Co. Differences exist
among these processes in terms of type of raw material

Fortification
Animal Feeds
Baking
Processed
Foods
Imitation
MeaWFish
25%
20%
EUROPEAN ECONOMIC
COMMUNITY
Pet Foods 8%
Flour
Fortification
14 % Meats
JAPAN
Cereals 2%
Baking
63%
WORLDWIDE Pet Foods 5.%
Pet Fowls
Others
5.w
FlOW
Fortification
11%
Seafood
Analogs
uaculture
Feeds
Cereals 21%
1%
1.2%
Baking
67.5%
NORTH AMERICA
AUSTRALIA
Figure 1. Food and non-food
uses of wheat gluten worldwide.
(whole wheat vs. flour, hard wheat vs. soft wheat, etc.), factors involved in the production of vital WG are the
dispersion procedure (water vs. chemical), consistency yield of WG, water balance, pH of flour slurry, the cost
of wheat flour/water mixture (dough vs. batter), and of a system from a capital standpoint, and the operating
equipment for starch and gluten separation (centrifuge
vs. shaker screen vs. hydrocyclone vs. agitator/ribbon
blender).
costs of the system.
Martin Process
The Martin, Batter, and Hydrocyclone processes are Historically, the Martin process, developed in Paris in
regarded as the most popular manufacturing methods 1835, was among the earliest and most successful proc-
(discussed later) for WG production. The choice of a ess for the recovery of vital WG. A flow diagram of the
process to produce vital WG is dependent on a number generalized Martin process is shown in Figure 2, but varof
different factors. In order to produce WG, it is neces- iations of this process are wideiy practiced. The Martin
sary to have three things: (a) a good source of raw ma- process utilized wheat flour as the starting raw material
terial flour, (b) a way to process wheat starch that is a co- and water was added in a mixer to form a dough. The
product in a ratio of up to 6 (starch) to 1 (gluten), and dough was allowed to develop so that it was thoroughly
(c) a method of handling the effluent water from the hydrated. It then would undergo an extraction step
gluten and starch manufacturing process. In cases where more water was added to begin the separation
where sub-quality flour is used, the use of the enzymes process between the gluten and the starch. The dough
pentosanases and cellulases is recommended to im- washing step is designed to release the starch without
prove gluten yield and starch recovery. Other important dispersing or breaking up the gluten into small pieces.
Page 2

COMPOSITION
TABLE I
OF DRIED WHEAT GLUTEN
Component
Wheat Gluten
Flash
Dried
Spray
Dried
Major Components, %
Moisture
Protein (N x 5.7) 69.0?$.28 71.9:+&o)”
Fat 1.2
Fiber $‘Z 0.6
Ash l:o 1.0
Carbohydrates 19.4 19.9
Energy, Calories/100 g 370 378
Figure 2. Flow diagram of a typical Martin process for
manufacture of wheat gluten and starch (From reference
5).
Sufficient water is used to wash the starch from the
dough while it is kneaded or rolled; devices such as ribbon
blenders, rotating drums, twin screw troughs, and
agitator vessels have been designed for this purpose.
The wet gluten would then be mechanically separated
from the starch in rotating or vibratory screens to
achieve a gluten with a protein content of 75% (dry basis).
The major drawback to this system was the excessive
use of water, as much as 10 to 1, which complicates
starch recovery and presents a significant effluent problem
which has to be addressed. Modifications of the
process have been utilized in the industry for years.
Batter Process
The batter process was invented in 1944. In this process,
the batter is prepared by mixing flour and water to
yield suspended curds of gluten from which the starch
has been washed out. The curds are recovered on a gyrating
screen and the starch milk passes through. The
starch is refined through a series of screens, sieves and
centrifuges, and dried as in the Martin process.
Hydrocyclone Process
Recently, KSH Company of Holland has described a,
hydrocyclone process for producing starch and gluten
from wheat flour. A batter formed with recycled wash
water and flour is introduced directly into a series of hydrocyclones.
