Chickpea polypeptide purification method

Abstract

The invention belongs to the technical field of chickpea polypeptide purification, and particularly relates to a chickpea polypeptide purification method. The chickpea polypeptide purification method comprises the following steps: (1) preparing a chickpea powder mixed solution; (2) sequentially carrying out enzymolysis on the chickpea powder mixed solution by using alkaline protease, neutral protease and bromelain to obtain enzymatic hydrolysate; (3) adding compound bacteria into the enzymatic hydrolysate, fermenting, and sterilizing to obtain fermentation liquor; and (4) centrifuging the fermentation liquor, taking supernate, and performing ultrafiltration by using an ultrafiltration membrane to obtain chickpea polypeptide liquid. And (5) freeze-drying the chickpea polypeptide liquid to obtain purified chickpea polypeptide powder. The purified chickpea polypeptide powder prepared by the preparation method disclosed by the invention is high in nutritional value and good in storage stability when being used for preparing yoghourt.

Description

Technical Field

[0001] The invention belongs to the technical field of chickpea polypeptide purification, and particularly relates to a chickpea polypeptide purification method. Background Art

[0002] Chickpea peptides not only have potential biological activity, but are also rich in a variety of nutrients, which makes them widely used in the food industry, especially in fermented dairy products such as yogurt. Chickpea peptides can increase the protein content of yogurt, provide more essential amino acids, and enhance its nutritional value, which is very beneficial for people who need to supplement protein (such as athletes, the elderly, etc.). At the same time, chickpea peptides contain a certain amount of dietary fiber, which can increase the satiety of yogurt, promote intestinal health, and improve digestive function.

[0003] When chickpea peptides currently available on the market are added to milk containing lactobacilli to prepare yogurt, due to the low purity of the peptides, a series of problems may occur, affecting the quality, flavor, texture and functionality of the yogurt. 1. Unstable fermentation process: Inhibition or promotion of lactobacillus growth: Impurities in chickpea peptides (such as incompletely hydrolyzed proteins, polysaccharides, phenolic compounds, etc.) may inhibit or promote the growth of lactobacilli. Some impurities may compete with lactobacilli for nutrients or release metabolites that inhibit bacterial growth, resulting in slower or uneven fermentation. On the contrary, some impurities may provide additional carbon or nitrogen sources, accelerate the fermentation process, and cause the yogurt to coagulate prematurely or be too acidic. 2. Abnormal flavor and aroma: Impurities in chickpea peptides may produce undesirable flavors during the fermentation process. For example, incompletely hydrolyzed proteins may decompose into bitter or peptides, affecting the overall taste of the yogurt; some impurities may adsorb or consume volatile aroma components in the yogurt, causing the aroma of the yogurt to weaken or disappear, affecting its flavor quality. 3. Stability issues: Some impurities may continue to catalyze the reaction, causing changes in the texture and flavor of the yogurt, affecting its stability and shelf life. 4. Decreased nutritional value: If chickpea peptides contain too many impurities, the content of biologically active peptides may be reduced, weakening their antioxidant, anti-inflammatory, and immunomodulatory functions. This will directly affect the functional value of yogurt, especially for consumers who hope to gain health benefits from eating yogurt. At the same time, the presence of impurities may interfere with the digestion and absorption of peptides and reduce their bioavailability. For example, incompletely hydrolyzed proteins may be difficult to be effectively absorbed in the intestines, resulting in a decrease in their nutritional value.

[0004] Currently, chickpea peptides are mainly purified by ultrafiltration membranes, which have large pore sizes and cannot effectively remove small molecule impurities (such as organic acids, phenolic compounds, minerals, etc.). These small molecules will still affect the growth of lactobacilli, resulting in an unstable fermentation process or affecting the flavor and aroma of yogurt.

