A green processing method for high-protein chickpea protein and its applications

Abstract

This invention discloses a green processing method for high-protein chickpea protein and its applications, belonging to the field of protein extraction technology. The green processing method for high-protein chickpea protein of this invention includes: (1) mixing chickpea flour and water, adjusting the pH to 7.5, stirring, centrifuging, removing solid residue, and obtaining the clear liquid as chickpea milk; (2) heating the chickpea milk at 30–90°C for 10–60 min, cooling to room temperature, adjusting the pH to 5.1–7.0, and freezing at -20–-5°C for 6–12 h; (3) thawing the frozen chickpea milk, centrifuging, obtaining the clear liquid and precipitate; adding water to the precipitate, stirring evenly, adjusting the pH to 7.0, and freeze-drying to obtain chickpea protein. This invention does not involve the introduction of organic solvents or enzymes, effectively increasing the protein content of chickpea protein to over 90%, and exhibiting good antioxidant capacity.

Description

Technical Field

[0001] This invention relates to a green processing method for high-protein chickpea protein and its applications, belonging to the field of protein extraction technology. Background Technology

[0002] Chickpeas (Cicer arietinum L.) are plants belonging to the genus Cicera in the legume family and are the world's third most consumed legume crop. Chickpeas are rich in protein (14.9%–24.6%), fat (1.5%–3.5%), starch (44.9%–52.8%), as well as vitamins and minerals, possessing high nutritional, health, and medicinal value. Chickpea protein, in particular, boasts a balanced essential amino acid composition, high bioavailability, and low allergenicity. It is also rich in lysine, an amino acid lacking in cereal proteins, making it a superior protein source. Chickpea protein not only enriches the diet but can also be used as a dietary supplement, offering numerous health benefits in areas such as antioxidant activity, immune system enhancement, fatigue reduction, and cardiovascular disease prevention.

[0003] Different processing techniques result in varying protein content in chickpea protein. Currently, the main extraction processes for chickpea protein fall into the following categories:

[0004] (1) Chickpeas are not defatted, and chickpea protein is prepared by alkali dissolution and acid precipitation. The protein content of the resulting product is less than 80%. The extraction process of chickpea protein is often accompanied by the simultaneous enrichment of fat. For example, CN115251225A discloses a method for improving the solubility of chickpea protein isolate. The method includes: mixing chickpea powder with distilled water, adjusting the pH to 7.5-8.5, stirring at room temperature to obtain a mixture; centrifuging the mixture and collecting the supernatant, adjusting the pH of the supernatant to 4.5-4.6, centrifuging to collect the precipitate; dissolving the precipitate with distilled water and adjusting the pH to 7.0, and lyophilizing by dialysis to obtain chickpea protein isolate. This patent does not disclose the protein content of the obtained chickpea protein isolate. Similar to the method in patent CN115251225A, Du Mengyao (Du Mengyao. Comprehensive extraction, characteristic study and application of chickpea starch and protein [D]: [Master's thesis]. Alar, Xinjiang: Tarim University, 2023) obtained chickpea protein isolate by alkaline dissolution (pH 8.3) and acid precipitation (pH 4.5), but the protein content was only 77.18%.

[0005] (2) Chickpeas are not defatted, and chickpea protein is prepared by membrane separation. The protein content of the obtained product is 60% to 90%. For example, CN107259067A discloses a method for producing a soluble protein solution from beans. The method includes: extracting protein from beans with a calcium salt aqueous solution, centrifuging, adjusting the pH of the obtained protein aqueous solution to 1.5 to 4.4, centrifuging for clarification, and drying after membrane separation to obtain a bean protein product that can be used in acidic soft drinks and other aqueous systems. The protein content of the product prepared from chickpeas is 60% to 90%, but the specific data is not disclosed.

[0006] (3) Chickpeas are not defatted. Chickpea protein is prepared by enzymatic hydrolysis and membrane separation. The protein content of the obtained product can be higher than 90%. For example, CN107385002A discloses a co-production technology of chickpea starch and chickpea soluble protein. The method includes: soaking, peeling, crushing, and grinding chickpeas to prepare chickpea soy milk; preparing chickpea starch by compound enzyme method; separating chickpea soluble protein by compound enzyme; inactivating enzyme by heat exchange; and purifying chickpea soluble protein by membrane separation method. The protein contents are 88.2%, 90.4%, and 92.5%, respectively.