The “A” starch is washed out directly with
counter-current fresh water. Because of the intense fluid
shear in the hydrocyclones, the gluten agglomerates into
small curds rather than large lumps. The gluten curds
can be washed and separated on a rotating washer
screen. The main advantage of this process is its low
usage of water. Older plants, based on the Martin or the
Batter process, are being retrofitted with hydrocyclones
Minerals, mg/lOO g
Calcium 142 166
Phosphorus 260 280
Iron 5.2 5.7
Sodium 29 106
Potassium 100 68
aOn dry basis.
to lower operating costs and almost eliminate effluent
waste.
WHEAT GLUTEN PRODUCTS
Vital Wheat Gluten
WG available in the market place is predominantly
vital WG which has been dried in a flash drier. During
the manufacturing process, wet gluten is extruded into
small pellets and injected into a ring or flash drier. There
it is to be coated by recycling dry gluten in the disintegrator
mill and subsequently dried by hot air stream.
This drying step subjects WG to a minimum of heat denaturation
and preserves the original vital-viscoelastic
and cohesive-properties of wet gluten useful in baking
and pet food applications. Table I lists the composition
of flash-dried (and spray-dried) WG.
WG exhibits good solubility in both acidic and alkaline
pH. This property of gluten makes it suitable for dispersion
in aqueous ammonia or acetic acid solution at
lo-128 solids where the dispersion can be atomized inside
the hot air chamber of a spray-drier. WG dispersed
in O.OlN acetic acid at 12% solids and spray dried has
been reported to retain its baking properties. Carbon dioxide
can also be used to disperse WG to a liquid consistency
suitable for pumping and spraying into a drying
chamber. Popular applications of commercial ammoniadispersed
spray-dried WG (Table I) are as a protein
source in nursing pig diets and as a binder in floating
and sinking aquaculture feeds. By varying the drying
procedure, other forms of WG can be produced. Aside
Page 3

from flash and spray drying, other methods {not presently
commercially employed) of drying WG are: vacuum
drying, drum drying, and freeze drying. Drum drying
procedures include dispersing WG in dilute acetic
acid (pH, 4.3~5.1), carbon dioxide, and ethanol followed
by drying in a heated drum at atmospheric pressure
and at a temperature of 260OF.
Other WG products are available in modified forms or
as a complex with other compounds. Activated Gluten@
is a functiona baking ingredient produced by codrying
a complex of partially enzymaticalIy hydrolyzed
soy lecithin and wet gluten (Kyowa Hakko Kogyo brochure).
This product has dough s~engthening, crumb
softening, and anti-staling effects in bakery products.
Enhancedn Gluten is a mixture of vital WG, a type of
diacetyl tartaric acid ester surfactant, and a protected
form of ascorbic acid (Atochem Company brochure).
When added at at level of 1% for every 2.5% fiber, EnhancedR
Gluten strengthens the structure of bread
ai~owing it to carry higher levels of fiber without deleterious
effect to grain or loaf volume. A physically modified
WG (Texturized Wheat Protein) produced by extrusion
cooking is currently gaining acceptance in pet food
and vegetarian diets,
In 1972, a process was patented for producing an agglomerated
WG which, unlike powdered WG, can be
readily wetted out and dispersed in water to form a relatively
stable dispersion. Another gluten product with improved
dispersibility in water has been prepared by mixing
emulsifiers at a level of 15-30% with hydrated WG
and then dying the mix~re to form an emulsified gluten.
Solubiltzed Wheat Gluten
Soiub~l~zation of WG proteins can be achieved by
treatment with chaotropic agents, alteration of amide
groups by chemical modification, removal of amide
groups (deamidation) , or by depolymerization of gluten
by enzymatic methods.
Chemical Solubilization of Gluten: A large
number of solvents are known to solubilize or disperse
gluten. These include: 1M urea, 0.005M lactic acid,
O.lM acetic acid + 3M urea-t O.OlM cetyl trimethylammonium
bromide, 70% aqueous 2chloroethanol, 70%
ethanol, 0.025M borate buffer, 0.025M borate buffer
c 0.5% sodium dodecyl sulfate, 0.1% sodium stearate,
50% propanol + 25 milIimo~ar dith~oerythrito1,
0.05M acetic acid and 0.2M sodium hydroxide.