[0005] Therefore, a method for purifying chickpea polypeptides is urgently needed. Summary of the invention

[0006] The purpose of the invention is to provide a method for purifying chickpea polypeptide.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A method for purifying chickpea polypeptides comprises the following steps:

[0009] (1) drying and crushing chickpea pods to obtain chickpea flour; mixing the chickpea flour with water and adjusting the pH to 8.5-8.7 to obtain a chickpea flour mixed solution;

[0010] (2) adding alkaline protease to the chickpea flour mixture, performing enzymolysis at 45° C.-48° C. for 60-70 minutes; inactivating the enzyme, adjusting the pH value to neutral, adding neutral protease, performing enzymolysis at 45° C.-48° C. for 30-50 minutes; inactivating the enzyme, continuing to add bromelain, performing enzymolysis at 45° C.-48° C. for 30-40 minutes; inactivating the enzyme, and obtaining an enzymolysis solution;

[0011] (3) adding composite bacteria to the enzymatic hydrolyzate for fermentation and sterilization to obtain a fermentation liquid;

[0012] (4) After the fermentation liquid is centrifuged, the supernatant is taken out and ultrafiltration is performed using an ultrafiltration membrane to obtain a chickpea polypeptide liquid.

[0013] (5) The chickpea polypeptide liquid is subjected to a low-temperature freeze-drying treatment to obtain a purified chickpea polypeptide powder.

[0014] Furthermore, in the step (1), the chickpeas are dried and crushed to less than 100 meshes to obtain chickpea flour.

[0015] Furthermore, in the step (1), chickpea flour and water are mixed in a weight ratio of 1:(10-12).

[0016] Furthermore, in step (1), the pH value is adjusted to 8.5-8.7 using a 5-7 wt% NaOH solution.

[0017] Furthermore, in step (2), citric acid with a concentration of 7-9 wt % is used to adjust the pH value to neutral.

[0018] Furthermore, in the step (2), the amount of alkaline protease is 600-800u / mL of chickpea flour mixture; the amount of neutral protease is 1000-1200u / mL of chickpea flour mixture; and the amount of bromelain is 800-900u / mL of chickpea flour mixture.

[0019] The present invention can improve the purity of chickpea polypeptides and the small intestinal propulsion rate of chickpea polypeptides by using enzymes of specific types and amounts to perform gradient fermentation on chickpeas. By selecting a plurality of proteases for combined use, chickpea proteins can be hydrolyzed at multiple levels at different stages. First, endoproteases are used to decompose the proteins into larger polypeptide fragments, and then exoproteases are used to further decompose these polypeptide fragments into smaller peptide segments or amino acids. This multi-enzyme combination method can ensure that the proteins are fully hydrolyzed, reduce the residual proteins that are not completely hydrolyzed, and thus improve the purity of the polypeptides. Some short-chain polypeptides in chickpea polypeptides have the effect of prebiotics, which can promote the growth of beneficial bacteria in the intestines and inhibit the reproduction of harmful bacteria. The increase of beneficial bacteria can improve the balance of intestinal microecology, promote intestinal health, and thus improve the small intestinal propulsion rate.

[0020] Furthermore, the fermentation conditions in step (3) are: fermentation at 35-40° C. for 15-20 hours.

[0021] Furthermore, the composite bacteria in step (3) include Lactobacillus casei, Bifidobacterium bifidum and Bifidobacterium longum.

[0022] Furthermore, in step (3), the amount of Lactobacillus casei is 10 7 -10 8 CFU / mL enzymatic solution; the dosage of Bifidobacterium bifidum is 10 9 -10 10 CFU / mL enzymatic solution; the dosage of Bifidobacterium longum is 10 8 -10 9 CFU / mL enzymatic solution.

[0023] The present invention uses a specific composite bacteria for fermentation after enzymatic hydrolysis to prepare a polypeptide, which can improve the sensory effect of yogurt and improve the stability of yogurt. By selecting a specific composite bacteria, the synergistic generation of multiple metabolites can be achieved during the fermentation process, and the flavor, texture and functionality of the yogurt can be enhanced. The active components produced during the composite bacteria fermentation process can adjust the pH value of the yogurt and inhibit the growth of harmful microorganisms. In addition, the substances produced by the composite bacteria can further inhibit the reproduction of harmful microorganisms, ensuring the safety and stability of the yogurt.

[0024] Furthermore, in step (4), ultrafiltration is performed using a 3000-4000Da ultrafiltration membrane.

[0025] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0026] 1. The present invention can improve the purity of chickpea polypeptides and the small intestine propulsion rate of chickpea polypeptides by using specific types and amounts of enzymes to perform gradient fermentation on chickpeas.

