U.S. patent application number 10/767979 was filed with the patent office on 2005-04-21 for food products containing partially and/or totally denatured milk proteins.
Invention is credited to Onwulata, Charles I..
Application Number | 20050084579 10/767979 |
Document ID | / |
Family ID | 34468070 |
Filed Date | 2005-04-21 |
United States Patent
Application |
20050084579 |
Kind Code |
A1 |
Onwulata, Charles I. |
April 21, 2005 |
Food products containing partially and/or totally denatured milk
proteins
Abstract
The present invention relates to a dietary composition produced
by a process involving extruding a milk containing product (e.g.,
milk, milk concentrate, milk protein concentrate, whey, whey
concentrate, whey protein isolate, whey protein concentrate)
through an extruder at about 50-about 450 rpm and at a temperature
of about 40.degree. to about 120.degree. C. to produce the dietary
fiber composition (which contains partially or totally denatured
milk containing product). The present invention also concerns a
food product containing at least one food ingredient and the
dietary composition described herein; for example the dietary
composition containing partially denatured proteins may be used to
create a fully cooked, totally expanded or puffed ready-to-eat
snack food product (or pellets or half products). In addition, the
present invention relates to a method of making a food product,
involving adding the dietary composition described herein to one or
more food ingredients or adding one or more food ingredients to the
dietary composition described herein. Furthermore, the present
invention concerns a method of increasing fiber in the diet of a
mammal, involving feeding to the mammal the fiber enriched food
product described herein.
Inventors: |
Onwulata, Charles I.;
(Cheltenham, PA) |
Correspondence
Address: |
USDA, ARS, OTT
5601 SUNNYSIDE AVE
RM 4-1159
BELTSVILLE
MD
20705-5131
US
|
Family ID: |
34468070 |
Appl. No.: |
10/767979 |
Filed: |
January 29, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10767979 |
Jan 29, 2004 |
|
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|
10686834 |
Oct 16, 2003 |
|
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Current U.S.
Class: |
426/516 |
Current CPC
Class: |
A23L 33/19 20160801;
A23J 3/265 20130101; A23P 30/30 20160801; Y10S 426/804
20130101 |
Class at
Publication: |
426/516 |
International
Class: |
A23P 001/00 |
Claims
We claim:
1. A dietary composition produced by a process comprising extruding
a protein containing product through an extruder at about 50-about
450 rpm and at a temperature of about 40.degree. to about
120.degree. C. to produce said dietary composition, wherein said
dietary composition contains partially denatured protein containing
product or totally denatured protein containing product or mixtures
thereof.
2. The dietary composition according to claim 1, wherein the
residence time of said protein containing product in said extruder
is about 15-about 90 seconds.
3. The dietary composition according to claim 1, wherein said
protein containing product is selected from the group consisting of
milk, milk concentrate, milk protein concentrate, whey, whey
concentrate, whey protein isolate, whey protein concentrate, and
mixtures thereof.
4. The dietary composition according to claim 1, wherein said
protein containing product is selected from the group consisting of
whey concentrate, whey protein isolate, whey protein concentrate
and mixtures thereof.
5. The dietary composition according to claim 1, wherein said
protein containing product is whey protein concentrate.
6. The dietary composition according to claim 1, wherein said
temperature is about 90.degree. to about 120.degree. C., wherein
said rpm is about 50-about 100 rpm, and wherein said dietary
composition contains totally denatured protein containing
product.
7. The dietary composition according to claim 1, wherein said
temperature is about 40.degree. to about 90.degree. C., wherein
said rpm is about 150-about 250 rpm, and wherein said dietary
composition contains partially denatured protein containing
product.
8. A food product comprising at least one food ingredient and the
dietary composition according to claim 1.
9. The food product according to claim 8, wherein said dietary
composition contains totally denatured protein containing product
and partially denatured protein containing product.
10. The food product according to claim 8, wherein said dietary
composition contains totally denatured protein containing
product.
11. The food product according to claim 8, wherein said dietary
composition contains partially denatured protein containing
product.
12. The food product according to claim 8, wherein said food
product is a puffed or expanded food product and said dietary
composition contains partially denatured milk protein containing
product.
13. The food product according to claim 12, wherein said food
ingredient is selected from the group consisting of corn, wheat,
rice, barley, rye, potato, and mixtures thereof.
14. A method of making a fiber enriched food product, comprising
adding the dietary composition according to claim 6 to one or more
food ingredients or adding one or more food ingredients to the
dietary composition according to claim 6.
13. A method of increasing fiber in the diet of a mammal,
comprising feeding to said mammal the food product according to
claim 10.
14. A method of replacing starch in a food product, said method
comprising substituting the dietary composition according to claim
7 for a portion of the starch.
15. The method according to claim 14, said method comprising
substituting the dietary composition according to claim 7 for
>0-about 60% of the starch.
16. The method according to claim 14, wherein said food product is
a puffed or expanded food product.
17. A food product prepared by the method according to claim
14.
18. The food product according to claim 17, wherein said food
product is a puffed or expanded food product.
19. The food product according to claim 17, wherein said food
product contains >0-about 80% of said dietary composition.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. patent
application Ser. No. 10/686,834, filed 16 Oct. 2003, which is
incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a dietary composition
produced by a process involving extruding a protein containing
product (e.g., milk protein containing product such as milk, milk
concentrate, milk protein concentrate, whey, whey concentrate, whey
protein isolate, whey protein concentrate) through an extruder at
about 50-about 450 rpm and at a temperature of about 40.degree. to
about 120.degree. C. to produce the dietary composition (which
contains partially or totally denatured milk protein containing
product). The present invention also concerns a food product
containing at least one food ingredient and the dietary fiber
composition described herein. In addition, the present invention
relates to a method of making a food product, involving adding the
dietary fiber composition described herein to one or more food
ingredients or adding one or more food ingredients to the dietary
fiber composition described herein. Furthermore, the present
invention concerns a method of increasing fiber in the diet of a
mammal, involving feeding to the mammal the fiber enriched food
product described herein.
