阅读说明：本技术 一种玉米蛋白肽及其提取方法 (Corn protein peptide and extraction method thereof ) 是由 程林春 王俊青 吕少英 崔志英 于 2020-12-31 设计创作，主要内容包括：本发明属于玉米蛋白肽提取技术领域,具体涉及一种玉米蛋白肽及其提取方法。本发明玉米蛋白肽的提取方法包括以下步骤：先将玉米蛋白粉粉碎,过筛,对所得玉米蛋白微粉进行预处理,对预处理后玉米蛋白进行汽蒸处理,加入亚硫酸钠水溶液,浸泡,过滤,除去滤液,向处理后玉米蛋白中加水,搅拌,向浆料中加入多功能添加剂,搅拌,调节混合料的pH,升温,加入碱性蛋白酶,酶解,进行酶灭活,冷却；向酶解液中加入活性炭,搅拌,抽滤,将滤液浓缩、冷冻干燥,得玉米蛋白肽。采用本发明提供的玉米蛋白肽的提取方法制得的玉米蛋白肽水解度高,提高了玉米蛋白的利用率。且采用本发明提供的玉米蛋白肽的提取方法制得的玉米蛋白肽具有优异的抗氧化活性。(The invention belongs to the technical field of corn protein peptide extraction, and particularly relates to a corn protein peptide and an extraction method thereof. The extraction method of the corn protein peptide comprises the following steps: firstly, pulverizing corn protein powder, sieving, pretreating the obtained corn protein micropowder, steaming the pretreated corn protein, adding a sodium sulfite aqueous solution, soaking, filtering, removing filtrate, adding water into the treated corn protein, stirring, adding a multifunctional additive into the slurry, stirring, adjusting the pH value of the mixture, heating, adding alkaline protease, carrying out enzymolysis, carrying out enzyme inactivation, and cooling; adding activated carbon into the enzymolysis liquid, stirring, carrying out suction filtration, concentrating the filtrate, and freeze-drying to obtain the corn protein peptide. The corn protein peptide prepared by the extraction method of the corn protein peptide provided by the invention has high hydrolysis degree, and the utilization rate of the corn protein is improved. The corn protein peptide prepared by the extraction method of the corn protein peptide provided by the invention has excellent antioxidant activity.)

1. The extraction method of the corn protein peptide is characterized by comprising the following steps:

s1, crushing the corn protein powder, and sieving the crushed corn protein powder with a 50-100-mesh sieve to obtain corn protein micropowder;

s2, pretreating the corn protein micropowder obtained in the step S1 to obtain pretreated corn protein;

s3, steaming the pretreated corn protein obtained in the step S2, adding a sodium sulfite aqueous solution into the steamed corn protein, wherein the adding amount of the sodium sulfite aqueous solution is 2-4 times of the mass of the corn protein micro powder, soaking for 1-2 hours, filtering, and removing filtrate to obtain the treated corn protein;

s4, adding water into the treated corn protein obtained in the step S3, wherein the adding amount of the water is 9-13 times of the mass of the treated corn protein, and stirring at the speed of 100-200 r/min for 25-35 min to obtain slurry;

s5, adding a multifunctional additive into the slurry obtained in the step S4, wherein the adding amount of the multifunctional additive is 0.1-0.15% of the mass of the slurry, and stirring at the speed of 150-250 r/min for 20-30 min to obtain a mixture;

s6, adjusting the pH value of the mixture obtained in the step S5 to 8-10, heating to 30-40 ℃, adding alkaline protease, wherein the amount of the alkaline protease is 3-5 per mill of the mass of the mixture, carrying out enzymolysis for 1-2 hours, heating to 90 ℃, carrying out enzyme inactivation for 15min, and cooling to 25 ℃ to obtain an enzymolysis liquid;

s7, adding activated carbon into the enzymatic hydrolysate obtained in the step S6, wherein the adding amount of the activated carbon is 2-5% of the mass of the enzymatic hydrolysate, stirring at the speed of 200-300 r/min for 50-60 min, performing suction filtration to obtain filtrate, concentrating the filtrate, and performing freeze drying to obtain the corn protein peptide.

