Soybean protein powder and preparation method thereof

Abstract

The invention relates to the technical field of food processing, and discloses soybean protein powder and a preparation method thereof. According to the soybean protein powder, the soybean protein isolate is extracted through an alkali extraction and acid precipitation method, high efficiency is achieved, the extracted soybean protein isolate is high in nutritional value, the extracted soybean protein isolate is subjected to glycosylation modification and porphyra polysaccharide modification, and finally the soybean protein powder is prepared through a spray drying method. The soybean protein powder prepared by the method has good stability, prolongs the shelf life of the soybean protein powder, is more convenient to store, ensures the nutritional value of the soybean protein powder, also has low sensitization, can meet the eating requirements of more people, reduces rejection reaction, reduces safety risks caused by anaphylactic reaction, and is suitable for industrial production. The application range of the soybean protein powder is widened.

Description

Technical Field

[0001] The present invention relates to the technical field of food processing, in particular to soybean protein powder and a preparation method thereof. Background Art

[0002] Soybeans are an important source of high-quality plant protein. Soy protein powder is a protein powder extracted from soybeans through a series of processes. Its main ingredient is protein. It has the advantages of rich nutrition, wide sources, and low production cost. It is easy to be digested and absorbed by the human body. It is often used as a nutritional health product to provide the human body with high-quality protein. Soy protein powder has many functions. It is a rich source of bioactive peptides and has antihypertensive effects. Soy protein has a high lysine content and does not contain cholesterol. It is a complete plant protein that can lower cholesterol, regulate blood lipids, and is beneficial for preventing cardiovascular diseases. It helps enhance human immunity, and can also improve nutrition for fitness people, promote muscle growth, and increase muscle mass. At the same time, soy protein powder can also increase satiety and is suitable for people who are losing weight.

[0003] However, soy protein powder can cause allergic reactions in some people, leading to dermatitis allergies, gastrointestinal disorders, nausea, vomiting, and even shock and death in severe cases. This not only limits the food choices of allergic people and affects their quality of life, but also affects the application of soy protein resources. Therefore, with the continuous development of the food industry and people's pursuit of health, research on reducing the allergenicity of soy protein has important practical significance.

[0004] Patent publication number CN115590202B discloses a nutritional powder that is beneficial to the absorption of soy protein and a preparation method thereof. The coconut powder in the nutritional powder is rich in nutrients such as cellulose and B vitamins, has the effects of nourishing the spleen and stomach, promoting metabolism, and enhancing the body's absorption of soy protein. The soy protein and coconut powder form a polymer through covalent bonds, which further promotes the body's absorption of soy protein. The avocado oil therein is rich in unsaturated fatty acids such as oleic acid, palmitoleic acid, and linoleic acid, is rich in vitamins E, B5 and β-carotene, is low in sugar, can lower blood lipids and cholesterol, and has the effects of unblocking blood vessels and lowering blood pressure. The addition of coconut powder and avocado oil is beneficial to the digestion and absorption of soy protein. However, the patent does not take into account the allergic problem caused by soy protein. Therefore, the present invention provides a soy protein powder with good stability and low allergenicity, which broadens the audience population. Summary of the Invention

[0005] In order to solve the problems mentioned in the background technology, the purpose of the present invention is to provide a soybean protein powder and a preparation method thereof.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing soybean protein powder comprises the following steps: Step 1: Extraction of soy protein isolate The soybeans are removed from impurities, washed, and dried, then crushed and sieved, distilled water is added, the pH value is adjusted to alkaline, the temperature of the water bath is 40-60° C., stirring is carried out at 500-1000 r / min for 30-60 min, and the mixture is centrifuged at a speed of 5000-6000 r / min for 10-25 min, and the operation is repeated 1-3 times to obtain a supernatant, the pH value of the supernatant is adjusted to acidic, the temperature of the water bath is 40-60° C., centrifuged at a speed of 5000-8000 r / min for 10-25 min, and the operation is repeated 1-3 times, the supernatant is collected, water is added to dissolve the precipitate, dialyzed overnight with a dialysis bag, and then freeze-dried in a vacuum to obtain soy protein isolate; Step 2: Preparation of modified xanthan gum Add xanthan gum to distilled water, raise the temperature to 40-50°C, stir evenly, add arginine and catalytic components, raise the temperature again, react for 4-6 hours, cool and separate the product to obtain modified xanthan gum; Step 3: Glycosylation of soy protein isolate Soy protein isolate and modified xanthan gum are added to distilled water and mixed, stirred at 22-28°C for 1-3 hours, then reacted in a water bath for 3-5 hours, cooled to room temperature, centrifuged at 6000-8000 r / min for 15-30 minutes, and the supernatant is collected to obtain a glycosylated product of soy protein isolate; Step 4: Preparation of soy protein powder Add the glycosylated product of isolated soybean protein and laver polysaccharide into distilled water, raise the temperature to 50-60° C., stir for 30-60 minutes, let stand for 1-3 hours, and spray dry to obtain soybean protein powder.