[0003] As the reports of the health and nutraceutical benefits of
consuming dietary fibers continue to grow, research is focused on
increasing the amount, content and quality of fibers in human diet.
Consumers as well as nutrition-focused professional organizations
are demanding increased amounts of fiber in processed foods. The
results of recent surveys of the amount of fiber consumed by
Americans reveal that most consume less than 50% of the estimated
desirable daily fiber intake. Current average fiber intake is
estimated at about 12 g/day, but the American Dietetic Association
recommends 20-35 g/day (J. Am. Dietetic Assoc., 93: 1446-1447
(1993)).
[0004] Foods rich in fiber help with the management of a host of
conditions. Associated healthful benefits of increasing fiber
consumption include reduced risk of some types of cancer (including
breast cancer) and coronary heart disease, regulation of blood
glucose and insulin, lowering the concentration of blood lipids,
reduced risk of cardiovascular disease and controlling diabetes,
alleviating constipation, hemorrhoids and diverticulitis (Wolk, A.,
et al., JAMA, 281(21): 1998-2004 (1999); Kritchevsky, D., Cereal
Foods World, 42(2): 81-85 (1977)). Thus it is desirable and
beneficial to increase the amount of fiber in most prepared
foods.
[0005] The Food and Agricultural Organization/World Health
Organization (FAO/WHO), 1995 Codex Alimentarius Commission defines
dietary fiber as, "the edible plant or animal material not
hydrolyzed by the endogenous enzymes of the human digestive tract
as determined by the agreed upon method." Typical fiber sources are
plant-based and include grains, fruits and vegetables; other
less-traditional food fibers include Chitosan, a fat-binding
dietary fiber derived from shellfish, and polymeric components such
as cell-wall proteins and phenolic compounds such as tannin and
cutin.
[0006] Traditionally, the food industry uses native (folded) whey
proteins for their functional and nutritional properties in
formulating different foods. Though new products incorporating whey
proteins, such as sports drinks, are being developed, innovation in
process and product development is still needed (Anon., American
Dairy Products Institute, Bulletin No. 25, p. 17 (2000)).
Fortifying snacks with whey proteins could provide a particularly
attractive outlet for surplus whey proteins; however, this practice
has been limited due to known adverse textural effects when the
whey protein concentrate supplementation is greater than 10% of the
main starch component (Kim, C. H., and J. A. Maga,
Lebensmittel-Wissenchaft und-Technologie, 20: 311-318 (1987)).
[0007] The present invention provides, in one aspect, proteins
(e.g., whey proteins) that are totally denatured and are insoluble
to enzymes and protein cleaving chemicals (e.g., urea). The new
product is indigestible and can therefore serve as a fiber source.
The fiber-like product described in this invention may be from an
animal source (e.g., milk), but its properties are physiologically
similar to plant-source dietary fiber, thus serving as a bulking
agent and being nondigestible to enzymes. Alternate use for this
product include use in biodegradable products and utilization in
ingredients that require low gelling temperatures.
SUMMARY OF THE INVENTION
[0008] The present invention relates to a dietary composition
produced by a process involving extruding a milk protein containing
product (e.g., milk, milk concentrate, milk protein concentrate,
whey, whey concentrate, whey protein isolate, whey protein
concentrate) through an extruder at about 50-about 450 rpm and at a
temperature of about 40.degree. to about 120.degree. C. to produce
the dietary composition (which contains partially or totally
denatured milk protein containing product). The present invention
also concerns a food product containing at least one food
ingredient and the dietary composition described herein. In
addition, the present invention relates to a method of making a
food product, involving adding the dietary composition described
herein to one or more food ingredients or adding one or more food
ingredients to the dietary composition described herein.
Furthermore, the present invention concerns a method of increasing
fiber in the diet of a mammal, involving feeding to the mammal the
fiber enriched food product described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 shows electron micrograms of whey protein isolates
(WPI): (A) scanning microscopy was used to examine dry powder; (B)
the non extruded WPI Paste (40% moisture) was embedded, stained
with uranyl acetate and sections examined by transmission electron
microscopy; (C) extruded (100.degree. C.) WPI (40% moisture)
treated as in (B);
[0010] FIG. 2 shows SDS PAGE of extruded whey isolates: (A) with
2-mercaptoethanol; (B) without 2-mercaptoethanol; the lanes are:
1=100.degree. C.; 2=75.degree. C.; 3=50.degree. C.; 4=35.degree.
C.; 5=Native WPI; 6=laboratory whey;
[0011] FIG. 3 shows transmission electron micrographs of whey
protein isolates (WPI) positively stained with uranyl acetate and
lead citrate: (A) enlargement of denatured whey as in FIG. 1C; (B)
enlargement of a selected protein-dense area of FIG. 1B; (C) Fast
Fourier Transforms of electron density images of native WPI; and
(D) Fast Fourier Transforms of electron density images of denatured
WPI; and
[0012] FIG. 4 shows electron-density mapping corresponding to the
Fourier Transforms (A) for denatured and native WPI, and (B)
inverse reciprocal spacing of electron-density images.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The present invention relates to a dietary composition
containing partially or completely denatured proteins. The dietary
composition is produced by a process wherein the proteins in a
protein containing product (e.g., milk protein containing product
such as milk, milk concentrate, milk protein concentrate, whey,
whey concentrate, preferably whey protein isolate) are partially or
completely denatured. This process involves processing the protein
containing product through an extruder (e.g., single screw
extruder, preferably twin screw extruder) at low shear (generally
about 50-about 450 rpm (e.g., 50-450 rpm), preferably about
50-about 300 rpm (e.g., 50-300 rpm), more preferably about 50-about
200 rpm (e.g., 50-200 rpm), most preferably about 50-about 100 rpm
(e.g., 50-100 rpm)), at a temperature in the extruder of about 40'
to about 120.degree. C. (e.g., 40' to 120.degree. C.). Pressures
may range from about 10 to about 2000 psi (e.g., 10-2000 psi,
preferably about 500 to about 1500 psi (e.g., 500-1500 psi), more
preferably about 800 to about 1200 psi (e.g., 800-1200 psi)), and
torque may range from about 30 to about 70% (e.g., 30-70%,
preferably about 45 to about 55% (e.g., 45-55%)). Residence time of
the protein containing product in the extruder is generally about
15-about 90 seconds (e.g., 15-90 seconds), preferably about
20-about 75 seconds (e.g., 20-75 seconds), and more preferably
about 35-about 60 seconds (e.g., 35-60 seconds). To produce a
dietary composition containing completely denatured proteins, the
temperature generally is about 90.degree. to about 120.degree. C.