Deamidation of Gluten: Ninety percent of giutamic
acid (40% of the total amino acids in WG) in WG is
present as glutamine which can be deamidated by hydrolysis
to the corresponding carboxytic acid; ionic carboxyfic
groups increase protein so~ubili~. Deamidated
WG possesses good dispersibility which makes it suitable
for fortifying foods or for foam stabilization and fat
dispersion in fruit-flavored beverages. Other uses include
meat pastes, sausages, coffee whiteners, and milk
puddings. Deamidation of WG can be accomplished in
acid, alkali, or enzyme systems, In acid or alkali systems,
the proteins which have been solubilized require
neutralization before final isolation. This step results in
the formation of salts which may be removed by dialysis
or ultrace~~ifuga~on or by precipitation of protein at
isoelectric point followed by centrifugation. Alternative-
Iy, the formation of salts can be avoided by using acidic
or basic proteins in the neu~alization step. Deamidation,
even a mild one, may produce an unpleasant
soapy flavor. Using defatted WG may overcome this
problem, but other problems arise.
As mentioned earlier, deamidation of WG leads to an
increase in free carboxyl groups and net negative
charge. Deamidation causes a gradual decrease in the
size of gliadin-like proteins and corresponding increase
in low molecular weight fractions. Deamidation also
causes conformational changes in gluten proteins and
exposure of buried hydrophobic groups resulting in a
dramatic increase in surface hydrophobicity. No benefits
in baking were observed when deamidated WG was
added at l-4% level.
Enzymatic Sol~bil~zat~on of Gluten: Molecular
properties of proteins contribute to their functionality as
food in~edients, Some proteins, however, are sometimes
denatured during extraction or processing and,
therefore, have limited functional properties. The most
impo~ant functional property of a protein is soiubili~
since a protein generally has to be in solution to exert its
other desirable effects. Solubilities of protein can be increased
by proteolysis using enzymes such as ficin,
bromelain, papain, trypsin and pronase.
Enzymatic modification involves hydrolysis of peptide
bonds. On a commercial scale, these hydroIytic modifications
include chill proofing of beer, cheese formation
from milk, meat tenderization, soiubil~ation of protein
concentrates, production of protein hydrolyzates, and
limited hydrolysis of protein in bread doughs among
others. Soluble proteins also have a muititude of uses in
foods such as protein fortified beverages, artificial coffee
whiteners, and egg white and dairy product replacers.
Enzymatic protein hydrolysis, using a suitable substrate
like WG, also produces derivatives which exhibit aerating
and whipping properties, Hyfoama 66, an enzymemodified
whipping wheat protein, was reported to whip
much faster and to a greater volume than does egg
albumin or soy isolate.
Enzyme modified WG, when bIended with flour at 1,
1.5 or 2% levels, reduced mixograph mixing time,
farinograph development time, and extensograph peak
time. The reduction in mixing time was ascribed to en-
~matically modified WG interfering with the normal hydrophobic
intera~~on occurring between the large gluten
poiypeptides comprising the dough structure. Test
baking trials produced evidence that l-1.5% level of
en~me-modified WG reduced optimal dough mixing
time and improved slightly loaf volume and crumb
structure. Hyfoama 66, a solubilized wheat protein with
whipping properties, has appii~a~ons in puddings, low
fat instant desserts, water ices, sherbets, frozen confections,
frozen desserts and icings.
Hydrolyzed proteins have been used as flavorings in
Page 4

0 UNNODIRED WNAY-WED OLvrw
Ayw?ND4m
b
0
1 2 3 4 5 6 7 3 9 10 11
Figure 3. Solubility profile of So/u Pro 400 and unmodified
spray dried wheat gluten at different pH levels.
soup mixes, dietary supplements and whipping agents.