[0007] (4) Chickpeas are first defatted with organic solvents, and then chickpea protein is prepared by alkali dissolution and acid precipitation. The protein content of the obtained product is higher than 90%. For example, CN116584574A discloses a modified chickpea protein isolate and its preparation method. The method includes: chickpeas being peeled, crushed, defatted with n-hexane, alkali dissolved, acid precipitated and freeze-dried to obtain chickpea protein isolate. This patent does not disclose the protein content of the obtained chickpea protein isolate. Similar to the method of patent CN116584574A, Zhang Tao et al. (Zhang Tao, Jiang Bo, Wang Zhang. Properties of chickpea protein isolate [J]. China Oils and Fats, 2005, 24(3):66-71) prepared chickpea protein isolate with a protein content of 91.53% by peeling, crushing, defatting with n-hexane, alkali dissolved (pH 8.3), acid precipitation, neutralization and spray drying of chickpeas.

[0008] As can be seen from the above methods, when chickpeas are not defatted with organic solvents, the protein content of chickpea protein prepared by the alkali dissolution-acid precipitation method is less than 80%, while the protein content of chickpea protein prepared by membrane separation is between 60% and 90%. When chickpeas are defatted with organic solvents or enzymatically hydrolyzed, the protein content of chickpea protein prepared by the alkali dissolution-acid precipitation method or membrane separation method can reach over 90%. In summary, to achieve a protein content of over 90% using existing processes for preparing chickpea protein, the use of organic solvents or enzymes is inevitable. However, organic solvents are prone to residue, and enzymatic hydrolysis can lead to smaller protein molecules, thus affecting their functional properties. These problems significantly limit the application range of chickpea protein. There is a need to develop an alkali dissolution-acid precipitation process that does not involve organic solvents to prepare chickpea protein with a protein content of over 90%.

[0009] Legume protein products mainly come from soybeans, peas, chickpeas, broad beans, and mung beans. Due to the significant differences in fat content among the raw materials, the processing steps differ depending on the desired protein content (greater than 90%) obtained through alkali dissolution and acid precipitation. Soybeans have a high fat content (18%–20%), typically requiring defatting with organic solvents before soy protein preparation. Broad beans and mung beans have low fat content (approximately 1%), requiring no defatting and allowing direct preparation of broad bean and mung bean proteins. Peas have a fat content (1.5%–3.0%) similar to chickpeas, but unlike chickpeas where the fat is primarily neutral, pea fat is mainly polar lipids tightly bound to protein, requiring defatting with organic solvents before pea protein preparation.

[0010] Moreover, the conventional alkaline dissolution and acid precipitation method for extracting chickpea protein typically uses an acid precipitation pH of 4.5–5.0, as seen in literature such as (Du Mengyao. Comprehensive extraction, characteristic study and application of chickpea starch and protein [D]: [Master's thesis]. Xinjiang Alar: Tarim University, 2023), (Zhang Tao, Jiang Bo, Wang Zhang. Emulsifying properties and structural relationship of chickpea protein isolate [J]. Food and Fermentation Industries, 2004, 30(12):10-14), and CN115251225A (A method to improve the solubility of chickpea protein isolate). It can be confirmed that at pH 4.5–5.0, both protein and fat in chickpeas will precipitate simultaneously. Current reports do not reveal the distribution patterns of protein and fat in chickpeas. Whether changing process parameters such as precipitation pH and precipitation temperature can separate protein and fat, thereby increasing the protein content of the product, is currently unclear, and therefore existing processes cannot be referenced.

[0011] Furthermore, with age, under certain pathological conditions, or when the body is injured, the oxygen-containing free radicals generated during physiological metabolism cannot be eliminated in a timely manner, affecting the normal functioning of cellular material and energy metabolism. Chickpea protein has a certain antioxidant capacity and can eliminate oxygen-containing free radicals in the body. Chickpea protein is mainly composed of globulin (42.16%), albumin (39.76%), glutenin (9.57%), and prolamins (8.51%). Among them, globulin has the strongest antioxidant capacity and, after purification, can be used as a natural antioxidant in dietary supplements to improve human immunity. Therefore, how to better increase the proportion of globulin in chickpea protein is of great significance. Summary of the Invention

[0012] [Technical Issues]

[0013] Conventional alkaline dissolution and acid precipitation processes for extracting chickpea protein without organic solvents suffer from low protein content.