(e.g., 90.degree. to 120.degree. C.), more preferably about 950 to
about 120.degree. C. (e.g., 95.degree. to 120.degree. C.), most
preferably about 100.degree. to about 110.degree. C. (e.g., 1000 to
110.degree. C.); the shear is preferably about 50 to about 100 rpm
(e.g., 50-100 rpm). Completely denatured proteins are generally
.gtoreq.95% (e.g., 95%) denatured, preferably .gtoreq.99% (e.g.,
99%) denatured, more preferably about 100% (e.g., 100%) denatured.
To produce a dietary composition containing partially denatured
proteins, the temperature generally is about 40.degree. to about
90.degree. C. (e.g., 40.degree. to 90.degree. C.), more preferably
about 55.degree. to about 80.degree. C. (e.g., 550 to 80.degree.
C.), most preferably about 60.degree. to about 70.degree. C. (e.g.,
60.degree. to 70.degree. C.); the shear is preferably about 150 to
about 250 rpm (e.g., 150-250 rpm). Partially denatured proteins are
generally <95% denatured, preferably <about 90% (e.g.,
<90%) denatured, more preferably about 40-about 80% (e.g.,
40-80%) denatured. Low shear increases the residence time of the
milk containing product in the extruder since residence time is a
function of the rpm of the extruder, the residence time can
increase from 45 to 90 seconds. The process may also utilize other
proteins such as, for example, soy protein, vegetable protein,
animal protein. The dietary composition is a dietary fiber
composition when it contains completely denatured proteins since
completely denatured proteins are indigestible.
[0014] The present invention also concerns a food product
containing at least one food ingredient and the dietary composition
(containing partially or completely denatured proteins or
combinations thereof) described above; the food product is a fiber
enriched food product if it contains at least one food ingredient
and the dietary composition containing completely denatured
proteins. The food ingredient may be any food ingredient. For
example, the food ingredient may be the ingredients for cookies or
muffins such as flour. Furthermore, the food ingredient may be
shelf-stable packaged pre-mixes for preparing food and beverage
compositions, usually requiring the addition of other ingredients
(e.g., eggs, shortening, water or milk) to be supplied and added by
the preparer. Additionally, the food ingredient may be a
ready-to-cook mix (combined food ingredients that require
additional cooking (e.g., baking, frying, micro waving) to form a
ready-to-eat food or beverage product). Generally, the food product
(e.g., fiber enriched) may be any food product such as a drink,
yogurt, or pizza, or a bakery product such as cake, biscuit, pie
crust, cookie, muffin, bread, cereal, doughnut, noodle, brownie,
cracker or snack food. The amount of the dietary composition
contained in the enriched food product may be any amount that does
not adversely affect the food product (for example, the food
product may contain about 1% to about 40% of the dietary
composition, preferably about 5% to about 30%, more preferably
about 5% to about 20%, most preferably about 10% to about 15%).
[0015] The dietary composition containing partially denatured
proteins of the present invention may be used to create a totally
expanded or puffed snack food product (or pellets or half
products), which may be fully cooked or ready-to-eat, that also
contains at least one food ingredient (e.g., any starch source such
as corn, wheat, rice, barley, rye, potato). Currently, unmodified
milk protein containing products (e.g., whey) when added to
expanded products collapse the matrix and do not puff, and thus it
is necessary to limit substituting whey for starch to about 5%.
Surprisingly, the dietary composition containing partially
denatured proteins can replace well over 5% of the starch without
affecting puff characteristics while allowing one to obtain
desirable crunch and crispness notwithstanding the high level of
milk protein containing products contained therein. The dietary
composition containing partially denatured proteins can replace
more than about 35% of the starch without affecting puff
characteristics. Generally, the composition containing partially
denatured proteins can replace >0% to about 60% of the starch
(e.g., >0-60%), preferably >5% to about 60% (e.g.,
>5-60%), more preferably about 10-about 50% (e.g., 10-50%), most
preferably about 20-about 40% (e.g., 20-40%). The totally expanded
or puffed snack food product may contain about 5-about 80% (e.g.,
5-80%) of the dietary composition containing partially denatured
proteins, preferably about 15-about 60% (e.g., 15-60%), more
preferably about 20-about 40% (e.g., 20-40%). The expanded or
puffed food product (or pellets or half products) may be made by
methods known in the art. For example, the dietary composition
containing partially denatured proteins of the present invention
was blended with corn meal at the ratio of 25 g of the dietary
composition containing partially denatured proteins and 75 g corn
meal. The blend of corn meal and the dietary composition containing
partially denatured proteins was extruded in a ZSK30 twin screw
extruder (Krupp, Werner & Pfleiderer Company, Ramsey, N.J.)
consisting of nine heating-barrel sections each individually
controlled; the first six zones were preset at 35.degree.,
35.degree., 50.degree., 50.degree., 75.degree., and 90.degree. C.
