阅读说明：本技术 植物蛋白增稠剂及其制备方法 (Vegetable protein thickening agent and preparation method thereof ) 是由 方亚鹏 葛姣 孙翠霞 王晋源 邓念想 孙慢慢 于 2021-01-27 设计创作，主要内容包括：本发明提供了五种豆类植物蛋白增稠剂及其制备方法,属于技术领域天然植物蛋白增稠剂技术领域。本发明的五种豆类蛋白分别源自熊猫豆、黑芸豆、奶花芸豆、豇豆和绿豆,即分别将其的蛋白质通过碱溶酸沉法提取出来,得到豆类蛋白粉,并用乙酸溶液或柠檬酸溶液调节pH值为2.0-3.0,得到蛋白浓度为1-4％(w/v)的各种豆类蛋白溶液；最后分别将熊猫豆、黑芸豆、奶花芸豆、豇豆和绿豆的蛋白溶液置于温度为80-90℃和转速为200-300rpm的条件下加热不同的时间,加热完成后立即将其置于冰浴中冷却终止反应,并干燥,得到熊猫豆、黑芸豆、奶花芸豆、豇豆和绿豆的蛋白纤维增稠剂。本发明方法简单,成本低,所有原料都是源自各种豆类蛋白,没有多余的添加剂,食用安全性极高。(The invention provides five bean plant protein thickeners and a preparation method thereof, belonging to the technical field of natural plant protein thickeners. The five bean proteins are respectively derived from panda beans, black kidney beans, milky flower kidney beans, cowpeas and mung beans, namely the proteins of the five bean proteins are respectively extracted by an alkali-dissolving acid-precipitation method to obtain bean protein powder, and the pH value is adjusted to be 2.0-3.0 by using an acetic acid solution or a citric acid solution to obtain various bean protein solutions with the protein concentration of 1-4% (w/v); and finally, respectively heating the protein solutions of the panda pea, the black kidney bean, the milky flower kidney bean, the cowpea and the mung bean for different times under the conditions that the temperature is 80-90 ℃ and the rotating speed is 200-300rpm, immediately placing the heated protein solutions in an ice bath to cool and terminate the reaction after the heating is finished, and drying the reaction product to obtain the protein fiber thickening agent of the panda pea, the black kidney bean, the milky flower kidney bean, the cowpea and the mung bean. The method is simple, the cost is low, all the raw materials are derived from various bean proteins, no redundant additives are needed, and the edible safety is extremely high.)

1. A vegetable protein thickener characterized by: the vegetable protein thickener is modified vegetable protein obtained by heating panda bean protein solution with the pH value of 2.0-3.0 for 12-24 hours at the temperature of 80-90 ℃ and the rotating speed of 200-300 rpm.

2. A vegetable protein thickener characterized by: the vegetable protein thickening agent is modified vegetable protein obtained by heating black kidney bean protein solution with the pH value of 2.0-3.0 for 10-20 hours at the temperature of 80-90 ℃ and the rotating speed of 200-300 rpm.

3. A vegetable protein thickener characterized by: the vegetable protein thickener is modified vegetable protein obtained by heating a milk flower kidney bean protein solution with the pH value of 2.0-3.0 for 6-16 h under the conditions that the temperature is 80-90 ℃ and the rotating speed is 200-300 rpm.

4. A vegetable protein thickener characterized by: the vegetable protein thickening agent is modified vegetable protein obtained by heating cowpea protein solution with the pH value of 2.0-3.0 for 16-24 hours at the temperature of 80-90 ℃ and the rotating speed of 200-300 rpm.

5. A vegetable protein thickener characterized by: the vegetable protein thickening agent is modified vegetable protein obtained by heating mung bean protein solution with the pH value of 2.0-3.0 for 16-24h at the temperature of 80-90 ℃ and the rotating speed of 200-300 rpm.