[0014] Conventional methods for extracting chickpea protein using organic solvents or enzyme preparations can result in solvent residues or affect the functional properties of the product.

[0015] Existing reports do not reveal the distribution patterns of protein and fat in chickpeas. It remains to be seen whether changing process parameters such as sedimentation pH and sedimentation temperature can separate protein and fat, thereby increasing the protein content of the product.

[0016] Improving the proportion of globulin in chickpea protein is of great significance.

[0017] [Technical Solution]

[0018] To address the aforementioned issues, this invention provides a green processing method for high-protein chickpea protein and its applications. It establishes a chickpea protein preparation process that does not introduce organic solvents or enzymes, meets green product standards, and has a protein content greater than 90%. The prepared chickpea protein exhibits excellent antioxidant capacity and can be used as a dietary supplement.

[0019] The first objective of this invention is to provide a green processing method for high-protein chickpea protein, comprising the following steps:

[0020] (1) Mix chickpea flour and water, adjust the pH to 7.5, stir, centrifuge, remove solid residue, and the clear liquid is chickpea milk liquid;

[0021] (2) Heat the chickpea milk at 30-90℃ for 10-60 min, cool it to room temperature, adjust the pH to 5.1-7.0, and freeze it at -20--5℃ for 6-12 h to obtain frozen chickpea milk.

[0022] (3) Thaw the frozen chickpea milk, centrifuge to obtain clear liquid and precipitate; add water to the precipitate, stir evenly, adjust to pH 7.0, freeze dry to obtain chickpea protein.

[0023] In one embodiment of the present invention, the chickpea flour in step (1) is obtained by dry grinding of chickpeas; the particle size of the chickpea flour is 100-150 mesh.

[0024] In one embodiment of the present invention, the mass ratio of chickpea flour to water in step (1) is 1:10 to 20, more preferably 1:15.

[0025] In one embodiment of the present invention, the solution used to adjust the pH in step (1) is an aqueous solution of NaOH with a concentration of 1.5 to 2.5 mol / L.

[0026] In one embodiment of the present invention, the stirring in step (1) is carried out at 20-30°C (room temperature) and 100-200 rpm for 0.5-2 hours, and more preferably at 20-30°C (room temperature) and 150 rpm for 1 hour.

[0027] In one embodiment of the present invention, the centrifugation in step (1) is performed at 1000-5000g for 10-20 minutes, and more preferably at 3000g for 15 minutes.

[0028] In one embodiment of the present invention, the chickpea milk liquid in step (2) is heated at 80°C for 30 minutes.

[0029] In one embodiment of the present invention, cooling to room temperature in step (2) involves placing the heated chickpea milk in tap water to cool it to 20-30°C (room temperature).

[0030] In one embodiment of the present invention, the solution used to adjust the pH in step (2) is an aqueous HCl solution with a concentration of 1.5 to 2.5 mol / L.

[0031] In one embodiment of the present invention, the pH is adjusted to 6.4 in step (2).

[0032] In one embodiment of the present invention, freezing in step (2) is freezing at -18°C for 8 hours.

[0033] In one embodiment of the present invention, the thawing in step (3) is natural thawing at 20-30°C (room temperature).

[0034] In one embodiment of the present invention, the centrifugation in step (3) is performed at 3000-6000g for 15-30 minutes; more preferably, it is performed at 5000g for 20 minutes.

[0035] In one embodiment of the present invention, in step (3), the mass ratio of precipitate to water is 1:1 to 3, more preferably 1:2.

[0036] In one embodiment of the present invention, the stirring in step (3) is performed by shearing at 10,000 rpm for 1 minute at 20-30°C (room temperature) using a high-speed shearing machine, followed by stirring at 150 rpm for 1 hour.

[0037] In one embodiment of the present invention, the solution used to adjust the pH in step (3) is an aqueous solution of NaOH with a concentration of 1.5 to 2.5 mol / L.

[0038] The second objective of this invention is to prepare chickpea protein using the method described herein.

[0039] In one embodiment of the present invention, the protein content of chickpea protein reaches more than 80%, and can reach about 92%; the globulin content reaches more than 55%, and can reach about 85%.

[0040] The third objective of this invention is to provide a method for increasing the protein content of chickpea protein, which employs the green processing method for high-protein chickpea protein described in this invention.

