Low-GI corn starch as well as preparation method and application thereof

Abstract

The invention provides low-GI corn starch as well as a preparation method and application thereof, and belongs to the technical field of functional starch preparation. The preparation method of the low-GI corn starch comprises the following steps: (1) preparing corn starch into a corn starch solution; (2) adjusting the pH value of the corn starch solution, carrying out heat preservation treatment, and adding branching enzyme to carry out first enzymolysis reaction after the heat preservation treatment; (3) adding branching enzyme again after the first enzymolysis reaction, and carrying out second enzymolysis reaction; and (4) carrying out alcohol washing, water washing, drying and crushing on a product obtained after the second enzymolysis reaction to obtain the low-GI corn starch. According to the preparation method disclosed by the invention, the content of resistant starch in the corn starch can be remarkably increased, the digestibility of the corn starch is reduced, and the GI value of the prepared low-GI corn starch can be as low as 35.

Description

Technical Field

[0001] The present invention relates to the technical field of functional starch preparation, and in particular to low GI corn starch and a preparation method and application thereof. Background Art

[0002] Glycemic Index (GI) is an indicator that reflects the degree to which food causes blood sugar to rise in the human body. Low GI starch is a resistant starch, also known as resistant starch or indigestible starch, which cannot be enzymatically hydrolyzed in the small intestine. Compared with other starches, low GI starch is difficult to degrade, digests slowly in the body, and is absorbed and enters the blood slowly. It will not cause great fluctuations in blood sugar, can provide a long-term feeling of fullness, and is beneficial to maintaining intestinal health, regulating blood sugar, and regulating body weight. Low GI starch is widely used in diabetes research due to its unique physiological characteristics.

[0003] The existing patent CN202410405941.7 (publication number: CN118252258A) discloses a method for preparing resistant starch, and through in vitro simulation tests, the GI value of the prepared corn resistant starch was determined to be reduced from 55.93 to 46.23. The effect of reducing the GI value by the preparation method is not ideal, so it is urgent to develop a preparation method that can more significantly reduce the GI value of corn starch. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing low GI corn starch, further reduce the GI value of corn starch, and reduce the digestibility of corn starch.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing low GI corn starch, comprising the following steps:

[0007] (1) taking corn starch and preparing a corn starch solution;

[0008] (2) adjusting the pH of the corn starch solution and performing heat preservation treatment, and adding a branching enzyme after the heat preservation treatment to perform a first enzymatic hydrolysis reaction;

[0009] (3) adding branching enzyme again after the first enzymatic hydrolysis reaction to perform a second enzymatic hydrolysis reaction;

[0010] (4) washing the product after the second enzymatic hydrolysis reaction with alcohol, washing with water, drying and pulverizing to obtain low GI corn starch.

[0011] Preferably, the corn starch in step (1) is high-amylose corn starch, the GI value of the high-amylose corn starch is 65-69, and the high-amylose corn starch solution is prepared with water at a concentration of 8-12%.

[0012] Preferably, in step (2), the pH is adjusted to 7.0-7.5, the temperature of the heat preservation treatment is 50-60° C., and the heat preservation time is 10-20 min.

[0013] Preferably, the amount of the branching enzyme added in step (2) is 2-4wt% of the dry weight of the high-amylose corn starch, the temperature of the first enzymatic hydrolysis reaction is 50-60°C, the pH is 7.0-7.5, and the reaction time is 6-10h.

[0014] Preferably, the amount of branching enzyme added in step (3) is 2-3wt% of the dry weight of the high-amylose corn starch, the temperature of the second enzymatic hydrolysis reaction is 50-60°C, the pH is 7.0-7.5, and the reaction time is 3-5h.

[0015] Preferably, the alcohol washing and water washing in step (4) are performed 2 to 3 times, and the alcohol washing is performed using a 45 to 55% ethanol solution; the drying temperature is 45 to 55° C., and the drying time is 8 to 10 hours; and the pulverization mesh size is 80 to 120 meshes.

[0016] Preferably, the method for preparing the high-amylose corn starch comprises the following steps:

[0017] 1) Soak corn in H2SO3 solution;

[0018] 2) adding water to the corn soaked in step 1), crushing it and separating the germ to obtain a starch mixture 1;

[0019] 3) adding water to the starch mixture 1 and grinding it to separate the fibers to obtain a starch mixture 2;

[0020] 4) the starch mixture 2 is centrifuged again to separate the gluten protein, thereby obtaining high-amylose corn starch milk;

[0021] 5) The high-amylose corn starch milk is dehydrated, dried and sieved to obtain high-amylose corn starch.

[0022] Preferably, the concentration of the H2SO3 solution in step 1) is 0.25-0.5wt%, the soaking temperature is 48-55°C, and the time is 48-90h; the moisture content of the corn after soaking is 40-50%, and the soluble matter content is 2-3%; the mass volume ratio of corn to water in step 2) is 1kg:1.5-3.0L; the crushing adopts a hammer crusher; the mass volume ratio of the starch mixture 1 to water in step 3) is 1kg:1-2L, and the grinding adopts a vertical pin-type impact mill; the centrifugation in step 4) adopts a butterfly centrifuge.