6. A method of preparing the vegetable protein thickener of claim 1, wherein: the method comprises the following steps:

peeling and degreasing panda beans, extracting panda bean protein, and drying to obtain panda bean protein powder;

adjusting the pH value of the panda bean protein solution to 2.0-3.0 by using an acetic acid solution or a citric acid solution, and uniformly mixing to obtain the panda bean protein solution with the protein concentration of 1-4% (w/v);

thirdly, heating the panda bean protein solution for 12-24 hours under the conditions that the temperature is 80-90 ℃ and the rotating speed is 200-300rpm, immediately placing the solution in an ice bath to cool and stop the reaction after the heating is finished, and drying the solution to obtain the panda bean protein fiber thickening agent.

7. A method of preparing the vegetable protein thickener of claim 2, wherein: the method comprises the following steps:

removing peel and degreasing of black kidney beans, extracting black kidney bean protein, and drying to obtain black kidney bean protein powder;

adjusting the pH value of the black kidney bean protein solution to 2.0-3.0 by using an acetic acid solution or a citric acid solution, and uniformly mixing to obtain a black kidney bean protein solution with the protein concentration of 1-4% (w/v);

thirdly, heating the black kidney bean protein solution for 10-20 h under the conditions that the temperature is 80-90 ℃ and the rotating speed is 200-300rpm, immediately placing the heated black kidney bean protein solution in an ice bath to cool and terminate the reaction, and drying the reaction product to obtain the black kidney bean protein fiber thickening agent.

8. A method of preparing a vegetable protein thickener according to claim 3 wherein: the method comprises the following steps:

peeling and degreasing the kidney bean of the milk flower, extracting protein of the kidney bean of the milk flower, and drying to obtain protein powder of the kidney bean of the milk flower;

adjusting the pH value of the milky flower kidney bean protein solution to 2.0-3.0 by using an acetic acid solution or a citric acid solution, and uniformly mixing to obtain a milky flower kidney bean protein solution with the protein concentration of 1-4% (w/v);

thirdly, heating the milky flower kidney bean protein solution for 6-16 h under the conditions that the temperature is 80-90 ℃ and the rotating speed is 200-300rpm, immediately placing the milky flower kidney bean protein solution in an ice bath to cool and terminate the reaction after the heating is finished, and drying the milky flower kidney bean protein solution to obtain the milky flower kidney bean protein fiber thickening agent.

9. A method of preparing the vegetable protein thickener of claim 4, wherein: the method comprises the following steps:

peeling and degreasing cowpeas, extracting cowpea protein, and drying to obtain cowpea protein powder;

adjusting the pH value of the cowpea protein solution to 2.0-3.0 by using an acetic acid solution or a citric acid solution, and uniformly mixing to obtain a cowpea protein solution with the protein concentration of 1-4% (w/v);

thirdly, heating the cowpea protein solution for 16-24 hours under the conditions that the temperature is 80-90 ℃ and the rotating speed is 200-300rpm, immediately cooling the cowpea protein solution in an ice bath to terminate the reaction after the heating is finished, and drying the cowpea protein solution to obtain the cowpea protein fiber thickening agent.

10. A method of preparing the vegetable protein thickener of claim 5, wherein: the method comprises the following steps:

peeling and degreasing mung beans, extracting mung bean protein, and drying to obtain mung bean protein powder;

regulating the pH value of the mung bean protein solution to 2.0-3.0 by using an acetic acid solution or a citric acid solution, and uniformly mixing to obtain a mung bean protein solution with the protein concentration of 1-4% (w/v);

thirdly, heating the mung bean protein solution for 16-24 hours under the conditions that the temperature is 80-90 ℃ and the rotating speed is 200-300rpm, immediately placing the mung bean protein solution in an ice bath to cool and stop the reaction after the heating is finished, and drying to obtain the mung bean protein fiber thickening agent.

Technical Field

The invention belongs to the technical field of natural vegetable protein thickeners, and particularly relates to a bean protein thickener and a preparation method thereof.