2. The method for preparing zein peptide of claim 1 and in which the conditions of the pretreatment of step S2 are: and (3) freezing the mixture in an environment with the temperature of-23 to-10 ℃ for 20 to 30 min.

3. The method for preparing zein peptide of claim 2 and in which the conditions of the pretreatment of step S2 are: freezing at-18 deg.C for 24 min.

4. The method for preparing zein peptide of claim 1 in which the conditions of the steaming step S3 are: the steaming temperature is 30-40 ℃, the vacuum degree is 0.04-0.08 Mpa, and the steaming time is 20-30 min.

5. The method for preparing zein peptide of claim 1 in which the conditions of the steaming step S3 are: steaming at 35 deg.C under 0.05Mpa for 26 min.

6. The method for preparing zein peptide in claim 1, wherein the mass concentration of the aqueous solution of sodium sulfite in step S3 is 0.1-0.2%.

7. The method of claim 1, wherein the multifunctional additive of step S5 is a combination of polyvinylpyrrolidone, sodium alginate and L-fucose.

8. The method for preparing zein peptide in claim 7, wherein the multifunctional additive in step S5 is prepared from polyvinylpyrrolidone, sodium alginate and L-fucose in a mass ratio of 11-13: 5-8: 2-3.

9. The method for preparing zein peptide in claim 8, wherein said multifunctional additive of step S5 is prepared from polyvinylpyrrolidone, sodium alginate and L-fucose in a mass ratio of 12: 7: 3, and (3).

10. The zein peptide prepared by the extraction method of the zein peptide of any one of claims 1 to 9.

Technical Field

The invention belongs to the technical field of corn protein peptide extraction, and particularly relates to a corn protein peptide and an extraction method thereof.

Background

Corn is an annual herbaceous plant of the family gramineae, also known as corn, corn cobs, maize, pearl rice and the like, native to central and south america, is an important food crop in the world and widely distributed in the united states, china, brazil and other countries. Compared with traditional grain crops such as rice, wheat and the like, the corn has strong drought tolerance, cold tolerance, barren tolerance and excellent environmental adaptability. The corn has higher nutritive value and is an excellent grain crop. Besides wheat and rice, corn is the 3 rd crop of food crops in China, and the corn planting amount in China is only second to that in the United states at present. As a high-yield grain crop in china, corn is an important feed source in animal husbandry, aquaculture, and the like, and is one of indispensable raw materials for food, medical care, light industry, chemical industry, and the like.

The corn contains more comprehensive nutrients, and the preparation and application of the corn protein obtain wide and good sources. Corn protein powder is the by-product of corn starch in wet processing, corn kernel is wet milled to obtain coarse starch, the protein separated from starch milk in starch separator is called gluten water, and the gluten water is concentrated in concentrating centrifuge or depositing tank and dewatered and dried to obtain corn protein powder. The corn protein powder is golden yellow granular powder, has special smell generated by corn fermentation, has high hardness and low water content, and is difficult to dissolve in water. The corn protein powder has special smell and color, poor water solubility, rough mouthfeel and low production added value because of serious lack of essential amino acid such as lysine, tryptophan and the like, so the application of the corn protein powder is greatly limited. Therefore, the method has important economic significance for improving the utilization rate of the corn protein powder.

The corn protein peptide is a plurality of peptide chain fragments obtained by hydrolyzing corn protein powder, a series of short peptides consisting of five or more amino acid residues can be obtained after the hydrolysis by protease, particularly alkaline protease, the water solubility of the short peptides is higher than that of the corn protein powder, the short peptides have lower viscosity, and the product also has certain special biological activity. By utilizing the special biological activity, the compound can be effectively applied by being added into food and feed. However, the existing method for preparing the zein peptide has the problems of low hydrolysis degree of the product and poor antioxidant activity.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a corn protein peptide and an extraction method thereof. The corn protein peptide prepared by the extraction method of the corn protein peptide provided by the invention has high hydrolysis degree, and the utilization rate of the corn protein is improved. The corn protein peptide prepared by the extraction method of the corn protein peptide provided by the invention has excellent antioxidant activity.