[0023] The present invention also provides a method for preparing low GI high-amylose corn starch by the above-mentioned preparation method, wherein the GI value of the low GI high-amylose corn starch is 35-38.

[0024] The present invention also provides an application of the low GI high-amylose corn starch in preparing low GI functional food.

[0025] The present invention introduces a branching enzyme for decomposing amylopectin into corn starch or high-amylose corn starch, and through secondary enzymolysis, significantly reduces the content of amylopectin in the corn starch, increases the content of resistant starch, and reduces the GI value of the prepared low GI corn starch to 35-38. DETAILED DESCRIPTION

[0026] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0027] The branching enzyme used in the following examples was purchased from Beijing Gaoruisen Technology Co., Ltd., and the enzyme activity was 25000 U / g.

[0028] Example 1 Preparation of high amylose corn starch

[0029] Corn kernels with an amylose content of about 30% are screened using a vibrating screen and an air suction separator, the frequency of the vibrating screen is 50-60 Hz, the air velocity at the air suction outlet of the air suction separator is 7 m / s, and after screening, the broken corn content is ≤3% and the impurity content is ≤0.3%. The screened high-amylose corn is soaked in a 0.3% H2SO3 solution, the liquid is more than 20 cm higher than the high-amylose corn, and the high-amylose corn is soaked in a single tank cycle at 50°C for 72 hours. The moisture content of the high-amylose corn after soaking is 45%, and the soluble content is 3%. The soaked corn was added with water at a mass volume ratio of corn to water of 1:2 (kg / L), and the material was crushed into 3-5 pieces by a PCZ-180x150 hammer crusher. The crushed corn was separated and the germ was removed by a MKGC-12.5 suspension separator (feed pressure 0.5 MPa, 10 L / min) to obtain a starch mixture 1. The starch mixture 1 was added with water at a mass volume ratio of 1:1.5 (kg / L), and then separated by a LZM685-N vertical needle impact mill (3750 r / min, 10 min). After separation and removal of fibers, a starch mixture was obtained. The mixture 2 is prepared by adding water in a mass volume ratio of starch mixture 2 to water of 1:1.5, and the gluten protein is separated by a butterfly centrifuge (7000 r / min, 5 min) according to a feed concentration of 15 Bé, a feed pressure of 0.1 MPa, a slurry concentration of 6 Bé, and a washing water pressure of 0.1 MPa to obtain high-amylose corn starch milk, which is mechanically dehydrated by a horizontal scraper unloading centrifuge (4000 r / min, 10 min), and then the moisture content is controlled to be less than 13% by heating and drying at 130°C, and then sieved with a 100-mesh sieve to obtain dry high-amylose corn starch.

[0030] Example 2

[0031] Weigh 100 grams of dry high-amylose corn starch prepared in Example 1, add water to prepare a 10% starch solution, adjust the pH to 7.5, keep warm at 50°C for 15 minutes, then add 2wt% branching enzyme (by starch dry weight), at 60°C, pH 7.5, after 8 hours of enzymatic hydrolysis, then add 2wt% branching enzyme (by starch dry weight) for a second time, at 60°C, pH 7.5, after 3 hours of enzymatic hydrolysis, wash twice with 50% ethanol, then wash twice with water, dry at 50°C, crush, and pass through a 100-mesh sieve to obtain low GI high-amylose corn starch. According to in vitro digestion simulation, the GI value of low GI high-amylose corn starch is 35, and the GI value of original high-amylose corn starch is 68.

[0032] Example 3

[0033] Weigh 100 grams of dry high-amylose corn starch prepared in Example 1, add water to prepare a 10% starch solution, adjust the pH to 7.5, keep warm at 50°C for 15 minutes, then add 1wt% branching enzyme (based on starch dry weight), at 60°C, pH 7.5, after enzymatic hydrolysis for 8 hours, then add 1wt% branching enzyme (based on starch dry weight) for a second time, at 60°C, pH 7.5, after enzymatic hydrolysis for 3 hours, wash twice with 50% ethanol, then wash twice with water, dry at 50°C and crush, pass through a 100-mesh sieve, and obtain low GI high-amylose corn starch. According to in vitro digestion simulation, the GI value of low GI high-amylose corn starch is 46, and the GI value of original high-amylose corn starch is 68.

[0034] Example 4

[0035] Weigh 100 grams of dry high-amylose corn starch prepared in Example 1, add water to prepare a 10% starch solution, adjust the pH to 7.5, keep warm at 50°C for 15 minutes, then add 3wt% branching enzyme (based on starch dry weight), at 60°C, pH 7.5, after 8 hours of enzymatic hydrolysis, then add 3wt% branching enzyme (based on starch dry weight) for a second time, at 60°C, pH 7.5, after 3 hours of enzymatic hydrolysis, wash twice with 50% ethanol, then wash twice with water, dry at 50°C, crush, and pass through a 100-mesh sieve to obtain low GI high-amylose corn starch. According to in vitro digestion simulation, the GI value of low GI high-amylose corn starch is 38, and the GI value of original high-amylose corn starch is 68.