respectively, and the last 3 barrel temperatures were set at
100.degree., 110.degree. and 125.degree. C., respectively. The die
plate was fitted with two circular inserts (3.18 mm diameter). Melt
temperatures was recorded at the die. The blend was fed into the
extruder with a series 6300 digital type 35 twin screw volumetric
feeder (K-Tron Corp., Pitman, N.J.) at a constant setting of 800
rpm yielding a feed rate of 128.5 g/min. Water was added at a rate
of 1.3 L/h with an electromagnetic dosing pump (Milton Roy, Acton
Mass.) to bring the moisture content of the feed to approximately
18 g H.sub.2O/100 g product (wet basis). The screw speed of the
extruder was maintained at 300 rpm. The screw elements were
selected to provide high shear at 300 rpm by adding kneading blocks
to the configuration. The process may also utilize other proteins
such as, for example, soy protein, vegetable protein, animal
protein, and other carbohydrate sources such as wheat, barley,
rice, and starch.
[0016] The dietary composition containing completely denatured
proteins of the present invention can be added to baked sweet
wafers to offer another type of protein enrichment to cookies or
snack bars. It may also be possible to utilize the dietary
composition containing completely denatured proteins of the present
invention in meal extenders and meat alternatives, function as
instant thickeners for beverage and dairy applications, and also
finding use as edible films and encapsulating agents. The dietary
composition containing completely denatured proteins of the present
invention may also function as an instant thickening product which
can be used in place of starch and other hydrocolloids; potential
applications include baby food, sports drink and dairy foods such
as sour cream, yogurt and cottage cheese.
[0017] The possibilities for the dietary composition containing
completely denatured proteins of the present invention extend past
the grocery aisle. The dietary composition containing completely
denatured proteins of the present invention may make oxygen, aroma
and oil barrier films at low-to-intermediate relative humidity; may
provide mechanical properties and adequate functionality when used
as coating or encapsulating agents, providing durability when
applied directly on foods or as films when separating layers of
heterogeneous foods, or films formed into pouches for food
ingredients; and may also be used as encapsulating agents.
[0018] Additionally, the present invention also relates to a method
of making a food product involving adding the dietary composition
of the present invention to one or more food ingredients (or vice
versa). For example, in making cookies or muffins, the dietary
composition of the present invention can partially substitute for
flour or be added in addition to flour in the preparation of
cookies or muffins. If cooking (e.g., baking, frying, micro waving)
is required, then normal cooking conditions are utilized.
[0019] Furthermore, the present invention concerns a method of
increasing fiber in the diet of a mammal involving feeding to the
mammal the fiber enriched food product described herein. Generally,
the mammal is a human.
[0020] Denaturation of proteins such as milk containing products
may be measured by methods known in the art, including the
solubility index and the method of Kilara (Kilara, A., J. Dairy
Sci., 67:2734-2744 (1984)) where protein insolubility
(denaturation) was calculated as: (% Total Protein-% Soluble
Protein=% Insoluble (denatured)). Proteins which are partially
denatured will absorb more water than proteins which are totally
denatured. Partially denatured proteins are partly soluble and
partly insoluble depending on the temperature and severity of
shear. Totally denatured proteins are totally insoluble.
[0021] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which the invention belongs. Although
any methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, the preferred methods and materials are now
described.
[0022] The following examples are intended only to further
illustrate the invention and are not intended to limit the scope of
the invention as defined by the claims.
EXAMPLES
[0023] Materials And Methods:
[0024] Whey protein concentrate (ALACEN 834) and lactalbumin
(ALATAL 825) were purchased from New Zealand Milk Products, Inc.
(Santa Rosa, Calif.). Whey Protein Isolate (PROVON 190) was
purchased from Glanbia Ingredients. The compositions were as
follows: WPC80 (whey protein concentrate, 80% protein), moisture
2.8%, protein 83.6%, fat 0.8, ash 3.3%, carbohydrate by difference;
WLAC (whey lactalbumin), moisture 5.5%, protein 89.9%, fat 3.8, ash
0.5%, carbohydrate by difference; Whey Protein Isolate (WPI),
moisture 2.8%, protein 89.6%, fat 25, ash 3.3%, carbohydrate by
difference.
[0025] A ZSK-30 twin screw extruder (Krupp Werner Pfleiderer Co.,
Ramsey, N.J.) with a smooth barrel was used. The extruder had nine
zones, and the effective cooking zones 6, 7, 8, and 9 were set to
the same temperature for each test. To achieve different melt
temperatures the cooking zones were set to the same barrel
temperature of 35, 50, 75, or 100.degree. C. respectively. Zones 1
to 3 were set to 35.degree. C. and zones 4 and 5 were set to
75.degree. C. Melt temperature was monitored behind the die. The
die plate was fitted with two circular inserts of 3.18 mm diameter
each. The screw elements were selected to provide low shear at 300
rpm; the screw profile was described by Onwulata et al. (Onwulata,
C. I., et al., J. Food Sci. Vol., 63(5): 814-818). Feed was
conveyed into the extruder with a series 6300 digital feeder, type
T-35 twin screw volumetric feeder (K-tron Corp., Pitman, N.J.). The
feed screw speed was set at 600 rpm, corresponding to a rate of
3.50 kg/h. Water was added into the extruder at the rate of 1.0 L/h
with an electromagnetic dosing pump (Milton Roy, Acton, Mass.).
Samples were collected after 25 min of processing, freeze-dried
overnight in a VirTis Freeze Mobile 12XL Research Scale Freeze
Dryer (Gardiner, N.Y.), and stored at 4.4.degree. C. until
analyzed. The experiments were performed in triplicate.
[0026] Analysis of variance was used to identify differences in
physical properties at various processing conditions. Duncan's
multiple range test was used for mean separation and correlation
coefficients were calculated. The Statistical Analysis System (SAS)
package was used (SAS Institute Inc, Cary, N.C.) in all cases.