This use, however, has been known to develop a bitter
taste, attributed to peptides with hydrophobic character
and with a molecular weight of 1000-5000. Exopeptidases
which split off hydrophobic amino acids are reported
to overcome this bitterness, or move the bitter
point to a higher degree of hydrolysis. For example, up
to 30% degree of hydrolysis of WG can be achieved before
any bitterness can be detected. A new solubilized
wheat protein, Solu Pro 400 (Midwest Grain Products
brochure), has been introduced for use as a flavor enhancer
and as a protein source to replace skimmed milk
in calf milk replacer formula. Solu Pro 400 exhibits excellent
solubility (60~80%) in water. The effect of pH on
solubility of Solu Pro 400 including its nitrogen solubility
as compared to unmodified spray-dried WG is shown in
Figure 3. Whereas spray-dried WG is least soluble at pH
6-8, Solu Pro exhibited excellent solubility at acidic,
neutral and alkaline pHs.
Hydrolyzed wheat proteins have recently gained
popularity in cosmetics as a component of shampoos,
conditioners, creams, lotions, syndets, soap bars, lowirritating
toothpastes and shaving products. The benefits
of hydrolyzed wheat protein are: natural (non-animal),
light color, mild odor, low ash, low molecular weight,
non-irritant to eyes and skin, non-toxic, non-sensitizing,
good solubility, good clarity and good shelf-life stability.
Aqua-Pro II is a commercially available wheat protein
hydrolyzate used in cosmetics. Hydrolyzed wheat proteins
can also be used to give moistness to sponge cake,
bread and Japanese confectionery.
A powerful flavor enhancer derived from WG by hydrolysis
(Amiflex AL-G from Takeda USA) is recommended
for complete replacement of monosodium
glutamate.
PH
d
9
Wheat Protein Isolate
Soy protein isolate, introduced in the 193Os, was
considered to be the last major protein isolate introduced
in the U.S. market. In 1984, three wheat protein
isolates, produced by spray drying, were also introduced
in the U.S. market. Wheatpro 1000 wheat protein
isolate is the insoluble isoelectric form and is comparable
to acid casein and isoelectric soy protein.
Wheatpro 1100 is the soluble sodium form and Wheatpro
1200 is the calcium form. These products are low in
lysine, threonine and valine but rich in phenylalanine
and cystine. Wheatpro proteins are not plagued with
anti-nutritional (e.g., phytic acid and trypsin inhibitor)
and flatulence problems. Wheatpro proteins are hygroscopic
and their bland clean cereal flavor is unobtrusive,
which makes them appealing in flavor applications. In
1988, Melopro 7500 and Melopro 7600 were introduced
in the wheat protein isolate market. They contain
about 95% protein (dry basis) and are recommended as
a partial or total replacer for sodium caseinate and calcium
caseinate, respectively. Applications include bakery
products, breadings and batters, dietary beverages
and meat emulsions.
WPI 100 and LSI are two wheat protein isolates presently
being marketed for use in imitation cheese, bakery
products, whipped toppings, coffee whiteners, meat
emulsions, powdered shortenings, and nutritional beverages.
They contain 94.0-96.046 protein (dry basis),
6.4-7.0% moisture, and 1.1-1.68 ash. Wheatpro and
Melopro protein isolates are presently not commercially
available.
Chemically Modified Wheat Gluten
The functional properties of proteins in foods determine
its overall behavior or performance during manufacturing,
processing, storage and consumption. These
properties are affected by the composition (amino acid
profile) and conformation (structural) of protein and its
interaction with other food constituents. The functional
properties of protein that are of paramount importance
in food systems include solubility, emulsification, water
and oil absorption, gelation or coagulation, foaming,
viscosity, texture, adhesion, cohesion and film formation.
Food applications require proteins with (a) emulsifying
properties which are important in sausage-type
meats and coffee whiteners, (b) hydration and water
binding which are critical in doughs and meat products,
(c) viscosity which is important for beverages like liquid
instant breakfasts, (d) gelation which is required in
marshmallows and cold meat products, (e) foaming or
whipping property which is vital in whipped toppings,
and (f) cohesion which is important in textured products.