[0027] 2. The polypeptide prepared by the present invention is fermented with specific composite bacteria after enzymatic hydrolysis, and the use of the polypeptide in preparing yogurt can improve the sensory effect of the yogurt and improve the stability of the yogurt. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The raw materials used in the following examples of the present invention are all commercially available products:

[0030] Lactobacillus brevis, number: SHBCCD14346, was purchased from Shanghai Microbiological Collection Center.

[0031] Lactobacillus plantarum, number: CCTCCAB2010210, was purchased from China Center for Type Culture Collection.

[0032] Bifidobacterium animalis, number: SHBCCD24407AS1.1852, was purchased from China Center for Type Culture Collection.

[0033] Lactobacillus casei, number: SHBCCD24737, was purchased from Shanghai Microbiological Collection Center.

[0034] Bifidobacterium bifidum, number: SHBCCD24408ATCC35914, was purchased from Shanghai Microbiological Collection Center.

[0035] Bifidobacterium longum was purchased from Shanghai Microbiological Collection Center, with the number: SHBCCD24310.

[0036] The enzymes used in the present invention were purchased from Shanghai Yuanye Biotechnology Co., Ltd. Alkaline protease, item number S10154 Neutral protease, item number S10013.

[0037] Example 1

[0038] This embodiment provides a method for purifying chickpea polypeptides, comprising the following steps:

[0039] (1) drying chickpea pods and crushing them to less than 100 mesh to obtain chickpea flour; mixing the chickpea flour and water in a weight ratio of 1:11, and adjusting the pH to 8.6 with a 7wt% NaOH solution to obtain a chickpea flour mixed solution;

[0040] (2) adding alkaline protease to the chickpea flour mixture, and performing enzymolysis at 46° C. for 65 minutes; inactivating the enzyme, adjusting the pH value to neutral with 9 wt % citric acid, adding neutral protease, and performing enzymolysis at 47° C. for 40 minutes; inactivating the enzyme, continuing to add bromelain, and performing enzymolysis at 46° C. for 35 minutes; inactivating the enzyme, and obtaining an enzymolysis solution;

[0041] In the step (2), the amount of alkaline protease is 700u / mL chickpea flour mixture; the amount of neutral protease is 1100u / mL chickpea flour mixture; and the amount of bromelain is 850u / mL chickpea flour mixture.

[0042] (3) adding composite bacteria to the enzymatic hydrolyzate, fermenting at 38° C. for 16 h, and sterilizing to obtain a fermentation liquid; the composite bacteria include Lactobacillus casei, Bifidobacterium bifidum, and Bifidobacterium longum;

[0043] The dosage of Lactobacillus casei is 10 7 CFU / mL enzymatic solution; the dosage of Bifidobacterium bifidum is 10 10 CFU / mL enzymatic solution; the dosage of Bifidobacterium longum is 10 8 CFU / mL enzymatic solution;

[0044] (4) After the fermentation liquid is centrifuged, the supernatant is taken and ultrafiltered using a 3000Da ultrafiltration membrane to obtain a chickpea polypeptide liquid.

[0045] (5) The chickpea polypeptide liquid is subjected to a low-temperature freeze-drying treatment to obtain a purified chickpea polypeptide powder.

[0046] Example 2

[0047] This embodiment provides a method for purifying chickpea polypeptides, comprising the following steps:

[0048] (1) drying chickpea pods and crushing them to less than 100 mesh to obtain chickpea flour; mixing the chickpea flour and water in a weight ratio of 1:12, and adjusting the pH to 8.7 with a 7wt% NaOH solution to obtain a chickpea flour mixed solution;

[0049] (2) adding alkaline protease to the chickpea flour mixture, and performing enzymolysis at 48° C. for 70 minutes; inactivating the enzyme, adjusting the pH value to neutral with 9 wt % citric acid, adding neutral protease, and performing enzymolysis at 48° C. for 30 minutes; inactivating the enzyme, continuing to add bromelain, and performing enzymolysis at 48° C. for 30 minutes; inactivating the enzyme, and obtaining an enzymolysis solution;

[0050] In the step (2), the amount of alkaline protease is 800u / mL of chickpea flour mixture; the amount of neutral protease is 1000u / mL of chickpea flour mixture; and the amount of bromelain is 900u / mL of chickpea flour mixture.