[0041] The fourth objective of this invention is to provide a method for increasing the proportion of globulin in chickpea protein, which employs the green processing method for high-protein chickpea protein described in this invention.

[0042] The fifth objective of this invention is to provide a method for enhancing the antioxidant capacity of chickpea protein, which employs the green processing method for high-protein chickpea protein described in this invention.

[0043] A sixth object of the present invention is to provide a dietary supplement that uses the chickpea protein described in the present invention.

[0044] The seventh objective of this invention is the application of the chickpea protein described herein in the fields of food processing, cosmetics, pharmaceuticals, and health products.

[0045] In one embodiment of the present invention, food processing includes the preparation of biscuits, bread, noodles, dietary supplements, etc.

[0046] In one embodiment of the present invention, cosmetics include ingredients added to a cosmetic formulation as moisturizers and antioxidants.

[0047] In one embodiment of the present invention, the preparation of pharmaceuticals and health products includes the preparation of drugs or health products for lowering blood sugar, anti-oxidation, anti-fatigue, etc.

[0048] [Beneficial Effects]

[0049] (1) Compared with the prior art, the present invention does not introduce organic solvents and enzyme preparations, making it greener and safer, and realizing the high-value utilization of chickpeas.

[0050] (2) The method of the present invention can effectively increase the protein content of chickpea protein to 92.05% ± 0.17%; effectively enhance the antioxidant capacity to 6.56 ± 0.19 mg / g, which is about 3.4 times higher than that of chickpea protein prepared by conventional alkali dissolution and acid precipitation process; and the globulin content reaches 85.89% ± 0.31%. Attached Figure Description

[0051] Figure 1 This illustrates the effect of heating temperature on protein content in chickpea milk in Example 2.

[0052] Figure 2 This illustrates the effect of chickpea milk freezing time on protein extraction rate in Example 3.

[0053] Figure 3 This is an example of the effect of freezing pH on protein content of chickpea milk in Example 4.

[0054] Figure 4 This study examines the effect of frozen pH on the proportion of globulins and antioxidant capacity of chickpea milk in Example 4. Detailed Implementation

[0055] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0056] Test method:

[0057] 1. Basic component test of chickpea protein

[0058] Protein content was determined according to the Kjeldahl method in GB5009.5-2016, with a protein conversion factor of 6.25.

[0059] Moisture content was determined according to the direct drying method in GB5009.3-2016;

[0060] Data processing: All experiments were repeated three times. Origin was used to analyze and plot the data. The results are expressed as "mean ± standard deviation".

[0061] 2. Calculation of protein extraction rate

[0062]

[0063] 3. Determination and calculation of the proportion of globulin in chickpea protein

[0064] SDS-PAGE gel electrophoresis was used to identify the protein composition of chickpea protein.

[0065] The concentrations of the separating gel and the stacking gel were 16.5% and 4%, respectively. The anode buffer was a Tris-HCl buffer (containing 2.42% Tris) at pH 8.9, and the cathode buffer was a buffer system containing 1.2% Tris, 1.79% Tricine, and 0.1% SDS.

[0066] Add 1.5 mg of protein sample to 1 mL of prepared sample lysis buffer (containing 20% ​​(v / v) pH 6.8 Tris-HCl, 24% (w / v) glycerol, 8% (w / v) SDS, and 0.02% (w / v) Coomassie Brilliant Blue G-250), and then add 2% (v / v) β-mercaptoethanol.

[0067] Before electrophoresis, the protein solution treated above was boiled in boiling water for 4 minutes, cooled, and 10 μL was injected into each electrophoresis lane. Electrophoresis was performed at 30 V to the separating gel (~2 h), and then electrophoresis was performed at a constant voltage of 100 V until the end. After fixation, Coomassie Brilliant Blue G-250 was stained, and 30% acetic acid was used to decolorize until the background was transparent. The gel was then scanned using a gel imaging system.

[0068] The formula for calculating the globulin ratio is as follows:

[0069]

[0070] 4. Test of the antioxidant capacity of chickpea protein

[0071] Accurately weigh 0.5g of protein sample and dilute to 100mL with distilled water. Take 10mL of the solution, add 0.25mL of 1.0mol / L H2SO4 and 5mL of 0.25mol / L H2O2, react at room temperature for 10min, then add 20mL of 10% (w / v) KI solution, let stand in the dark for 5min, and titrate with 0.05mol / L NaS2O3.