[0036] Example 5

[0037] Weigh 100 grams of dry high-amylose corn starch prepared in Example 1, add water to prepare a 10% starch solution, adjust the pH to 7.5, keep warm at 50°C for 15 minutes, then add 4wt% branching enzyme (based on starch dry weight), and after enzymatic hydrolysis at 60°C and pH 7.5 for 11 hours, wash twice with 50% ethanol, wash twice with water, dry at 50°C, crush, and pass through a 100-mesh sieve to obtain low GI high-amylose corn starch. According to in vitro digestion simulation, the GI value of low GI high-amylose corn starch is 48, and the GI value of original high-amylose corn starch is 68.

[0038] Example 6

[0039] Weigh 100 grams of dry high-amylose corn starch prepared in Example 1, add water to prepare a 10% starch solution, adjust the pH to 7.5, keep warm at 50°C for 15 minutes, then add 4wt% branching enzyme (by starch dry weight), at 60°C, pH 7.5, after 8 hours of enzymatic hydrolysis, then add 4wt% branching enzyme (by starch dry weight) for a second time, at 60°C, pH 7.5, after 3 hours of enzymatic hydrolysis, wash twice with 50% ethanol, then wash twice with water, dry at 50°C, crush, and pass through a 100-mesh sieve to obtain low GI high-amylose corn starch. According to in vitro digestion simulation, the GI value of low GI high-amylose corn starch is 38, and the GI value of original high-amylose corn starch is 68.

[0040] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing low GI corn starch, characterized in that: The following steps are involved: (1) taking corn starch and preparing a corn starch solution; (2) adjusting the pH of the corn starch solution and performing heat preservation treatment, and adding a branching enzyme after the heat preservation treatment to perform a first enzymatic hydrolysis reaction; (3) adding branching enzyme again after the first enzymatic hydrolysis reaction to perform a second enzymatic hydrolysis reaction; (4) washing the product after the second enzymatic hydrolysis reaction with alcohol, washing with water, drying and pulverizing to obtain low GI corn starch.

2. The preparation method according to claim 1, characterized in that The corn starch in step (1) is high-amylose corn starch, the GI value of the high-amylose corn starch is 65-69, and the high-amylose corn starch solution is prepared with water with a concentration of 8%-12%.

3. The preparation method according to claim 2, characterized in that: In step (2), the pH is adjusted to 7.0-7.5, the temperature of the heat preservation treatment is 50-60° C., and the heat preservation time is 10-20 min.

4. The preparation method according to claim 3, characterized in that: The amount of the branching enzyme added in step (2) is 2-4wt% of the dry weight of the high-amylose corn starch, the temperature of the first enzymatic hydrolysis reaction is 50-60°C, the pH is 7.0-7.5, and the reaction time is 6-10h.

5. The preparation method according to claim 4, characterized in that: In step (3), the amount of branching enzyme added is 2-3wt% of the dry weight of the high-amylose corn starch, the temperature of the second enzymatic hydrolysis reaction is 50-60°C, the pH is 7.0-7.5, and the reaction time is 3-5h.

6. The preparation method according to claim 5, characterized in that: The alcohol washing and water washing in step (4) are performed 2 to 3 times, and the alcohol washing is performed using a 45 to 55% ethanol solution; the drying temperature is 50 to 60° C., and the drying time is 8 to 10 hours; and the pulverization mesh size is 80 to 120 meshes.

7. The preparation method according to claim 2, characterized in that: The preparation method of the high-amylose corn starch comprises the following steps: 1) Soak corn in H2SO3 solution; 2) adding water to the corn soaked in step 1), crushing it and separating the germ to obtain a starch mixture 1; 3) adding water to the starch mixture 1 and grinding it to separate the fibers to obtain a starch mixture 2; 4) the starch mixture 2 is centrifuged again to separate the gluten protein, thereby obtaining high-amylose corn starch milk; 5) The high-amylose corn starch milk is dehydrated, dried and sieved to obtain high-amylose corn starch.

8. The preparation method according to claim 7, characterized in that: The concentration of the H2SO3 solution in step 1) is 0.25-0.5wt%, the soaking temperature is 48-55°C, and the time is 48-90h; the moisture content of the corn after soaking is 40-50%, and the soluble matter content is 2-3%; the mass volume ratio of corn to water in step 2) is 1kg:1.5-3.0L; the crushing adopts a hammer crusher; the mass volume ratio of the starch mixture 1 to water in step 3) is 1kg:1-2L, and the grinding adopts a vertical pin-type impact mill; the centrifugation in step 4) adopts a butterfly centrifuge.

9. A method for preparing low GI high amylose corn starch according to any one of claims 1 to 8, characterized in that: The GI value of the low GI high amylose corn starch is 35-38.

10. Use of the low GI high amylose corn starch according to claim 9 in preparing low GI functional foods.