[0051] (3) adding composite bacteria to the enzymatic hydrolyzate, fermenting at 40° C. for 15 h, and sterilizing to obtain a fermentation liquid; the composite bacteria include Lactobacillus casei, Bifidobacterium bifidum, and Bifidobacterium longum;

[0052] The dosage of Lactobacillus casei is 10 7 CFU / mL enzymatic solution; the dosage of Bifidobacterium bifidum is 10 9 CFU / mL enzymatic solution; the dosage of Bifidobacterium longum is 10 8 CFU / mL enzymatic solution;

[0053] (4) After the fermentation liquid is centrifuged, the supernatant is taken and ultrafiltered using a 4000Da ultrafiltration membrane to obtain a chickpea polypeptide liquid.

[0054] (5) The chickpea polypeptide liquid is subjected to a low-temperature freeze-drying treatment to obtain a purified chickpea polypeptide powder.

[0055] Comparative Example 1

[0056] The difference between this comparative example and Example 1 is that no fermentation is performed.

[0057] A chickpea polypeptide purification method comprises the following steps:

[0058] (1) drying chickpea pods and crushing them to less than 100 mesh to obtain chickpea flour; mixing the chickpea flour and water in a weight ratio of 1:11, and adjusting the pH to 8.6 with a 7wt% NaOH solution to obtain a chickpea flour mixed solution;

[0059] (2) adding alkaline protease to the chickpea flour mixture, and performing enzymolysis at 46° C. for 65 minutes; inactivating the enzyme, adjusting the pH value to neutral with 9 wt % citric acid, adding neutral protease, and performing enzymolysis at 47° C. for 40 minutes; inactivating the enzyme, continuing to add bromelain, and performing enzymolysis at 46° C. for 35 minutes; inactivating the enzyme, and obtaining an enzymolysis solution;

[0060] In the step (2), the amount of alkaline protease is 700u / mL chickpea flour mixture; the amount of neutral protease is 1100u / mL chickpea flour mixture; and the amount of bromelain is 850u / mL chickpea flour mixture.

[0061] (3) After the enzymatic hydrolyzate is centrifuged, the supernatant is taken and ultrafiltered using a 3000Da ultrafiltration membrane to obtain a chickpea polypeptide liquid.

[0062] (4) The chickpea polypeptide liquid is subjected to a low-temperature freeze-drying treatment to obtain a purified chickpea polypeptide powder.

[0063] Comparative Example 2

[0064] The difference between this comparative example and Example 1 is that the neutral protease is replaced by ficin and the bromelain is replaced by pectinase.

[0065] A chickpea polypeptide purification method comprises the following steps:

[0066] (1) drying chickpea pods and crushing them to less than 100 mesh to obtain chickpea flour; mixing the chickpea flour and water in a weight ratio of 1:11, and adjusting the pH to 8.6 with a 7wt% NaOH solution to obtain a chickpea flour mixed solution;

[0067] (2) adding alkaline protease to the chickpea flour mixture, and performing enzymolysis at 46° C. for 65 minutes; inactivating the enzyme, adjusting the pH value to neutral with 9 wt % citric acid, adding ficin, and performing enzymolysis at 47° C. for 40 minutes; inactivating the enzyme, and continuously adding pectinase, and performing enzymolysis at 46° C. for 35 minutes; inactivating the enzyme, and obtaining an enzymolysis solution;

[0068] In the step (2), the amount of alkaline protease used is 700u / mL chickpea flour mixed solution; the amount of ficin used is 1100u / mL chickpea flour mixed solution; and the amount of pectinase used is 850u / mL chickpea flour mixed solution.

[0069] (3) adding composite bacteria to the enzymatic hydrolyzate, fermenting at 38° C. for 16 h, and sterilizing to obtain a fermentation liquid; the composite bacteria include Lactobacillus casei, Bifidobacterium bifidum, and Bifidobacterium longum;

[0070] The dosage of Lactobacillus casei is 10 7 CFU / mL enzymatic solution; the dosage of Bifidobacterium bifidum is 10 10 CFU / mL enzymatic solution; the dosage of Bifidobacterium longum is 10 8 CFU / mL enzymatic solution;

[0071] (4) After the fermentation liquid is centrifuged, the supernatant is taken and ultrafiltered using a 3000Da ultrafiltration membrane to obtain a chickpea polypeptide liquid.

[0072] (5) The chickpea polypeptide liquid is subjected to a low-temperature freeze-drying treatment to obtain a purified chickpea polypeptide powder.