The technical scheme of the invention is as follows:

a method for extracting zein peptide comprises the following steps:

s1, crushing the corn protein powder, and sieving the crushed corn protein powder with a 50-100-mesh sieve to obtain corn protein micropowder;

s2, pretreating the corn protein micropowder obtained in the step S1 to obtain pretreated corn protein;

s3, steaming the pretreated corn protein obtained in the step S2, adding a sodium sulfite aqueous solution into the steamed corn protein, wherein the adding amount of the sodium sulfite aqueous solution is 2-4 times of the mass of the corn protein micro powder, soaking for 1-2 hours, filtering, and removing filtrate to obtain the treated corn protein;

s4, adding water into the treated corn protein obtained in the step S3, wherein the adding amount of the water is 9-13 times of the mass of the treated corn protein, and stirring at the speed of 100-200 r/min for 25-35 min to obtain slurry;

s5, adding a multifunctional additive into the slurry obtained in the step S4, wherein the adding amount of the multifunctional additive is 0.1-0.15% of the mass of the slurry, and stirring at the speed of 150-250 r/min for 20-30 min to obtain a mixture;

s6, adjusting the pH value of the mixture obtained in the step S5 to 8-10, heating to 30-40 ℃, adding alkaline protease, wherein the amount of the alkaline protease is 3-5 per mill of the mass of the mixture, carrying out enzymolysis for 1-2 hours, heating to 90 ℃, carrying out enzyme inactivation for 15min, and cooling to 25 ℃ to obtain an enzymolysis liquid;

s7, adding activated carbon into the enzymatic hydrolysate obtained in the step S6, wherein the adding amount of the activated carbon is 2-5% of the mass of the enzymatic hydrolysate, stirring at the speed of 200-300 r/min for 50-60 min, performing suction filtration to obtain filtrate, concentrating the filtrate, and performing freeze drying to obtain the corn protein peptide.

Further, the conditions of the preprocessing in step S2 are: and (3) freezing the mixture in an environment with the temperature of-23 to-10 ℃ for 20 to 30 min.

Further, the conditions of the preprocessing in step S2 are: freezing at-18 deg.C for 24 min.

Further, the conditions of the steaming treatment of step S3: the steaming temperature is 30-40 ℃, the vacuum degree is 0.04-0.08 Mpa, and the steaming time is 20-30 min.

Further, the conditions of the steaming treatment of step S3: steaming at 35 deg.C under 0.05Mpa for 26 min.

Further, the mass concentration of the sodium sulfite aqueous solution in the step S3 is 0.1-0.2%.

Further, the multifunctional additive in step S5 is a combination of polyvinylpyrrolidone, sodium alginate and L-fucose.

Further, the multifunctional additive in the step S5 is prepared from polyvinylpyrrolidone, sodium alginate and L-fucose in a mass ratio of 11-13: 5-8: 2-3.

Further, the multifunctional additive in step S5 is prepared from polyvinylpyrrolidone, sodium alginate and L-fucose in a mass ratio of 12: 7: 3, and (3).

The invention also aims to provide the corn protein peptide prepared by the extraction method of the corn protein peptide.

The multifunctional additive which is added in the invention and consists of polyvinylpyrrolidone, sodium alginate and L-fucose according to a certain mass ratio not only can uniformly disperse zein in a slurry system, but also can stably exist zein in the system, and simultaneously, the invention can also greatly improve the contact chance of zein and alkaline protease, promote the extraction of zein peptide and improve the hydrolysis degree of zein.

