U.S. patent application number 11/836350 was filed with the patent office on 2007-11-29 for production of enzyme-resistant starch by extrusion.
This patent application is currently assigned to Tate and Lyle Ingredients Americas, Inc.. Invention is credited to Warren L. Nehmer, Geoffrey A.R. Nobes, Walter C. Yackel.
Application Number | 20070275155 11/836350 |
Document ID | / |
Family ID | 36954745 |
Filed Date | 2007-11-29 |
United States Patent
Application |
20070275155 |
Kind Code |
A1 |
Nehmer; Warren L. ; et
al. |
November 29, 2007 |
Production of Enzyme-Resistant Starch by Extrusion
Abstract
A process for producing alpha-amylase resistant starch comprises
extruding a feed starch at a temperature in the range of about
60-220.degree. C., thereby producing a product alpha-amylase
resistant starch. The feed starch can be in the form of an aqueous
slurry or paste that has a dry solids concentration of at least
about 50% by weight. The process optionally can include the
additional step of heating the product starch to a temperature of
at least about 90.degree. C. in the presence of moisture, to
increase further the alpha-amylase resistance of the product.
Inventors: |
Nehmer; Warren L.; (Decatur,
IL) ; Nobes; Geoffrey A.R.; (Decatur, IL) ;
Yackel; Walter C.; (Blaine, WA) |
Correspondence
Address: |
WILLIAMS, MORGAN & AMERSON
10333 RICHMOND, SUITE 1100
HOUSTON
TX
77042
US
|
Assignee: |
Tate and Lyle Ingredients Americas,
Inc.
|
Family ID: |
36954745 |
Appl. No.: |
11/836350 |
Filed: |
August 9, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11144391 |
Jun 3, 2005 |
7276126 |
|
|
11836350 |
Aug 9, 2007 |
|
|
|
Current U.S.
Class: |
426/661 ;
426/465 |
Current CPC
Class: |
A23L 29/219 20160801;
C08B 30/12 20130101; A23L 29/35 20160801 |
Class at
Publication: |
426/661 ;
426/465 |
International
Class: |
A23L 1/05 20060101
A23L001/05 |
Claims
1. A process for producing alpha-amylase resistant starch,
comprising extruding a feed starch at a temperature in the range of
about 60-220.degree. C., thereby producing a product alpha-amylase
resistant starch.
2. The process of claim 1, wherein the feed starch comprises at
least about 50% by weight amylose.
3. The process of claim 1, wherein the feed starch comprises at
least about 65% by weight amylose.
4. The process of claim 1, wherein the feed starch is dry
starch.
5. The process of claim 1, wherein the feed starch is in an aqueous
slurry or paste that has a dry solids concentration of at least
about 50% by weight.
6. (canceled)
7. The process of claim 1, wherein the feed starch is in an aqueous
slurry or paste that has a dry solids concentration of at least
about 60% by weight.
8. The process of claim 1, wherein the feed starch is in an aqueous
slurry or paste that has a dry solids concentration of at least
about 70% by weight.
9. The process of claim 1, wherein the feed starch is from corn,
potato, tapioca, rice, pea, wheat, or a combination of two or more
thereof.
10. The process of claim 1, wherein the feed starch is chemically
modified starch.
11. The process of claim 1, wherein the extrusion is done in a
single-screw for twin-screw extruder.
12. The process of claim 1, wherein the temperature of the feed
starch during extrusion is in the range of about 70-145.degree.
C.
13. The process of claim 1, wherein the product starch has a total
dietary fiber content of at least about 30% by weight.
14. The process of claim 1, further comprising heating the product
starch to a temperature of at least about 90.degree. C. in the
presence of moisture.
15. The process of claim 14, wherein the product starch is heated
to at least about 120.degree. C. at a moisture content of about
15-35% by weight.
16. The process of claim 14, wherein the product starch is heated
to at least about 150.degree. C. at a moisture content of about
15-35% by weight.
17. The process of claim 14, wherein the moisture content of the
product starch during the heating is about 20-25% by weight.