[0072] Use a 1%–2% starch solution to indicate the endpoint, and simultaneously perform a blank control.

[0073] The formula for calculating antioxidant capacity is:

[0074]

[0075] In the formula: V 空 V 样 34 represents the volume of NaS2O3 consumed by the blank and sample, in mL; C represents the concentration of NaS2O3, in mol / L; 34 represents the molar mass of H2O2, in g / mol; and m represents the mass of the chickpea protein sample.

[0076] Raw materials used in the examples:

[0077] Chickpea flour: Chickpeas are dry-crushed to obtain chickpea flour with a particle size of 100 mesh.

[0078] In the examples and comparative examples, room temperature refers to 20–30°C; solutions for which the solvent is not specifically specified use deionized water; and operations for which the temperature is not specifically specified refer to room temperature.

[0079] Example 1

[0080] A green processing method for high-protein chickpea protein includes the following steps:

[0081] (1) Mix chickpea flour and water at a ratio of 1:15 (w / w), adjust the pH to 7.5 with 2 mol / L NaOH solution, stir at room temperature and 150 rpm for 1 h, centrifuge at 3000g for 15 min, remove solid residue, and the resulting clear liquid is chickpea milk liquid.

[0082] (2) Heat the chickpea milk in an 80℃ water bath for 30 minutes, then cool it down to room temperature in tap water, adjust the pH to 6.4 with 2mol / L HCl solution, and freeze it at -18℃ for 8 hours to obtain frozen chickpea milk.

[0083] (3) Thaw the frozen chickpea milk at room temperature, centrifuge at 5000g for 20min to obtain the supernatant and precipitate; weigh the precipitate, add water at a ratio of 1:2 (w / w), shear at 10000rpm for 1min at room temperature, adjust the pH to 7.0 with 2mol / L NaOH solution, stir at 150rpm for 1h, freeze dry at -35℃ for 24h to obtain chickpea protein.

[0084] Comparative Example 1: Conventional Alkali Dissolution and Acid Precipitation

[0085] The conventional method for preparing alkali-soluble acid-precipitated solutions is as follows:

[0086] (1) Mix chickpea flour and water at a ratio of 1:15 (w / w), adjust the pH to 7.5 with 2 mol / L NaOH solution, stir at room temperature and 150 rpm for 1 h, centrifuge at 3000g for 15 min, remove solid residue, and the resulting clear liquid is chickpea milk liquid.

[0087] (2) Adjust the pH of chickpea milk to 4.5 with 2 mol / L HCl solution, centrifuge at 5000g for 20 min to obtain clear liquid and precipitate; weigh the precipitate, add water at a ratio of 1:2 (w / w), shear at 10000 rpm for 1 min at room temperature, adjust the pH to 7.0 with 2 mol / L NaOH solution, stir at 150 rpm for 1 h, freeze dry to obtain conventional chickpea protein.

[0088] The chickpea protein obtained in Example 1 and Comparative Example 1 was subjected to performance testing, and the test results are as follows:

[0089] Table 1

[0090] example Protein content (%) Antioxidant capacity (mg / g) Example 1 92.05±0.17 6.56±0.19 Comparative Example 1 76.17±0.09 1.92±0.15

[0091] As can be seen from Table 1, the protein content of Example 1 is much higher than that of Comparative Example 1, and its antioxidant capacity is about 3.4 times higher than that of conventional chickpea protein in Comparative Example 1.

[0092] Example 2: Effect of heating temperature on protein content of chickpea milk

[0093] A green processing method for high-protein chickpea protein includes the following steps:

[0094] (1) Mix chickpea flour and water at a ratio of 1:15 (w / w), adjust the pH to 7.5 with 2 mol / L NaOH solution, stir at room temperature and 150 rpm for 1 h, centrifuge at 3000g for 15 min, remove solid residue, and the resulting clear liquid is chickpea milk liquid.

[0095] (2) Divide the chickpea milk into 7 equal portions and heat them in water baths at 30℃, 40℃, 50℃, 60℃, 70℃, 80℃ and 90℃ for 30 minutes. Then cool them down to room temperature in tap water, adjust the pH to 6.4 with 2mol / L HCl solution, and freeze them at -18℃ for 8 hours to obtain frozen chickpea milk.