[0073] Comparative Example 3

[0074] The difference between this comparative example and Example 1 is that in the step (2), the amount of alkaline protease used is 1100u / mL chickpea flour mixture; the amount of neutral protease used is 8500u / mL chickpea flour mixture; and the amount of bromelain used is 700u / mL chickpea flour mixture.

[0075] Comparative Example 4

[0076] The difference between this comparative example and Example 1 is that the composite bacteria include Lactobacillus brevis, Lactobacillus plantarum and Bifidobacterium animalis. The dosage of Lactobacillus brevis is 10 7 CFU / mL enzymatic solution; the dosage of Lactobacillus plantarum is 10 10 CFU / mL enzymatic solution; the dosage of animal Bifidobacterium is 10 8 CFU / mL enzymatic solution.

[0077] Comparative Example 5

[0078] The difference between this comparative example and Example 1 is that the dosage of Lactobacillus casei is 10 10 CFU / mL enzymatic solution; the dosage of Bifidobacterium bifidum is 10 8 CFU / mL enzymatic solution; the dosage of Bifidobacterium longum is 10 7 CFU / mL enzymatic solution.

[0079] Performance Testing

[0080] 1. Using the chickpea polypeptide powder prepared in Examples 1-2 and Comparative Examples 1-5 to prepare yogurt, the specific steps are as follows:

[0081] (1) Weigh the raw materials according to the following weight percentages: chickpea polypeptide 9%, lactobacillus 1%, thermophilic streptococcus 1%, xylose 7%, whey protein 5%, and the remainder fresh milk.

[0082] (2) Heat half of the milk to 50° C., add chickpea polypeptide, xylose and whey protein, stir evenly, and then mix in the remaining milk to obtain a mixed material.

[0083] (3) preheating, degassing, homogenizing, sterilizing, cooling, inoculating bacteria, and fermenting the mixture at 45° C. When the acidity of the mixture reaches 70° C., the fermentation is stopped, and the mixture is pasteurized to obtain a finished chickpea polypeptide yogurt.

[0084] 2. Perform performance test on the chickpea polypeptide yogurt prepared above.

[0085] (1) Sensory test: 100 volunteers were selected to give a comprehensive score on the taste, aroma and appearance of the yogurt, with a score range of 1-10. The average value was calculated. The higher the average value, the better the quality of the yogurt.

[0086] Table 1 Performance test results

[0087] Sensory score Example 1 8.7 Example 2 8.5 Comparative Example 1 7.1 Comparative Example 2 7.4 Comparative Example 3 8.1 Comparative Example 4 7.6 Comparative Example 5 7.9

[0088] (2) Evaluation of the effect of yogurt on constipation model mice: BALB / c male mice, 8 mice per group, were gavaged at 9:00 am every day.

[0089] Each BALB / c male mouse gavaged with normal saline throughout the whole process served as the normal control group (NC).

[0090] Each mouse was gavaged with 0.25 mL of normal saline for 2 weeks and then gavaged with 5 mg / kg of loperamide for 3 days as the constipation model group (CM).

[0091] Each mouse was gavaged with 0.25 mL of phenolphthalein for 2 weeks and then gavaged with 5 mg / kg of loperamide for 3 days as the positive drug group (PC).

[0092] Each mouse was gavaged with 0.25 mL of yogurt for 2 weeks and then gavaged with 5 mg / kg of loperamide for 3 days as the positive drug group (PC).

[0093] Determination of the small intestinal propulsion rate of mice: On the third night, the mouse food was removed, and the mice were fasted for 12 hours and allowed to drink water freely. On the second morning, the mice were gavaged with 0.4 mL of phenol red meal, and 20 minutes later, the mice were killed by cervical dislocation. After soaking it in 75% alcohol for disinfection, the abdominal cavity was opened, the stomach was found, the small intestine segment was quickly separated, placed on filter paper, excess blood was sucked away, the small intestine was gently straightened, and carefully laid on white paper, the total length of the small intestine and the distance the phenol red meal advanced forward were measured, and the small intestinal propulsion rate was calculated according to the following formula:

[0094] Small intestine propulsion rate (%) = distance of phenol red meal propulsion / total small intestine length*100%.