According to the invention, the pulverized zein micropowder is pretreated under certain conditions, the pretreated zein is steamed under certain conditions, and then sodium sulfite aqueous solution is added into the steamed zein for soaking, so that the high-grade structure of the zein can be fully destroyed, the zein can be hydrolyzed by alkaline protease more efficiently in the subsequent enzymolysis process, the zein peptide with smaller molecular weight can be obtained while the hydrolysis degree is improved, and the ABTS of the zein peptide is improved⁺The clearance rate of the product is higher, so that the obtained product has more excellent antioxidant activity.

Compared with the prior art, the invention has the following advantages:

(1) the corn protein peptide prepared by the extraction method of the corn protein peptide provided by the invention has high hydrolysis degree, and the utilization rate of the corn protein is improved.

(2) The corn protein peptide pair ABTS prepared by the extraction method of the corn protein peptide provided by the invention⁺Has high clearance rate and excellent antioxidant activity.

(3) The extraction method of the corn protein peptide provided by the invention is simple to operate and easy for industrial mass production.

Detailed Description

The present invention is further described in the following description of the specific embodiments, which is not intended to limit the invention, but various modifications and improvements can be made by those skilled in the art according to the basic idea of the invention, within the scope of the invention, as long as they do not depart from the basic idea of the invention.

The starting materials used in the present invention are commercially available unless otherwise specified. For example, the corn protein powder can be purchased from Xiamen orange Pont happy Xuan Biotech Co., Ltd, the product number: 830; polyvinylpyrrolidone is available from Guangdong Yuebeautified industries, Inc., cat #: k 30; sodium alginate is available from Guangdong Hua Zhan pharmaceutical Co., Ltd, cat #: 1002; alkaline protease is available from gayowa biochem ltd, cat #: YC _ 240.

Example 1 extraction of zein peptide

The extraction method of the zein peptide comprises the following steps:

s1, crushing the corn protein powder, and sieving the crushed corn protein powder with a 50-mesh sieve to obtain corn protein micropowder;

s2, pretreating the corn protein micropowder obtained in the step S1, wherein the pretreatment conditions are as follows: freezing at-23 deg.C for 20min to obtain pretreated zein;

s3, steaming the pretreated corn protein obtained in the step S2, wherein the steaming conditions are as follows: steaming at 30 deg.C under 0.04Mpa for 20min, adding 0.1% sodium sulfite aqueous solution into steamed zein, the amount of sodium sulfite aqueous solution is 2 times of zein micropowder, soaking for 1 hr, filtering, and removing filtrate to obtain processed zein;

s4, adding water into the processed corn protein obtained in the step S3, wherein the adding amount of the water is 9 times of the mass of the processed corn protein, and stirring at the speed of 100r/min for 25min to obtain slurry;

s5, adding a multifunctional additive into the slurry obtained in the step S4, wherein the multifunctional additive is prepared from polyvinylpyrrolidone, sodium alginate and L-fucose according to a mass ratio of 11: 8: 3, the adding amount of the multifunctional additive is 0.1 percent of the mass of the slurry, and the mixture is stirred for 20min at the speed of 150r/min to obtain a mixture;

s6, adjusting the pH value of the mixture obtained in the step S5 to 8, heating to 30 ℃, adding alkaline protease, wherein the amount of the alkaline protease is 3 per mill of the mass of the mixture, carrying out enzymolysis for 1 hour, heating to 90 ℃, carrying out enzyme inactivation for 15min, and cooling to 25 ℃ to obtain an enzymolysis liquid;

s7 adding active carbon into the enzymolysis liquid obtained in the step S6, wherein the adding amount of the active carbon is 2% of the mass of the enzymolysis liquid, stirring for 50min at the speed of 200r/min, carrying out suction filtration to obtain filtrate, concentrating the filtrate, and carrying out freeze drying to obtain the corn protein peptide.