Despite the unique properties of WG, it lacks some
important functional characteristics that other cereal,
legume, microbial and animal proteins possess. Thus,
the opening of new markets and the potential diversification
of its uses requires the modification of its physicochemical
properties. The functional properties of a pro-
Page 5

tein can be modified by physical, biological or chemical
means.
Physical modification involves changes in particle size
through application of temperature, removal of volatiles
and moisture, and alteration in form through application
of stress. Biological modification essentially refers to
fermentation processes, while chemical modification refers
to alteration ofjthe physic~hemi~l’, nature of the
protein through pH change, derivatization, en~matic
digestion, ionic manipulation, and complex formation.
Chemical modifications of proteins can be classified
into two divisions: (a) those that are performed intentionally
for specific purposes, and (b) those that can be
described as deteriorative or incidental to the processing,
storage, or aging of protein-containing materials.
Intentional modification involves acylation or related reactions,
alkylation, reduction and oxidation and aromatic
ring substitution. Maillard reaction and lysinoalanine
forma~on are examples of incidental or nonintentional
type of modification.
WG treated with chiorosulfonic acid in pyridine, cold
sulfuric acid or with-phosphoric acid and urea yields
products which absorb 100-300 times their weight in
water and have therapeutic (e.g., post-operative drainage),
cosmetic (e.g., jellies and ointments) and food
(e.g., emulsifying agent in ice cream) uses.
Acylation of WG with succinic or citraconic anhydrides
increases protein solubility at phi 7 and 9 but decreases
at pH 3. Emulsifying capacity, water sorption,
and water holding capacity of wheat protein are improved
by acylation. Succinylation decreases dough
extensibility but does not significantly affect specific loaf
volume. Succinylated and maleylated WG exhibit better
water solubility and slightly better baking performance
compared to acetylated, propionylated, butyrylated,
palmitylated, and phthalylated derivatives of WG.
USE OF GLUTEN IN BAKERY PRODUCTS
As mentioned earlier (Figure l), the predominant use
of WG is in bakery products. In many wholesale and
large retail bakeries, vital WG is the standard ingredient
used in fortifying doughs where many variety bread ingredients
such as bran, cracked wheat, other grains, or
a dietary fiber stress the ability of wheat dough to retain
gas, and to give good oven spring and final loaf volume.
Table II lists bakery products where WG is routinely used.
In general, the functions of WC in food (or non-food)
products are as s~en~hener or enhancer, film former,
binder, texturizer, fat emulsifying agent, processing aid,
stabilizer and thickener, water absorption and retention
agent, thermosetting agent, and as an agent for flavor
and color. WG properties useful in bakery products are:
viscoelastic properties for dough strength, film-forming
ability for gas and moisture retention, thermose~ing
properties for structural rigidity, water absorption and
retention capacity for product softness, and natural
flavor.
During the process of bread dough formation, WG interacts
with water and undergoes glass transition to yield
Product
TABLE II
USE OF VITAL WHEAT GLWTEN
IN BAKERY PRODUCTS
Use Level
(X , Flour Basis)
Pizza Crust l-2
Vienna Bread, Hamburger
Buns, Hard Rolls? Bran
Bread, Brown Soft Roils 2
Wheat Bread with Bran 3
Salad Rolls 4
Multi-Grain Bread 4-5
High Protein Bread, Bagels 5
Whole Meal Fiber-Increased
Bread 6
Whole Wheat Bread from
Flaked Wheat 10
Bread with Low Slice
Weight 30
Source: International Wheat Gluten Ass~iation.
a rubbery and elastic mass. During oven baking, WG retards
the movement of water through the dough which
is the same type of phenomenon responsible for retention
of carbon dioxide in bread dough. Yeast produces
carbon dioxide which saturates the aqueous phase and
excess carbon dioxide diffuses into the unsaturated gaseous
phase. As a result, the viscoelastic dough will flow
or expand to equalize the pressure created by the excess
gas. The highly hydrated gluten matrix that forms the
continuous phase in bread dough has high apparent viscosity
that retards diffusion of leavening gas through the
matrix. During the conversion of dough to bread, heattriggered
changes occur. Disulfide and cross-linked
bonds are formed and the cross-links appear to be responsible
for the setting of the loaf of bread.