Significance of differences was defined as P.ltoreq.0.05.
[0027] Moisture was determined by the AOAC (Association of Official
Analytical Chemists) Official Method 925.10. Extrudate samples
weighing approximately 1.5 g were dried in a vacuum oven at
100.degree. C. overnight (AOAC, 2000, Official Methods of Analysis,
14th ed., Association of Official Analytical Chemists, Washington,
D.C.).
[0028] Ash was determined by the AOAC Official Method 923.03. Ash
was determined for each sample using 3 g assayed in a Muffler
furnace at 550.degree. C. for 16 h; percent ash was calculated.
[0029] Fat was determined using the AOAC Official Method 30-25. One
gram extrudate sample was placed in an Erlenmeyer flask and 1 ml of
sulfuric acid and 4 ml water was added to the flask. The samples
were mixed gently and after 60 min were transferred to a 60 ml
separatory funnel using 25 ml of dichloromethane: methanol solution
(1:1). Extrudate samples were shaken and allowed to separate for 15
min. The bottom layer was drained into a weighing pan and then
evaporated, and the amount of fat determined (American Association
of Cereal Chemists, 1995, Approved Methods of the American
Association of Cereal Chemists, 9th Edition., The Association, St
Paul, Minn.).
[0030] Protein was determined with 0.2 g extrudate analyzed with
the LECO Protein Analyzer Model FP2000 (LECO Corporation, St.
Joseph, Mich.). Percent protein was calculated with the nitrogen
conversion factor 6.38 for whey protein.
[0031] Gel strength was measured by Bloom determinations with a
TA-XT2 Texture Analyzer (Ju, Z. Y., and A. Kilara, J. Food Sci.
63(2):288-292 (1998)). A 12% WPI solution was made (3.204 g of
ground freeze-dried sample mixed with 26.7 ml deionized water and
3.3 ml 0.03 M CaCl.sub.2), and allowed to sit for 15 min in a
50.times.70 mm cylindrical jar. The sample was heated to 80.degree.
C. for 30 min in a water bath, cooled in an ice bath for 15 min and
then stored overnight at 4.degree. C. The specimen was thawed at
25.degree. C. in 50% relative humidity room. Gel strength was
determined with a TA-XT2 Texture Analyzer running a penetration
test with a 30 mm analytical probe to a depth of 6 mm at the rate
of 1 mm/sec. The weak gels were easily deformed with evidence of
syneresis.
[0032] Protein insolubility was determined with 1.0 g ground
freeze-dried extrudate sample mixed with 90 ml deionized water. The
protein suspension was stirred at 125 rpm at pH 7.0 for 2 h. The
suspension was centrifuged for 20 min and the supernatant was
freeze dried overnight. The LECO Protein Analyzer Model FP2000
(LECO Corporation, St. Joseph, Mich.) was used to analyze the
solids from the supernatant for protein content. Protein
insolubility (denaturation) was calculated (Kilara, A., J. Dairy
Sci., 67:2734-2744 (1984)) as: (% Total Protein-% Soluble Protein=%
Insoluble (denatured)).
[0033] Foam volume and stability of extruded proteins were
determined by heating 2.3 g samples mixed with 35 ml deionized
water to 60.degree. C. for 15 min. The slurry was then whipped for
15 sec in Waring Lab Micronizer FPC70 (Waring Products Division,
New Hartford, Conn.), then transferred to a 100 ml graduated
cylinder where the foam volume was read initially, and then every 5
min for 1 h. Foam stability (foam capacity at specific time) over
the one hour period was calculated.
[0034] Protein Digestibility was determined with 10 ml extrudate
sample dissolved in distilled water, the pH was adjusted to 8.0
with 0.1 N NaOH or HCl. One milliliter of freshly prepared enzyme
stock solution (1.6 mg/ml trypsin, 3.1 mg/ml chymotrypsin, and 1.3
mg/ml aminopeptidase) was added to the protein suspension at
37.degree. C. The pH after 10 min was recorded with a portable pH
meter (IQ Scientific Instruments, Inc. San Diego, Calif.), and a
Tris/HCl buffer containing 2.0% SDS (w/v) and 0.1% mercaptoethanol
(v/v) was added to the protein solution which was immediately
heated to 90.degree. C. to terminate the enzymatic reaction.
Samples were then analyzed by quantitative gel electrophoresis. The
% protein digestibility was calculated by the following equation
(Ju, Z. Y., and A. Kilara, J. Food Sci. 63(2):288-292 (1998)): %
Digestibility=210.46 B 18.10(X); where X is the pH.
[0035] For SDS PAGE assay, samples were vortexed and dissolved in
20 mM TRIS/HCl, 5 mM EDTA, 2.5% SDS with and without 5.0%
2-mercaptoethanol at pH=8.0 then heated in boiling water for 2 min.
Bromophenol blue is added to about 0.1% concentration. The samples
were at 2 mg/ml concentration. Phast gels (Amersham Pharmaica
Biotech, Uppsala, Sweden) were run according to the procedures
given by the manufacturer for SDS 20% homogeneous gels. The 6 lane
(4 ul per lane) sample applicators were used. Protein staining used
the coomassie blue procedure given by the manufacturer (Farrell,
H., E. D., et al., J. Dairy Sci., 81:2974-2984 (1998)).
[0036] For fine structure, transmission electron microscopy (TEM)
was done of thin sections made from epoxyembedded samples.
Millimeter-sized pieces of coarsely ground, freeze-dried segments
of ribbons of the extrudates were immersed in 2.5% glutaraldehyde
in 0.1 M imidazole buffer solution (pH 6.8) and stored in sealed
vials at 4.degree. C. For embedding and thin sectioning, the
segments were washed in imidazole buffer, immersed in 2% osmium
tetroxide in 0.1M imidazole buffer for 2 h at room temperature,
washed in distilled water, and gradually dehydrated in a series of
ethanol solutions and propylene oxide for one hour. Samples were
then infiltrated with a 1:1 mixture of propylene oxide and epoxy
resin mixture overnight and finally embedded in epoxy resin. Thin
sections were cut and stained with 2% uranyl acetate, and lead
citrate solutions. TEM was done in the bright field mode using a
model CM12 electron microscope (FEI/Philips, Hillsboro, Oreg.).