Example 2 extraction method of zein peptide

The extraction method of the zein peptide comprises the following steps:

s1, crushing the corn protein powder, and sieving the crushed corn protein powder with a 100-mesh sieve to obtain corn protein micropowder;

s2, pretreating the corn protein micropowder obtained in the step S1, wherein the pretreatment conditions are as follows: freezing at-10 deg.C for 30min to obtain pretreated zein;

s3, steaming the pretreated corn protein obtained in the step S2, wherein the steaming conditions are as follows: steaming at 40 deg.C under 0.08Mpa for 30min, adding 0.2% sodium sulfite aqueous solution into steamed zein, the amount of sodium sulfite aqueous solution is 4 times of zein micropowder, soaking for 2 hr, filtering, and removing filtrate to obtain processed zein;

s4, adding water into the processed corn protein obtained in the step S3, wherein the adding amount of the water is 13 times of the mass of the processed corn protein, and stirring at the speed of 200r/min for 35min to obtain slurry;

s5, adding a multifunctional additive into the slurry obtained in the step S4, wherein the multifunctional additive is prepared from polyvinylpyrrolidone, sodium alginate and L-fucose in a mass ratio of 13: 5: 2, the addition amount of the multifunctional additive is 0.15 percent of the mass of the slurry, and the mixture is stirred for 30min at the speed of 250r/min to obtain a mixture;

s6, adjusting the pH value of the mixture obtained in the step S5 to 10, heating to 40 ℃, adding alkaline protease, wherein the amount of the alkaline protease is 5 per mill of the mass of the mixture, carrying out enzymolysis for 2 hours, heating to 90 ℃, carrying out enzyme inactivation for 15min, and cooling to 25 ℃ to obtain an enzymolysis liquid;

s7 adding active carbon into the enzymolysis liquid obtained in the step S6, wherein the adding amount of the active carbon is 5% of the mass of the enzymolysis liquid, stirring at the speed of 300r/min for 60min, carrying out suction filtration to obtain filtrate, concentrating the filtrate, and carrying out freeze drying to obtain the corn protein peptide.

Embodiment 3, a method for extracting zein peptide, comprising the steps of:

s1, crushing the corn protein powder, and sieving the crushed corn protein powder with a 60-mesh sieve to obtain corn protein micropowder;

s2, pretreating the corn protein micropowder obtained in the step S1, wherein the pretreatment conditions are as follows: freezing at-18 deg.C for 24min to obtain pretreated zein;

s3, steaming the pretreated corn protein obtained in the step S2, wherein the steaming conditions are as follows: steaming at 35 deg.C under 0.05Mpa for 26min, adding 0.12% sodium sulfite aqueous solution into steamed zein, the amount of sodium sulfite aqueous solution is 3 times of zein micropowder, soaking for 1.5 hr, filtering, and removing filtrate to obtain processed zein;

s4, adding water into the processed corn protein obtained in the step S3, wherein the adding amount of the water is 11 times of the mass of the processed corn protein, and stirring at the speed of 150r/min for 30min to obtain slurry;

s5, adding a multifunctional additive into the slurry obtained in the step S4, wherein the multifunctional additive is prepared from polyvinylpyrrolidone, sodium alginate and L-fucose in a mass ratio of 12: 7: 3, the adding amount of the multifunctional additive is 0.12 percent of the mass of the slurry, and the mixture is stirred for 25min at the speed of 200r/min to obtain a mixture;

s6, adjusting the pH value of the mixture obtained in the step S5 to 9, heating to 35 ℃, adding alkaline protease, wherein the amount of the alkaline protease is 4 per mill of the mass of the mixture, carrying out enzymolysis for 1.5h, heating to 90 ℃, carrying out enzyme inactivation for 15min, and cooling to 25 ℃ to obtain an enzymolysis liquid;

s7 adding active carbon into the enzymolysis liquid obtained in the step S6, wherein the adding amount of the active carbon is 3% of the mass of the enzymolysis liquid, stirring at the speed of 250r/min for 55min, carrying out suction filtration to obtain filtrate, concentrating the filtrate, and carrying out freeze drying to obtain the corn protein peptide.