Background

The bean protein is rich in amino acids, glutamic acid, alanine and aspartic acid, and the content of 8 essential amino acids required by human body is quite reasonable compared with the ideal value suggested by FAO, wherein the essential amino acids are rich in lysine and leucine and play an important role in the development and metabolic regulation of human brain. Globulin is the main component of bean protein, and can reach 60-80%, and is the main storage protein, and in addition, the bean protein also contains albumin, glutelin and alcohol soluble protein. The bean protein has rich nutrients and also has some functional characteristics, such as foamability, emulsibility, water and oil holding property, gel property, etc. The excellent degree of these functional properties is very important for the application of pulse proteins in food processing, which in turn affects their application in functional foods.

Thickeners, also known as gelling agents, are substances that increase the viscosity of latex and liquids and are also known as pastes when used in food products. It can raise the viscosity of the system, and make the system keep uniform and stable suspension state or emulsion state, or form gel. At present, thickeners are widely used in food products, for example, in sauces, jams, yogurts, ice creams and the like, as appropriate for increasing the viscosity of the food or for forming a gel. Thickeners are classified by their chemical structure and composition into two broad categories, polysaccharides and polypeptides. The polysaccharide thickening agent comprises starch, cellulose, pectin, alginic acid and the like, and the thickening agent substances are widely distributed in nature and are also the thickening agents which are used in the food industry at present. The polypeptide thickening agent mainly comprises gelatin, sodium caseinate and the like, belongs to animal protein, has limited sources and higher price, and is less applied to the food product market.

The bean resources (such as panda bean, black kidney bean, milky flower kidney bean, cowpea, mung bean and the like) in China are rich and the planting is wide, wherein the protein content of the bean resources is up to 25-40 percent and is far higher than the animal protein content. Beans are used as an important raw material of a plant-based protein source, have wide sources and low price, have higher nutritional value and have great potential application prospects in the food product industry. In recent years, with consumer demand for healthy diets of low calorie, low fat and low cholesterol, legume proteins of plant-based origin have become the primary choice for nutrition supplementation by consumers.

Disclosure of Invention

At present, natural protein thickeners are generally derived from a portion of animal proteins such as: animal collagen, but no plant protein thickener has been prepared by human, the invention finds five proteins from numerous bean proteins by simple protein modification, and the thickening function can be realized after modification, which is specifically as follows:

a panda plant protein thickener is a modified panda plant protein obtained by heating a panda protein solution with a pH value of 2.0-3.0 at 80-90 ℃ and a rotation speed of 200-300rpm for 12-24 hours.

A black kidney bean vegetable protein thickening agent is modified black kidney bean vegetable protein obtained by heating a black kidney bean protein solution with a pH value of 2.0-3.0 for 10-20 hours at a temperature of 80-90 ℃ and a rotation speed of 200-300 rpm.

A milky flower kidney bean vegetable protein thickening agent is a modified milky flower kidney bean vegetable protein obtained by heating a milky flower kidney bean protein solution with the pH value of 2.0-3.0 for 6-16 hours at the temperature of 80-90 ℃ and the rotating speed of 200-300 rpm.

A cowpea vegetable protein thickening agent is modified cowpea vegetable protein obtained by heating cowpea protein solution with the pH value of 2.0-3.0 for 16-24 hours at the temperature of 80-90 ℃ and the rotating speed of 200-300 rpm.

A mung bean vegetable protein thickening agent is a modified vegetable protein obtained by heating a mung bean protein solution with a pH value of 2.0-3.0 at 80-90 ℃ and at a rotation speed of 200-300rpm for 16-24 h.

Wherein, the concentration of the protein in the protein solution is 1-4% (w/v).

Wherein the pH of the protein solution is adjusted with citric acid or acetic acid.

A preparation method of a panda bean vegetable protein thickener comprises the following steps:

peeling and degreasing panda beans, extracting panda bean protein, and drying to obtain panda bean protein powder;

adjusting the pH value of the panda bean protein solution to 2.0-3.0 by using an acetic acid solution or a citric acid solution, and uniformly mixing to obtain the panda bean protein solution with the protein concentration of 1-4% (w/v);

thirdly, heating the panda bean protein solution for 12-24 hours under the conditions that the temperature is 80-90 ℃ and the rotating speed is 200-300rpm, immediately placing the solution in an ice bath to cool and stop the reaction after the heating is finished, and drying the solution to obtain the panda bean protein fiber thickening agent.