USE OF GLUTEN IN PET FOODS
Widely used in pet foods, WG is used to supply protein
and specific amino acids and as a key ingredient in
specific formulations for .its water and fat binding and its
texturizing properties. In 1975, WG was used to develop
a high protein, low cost meat product which has the
appearance of chunks of red meat, especially fatmarbled
meat. WG not only has the property to bind
chunks of meat together, both in the raw and cooked
form, but also acts as a moisture binding agent to absorb
the natural juices of meat. Preparation of a semi-moist
meat product containing heat-coagulated WG suitable
for feeding to domestic pets has also been reported; patent
has also been issued for a simulated meat product
containing 1545% WG which is heat coaguiated to
form fibrous elements. WG has also been incorporated
as a stiffening or texturizing agent in a semi-moist food
product imitating the appearance of marbled meat in-
Page 6

tended for domestic animals.
USE OF GLUTEN IN MEAT PRODUCTS
Because of its binding property and meat-like characteristics,
the use of WG in meat products is widespread.
WG improved the utilization of beef, pork and lamb
meats by a restructuring process which converts less desirable
fresh meat cuts into more palatable steak-type
products. Vital WG has proven as a satisfactory binder
for turkey meat pieces because of its ability to produce
intact loaves with good slicing qualities. In processed
meat products, it is the salt-soluble myofibrillar protein
(myosin) which forms a viscoelastic gel matrix upon solubilization
and heating. WC participates in network formation
of myosin or performs other important functions.
For example, in formulated meat products, WG
at 12.4% is combined with pork fatback (43.1%), hot
water (43.1%), and salt (1.4%) to form emulsified fat
batters which are incorporated into finely cornminuted
sausages like frankfurters.
Simulated ‘meat products have been prepared from
WG (100 parts), defatted soybean meal (10 parts) and
TABLE III
USE LEVEL OF GLUTEN
IN NON-BAKERY PRODUCTS
Product Use Level (5%)
Seafood Analogs
Imitation Cheese
5X3
High-Protein Pasta 1.6
Frankfurters 3.2
Flour Tortillas 2.5
Pet Foods 3-28.2
Aquaculture Diet 5-10
Sausage Analog
Synthetic Cheese 1:2
Extruded/Fibrous Wheat
Gluten Products 20-23
Pharmaceutical Tablets
Paper Coating :-:
Biodegradable Gluten Plastic 60
Meat-Like Sausage 16.7
Meat-Like Balls and
Hamburger 10.6
Cigarette Filter 25
Chewing Gum 50
Edible Films and Coatings 4.9-13.2
Pressure Sensitive Adhesive
Tape 49.5
Crab Analog 2.1
Artificial Caviar l-30
Glue 10
Restructured Beef Steaks 3.6
Meringue 15.1
High-Protein Snack 2.2
Source: Sukh Bassi (Midwest Grain Products, Inc.)
dried egg whites (20 parts} which possessed a fibrous
texture. The product can be blended with natural meats
to make hamburger and sausage. In Japan, a crab meat
was produced by blending WG with a reducing agent
such as cysteine and a foaming agent such as sodium bicarbonate
and then coagulated by heat with stirring in
the presence of water and red dye to fiberize the structure.
Table III lists the use level of WG in various nonbakery-food
and non-food-products.
USE OF GLUTEN IN CALF MILK REPLACERS
Calf milk replacers are artificial milk or milk imitations
which were originally based on at least 60% skimmed
milk powder. In Western Europe and North America, it
is, for various reasons, a common practice to separate
the mother from young as soon as possible. Milk replacers
are, therefore, designed to be fed to weaned
youngs. Calves need a milk replacer that is soluble, or at
least held in a stable non-viscous emulsion, and is
palatable. The objective is to achieve protein quality in
the replacers equivalent to that of casein. Because of
the variability in price of skimmed milk and whey
powders, alternative sources of protein such as soy and
WG are being considered to provide the amino acid requirements
of calves. In particular, a solubilized wheat
protein, Solu-Pro 400, with 60-80% solubili~ in water
is being used commercially as a protein replacer for
skimmed milk in calf milk formula.