Average spacings of electron density, corresponding to fine
structure in the extrudates, were estimated from the intensity
distribution in Fourier transforms, computed from digital images
made from TEM photographic negatives, recorded at 45,000.times..
Negatives were digitized using a SprintScan 45 film scanner
(Polaroid Corp., Cambridge, Mass.) and square areas of 2.8 megabyte
images (512.times.512 pixels) were transformed after flattening,
adjustment of brightness and contrast and one cycle of a low pass
filter using a 3H 3 pixel kernel in Image Pro Plus software (Media
Cybernetics, Silver Spring, Md.). Line profiles of the radial
distribution of intensity in the Fourier transforms were made, and
reciprocal spacings were calculated based on the location of orders
of peaks in transforms of a line grating with an equivalent spacing
of 22 nm.
[0037] For scanning electron microscopy (SEM), a layer of dry
powder particles was adsorbed onto conductive carbon adhesive tabs
glued to aluminum specimen stubs (Electron Microscopy Sciences, Ft.
Washington, Pa.), and the surface was coated with a thin layer of
gold in a model Scancoat Six sputter coater (BOC Edwards,
Wilmington, Mass.). Images of the powder particles were made with a
model JSM 840A scanning electron microscope (JEOL USA, Peabody,
Mass.) operating in the secondary electron imaging mode and
integrated with a digital image workstation, model Imix1 (Princeton
Gamma-Tech, Princeton, N.J.).
[0038] Results And Discussion:
[0039] Extruding whey proteins at the preset temperature of
75.degree. C. resulted in varying degrees of melt temperatures and
denaturation for the different products (Table 1; % is percent of
denatured proteins). Following extrusion, whey protein concentrate
(WPC80) was the least denatured, and whey lactalbumin (WLAC) and
whey protein isolates (WPI) were significantly (p<0.05) more
denatured. WPI demonstrated the greatest effect, changing from 28
to 94.8% denatured. Therefore, further experiments were conducted
with WPI.
[0040] The effect of extrusion cooking on denatured proteins was
examined by electron microscopy. Changes in the microstructure of
WPI and the ultrastructure of the denatured proteins are presented
in FIG. 1. The microstructure of the dry powders, examined by
scanning electron microscopy, reveal particles ranging from 10 to
50 micrometers in diameter (A). Transmission electron microscopy
(B) shows the release of protein at the edge of powder particles
after brief exposure to water typical of initial mixing in the
extruder; irregular strings and granules, corresponding to
molecular aggregates, ranging from less than 10 nm to over 200 nm
can be seen (B). In contrast, the ultrastructure of
extruder-denatured insoluble whey protein shows a closely-packed
arrangement of electron dense particles, typical of denatured
protein matrix, ranging from approximately 2 to 6 nm in diameter
(C).
[0041] With the addition of shear in the extruder, significant
unfolding (denaturation) occurred at 75.degree. C. WPI extruded at
preset temperatures at or above 50.degree. C. denatured
significantly (p<0.05) with increased preset temperature. The pH
of the suspended protein remained stable as extrusion temperature
increased, but measurable nitrogen (protein) increased as shown in
Table 2. Loss of protein nitrogen might be expected as temperatures
increased above 80.degree. C., but we surprisingly observed no
significant change in protein nitrogen content after drying. Though
the amount of protein denatured increased, with increasing
temperature, denaturation had minimal overall effect on protein
digestibility. So the surprising result is increased protein
denaturation without a significant loss of digestibility due to
extrusion below 90.degree. C.
[0042] The WPI and variously heat treated samples were compared by
SDS-PAGE (FIG. 2). SDS gel of the variously denatured WPI indicated
minimal change in solubility (FIG. 2). SDS gels were initially
developed without reducing reagent so the protein disulfide bonds
are intact. The unreduced samples at 35.degree. C. and 50.degree.
C. show somewhat diminished bands for the higher molecular weight
whey proteins (B). However, at 50.degree. C. and 70.degree. C.
samples were equivalent weight, and fainter than the native whey or
whey proteins produced in the lab on the SDS gel (compare lanes 1
and 2 with 6 in FIG. 2). In this respect, the SDS gels parallel the
solubility data in that increased temperature decreases solubility
in SDS alone, indicating sulfhydryl-disulfide crosslinking. When
the samples were reduced thoroughly and all disulfide bonds
cleaved, all the extruded whey samples at the different
temperatures were similar to each other and to the initial WPI (A).
Thus, extruding whey even at the highest temperatures surprisingly
does not affect the overall protein ratios. The native and extruded
whey still have the same amount of the different proteins (FIG. 2)
and their total nitrogen values were similar (Table 2).
[0043] Physical functional properties of extruded WPI such as gel
strength, foam volume and stability were significantly affected at
and above 75.degree. C., and proportionally at lower preset
temperatures. Greater than 30% moisture was needed to extrude the
whey protein isolates, but the only significant change in moisture
of the extruded products occurred at 100.degree. C. (Table 3).
Partial denaturation at temperatures between 35.degree. and
50.degree. C. significantly increased gel strength, but at
75.degree. C. or higher complete loss of gelling property resulted.
Foam volume remained high up to 50.degree. C., but decreased
significantly (p<0.05) after 75.degree. C. Foam stability
followed the same pattern as volume, being very stable for an hour
below 50.degree. C. However, with the addition of shear from the
extruder, we observed significant loss of volume and stability.
[0044] Denatured whey protein isolate looks quite different from
the non-denatured proteins at the ultrastructural level (FIG. 3).