A preparation method of a black kidney bean vegetable protein thickening agent comprises the following steps:

removing peel and degreasing of black kidney beans, extracting black kidney bean protein, and drying to obtain black kidney bean protein powder;

adjusting the pH value of the black kidney bean protein solution to 2.0-3.0 by using an acetic acid solution or a citric acid solution, and uniformly mixing to obtain a black kidney bean protein solution with the protein concentration of 1-4% (w/v);

thirdly, heating the black kidney bean protein solution for 10-20 h under the conditions that the temperature is 80-90 ℃ and the rotating speed is 200-300rpm, immediately placing the heated black kidney bean protein solution in an ice bath to cool and terminate the reaction, and drying the reaction product to obtain the black kidney bean protein fiber thickening agent.

A preparation method of a milky flower kidney bean vegetable protein thickener comprises the following steps:

peeling and degreasing the kidney bean of the milk flower, extracting protein of the kidney bean of the milk flower, and drying to obtain protein powder of the kidney bean of the milk flower;

adjusting the pH value of the milky flower kidney bean protein solution to 2.0-3.0 by using an acetic acid solution or a citric acid solution, and uniformly mixing to obtain a milky flower kidney bean protein solution with the protein concentration of 1-4% (w/v);

thirdly, heating the milky flower kidney bean protein solution for 6-16 h under the conditions that the temperature is 80-90 ℃ and the rotating speed is 200-300rpm, immediately placing the milky flower kidney bean protein solution in an ice bath to cool and terminate the reaction after the heating is finished, and drying the milky flower kidney bean protein solution to obtain the milky flower kidney bean protein fiber thickening agent.

A preparation method of a cowpea vegetable protein thickening agent comprises the following steps:

peeling and degreasing cowpeas, extracting cowpea protein, and drying to obtain cowpea protein powder;

adjusting the pH value of the cowpea protein solution to 2.0-3.0 by using an acetic acid solution or a citric acid solution, and uniformly mixing to obtain a cowpea protein solution with the protein concentration of 1-4% (w/v);

thirdly, heating the cowpea protein solution for 16-24 hours under the conditions that the temperature is 80-90 ℃ and the rotating speed is 200-300rpm, immediately cooling the cowpea protein solution in an ice bath to terminate the reaction after the heating is finished, and drying the cowpea protein solution to obtain the cowpea protein fiber thickening agent.

A preparation method of a mung bean vegetable protein thickening agent comprises the following steps:

peeling and degreasing mung beans, extracting mung bean protein, and drying to obtain mung bean protein powder;

regulating the pH value of the mung bean protein solution to 2.0-3.0 by using an acetic acid solution or a citric acid solution, and uniformly mixing to obtain a mung bean protein solution with the protein concentration of 1-4% (w/v);

thirdly, heating the mung bean protein solution for 16-24 hours under the conditions that the temperature is 80-90 ℃ and the rotating speed is 200-300rpm, immediately placing the mung bean protein solution in an ice bath to cool and stop the reaction after the heating is finished, and drying to obtain the mung bean protein fiber thickening agent.

Advantageous effects

Mechanism of protein self-assembly fibrosis: the native state of the globulin monomers (monomers) is thermally stable and difficult to aggregate. When the globulin is heated, if the heating temperature exceeds the protein denaturation temperature, the globulin is heated and denatured, and hydrophobic groups are exposed on the surface of the molecules, so that the hydrophobic interaction between protein molecules is enhanced. Under the action of heat and strong acid, protein is hydrolyzed to release polypeptide (construction units), and under the combined action of hydrophobic interaction and electrostatic repulsion, the construction units are combined with each other to form fiber precursors (protofibers) and finally form ordered long fibers (fibers). The formation of fibers promotes increased intermolecular entanglement points, thereby increasing the viscosity of the sample.