[0096] (3) Thaw the frozen chickpea milk at room temperature, centrifuge at 5000g for 20min to obtain the supernatant and precipitate; weigh the precipitate, add water at a ratio of 1:2 (w / w), shear at 10000rpm for 1min at room temperature, adjust the pH to 7.0 with 2mol / L NaOH solution, stir at 150rpm for 1h, freeze dry at -35℃ for 24h to obtain chickpea protein.

[0097] The obtained chickpea protein was subjected to performance testing, and the test results are as follows:

[0098] Figure 1Table 2 shows the effect of heating temperature on the protein content of chickpea milk. Figure 1 As shown in Table 2, when chickpea milk was heated in a water bath at approximately room temperature (30°C), the protein content of chickpea protein was 79.03% ± 0.15%. Increasing the heating temperature of the milk increased the protein content of the product. This indicates that appropriate heating promotes the dissociation between protein and fat. At a heating temperature of 80°C, the protein content of chickpea protein reached 92.05% ± 0.17%, and the increase after further increasing the heating temperature was negligible.

[0099] Table 2

[0100] Temperature (°C) Protein content (%) 30 79.03±0.15 40 82.77±0.13 50 88.21±0.08 60 90.28±0.16 70 91.89±0.06 80 (Example 1) 92.05±0.17 90 92.06±0.12

[0101] Example 3: Effect of freezing time of chickpea milk on protein extraction rate

[0102] A green processing method for high-protein chickpea protein includes the following steps:

[0103] (1) Mix chickpea flour and water at a ratio of 1:15 (w / w), adjust the pH to 7.5 with 2 mol / L NaOH solution, stir at room temperature and 150 rpm for 1 h, centrifuge at 3000g for 15 min, remove solid residue, and the resulting clear liquid is chickpea milk liquid.

[0104] (2) Heat the chickpea milk in an 80℃ water bath for 30 minutes, then cool it down to room temperature in tap water, adjust the pH to 6.4 with 2mol / L HCl solution, and freeze it at -18℃ for 0h, 6h, 8h, 10h and 12h respectively to obtain frozen chickpea milk.

[0105] (3) Thaw the frozen chickpea milk at room temperature, centrifuge at 5000g for 20min to obtain the supernatant and precipitate; weigh the precipitate, add water at a ratio of 1:2 (w / w), shear at 10000rpm for 1min at room temperature, adjust the pH to 7.0 with 2mol / L NaOH solution, stir at 150rpm for 1h, freeze dry at -35℃ for 24h to obtain chickpea protein.

[0106] The obtained chickpea protein was subjected to performance testing, and the test results are as follows:

[0107] Figure 2 Table 3 shows the effect of chickpea milk freezing time on protein extraction rate. From... Figure 2As shown in Table 3, when the chickpea milk is not frozen, its protein extraction rate is low, only 13.28% ± 0.21%. With increasing freezing time, the protein extraction rate further increases, but after a certain freezing time, the increase in protein extraction rate is not significant. Freezing can improve the protein extraction rate at pH 6.4, reaching 35.69% ± 0.18%; however, after 8 hours of freezing, further extending the freezing time results in negligible increases in protein extraction rate.

[0108] Table 3

[0109] Freezing time (h) Protein extraction rate (%) 0 13.28±0.21 6 31.39±0.12 8 (Example 1) 35.69±0.18 10 35.73±0.25 12 35.76±0.27

[0110] Example 4: Effects of freezing pH on protein content, globulin ratio, and antioxidant capacity of chickpea milk.

[0111] A green processing method for high-protein chickpea protein includes the following steps:

[0112] (1) Mix chickpea flour and water at a ratio of 1:15 (w / w), adjust the pH to 7.5 with 2 mol / L NaOH solution, stir at room temperature and 150 rpm for 1 h, centrifuge at 3000g for 15 min, remove solid residue, and the resulting clear liquid is chickpea milk liquid.

[0113] (2) Heat the chickpea milk in an 80℃ water bath for 30 minutes, then cool it down to room temperature in tap water, adjust the pH to 4.5, 5.1, 5.4, 5.6, 5.8, 6.0, 6.2, 6.4, 6.6, 6.8 and 7.0 with 2mol / L HCl solution, and freeze it at -18℃ for 8 hours to obtain frozen chickpea milk.