Comparative example 1, a method for extracting zein peptide, comprising the steps of:

s1, crushing the corn protein powder, and sieving the crushed corn protein powder with a 60-mesh sieve to obtain corn protein micropowder;

s2, pretreating the corn protein micropowder obtained in the step S1, wherein the pretreatment conditions are as follows: freezing at-18 deg.C for 24min to obtain pretreated zein;

s3, adding a sodium sulfite aqueous solution with the mass concentration of 0.12% into the pretreated corn protein, wherein the adding amount of the sodium sulfite aqueous solution is 3 times of the mass of the corn protein micropowder, soaking for 1.5h, filtering, and removing filtrate to obtain the treated corn protein;

s4, adding water into the processed corn protein obtained in the step S3, wherein the adding amount of the water is 11 times of the mass of the processed corn protein, and stirring at the speed of 150r/min for 30min to obtain slurry;

s5, adding a multifunctional additive into the slurry obtained in the step S4, wherein the multifunctional additive is prepared from polyvinylpyrrolidone, sodium alginate and L-fucose in a mass ratio of 12: 7: 3, the adding amount of the multifunctional additive is 0.12 percent of the mass of the slurry, and the mixture is stirred for 25min at the speed of 200r/min to obtain a mixture;

s6, adjusting the pH value of the mixture obtained in the step S5 to 9, heating to 35 ℃, adding alkaline protease, wherein the amount of the alkaline protease is 4 per mill of the mass of the mixture, carrying out enzymolysis for 1.5h, heating to 90 ℃, carrying out enzyme inactivation for 15min, and cooling to 25 ℃ to obtain an enzymolysis liquid;

s7 adding active carbon into the enzymolysis liquid obtained in the step S6, wherein the adding amount of the active carbon is 3% of the mass of the enzymolysis liquid, stirring at the speed of 250r/min for 55min, carrying out suction filtration to obtain filtrate, concentrating the filtrate, and carrying out freeze drying to obtain the corn protein peptide.

The preparation method of the zein peptide is similar to that of example 3.

The difference from example 3 is that the zein was not steamed.

Comparative example 2, a method for extracting zein peptide, comprising the steps of:

s1, crushing the corn protein powder, and sieving the crushed corn protein powder with a 60-mesh sieve to obtain corn protein micropowder;

s2, steaming the corn protein micropowder obtained in the step S1, wherein the steaming conditions are as follows: steaming at 35 deg.C under 0.05Mpa for 26min, adding 0.12% sodium sulfite aqueous solution into steamed zein, the amount of sodium sulfite aqueous solution is 3 times of zein micropowder, soaking for 1.5 hr, filtering, and removing filtrate to obtain processed zein;

s3, adding water into the processed corn protein obtained in the step S2, wherein the adding amount of the water is 11 times of the mass of the processed corn protein, and stirring at the speed of 150r/min for 30min to obtain slurry;

s4, adding a multifunctional additive into the slurry obtained in the step S3, wherein the multifunctional additive is prepared from polyvinylpyrrolidone, sodium alginate and L-fucose in a mass ratio of 12: 7: 3, the adding amount of the multifunctional additive is 0.12 percent of the mass of the slurry, and the mixture is stirred for 25min at the speed of 200r/min to obtain a mixture;

s5, adjusting the pH value of the mixture obtained in the step S4 to 9, heating to 35 ℃, adding alkaline protease, wherein the amount of the alkaline protease is 4 per mill of the mass of the mixture, carrying out enzymolysis for 1.5h, heating to 90 ℃, carrying out enzyme inactivation for 15min, and cooling to 25 ℃ to obtain an enzymolysis liquid;

s6 adding active carbon into the enzymolysis liquid obtained in the step S5, wherein the adding amount of the active carbon is 3% of the mass of the enzymolysis liquid, stirring at the speed of 250r/min for 55min, carrying out suction filtration to obtain filtrate, concentrating the filtrate, and carrying out freeze drying to obtain the corn protein peptide.