Although proteins generally have the property of forming a highly ordered structure by self-assembly using proteins as building units, not all proteins are capable of undergoing water-induced liberation of effective polypeptide building units under the action of heat and acid treatment and further self-assembly to form fibers, and therefore a protein fiber sample with high viscosity cannot be formed, and the protein fiber sample cannot be used as a thickener.

The thickener disclosed by the invention is simple in preparation method, free of complex steps, high in edible safety, and in line with the development trend of the natural product thickener advocated at present, all the raw materials are derived from different bean proteins, and no redundant additive is added, so that the thickener has a good market prospect.

Drawings

FIG. 1: graph of thickening performance data for panda bean protein treatment at different times.

FIG. 2: thickening effect of panda pea white treatment for different times.

FIG. 3: graph of thickening performance data for black kidney bean protein treatment at different times.

FIG. 4: and (3) thickening effect graphs of black kidney bean white treatment at different times.

FIG. 5: thickening performance data plots of the creamer kidney bean protein treatment at different times.

FIG. 6: thickening effect graph of the milky flower kidney bean white treatment at different time.

FIG. 7: graph of thickening performance data for cowpea protein treatment at different times.

FIG. 8: thickening effect graph of cowpea protein treatment in different time.

FIG. 9: graph of thickening performance data for mung bean protein treatment at different times.

FIG. 10: thickening effect graph of mung bean protein treatment at different time.

FIG. 11: effect pattern of other four kinds of bean protein in different time.

Detailed Description

The invention is further illustrated by the following examples, which are intended to be purely exemplary of the invention and are not intended to limit its scope, which after reading the present invention, is susceptible of modification in various equivalent forms by those skilled in the art, all falling within the scope of the invention as defined in the appended claims.

Example 1

The embodiment provides a high-viscosity panda bean protein fiber thickener, which is prepared by the following steps:

(1) soaking panda beans in distilled water for 18-36 h, peeling, and sequentially freezing, freeze-drying and grinding the peeled panda beans in a refrigerator at-85 to-70 ℃ to obtain peeled panda bean powder;

(2) mixing the peeled panda bean powder obtained in the step (1) with n-hexane according to a ratio of 1:3-1:6(w/v), stirring for degreasing, repeatedly degreasing for 2-3 times, pouring out the n-hexane, and naturally air-drying in a fume hood for 12 hours to obtain degreased panda bean powder;

(3) uniformly stirring and mixing the defatted panda bean powder obtained in the step (2) with distilled water according to a ratio of 1:10(w/v), and adjusting the pH value of the mixed solution to 9.0-10.0 by using a sodium bicarbonate solution with the concentration of 10% (w/v); magnetically stirring and alkali extracting at the stirring speed of 400-; then the mixed solution is centrifugally separated, the rotating speed is 4500 and 5000rpm/min, and the mixed solution is centrifuged for 20-30mins to obtain alkali extraction supernatant; adding 10% (w/v) acid solution into the alkali extraction supernatant, and adjusting pH to 4.0-5.0; centrifuging at the speed of 4500-; uniformly mixing the precipitate with pure water according to a ratio of 1:10(w/v), adjusting the pH value to 7.0-8.0 by using a sodium bicarbonate solution with the concentration of 10% (w/v) until the solution is clear to obtain a redissolution; and sequentially freezing the redissolved solution in a refrigerator at the temperature of between 85 and 70 ℃ below zero, and carrying out freeze drying and grinding treatment to obtain the required panda bean protein powder.

(4) Adding water into the panda bean protein powder at room temperature, stirring and mixing uniformly, and adjusting the pH value of the protein solution to 2.0-3.0 by using an acetic acid solution with the concentration of 2-50% (w/v) to finally obtain the panda bean protein solution with the concentration of 1-4% (w/v).

(5) And (3) putting the panda bean protein solution obtained in the step (4) into a glass bottle, then heating the glass bottle in a water bath kettle with the temperature of 80-90 ℃ and the rotation speed of 200-300rpm for 12-24 h, immediately cooling the glass bottle in an ice bath for 5-10min after heating to terminate the reaction, and performing spray drying to obtain the panda bean protein fiber thickener.