[0114] (3) Thaw the frozen chickpea milk at room temperature, centrifuge at 5000g for 20min to obtain the supernatant and precipitate; weigh the precipitate, add water at a ratio of 1:2 (w / w), shear at 10000rpm for 1min at room temperature, adjust the pH to 7.0 with 2mol / L NaOH solution, stir at 150rpm for 1h, freeze dry at -35℃ for 24h to obtain chickpea protein.

[0115] The obtained chickpea protein was subjected to performance testing, and the test results are as follows:

[0116] Figure 3 , Figure 4 Table 4 shows the effect of frozen pH on protein content, globulin ratio, and antioxidant capacity of chickpea milk.

[0117] from Figure 3As shown in Table 4, when chickpea milk was frozen at a conventional acid precipitation pH of 4.5, the protein content of the obtained chickpea protein was 77.58% ± 0.15%. When the freezing pH of the chickpea milk was increased to 5.1, 5.4, 5.6, 5.8, 6.0, 6.2, 6.4, 6.6, 6.8 and 7.0, respectively, the protein content of the obtained chickpea protein gradually increased. This shows that adjusting the pH during freezing can separate some protein from fat, and then centrifugation can yield chickpea protein with high protein content. pH 6.4 is the optimal condition, with a protein content of 92.05% ± 0.17%.

[0118] from Figure 4 As shown in Table 4, when the freezing pH of chickpea milk increases from 4.5 to 7.0, the proportion of globulin in the prepared chickpea protein gradually increases, reaching its highest value at pH 6.4; and, with the increase of the proportion of globulin, its antioxidant capacity also gradually increases.

[0119] Table 4

[0120] pH Protein content (%) Globulin percentage (%) Antioxidant capacity (mg / g) 4.5 77.58±0.15 52.67±0.25 2.03±0.15 5.1 77.91±0.09 56.36±0.22 2.87±0.09 5.4 82.05±0.20 58.92±0.36 3.52±0.11 5.6 83.16±0.16 63.67±0.49 4.30±0.27 5.8 85.29±0.11 71.65±0.59 4.51±0.25 6.0 87.32±0.09 77.17±0.66 4.86±0.13 6.2 89.67±0.22 81.26±0.33 5.89±0.21 6.4 (Example 1) 92.05±0.17 85.89±0.31 6.56±0.19 6.6 91.96±0.23 85.33±0.52 6.52±0.17 6.8 91.83±0.15 85.52±0.43 6.53±0.12 7.0 91.32±0.18 85.72±0.28 6.55±0.08

[0121] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A green processing method for high-protein chickpea protein, characterized in that, Includes the following steps: (1) Mix chickpea flour and water, adjust the pH to 7.5, stir, centrifuge, remove solid residue, and the clear liquid is chickpea milk liquid; (2) Heat the chickpea milk at 30-90℃ for 10-60 min, cool it to room temperature, adjust the pH to 5.1-7.0, and freeze it at -20--18℃ for 6-12 h to obtain frozen chickpea milk. (3) Thaw the frozen chickpea milk, centrifuge to obtain clear liquid and precipitate; add water to the precipitate, stir evenly, adjust to pH 7.0, freeze dry to obtain chickpea protein.

2. The green processing method according to claim 1, characterized in that, In step (1), the mass ratio of chickpea flour to water is 1:10 to 20.

3. The green processing method according to claim 2, characterized in that, In step (1), the mass ratio of chickpea flour to water is 1:

15.

4. The green processing method according to claim 1, characterized in that, In step (2), cooling to room temperature involves placing the heated chickpea milk in tap water to cool it down to 20-30°C.

5. The green processing method according to claim 1, characterized in that, In step (3), the water added to the precipitate is in a mass ratio of precipitate to water of 1:1 to 3.

6. The green processing method according to claim 5, characterized in that, In step (3), the precipitate is added to water in a mass ratio of precipitate to water of 1:

2.

7. Chickpea protein prepared by the green processing method according to any one of claims 1 to 6.

8. A method for increasing the protein content in chickpea protein, characterized in that, The green processing method described in any one of claims 1 to 6 was adopted.

9. A method for increasing the proportion of globulin in chickpea protein, characterized in that, The green processing method described in any one of claims 1 to 6 was adopted.

10. A method for enhancing the antioxidant capacity of chickpea protein, characterized in that, The green processing method described in any one of claims 1 to 6 was adopted.

11. A dietary supplement, characterized in that, The chickpea protein described in claim 7 was used.

12. The application of chickpea protein according to claim 7 in the fields of food processing or cosmetics.

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