18. The process of claim 12, wherein the total dietary fiber
content of the product starch is increased to at least about 50% by
weight by the heating in the presence of moisture.
19. A starch composition produced by the process of claim 1.
20. The composition of claim 19, wherein the feed starch comprises
at least about 50% by weight amylose.
21. The composition of claim 19, wherein the feed starch is dry
starch.
22. The composition of claim 19, wherein the feed starch is in an
aqueous slurry or paste that has a dry solids concentration of at
least about 50% by weight.
23. (canceled)
24. The composition of claim 19, wherein the extrusion is done in a
single-screw or twin-screw extruder.
25. The composition of claim 19, wherein the temperature of the
feed starch during extrusion is in the range of about
70-145.degree. C.
26. The composition of claim 19, wherein the product starch has a
total dietary fiber content of at least about 30% by weight.
27. (canceled)
Description
BACKGROUND OF THE INVENTION
[0001] Starch comprises two polysaccharides: amylose and
amylopectin. Amylose is a generally linear polymer of glucose units
connected by alpha 1-4 glycosidic linkages. Amylopectin is a
branched polymer in which many of the glucose units are connected
by alpha 1-4 glycosidic linkages, but some are connected by alpha
1-6 glycosidic linkages.
[0002] Alpha-amylase is an enzyme that is present in the human body
and which hydrolyzes alpha 1-4 linkages in starch, thus leading to
digestion of the starch. In certain situations it is desirable to
produce starch that resists hydrolysis by alpha-amylase, for
example to decrease the caloric content of the starch, or to
increase its dietary fiber content. However, attempts to produce
such starch in the past have suffered from one or more problems,
such as process complexity and expense.
[0003] There is a need for improved processes for making starches
that are resistant to alpha-amylase.
SUMMARY OF THE INVENTION
[0004] One embodiment of the invention is a process for producing
alpha-amylase resistant starch. The process comprises extruding a
feed starch at a temperature in the range of about 60-220.degree.
C., thereby producing a product starch that is resistant to
alpha-amylase.
[0005] In some embodiments of the process, the feed starch is a
high amylose starch, for example one that comprises at least about
50% by weight amylose, or in some cases at least about 65% by
weight amylose. Other starches can be used in the process as well.
Examples of suitable starch sources include corn, potato, tapioca,
rice, pea, wheat, or a combination of two or more thereof.
[0006] In some embodiments, the feed starch is dry starch, and
water or an aqueous composition can be added to the extruder to
form a slurry or paste therein. In other embodiments, the feed
starch is in an aqueous slurry or paste that has a dry solids
concentration of at least about 50% by weight, or in some cases, at
least about 60% or 70% by weight.
[0007] Some embodiments of the process include the additional step
of heating the product starch to a temperature of at least about
90.degree. C. in the presence of moisture. In certain embodiments
of the process, this heat-moisture treatment step can be performed
at a temperature of at least about 120.degree. C., or in some cases
at least about 150.degree. C., with a moisture content of about
15-35% by weight. In certain embodiments, the moisture content of
the product starch during this step is about 20-25% by weight. In
some embodiments of the process, the total dietary fiber content of
the product starch is increased to at least about 50% by weight by
the heating in the presence of moisture.
DESCRIPTION OF SPECIFIC EMBODIMENTS
[0008] One embodiment of the present invention is a process in
which alpha-amylase resistant starch is produced by extruding a
feed starch at a temperature in the range of about 60-220.degree.
C. The term "alpha-amylase resistant starch" is used in this patent
to refer to a starch that has a component that is resistant to
alpha-amylase. It should be understood that the starch can also
have components that are not alpha-amylase resistant.
[0009] The feed starch can be a high amylose starch, for example
one that comprises at least about 50% by weight amylose, or at
least about 65% by weight amylose. Such high amylose starches are
commercially available. Alternatively, starches that are not as
high in amylose can be used.