The use method of the thickening agent is as follows: the thickening agent is directly dissolved in water to complete the thickening function.

Example 2

The embodiment provides a high-viscosity black kidney bean protein fiber thickener, and a preparation method of the black kidney bean protein fiber thickener comprises the following steps:

(1) soaking black kidney beans in distilled water for 18-36 h, peeling, and sequentially freezing, freeze-drying and grinding the obtained peeled black kidney beans in a refrigerator at-85 to-70 ℃ to obtain peeled black kidney bean powder;

(2) mixing the peeled black kidney bean powder in the step (1) with ether according to a ratio of 1:3-1:6(w/v), stirring for degreasing, repeatedly degreasing for 2-3 times, pouring out ether, and naturally air-drying in a fume hood for 12 hours to obtain degreased black kidney bean powder;

(3) uniformly stirring and mixing the defatted black kidney bean powder in the step (2) with distilled water according to a ratio of 1:10(w/v), and adjusting the pH value of the mixed solution to 9.0-10.0 by using a sodium bicarbonate solution with the concentration of 10% (w/v); magnetically stirring and alkali extracting at the stirring speed of 400-; then the mixed solution is centrifugally separated, the rotating speed is 4500 and 5000rpm/min, and the mixed solution is centrifuged for 20-30mins to obtain alkali extraction supernatant; adding 10% (w/v) acid solution into the alkali extraction supernatant, and adjusting pH to 4.0-5.0; centrifuging at the speed of 4500-; uniformly mixing the precipitate with pure water according to a ratio of 1:10(w/v), adjusting the pH value to 7.0-8.0 by using a sodium bicarbonate solution with the concentration of 10% (w/v) until the solution is clear to obtain a redissolution; and (3) sequentially freezing the redissolved solution in a refrigerator at-85 to-70 ℃, and carrying out freeze drying and grinding treatment to obtain the required black kidney bean protein powder.

(4) Adding water into black kidney bean protein powder at room temperature, stirring and mixing uniformly, adjusting the pH value of the protein solution to 2.0-3.0 by using a citric acid solution with the concentration of 2-15% (w/v), and finally obtaining a black kidney bean protein solution with the concentration of 1-4% (w/v);

(5) and (3) putting the black kidney bean protein solution obtained in the step (4) into a glass bottle, then heating the glass bottle in a water bath kettle with the temperature of 80-90 ℃ and the rotation speed of 200-300rpm for 10-20 h, immediately cooling the glass bottle in an ice bath for 5-10min after heating to terminate the reaction, and performing forced air drying to obtain the black kidney bean protein fiber thickener.

The use method of the thickening agent is as follows: the thickening agent is directly dissolved in water to complete the thickening function.

Example 3

The embodiment provides a high-viscosity milk flower kidney bean protein fiber thickener, which is prepared by the following steps:

(1) soaking the kidney bean with the milk flower in distilled water for 18-36 h, peeling, and sequentially freezing, freeze-drying and grinding the obtained peeled kidney bean with the milk flower in a refrigerator at-85-70 ℃ to obtain the peeled kidney bean powder with the milk flower;

(2) mixing the peeled milk flower kidney bean powder in the step (1) with No. 6 extraction solvent oil according to a ratio of 1:3-1:6(w/v), stirring for degreasing, repeatedly degreasing for 2-3 times, pouring out the No. 6 extraction solvent oil, and naturally drying in a fume hood for 12 hours to obtain degreased milk flower kidney bean powder;

(3) uniformly stirring and mixing the defatted milk flower kidney bean powder in the step (2) with distilled water according to a ratio of 1:10(w/v), and adjusting the pH value of the mixed solution to 9.0-10.0 by using a sodium bicarbonate solution with the concentration of 10% (w/v); magnetically stirring and alkali extracting at the stirring speed of 400-; then the mixed solution is centrifugally separated, the rotating speed is 4500 and 5000rpm/min, and the mixed solution is centrifuged for 20-30mins to obtain alkali extraction supernatant; adding 10% (w/v) acid solution into the alkali extraction supernatant, and adjusting pH to 4.0-5.0; centrifuging at the speed of 4500-; uniformly mixing the precipitate with pure water according to a ratio of 1:10(w/v), adjusting the pH value to 7.0-8.0 by using a sodium bicarbonate solution with the concentration of 10% (w/v) until the solution is clear to obtain a redissolution; and (3) sequentially freezing the redissolved solution in a refrigerator at-85 to-70 ℃, and carrying out freeze drying and grinding treatment to obtain the required milk flower kidney bean protein powder.