[0095] Table 2 Results of small intestinal propulsion rate measurement

[0096]

[0097]

[0098] 3. The yogurt was placed in a 30°C environment for 3 months to observe whether water precipitation occurred. The results are shown in Table 3.

[0099] Table 3 Storage stability of yogurt

[0100] stability Example 1 No water separated Example 2 No water separated Comparative Example 1 water analysis Comparative Example 2 water analysis Comparative Example 3 Slight dehydration Comparative Example 4 water analysis Comparative Example 5 Slight dehydration

[0101] From the above performance test results, it can be seen that the chickpea polypeptides of Examples 1-2 have high sensory quality, the yogurt prepared therefrom has good stability, and the intestinal propulsion rate is high, which is of great significance for digestive health, nutrient absorption and overall intestinal function, especially the comprehensive performance of Example 1 is the most outstanding.

[0102] The comparative examples, however, are significantly inferior to the embodiments in the corresponding performance tests because they do not adopt the necessary technical solutions. In comparative example 1, no fermentation is performed, the sensory quality of the yogurt decreases, and the storage stability decreases; the types and amounts of enzymes used in comparative examples 2-3 are different, and the intestinal propulsion rate of the prepared yogurt decreases; the types and amounts of composite bacteria in comparative examples 4-5 are changed, and the stability of the yogurt decreases. The above is 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 principles of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A chickpea polypeptide purification method, characterized in that: The following steps are involved: (1) drying and crushing chickpea pods to obtain chickpea flour; mixing the chickpea flour with water and adjusting the pH to 8.5-8.7 to obtain a chickpea flour mixed solution; (2) adding alkaline protease to the chickpea flour mixture, performing enzymolysis at 45° C.-48° C. for 60-70 minutes; inactivating the enzyme, adjusting the pH value to neutral, adding neutral protease, performing enzymolysis at 45° C.-48° C. for 30-50 minutes; inactivating the enzyme, continuing to add bromelain, performing enzymolysis at 45° C.-48° C. for 30-40 minutes; inactivating the enzyme, and obtaining an enzymolysis solution; (3) adding composite bacteria to the enzymatic hydrolyzate for fermentation and sterilization to obtain a fermentation liquid; (4) After the fermentation liquid is centrifuged, the supernatant is taken and ultrafiltered using an ultrafiltration membrane to obtain a chickpea polypeptide liquid; (5) The chickpea polypeptide liquid is subjected to a low-temperature freeze-drying treatment to obtain a purified chickpea polypeptide powder.

2. The chickpea polypeptide purification method according to claim 1, characterized in that: In the step (1), the chickpeas are dried and crushed to less than 100 meshes to obtain chickpea flour.

3. The chickpea polypeptide purification method according to claim 1, characterized in that: In the step (1), chickpea flour and water are mixed in a weight ratio of 1:(10-12).

4. The chickpea polypeptide purification method according to claim 1, characterized in that: In the step (1), a 5-7 wt% NaOH solution is used to adjust the pH to 8.5-8.

7.

5. The chickpea polypeptide purification method according to claim 1, characterized in that: In the step (2), citric acid with a concentration of 7-9 wt % is used to adjust the pH value to neutral.

6. The chickpea polypeptide purification method according to claim 1, characterized in that: In the step (2), the amount of alkaline protease is 600-800u / mL of chickpea flour mixture; the amount of neutral protease is 1000-1200u / mL of chickpea flour mixture; and the amount of bromelain is 800-900u / mL of chickpea flour mixture.

7. The chickpea polypeptide purification method according to claim 1, characterized in that: The fermentation conditions in step (3) are: fermentation at 35-40° C. for 15-20 hours.

8. The chickpea polypeptide purification method according to claim 1, characterized in that: The composite bacteria in step (3) include Lactobacillus casei, Bifidobacterium bifidum and Bifidobacterium longum.

9. The chickpea polypeptide purification method according to claim 8, characterized in that: The amount of Lactobacillus casei in step (3) is 10 7 -10 8 CFU / mL enzymatic solution; the dosage of Bifidobacterium bifidum is 10 9 -10 10 CFU / mL enzymatic solution; the dosage of Bifidobacterium longum is 10 8 -10 9 CFU / mL enzymatic solution.

10. The chickpea polypeptide purification method according to claim 1, characterized in that: In the step (4), ultrafiltration is performed using a 3000-4000Da ultrafiltration membrane.

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