[0010] The starch used in the process can come from a variety of
sources, including starches obtained from dent corn, high amylose
ae genetic corn (ae is the name of a genetic mutation commonly
known by corn breeders and is short for "amylose extender"),
potato, tapioca, rice, pea, and wheat varieties, as well as
purified amylose from these starches, and alpha-1,4 glucans
produced according to international patent application WO 00/14249,
which is incorporated herein by reference. Combinations of two more
types of starches can also be used in the present invention.
[0011] Chemically modified starches, such as hydroxypropyl
starches, starch adipates, acetylated starches, and phosphorylated
starches, can also be used in the present invention to produce
resistant starch. For example, suitable chemically modified
starches include, but are not limited to, crosslinked starches,
acetylated and organically esterified starches, hydroxypropylated
starches, phosphorylated and inorganically esterified starches,
cationic, anionic, nonionic, and zwitterionic starches, and
succinate and substituted succinate derivatives of starch. Such
modifications are known in the art, for example in Modified
Starches: Properties and Uses, Ed. Wurzburg, CRC Press, Inc.,
Florida (1986). Other suitable modifications and methods are
disclosed in U.S. Pat. Nos. 4,626,288, 2,613,206 and 2,661,349,
which are incorporated herein by reference.
[0012] In one embodiment of the process, the feed starch can be a
dry product "Dry" is this context does not mean that the moisture
content is 0%, but that the moisture content is low enough to be
regarded as dry in a commercial sense. When the feed is dry starch,
water or an aqueous composition can be added to the extruder to
form a slurry or paste therein.
[0013] In another embodiment of the process, the starch is fed to
the extruder while it is in the form of an aqueous slurry or paste
that has a dry solids concentration of at least about 50% by
weight. In some cases, the dry solids concentration of slurry or
paste can be at least about 60% by weight, or at least about 70% by
weight. The use of such a high solids concentration enhances rapid
crystallization of resistant starch crystallites.
[0014] The water used in the feed starch and/or added to the
extruder can optionally comprise one or more other substances, such
as lower alkanols (e.g., alkanols having 1-6 carbon atoms) or
salts. The pH can vary from about 3.5 to about 8.5.
[0015] In general, extrusion apparatus is well suited to handle
high-viscosity, high-solids compositions. Specific examples include
single-screw and twin-screw extruders. Such extrusion apparatus is
commercially available.
[0016] In some embodiments of the process, the temperature of the
feed starch during extrusion is in the range of about
70-145.degree. C. It should be understood that the temperature of
the starch need not remain constant during extrusion. For example,
the extrusion apparatus can comprise more than one zone, and each
zone can be held at a different temperature, although preferably
the temperature of each zone is within the broad ranges stated
herein.
[0017] The product starch produced by the process will in many
cases have a total dietary fiber (TDF) content of at least about
30% by weight This can be increased by the additional step of
heating the product starch to a temperature of at least about
90.degree. C. in the presence of moisture. The temperature of this
heat-moisture treatment step optionally can be at least about
120.degree. C., or in some cases at least about 150.degree. C. The
moisture content during this step can be about 15-35% by weight, or
in some cases about 20-25% by weight. In order to achieve the
desired moisture content during this step, it will be necessary in
many cases to add water or an aqueous composition to the product
starch. This heat-moisture treatment can increase the TDF of the
starch to at least about 50% by weight, and in some cases even
higher.
[0018] The starch can then be dried. For example, a tray dryer or
flash dryer can be used to remove moisture from the wet starch
cake, although other drying techniques could be used as well.
Persons skilled in this art will understand that a "dry starch
product" normally does not have 0% moisture content, but has a low
enough moisture content to be considered "dry" for commercial
purposes.
[0019] The starch product optionally can be milled to reduce its
particle size, either before or after heat-moisture treatment.
Milling will usually be performed on dried starch.
[0020] The starch produced by the process generally is heat-stable
and shear-stable, which makes it compatible with high temperature
and/or high shear processing. As a result, the starch is
well-suited for use in food applications such as baking and frying.