As sampled, denatured proteins (3A) (WPI extruded at 100.degree.
C.) are densely packed with spacing of 2 to 6 nm, while
non-denatured whey in the paste are loosely packed with a large
spacing 200 to 350 nm (3B). The differences in fine structure of
denatured and native whey protein are illustrated in FIGS. 3 and 4.
In the "native" whey protein (40% slurry), the distribution of
electron density surrounding the hydrating particles in FIG. 1B is
an open network with clear, electron-lucent spaces ranging from
15-40 nm and irregular structures of electron density of similar
dimensions. In contrast, the fine structure in segments where the
whey proteins are completely denatured is limited to close-packed
fine granules around 3-8 nm in diameter (FIG. 3). The corresponding
computed Fourier transforms indicate that images of extrudate
containing native whey proteins consist mainly of low spatial
frequencies indicating structures with average spacings ranging
from 15 to over 40 nm, whereas images of extrudate containing
denatured whey proteins have little intensity at low spatial
frequencies, but high intensity corresponding to high spatial
frequencies, relating to electron density changes ranging from
about 3 nm to less than 10 nm (FIG. 4). The constraint of extruding
whey is keeping the temperature below the point where pyrosis will
occur as evidenced by relatively constant nitrogen content (Table
2). We have seen evidence of fine structures with TEM images at
100.degree. C. in whey isolates.
[0045] We have thus created structured networks in whey proteins
using mild heat and shear, to create reversible denatured whey
proteins. By understanding on a molecular basis the effects of
shear, ways of creating new functionality can be developed. This
will enable development of extrusion parameters that permit
controlled denaturation of whey proteins.
[0046] Extrusion processing denatured whey protein concentrates,
whey lactalbumin (LAC) and whey protein isolate (WPI), but the
greatest amount of denaturing occurred with WPI. Denatured whey
protein isolate retained its native protein value, functionality,
and digestibility when extruded at 50.degree. C. or below; changes
in functionality occurred at 75 and 100.degree. C. Through careful
selection of extrusion conditions, denatured whey proteins with
unique functionality were produced. Denaturation increased with
temperature, but temperatures higher than 100.degree. C. may be
needed to form denatured fibrous products from whey protein
isolates. We show here that extrusion is an effective tool for
denaturing whey proteins to create denatured products.
[0047] Texturization is the process of inducing new form and
function in a polymer (e.g., protein), for example using the
extrusion shearing process described herein to change the globular
non-fibrous conformation of proteins (e.g., whey protein isolates)
into structured fibrous forms that function differently. Extruding
the whey protein isolate is what texturizes it. Without extrusion,
the conformation of whey protein isolates can be changed
(denatured) by heat or pH or pressure, but there is no
texturization. The texturization process described herein involves
heat, shear and pressure, unique conditions that denature and also
texturize proteins such as whey protein isolates, with shear being
the most important factor. Heat alone produces partially or totally
denatured milk proteins. Traditionally, milk proteins are denatured
by moist heat alone; this is the state of the art today and is
accomplished without shear and at temperatures below 75.degree. C.
for 30 to 90 minutes, so texturization does not occur. Texturizing
via the use of extrusion and heat accomplishes partial denaturation
in less than 2 minutes in the temperature range of 50.degree. to
80.degree. C.
[0048] All of the references cited herein are incorporated by
reference in their entirety. Also incorporated by reference in
their entirety are the following references: Aboagye, Y., and
Stanley, D. W., Can-Inst-Food-Sci-Technol-J., 20(3):148-153 (1987);
Batterman-Azcona, S. J., and Hamaker, B. R., Cereal Chem.,
75(2):217-221 (1998); Bhattarcharya, M., and Padmanabhan, M.,1999,
Extrusion Processing: Texture and Rheology, In: "Wiley Encyclopedia
of Food Science and Technology (2nd Edition), Editor, Frederick J.
Francis, John Wiley & Sons, New York, N.Y.; Farrell, H. M.,
Jr., et al., J. Dairy Sci., 85(3):459-471 (2002); Hale, A. B., et
al., J. Food Sci., 67(3):1267-1270 (2002); Harper, J. M., Extrusion
of Foods, Vol. I., 1981, CRC Press, Boca Rotan, Fla.; Harwalkar, V.
R., Michwissenchaft, 34(7):419-422 (1979); Hong, Y., and L. K.
Creamer, Int'l. Dairy J., 12:345-359 (2002); Kim, C. H., and J. A.
Maga, Lebensmittel-Wissenchaft und-Technologie, 20:311-318 (1987);
Kester, J. J., and T. Richardson, J. Dairy Sci., 67(11):2757-2774
(1983); Kollengode, A. N., et al., J. Food Sci., 61(3): 596-599,
603 (1996); Linden, G., and Lorient, D.,1999, Extraction and
Texturisation Processes, In: New Ingredients in Food Processing,
CRC Press, Boca Raton, Fla.; Martinez-Sema, M. D., and Villota, R.,
1992, Reactivity, functionality, and extrusion performance of
native and chemically modified whey proteins, pages 387-414 in Food
Extrusion Science and Technology, J. L. Kokini, C. Ho, and M. V.
Karwe, ed., Marcel Dekker, Inc. New York; Mohammed, Z. H., et al.,
J. Food Sci., 65(2):221-226 (2000); Kester, J. J., and T.
Richardson, J. Dairy Sci., 67(11):2757-2774 (1983); Lin, S., et
al., J. Food Sci., 67(3): 1066-1072 (2000); Phillips, L. G., et
al., J. Food Sci., 55(4):1116-1119 (1990); Singh, R. K., et al., J.
Food Processing and Preservation, 15:285-302 (1991); Taylor, S. M.
and Fryer, P. J., Food Hydrocoll., 8 (1):45-61 (1994); Walstra, P.,
T. J., et al., 1999, pages 189-199 in Dairy Technology: Principles
of Milk Properties and Processes, P. Walstra, T. J. Geurts, A.