(4) Adding water into the milk flower kidney bean protein powder at room temperature, stirring and mixing uniformly, and adjusting the pH value of the protein solution to 2.0-3.0 by using a phosphoric acid solution with the concentration of 10% (w/v) to finally obtain a milk flower kidney bean protein solution with the concentration of 1-4% (w/v);

(5) and (3) putting the milky flower kidney bean protein solution obtained in the step (4) into a glass bottle, then heating the milky flower kidney bean protein solution in a water bath kettle with the temperature of 80-90 ℃ and the rotating speed of 200-300rpm for 6-16 h, immediately cooling the milky flower kidney bean protein solution in an ice bath for 5-10min after heating to terminate the reaction, and freeze-drying to obtain the milky flower kidney bean protein fiber thickener.

The use method of the thickening agent is as follows: the thickening agent is directly dissolved in water to complete the thickening function.

Example 4

The embodiment provides a high-viscosity cowpea protein fiber thickening agent, and the preparation method of the cowpea protein fiber thickening agent comprises the following steps:

(1) soaking cowpeas in distilled water for 18-36 h, peeling, and sequentially freezing, freeze-drying and grinding the obtained peeled cowpeas in a refrigerator at-85 to-70 ℃ to obtain the peeled cowpea powder.

(2) Mixing the peeled cowpea powder in the step (1) with petroleum ether according to the ratio of 1:3-1:6(w/v), stirring for degreasing, repeatedly degreasing for 2-3 times, pouring out the petroleum ether, and naturally air-drying in a fume hood for 12h to obtain the degreased cowpea powder.

(3) Uniformly stirring and mixing the defatted cowpea powder in the step (2) with distilled water according to a ratio of 1:10(w/v), and adjusting the pH value of the mixed solution to 9.0-10.0 by using a sodium bicarbonate solution with the concentration of 10% (w/v); magnetically stirring and alkali extracting at the stirring speed of 400-; then the mixed solution is centrifugally separated, the rotating speed is 4500 and 5000rpm/min, and the mixed solution is centrifuged for 20-30mins to obtain alkali extraction supernatant; adding 10% (w/v) acid solution into the alkali extraction supernatant, and adjusting pH to 4.0-5.0; centrifuging at the speed of 4500-; uniformly mixing the precipitate with pure water according to a ratio of 1:10(w/v), adjusting the pH value to 7.0-8.0 by using a sodium bicarbonate solution with the concentration of 10% (w/v) until the solution is clear to obtain a redissolution; and (3) sequentially freezing the redissolved solution in a refrigerator at-85 to-70 ℃, and carrying out freeze drying and grinding treatment to obtain the required cowpea protein powder.

(4) Adding water into cowpea protein powder at room temperature, stirring and mixing uniformly, and adjusting the pH value of the protein solution to 2.0-3.0 by using a citric acid solution with the concentration of 15% (w/v) to finally obtain a cowpea protein solution with the concentration of 1-4% (w/v);

(5) and (3) putting the cowpea protein solution obtained in the step (4) into a glass bottle, then heating the cowpea protein solution in a water bath kettle with the temperature of 80-90 ℃ and the rotation speed of 200-300rpm for 16-24h, immediately cooling the cowpea protein solution in an ice bath for 5-10min after heating to terminate the reaction, and carrying out vacuum drying to obtain the cowpea protein fiber thickener.

The use method of the thickening agent is as follows: the thickening agent is directly dissolved in water to complete the thickening function.