In addition, the starch is relatively high in total dietary fiber
(TDF).
[0021] Resistant starch (RS) has been classified into four
different types: Type I results from the starch being physically
inaccessible to alpha-amylase (e.g. starch embedded in a protein or
fiber matrix, such as found in whole grain); Type II is intact,
native starch granules that as uncooked starch has a physical
structure that is digestive resistant, but after gelatinization
upon cooking is digestible (e.g. potato and banana starch); Type
III is starch that has been cooked and gelatinized, or otherwise
the native structure has been destroyed, and the starch molecules
have re-associated themselves during the processing so that the
starch is alpha-amylase resistant after cooking; and Type IV is a
result of starch chemical modification which interferes with
alpha-amylase digestion. The starch produced by the present process
is typically a Type III resistant starch, although it can be Type
IV resistant starch when chemically modified starch is used as the
starting material.
[0022] To a large extent, the native molecular structure of starch
can be destroyed in the process of making the resistant starch of
this invention. The starch molecules can then re-associate into an
ordered structure that results in alpha-amylase resistance.
[0023] The word "native" is used commonly in literature as a
description of starch. The inventors use the word "native" to mean
the properties of starch as it exists in the plant at harvest and
upon extraction from the plant with very minimal physical treatment
or chemical exposure. For example, wet milling of corn that
releases starch from corn kernels requires steeping the kernels in
a mild water solution of lactic acid near pH 4 and also containing
about 1500 ppm SO.sub.2 gas dissolved in the water. This solution
penetrates the corn kernels and the SO.sub.2 partially reduces
proteins in the endosperm protein matrix binding the starch,
thereby softening the endosperm so the starch granules can be
released upon grinding the kernels. Grinding is actually quite
gentle, since the wet milling operation is designed to tear apart
the soft kernels, releasing starch without breaking the germ sacs
containing oil. The molecular structure, the general morphology and
the shape of the starch granules extracted during milling are
virtually unchanged from the starch that exists in the kernels
prior to milling.
[0024] Native starch is often referred to as granular, and word
"granular" is often used in literature without definition. Native
starch granules generally have a roughly spheroid or ellipsoid
shape. They also have native molecular organization including
crystallite regions and amorphous regions. The crystallite regions
of native starch impart birefringence to it. Several authors refer
to native starch structure Gas "granular structure" or the starch
being in a "granular state." Although there is no standard,
agreed-upon definition of granular starch, it is the approximate
shape of the granule that is the point of reference in this patent
application. The inventors of this patent refer to and use the word
"granular" in the sense of a spherical or ellipsoidal shaped starch
particle. "Granule or granular" is not meant to imply native or
uncooked starch or non-cold water swelling starches. It is our
desire to distinguish between native, uncooked starches that have
intact native crystallinity versus other granular starches that
have a similar shape but have lost most or all of their native
molecular organization or native crystallite structure.
Non-chemically modified and some chemically modified starches that
are pasted on hot rolls and scraped off the rolls generally have
fragmented and glassy appearing particles of irregular shape, and
these starches are not referred to as "granular" by the
inventors.
[0025] Starch produced by this process can be used as a bulking
agent or flour substitute in foods, such as reduced calorie baked
goods. The starch is also useful for dietary fiber fortification in
foods. Specific examples of foods in which the starch can be used
include bread, cakes, cookies, crackers, extruded snacks, soups,
frozen desserts, fried foods, pasta products, potato products, rice
products, corn products, wheat products, dairy products,
nutritional bars, breakfast cereals, and beverages.
[0026] Total Dietary Fiber (TDF) is the parameter indicating the
degree of alpha-amylase resistance of starch. Suitable procedures
for determining TDF include AOAC (Association of Official
Analytical Chemists) Method 985.29 and 991.43, which can be carried
out using a test kit from Megazyme International Ireland Ltd. The
following is a very brief description of the TDF method. Generally,
in these procedures starch is dispersed in a MES/TRIS buffered
water solution of pH 8.2 in which a high temperature stable
alpha-amylase has been added and brought to 95-100.degree. C. for
35 minutes. The sample is cooled to 60.degree. C. and a protease is
added and the sample is treated for 30 minutes. Then the solution
is changed to pH 4.1-4.8 and glucoamylase is added to the solution.