The preparation method of the zein peptide is similar to that of example 3.

The difference from example 3 is that the zein was not pretreated.

Comparative example 3, a method for extracting zein peptide, comprising the steps of:

s1, crushing the corn protein powder, and sieving the crushed corn protein powder with a 60-mesh sieve to obtain corn protein micropowder;

s2, pretreating the corn protein micropowder obtained in the step S1, wherein the pretreatment conditions are as follows: freezing at-18 deg.C for 24min to obtain pretreated zein;

s3, steaming the pretreated corn protein obtained in the step S2, wherein the steaming conditions are as follows: steaming at 35 deg.C under 0.05Mpa for 26min, adding 0.12% sodium sulfite aqueous solution into steamed zein, the amount of sodium sulfite aqueous solution is 3 times of zein micropowder, soaking for 1.5 hr, filtering, and removing filtrate to obtain processed zein;

s4, adding water into the processed corn protein obtained in the step S3, wherein the adding amount of the water is 11 times of the mass of the processed corn protein, and stirring at the speed of 150r/min for 30min to obtain slurry;

s5, adding a multifunctional additive into the slurry obtained in the step S4, wherein the multifunctional additive is prepared from polyvinylpyrrolidone and sodium alginate in a mass ratio of 12: 7, the adding amount of the multifunctional additive is 0.12 percent of the mass of the slurry, and the mixture is stirred for 25min at the speed of 200r/min to obtain a mixture;

s6, adjusting the pH value of the mixture obtained in the step S5 to 9, heating to 35 ℃, adding alkaline protease, wherein the amount of the alkaline protease is 4 per mill of the mass of the mixture, carrying out enzymolysis for 1.5h, heating to 90 ℃, carrying out enzyme inactivation for 15min, and cooling to 25 ℃ to obtain an enzymolysis liquid;

s7 adding active carbon into the enzymolysis liquid obtained in the step S6, wherein the adding amount of the active carbon is 3% of the mass of the enzymolysis liquid, stirring at the speed of 250r/min for 55min, carrying out suction filtration to obtain filtrate, concentrating the filtrate, and carrying out freeze drying to obtain the corn protein peptide.

The preparation method of the zein peptide is similar to that of example 3.

The difference from example 3 is that no L-fucose is added to the multifunctional additive.

Comparative example 4, a method for extracting zein peptide, comprising the steps of:

s1, crushing the corn protein powder, and sieving the crushed corn protein powder with a 60-mesh sieve to obtain corn protein micropowder;

s2, pretreating the corn protein micropowder obtained in the step S1, wherein the pretreatment conditions are as follows: freezing at-18 deg.C for 24min to obtain pretreated zein;

s3, steaming the pretreated corn protein obtained in the step S2, wherein the steaming conditions are as follows: steaming at 35 deg.C under 0.05Mpa for 26min, adding 0.12% sodium sulfite aqueous solution into steamed zein, the amount of sodium sulfite aqueous solution is 3 times of zein micropowder, soaking for 1.5 hr, filtering, and removing filtrate to obtain processed zein;

s4, adding water into the processed corn protein obtained in the step S3, wherein the adding amount of the water is 11 times of the mass of the processed corn protein, and stirring at the speed of 150r/min for 30min to obtain slurry;

s5, adjusting the pH value of the slurry obtained in the step S4 to 9, heating to 35 ℃, adding alkaline protease, wherein the amount of the alkaline protease is 4 per mill of the mass of the suspension, carrying out enzymolysis for 1.5h, heating to 90 ℃, carrying out enzyme inactivation for 15min, and cooling to 25 ℃ to obtain an enzymolysis solution;

s6 adding active carbon into the enzymolysis liquid obtained in the step S5, wherein the adding amount of the active carbon is 3% of the mass of the enzymolysis liquid, stirring at the speed of 250r/min for 55min, carrying out suction filtration to obtain filtrate, concentrating the filtrate, and carrying out freeze drying to obtain the corn protein peptide.