FILMS AND COAnNGS FROM GLUTEN
Major industrial markets for proteins in general are as
fiber, films or adhesive compositions. WG does not lend
itself easily to fiber formation but films can be prepared
from a 20% solution of WG in a solvent mixture comprising
60% ethanol, 20% lactic acid and 20% water.
In 1972, a process was patented for producing edible
and odor-free gluten films and coatings which can be
used to wrap, package or encase cheese, sandwiches,
and hors d’oeuvres. In confectionery products, edible
films can serve as oxygen and moisture barriers. Recently,
there has been a revival of interest in WG films
and coatings to extend shelf-life of foods by offering a
selective barrier against the transmission of gases (vapors)
, moisture, and solutes while also offering mechanical
protection.
OTHER NON-FOOD USES OF GLUTEN
WG and its derivatives also have unique and special
applications in adhesive tapes, cigarette filters and pharmaceutical
tablets (Table III). Ethylene oxide-treated
WG, when copofymerized with hydroxyethyl methacrylate,
was shown to exhibit properties important in
pressure-sensitive tapes. WG has also been used as a
component of chewing gums to make it more hygienic,
palatable, nutritional and readily digestible, if accidentally
swallowed. As a component of cigarette filter material,
WG has a high adsorption rate of tar, shows no resistance
to the passage of smoke, and does not interfere
with the taste of cigarette smoke. In pharmaceutical
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tablets, WG can be added as a binder at a level of
2-5%. In the paper coating industry, chemically modified
WG when used as a co-binder (i.e., anchors the
pigments to each other and the raw paper) exhibits
equal or superior properties than modified soy protein
isolate in binding power, wet-picking resistance, whiteness,’
activation of optical brightness, printability and
water retention capacity.
Many other non-food and non-feed uses of WG are
possible. They include detergent formulations, adhesives
for plywood and ceramics, slow-release pharmaceuticals,
medical bandages and gloves, dry cell battery,
textiles and leather, construction materials such as
plaster and concrete, rubber, waste recovery, scale inhibitor
in water, thermal recording materials, fuel cells,
weed control, and fire-retardant polyurethane foam. Indeed,
WG is a multi-functional, annually renewable
protein product.
SUMMARY
Wheat gluten is unique among cereal and other plant
proteins because of its capacity to form a cohesive and
viscoelastic mass suitable for bakery and other food
products as well as for non-food uses. Worldwide, baking
represents the predominant, 63%, usage of wheat
gluten; the second leading use is in pet foods. A variety
of gluten products-vital wheat gluten, solubilized
wheat gluten, protein isolate, complexed gluten, and
hydrolyzed wheat protein-are commercially available
for food and non-food uses.
1.
2.
3.
4.
5.
REFERENCES
HOSENEY, R.C. and ROGERS, D.E. The formation
and properties of urheat flour doughs. Crit. Rev.
Food Sci. and Nutr., 29: 73, 1990.
BUSHUK, W, and McRlTCHlE, F. Wheat proteins:
Aspects of structure that determine breadmaking
quality. In: Protein Quality and the Effects of Processing
(eds. Finley and Phillips). Marcel Dekker,
NY; 1989.
ENDO, S., NOMURA, S., ISHIGAMI, S., and
KARIBE, S. Modified gluten product and bread improuer
composition. U.S. Patent 4, 879, 133, 1989.
HUANG, Y-W, and ANG, C. Y W Vegetarian foods
for Chinese Buddhists. Food Tech., 46:105, 1992.
KNIGHT, J. W, and OLSON, R.M. Wheat starch:
Production, modification and uses. In: Starch Chemistry
and Technology (eds. Whistler, BeMiller and
PaschalI). Academic Press, Inc., Nk: 1984.
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