After 30 minutes at 60.degree. C. of enzyme treatment the dietary
fiber is precipitated by adding 95% alcohol. The precipitate is
collected on a Celite coated crucible and dried overnight. The dry
precipitate weight is measured gravimetrically, and the percent TDF
is calculated based on the initial starch dry weight, so TDF is a
dry basis value.
[0027] Various embodiments of the present invention can be
understood from the following examples.
EXAMPLE 1
[0028] Resistant starch can be prepared from high amylose starch
(HS-7 Variety 4200, Honen Starch Co.) using the following
procedure:
[0029] (1) Measure the moisture content of the high amylose
starch.
[0030] (2) Place the high amylose starch in the feed hopper of a
Leistritz ZSE-18/HP Laboratory Twin Screw Extruder.
[0031] (3) Start the extruder and set the zone temperatures as
follows: TABLE-US-00001 Zone 1 70.degree. C. Zone 2 70.degree. C.
Zone 3 120.degree. C. Zone 4 145.degree. C. Zone 5 145.degree. C.
Zone 6 120.degree. C.
[0032] A suitable screw configuration for the 18 mm diameter, 540
mm length co-rotating twin screw extruder is as follows (with screw
element lengths in D's or diameters) moving from the inlet end of
the extruder to the outlet die. From the inlet to about 16.5 D
location long pitch, conveying screw elements are used with the
pitch decreasing slightly as the position of screw elements moves
forward. From about 16.5 D to 17.0 D, 30 degree forward kneading
blocks are used. From about 17 D to 18 D short pitch, conveying
screw elements which transition to 60 degree forward kneading
blocks from 18 D to 18.5 D. From the end of the 60 degree kneading
block section to the end of the extruder, long pitch, conveying
screw elements are used.
[0033] (4) Run the screw of the extruder at 200 rpm and feed the
high amylose starch at 25 grams/minute while injecting moisture at
a rate of 17.6 ml/minute.
[0034] (5) Collect and dry the extruded product.
[0035] (6) Mill the cooled product to the desired particle
size.
[0036] (7) Heat and moisture treat the product at 250.degree. F.
(121.degree. C.) and 25% moisture for two hours.
[0037] Prior to the heat and moisture treatment (step 7), the TDF
value of the starch is typically in the range of 30%. After the
heat and moisture treatment, the TDF value is typically around
60%.
EXAMPLE 2
[0038] Several runs of heat and moisture treatment were performed
on extruded starch at varying temperatures and moisture contents.
The extruded starch was produced as described in steps (1) through
(5) of Example 1, using a starch feed rate of 7.6 grams/minute, a
water injection rate of 6.9 ml/minute, and an extrusion temperature
of 150.degree. C. The results of the heat-moisture treatment are
summarized in Table 1. TABLE-US-00002 TABLE 1 Temperature Time TDF
Beginning Moisture content (.degree. C.) (hours) of % after TDF %
during treatment during treatment treatment treatment 35.24 15 93
1.5 30 35.24 15 121 1.0 37 35.24 15 121 2.0 38 35.24 15 149 1.5 59
35.24 25 93 1.0 34 35.24 25 93 2.0 36 35.24 25 121 1.5 60 35.24 25
149 1.0 61 35.24 25 149 2.0 48 35.24 35 93 1.5 43 35.24 35 121 1.0
n/a 35.24 35 121 2.0 53 35.24 35 149 1.5 36
[0039] The greatest improvement in TDF appeared to come from
treatment at about 20-25% moisture and a temperature of about
150.degree. C. or possibly higher.
[0040] The preceding description of specific embodiments of the
invention is not intended to be a list of every possible embodiment
of the invention. Persons skilled in the art will recognize that
other embodiments would be within the scope of the following
claims.
* * * * *