Noomen, A. Jellema, and M. A. J. S. van Boekel, ed., Marcel Dekker,
Inc., New York; Yada, R. Y., et al., 1999, Proteins: Denaturation
and Food Processing, In: "Wiley Encyclopedia of Food Science and
Technology (2nd Edition), Editor, Frederick J. Francis, John Wiley
& Sons, New York, N.Y.; U.S. Pat. No. 5,151,283.
[0049] Thus, in view of the above, the present invention concerns
(in part) the following:
[0050] A dietary composition produced by a process comprising (or
consisting essentially of or consisting of) extruding a protein
containing product through an extruder at about 50-about 450 rpm
and at a temperature of about 40.degree. to about 120.degree. C. to
produce said dietary composition, wherein said dietary composition
contains partially denatured protein containing product or totally
denatured protein containing product or mixtures thereof.
[0051] The above dietary composition, wherein the residence time of
said protein containing product in said extruder is about 15-about
90 seconds.
[0052] The above dietary composition, wherein said protein
containing product is selected from the group consisting of milk,
milk concentrate, milk protein concentrate, whey, whey concentrate,
whey protein isolate, whey protein concentrate, and mixtures
thereof; or wherein said protein containing product is selected
from the group consisting of whey concentrate, whey protein
isolate, whey protein concentrate and mixtures thereof; or wherein
said protein containing product is whey protein concentrate.
[0053] The above dietary composition, wherein said temperature is
about 90.degree. to about 120.degree. C., wherein said rpm is about
50-about 100 rpm, and wherein said dietary composition contains
totally denatured protein containing product. A method of making a
fiber enriched food product, comprising (or consisting essentially
of or consisting of) adding the dietary composition (contains
totally denatured protein containing product) to one or more food
ingredients or adding one or more food ingredients to the dietary
composition (contains totally denatured protein containing
product).
[0054] The above dietary composition, wherein said temperature is
about 400 to about 90.degree. C., wherein said rpm is about
150-about 250 rpm, and wherein said dietary composition contains
partially denatured protein containing product. A method of
replacing starch in a food product, said method comprising (or
consisting essentially of or consisting of) substituting the
dietary composition (contains partially denatured protein
containing product) for a portion of the starch. The above, said
method comprising (or consisting essentially of or consisting of)
substituting the dietary composition (contains partially denatured
protein containing product) for >0-about 60% of the starch. The
above method, wherein said food product is a puffed or expanded
food product. A food product prepared by the above method. The
above food product, wherein said food product is a puffed or
expanded food product. The above food product, wherein said food
product contains >0-about 80% of said dietary composition.
[0055] A food product comprising (or consisting essentially of or
consisting of) at least one food ingredient and the above dietary
composition.
[0056] The above food product, wherein said dietary composition
contains totally denatured protein containing product and partially
denatured protein containing product.
[0057] The above food product, wherein said dietary composition
contains totally denatured protein containing product. A method of
increasing fiber in the diet of a mammal, comprising (or consisting
essentially of or consisting of) feeding to said mammal the above
food product wherein said dietary composition contains totally
denatured protein containing product.
[0058] The above food product, wherein said dietary composition
contains partially denatured protein containing product.
[0059] The above food product, wherein said food product is a
puffed or expanded food product and said dietary composition
contains partially denatured milk protein containing product; the
above food product, wherein said food ingredient is selected from
the group consisting of corn, wheat, rice, barley, rye, potato, and
mixtures thereof.
[0060] Other embodiments of the invention will be apparent to those
skilled in the art from a consideration of this specification or
practice of the invention disclosed herein. It is intended that the
specification and examples be considered as exemplary only, with
the true scope and spirit of the invention being indicated by the
following claims.
1TABLE 1 Extrusion melt temperatures of whey proteins.
Post-Extrusion Product Melt Temperature (.degree. C.) Pre-Extrusion
(%) (%) WPC80 70 .+-. 2 40.9 59.9 WLAC 75 .+-. 1 68.7 94.4 WPI 74
.+-. 1 28.0 94.8 WPC80: Whey Protein Concentrate, 80% protein.
WLAC: Whey Lactalbumin. WPI: Whey Protein Isolate: Number reported
is mean of three samples.
[0061]
2TABLE 2 Properties of whey protein isolate (WPI) as function of
extrusion temperature. Insoluble Digestibility Extrusion Temp.
(.degree. C.)* pH Protein** (%) (%) (%) 35 6.7 90.7 28.4 89.6 50
6.8 90.9 33.3 88.2 75 6.9 91.7 77.7 85.7 100 7.0 91.4 87.2 84.5 PSD
0.2 0.7 1.2 0.6 WPI: Whey protein isolates. *Preset barrel
temperature of zones 6, 7, 8, 9. PSD: Pooled Standard Deviation.
**% Protein after drying. Properties of non extruded WPI: pH 6.8,
Protein 88.9%, Insoluble (Denatured) 28.0%, and Digestibility
87.7%.
[0062]
3TABLE 3 Physical properties of whey protein isolate (WPI) as
function of extrusion temperature. Extrusion Temp. Moisture Gel
strength Foam volume Foam (.degree. C.)* (%) (N) (%) stability 35
42.5 114.9 298.1 29.8 50 40.9 145.3 301.9 30.2 75 42.6 2.8 173.3
17.3 100 38.9 # 77.1 7.7 PSD 0.7 1.9 1.2 1.1 WPI: Whey protein
isolates. *Preset barrel temperature of zones 6, 7, 8, 9. PSD:
Pooled Standard Deviation. Properties of non-extruded WPI: Moisture
1.94%, Gel Strength 52.3 (N), Foam volume 288%, and Foam stability
28.7%. #: Value Not Reported.
* * * * *