Example 5

This example provides a high viscosity mung bean protein fiber thickener prepared as follows:

(1) soaking mung beans in distilled water for 18-36 h, peeling, and sequentially freezing, freeze-drying and grinding the peeled mung beans in a refrigerator at the temperature of-85 to-70 ℃ to obtain the peeled mung bean powder.

(2) Mixing the peeled mung bean powder obtained in the step (1) with petroleum ether according to the ratio of 1:3-1:6(w/v), stirring for degreasing, repeatedly degreasing for 2-3 times, pouring out the petroleum ether, and naturally air-drying in a fume hood for 12h to obtain the degreased mung bean powder.

(3) Uniformly stirring and mixing the defatted mung bean powder in the step (2) with distilled water according to a ratio of 1:10(w/v), and adjusting the pH value of the mixed solution to 9.0-10.0 by using a sodium bicarbonate solution with the concentration of 10% (w/v); magnetically stirring and alkali extracting at the stirring speed of 400-; then the mixed solution is centrifugally separated, the rotating speed is 4500 and 5000rpm/min, and the mixed solution is centrifuged for 20-30mins to obtain alkali extraction supernatant; adding 10% (w/v) acid solution into the alkali extraction supernatant, and adjusting pH to 4.0-5.0; centrifuging at the speed of 4500-; uniformly mixing the precipitate with pure water according to a ratio of 1:10(w/v), adjusting the pH value to 7.0-8.0 by using a sodium bicarbonate solution with the concentration of 10% (w/v) until the solution is clear to obtain a redissolution; and (3) sequentially freezing the redissolved solution in a refrigerator at the temperature of between 85 ℃ below zero and 70 ℃ below zero, and carrying out freeze drying and grinding treatment to obtain the required mung bean protein powder.

(4) Adding water into mung bean protein powder at room temperature, stirring and mixing uniformly, and adjusting the pH value of the protein solution to 2.0-3.0 by using a citric acid solution with the concentration of 15% (w/v) to finally obtain a mung bean protein solution with the concentration of 1-4% (w/v);

(5) and (3) putting the mung bean protein solution obtained in the step (4) into a glass bottle, then heating the mung bean protein solution in a water bath kettle at the temperature of 80-90 ℃ and the rotation speed of 200-300rpm for 16-24h, immediately cooling the mung bean protein solution in an ice bath for 5-10min after heating to stop the reaction, and performing vacuum drying to obtain the mung bean protein fiber thickener.

The use method of the thickening agent is as follows: the thickening agent is directly dissolved in water to complete the thickening function.

Table 1: different pulse protein samples at a shear rate of 0.1s^-1Shear viscosity (Pa. s) corresponding to time

Time (h)	Panda bean protein	Black kidney bean protein	Daihua kidney bean protein	Cowpea protein	Mung bean protein
						0	0.000803	0.000855	0.001698	0.1817	0.00216
2	0.000959	0.001261	0.002954	0.001058	0.001136
						4	0.002267	0.001882	0.1007	0.001923	0.001073
6	0.003551	0.004673	11.55	0.001169	0.001472
						8	0.01913	0.7514	3.022	0.001593	0.002675
10	3.071	11.92	3.285	0.001945	0.008489
						12	11.02	5.661	5.64	0.01081	0.2196
16	11.82	2.809	6.254	4.262	8.363
						20	6.02	11.25	2.317	4.67	2.738
24	7.596	19.31	1.01	3.373	3.747

Table 1 shows the shear rate of each protein at 0.1s after heating and magnetic stirring for different time periods in examples 1 to 4^-1The shear viscosity (Pa s) corresponding to the shear viscosity (Pa s) is shown in the table above, different bean protein samples have different viscosities at different times, the inventor conducts experiments on various bean proteins on the market, only the five bean proteins can form high-viscosity protein fibers, and other bean proteins cannot obviously increase the viscosity, which is related to the subunit compositions and the amino acid compositions of the five proteins. The applicant also selects peas, broad beans, soybeans and adzuki beans, and the proteins of the peas, the broad beans, the soybeans and the adzuki beans cannot form the thickening agent after being treated by the method.