The preparation method of the zein peptide is similar to that of example 3.

The difference from example 3 is that the step of adding the multifunctional additive is not included.

Test example I measurement of degree of proteolysis

1. Test materials: zein peptides prepared in example 3 and comparative examples 1-4.

2. The test method comprises the following steps:

the degree of proteolysis was determined by pH-Stat titration. Degree of hydrolysis DH ═ V_NaOH×N_NaOH/(α×Mp×H_tot) X 100%, wherein, V_NaOHVolume of base consumed for titration (mL); n is a radical of_NaOHBase equivalent concentration (mol/L) consumed for titration; mp is the total amount of protein involved in proteolysis (g); h_toThe number of gram equivalents of peptide bonds per gram of protein (9.2 mmol/g); alpha is the average degree of dissociation of the amino acid; alpha 10^pH-PK/(1+10^pH-PK) (ii) a pK 7.8+2400 × (298-T)/298T; t273.15 + T; t is the reaction ambient temperature (. degree. C.); the pH is the initial pH of the reaction.

3. And (3) test results:

the test results are shown in table 1.

Table 1: results of measurement of degree of proteolysis

Group of	Example 3	Comparative example 1	Comparative example 2	Comparative example 3	Comparative example 4
						Degree of hydrolysis (%)	45.3	37.8	35.2	38.1	31.9

As can be seen from Table 1, the degree of protein hydrolysis using the extraction method of zein peptide of example 3 of the present invention is significantly higher than that using the extraction method of zein peptide of comparative examples 1-4. Therefore, the extraction method of the corn protein peptide provided by the invention can enable the corn protein to have higher hydrolysis degree.

Test example two measurement of Oxidation resistance

1. Test materials: zein peptides prepared in example 3 and comparative examples 1-4.

2. The test method comprises the following steps:

preparing 7 mmol/L2, 2-dinitro-di (3-ethyl-benzothiazole-6-sulfonic acid) diammonium salt solution (ABTS solution) by using distilled water, mixing the ABTS solution and potassium persulfate solution (the final concentration is 2.45mmol/L) according to the volume ratio of 1: 1 to obtain ABTS free radical stock solution, standing for 12 hours in the dark at room temperature, and then using pH value7.4 concentration 0.2mol/L phosphate buffer solution ABTS free radical stock solution dilution, make it at wavelength 734nm absorbance 0.7 + -0.02, form ABTS working solution. And (3) sucking 180 mu L of ABTS working solution into each well of a 96-well plate by using a pipette gun, adding 20 mu L of sample solution into each well, oscillating for 10s, and measuring the absorbance of the reaction system at the wavelength of 734nm and recording the absorbance As. Add 200. mu.L of PBS solution to each well and measure the absorbance A_B. Adding 180. mu.L ABTS working solution and 20. mu.L PBS solution into each well, and measuring the absorbance as A_C. Maize protein peptide pairs ABTS⁺Clearance (%) of ═ a_C－A_s)/(A_C－A_B)×100。

3. And (3) test results:

the test results are shown in table 2.

Table 2: measurement result of Oxidation resistance

Group of	Example 3	Comparative example 1	Comparative example 2	Comparative example 3	Comparative example 4
						ABTS+Clearance of (C) (%)	77.4	66.2	63.4	68.7	59.6

As can be seen from Table 2, the zein peptide pair ABTS prepared by the zein peptide extracting method of the embodiment 3 of the invention⁺The clearance rate of the ABTS is obviously higher than that of the corn protein peptide pair ABTS prepared by the extraction method of the corn protein peptides of comparative examples 1 to 4⁺Clearance of. Therefore, the corn protein peptide prepared by the extraction method of the corn protein peptide provided by the invention has more excellent oxidation resistance.