[0007] By adopting the above technical scheme, the soy protein isolate is extracted by the alkali extraction and acid precipitation method with a high extraction rate and high nutritional value. The xanthan gum can be modified with arginine under the action of the catalytic component to obtain positively charged modified xanthan gum. At the same time, the amino group in the soy protein isolate and the hydroxyl group in the modified xanthan gum are used to undergo a non-enzymatic Maillard reaction, which is the glycosylation modification of the soy protein isolate, so that the glycosylation product of the soy protein isolate is positively charged. The negatively charged characteristic of laver polysaccharide is used to promote the self-assembly of the two through electrostatic adsorption, and then the soy protein powder is obtained through spray drying.

[0008] Furthermore, in step 1, the liquid-to-solid ratio of distilled water to soybeans is 10-12:1.

[0009] Furthermore, in step 1, the alkaline pH is 8-11, and the acidic pH is 3-6.

[0010] Furthermore, in step 2, the catalytic component is Novozym435 immobilized lipase.

[0011] Furthermore, in step 2, the re-heating temperature is 60-75°C.

[0012] Furthermore, in step three, the mass ratio of the soy protein isolate to the modified xanthan gum is 2-2.5:1-1.4.

[0013] Furthermore, in step 4, the mass ratio of the glycosylated product of the isolated soybean protein to the laver polysaccharide is 1-1.8:1-2.

[0014] Furthermore, in step 4, the spray drying conditions are as follows: the inlet air temperature is 120-150°C, and the outlet air temperature is 50-70°C.

[0015] A method for preparing soybean protein powder is disclosed, which is prepared by adopting the above-mentioned preparation method.

[0016] Beneficial effects of the present invention: The present invention modifies soybean protein by glycosylation, which, on the one hand, increases the solubility of soybean protein in aqueous solution, enables it to form a tight and stable network structure with stability, protects the nutrients therein from loss, improves the nutritional value of food, and extends the shelf life of food; on the other hand, it can change the structure of allergens in soybean protein and reduce allergic reactions. In addition, laver polysaccharide has immunoregulatory activity and can promote the body's immune response. Testing shows that after the glycosylated soybean protein is combined with laver polysaccharide, the binding ability of the soybean protein to immunoglobulin E is improved, which is beneficial to reducing allergic reactions. Through the synergistic effect of glycosylation modification and laver polysaccharide, the allergenicity of soybean protein powder is jointly reduced, which can meet the edible needs of more people, reduce rejection reactions, reduce safety risks caused by allergic reactions, improve their quality of life, and broaden the application of soybean protein powder.

[0017] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. DETAILED DESCRIPTION

[0018] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0019] The preparation of modified xanthan gum in the following examples and comparative examples is as follows: Preparation of modified xanthan gum 6 g of xanthan gum was added to distilled water, the temperature was raised to 45°C, and after stirring evenly, 2.6 g of arginine and 2.2 g of Novozym435 immobilized lipase were added, and the temperature was raised to 70°C again. After reacting for 6 hours, the temperature was lowered and the product was separated to obtain modified xanthan gum; The modified xanthan gum was analyzed using a Vario EL III elemental analyzer. The results showed that the percentage of nitrogen in the modified xanthan gum was 4.22%. Since xanthan gum does not contain nitrogen, it can be seen that the xanthan gum was successfully modified with arginine.

[0020] Example 1 Step 1: Extraction of soy protein isolate 10 g of soybeans were removed from impurities, washed, and dried, then crushed and sieved. 100 mL of distilled water was added, and the pH value was adjusted to 8. The mixture was heated in a water bath at 40° C., stirred at 500 r / min for 30 min, and centrifuged at 5000 r / min for 10 min. The operation was repeated once to obtain a supernatant. The pH value of the supernatant was adjusted to 3. The mixture was heated in a water bath at 40° C., centrifuged at 5000 r / min for 10 min, and repeated once. The supernatant was taken, water was added to dissolve the precipitate, and the mixture was dialyzed overnight with a dialysis bag. The mixture was then freeze-dried in a vacuum tube to obtain soy protein isolate. Step 2: Glycosylation of soy protein isolate 12 g of soy protein isolate and 6 g of modified xanthan gum were added to distilled water and mixed, stirred at 22°C for 1 hour, then heated in a water bath at 80°C for 3 hours, cooled to room temperature, centrifuged at 6000 r / min for 15 minutes, and the supernatant was collected to obtain the soy protein isolate glycosylation product; Step 3: Preparation of soy protein powder 8 g of glycosylated product of isolated soybean protein and 10 g of laver polysaccharide were added to distilled water, the temperature was raised to 50°C, stirred for 30 min, allowed to stand for 1 h, and spray-dried with an inlet air temperature of 120°C and an outlet air temperature of 50°C to obtain soybean protein powder.

[0021] Example 2 Step 1: Extraction of soy protein isolate 15 g of soybeans were removed from the impurities, washed, and dried, then crushed and sieved. 165 mL of distilled water was added, the pH value was adjusted to 9, the mixture was heated in a water bath at 45° C., stirred at 600 r / min for 40 min, and centrifuged at 5500 r / min for 15 min. This operation was repeated twice to obtain a supernatant. The pH value of the supernatant was adjusted to 4, the mixture was heated in a water bath at 45° C., and centrifuged at 6000 r / min for 15 min. This operation was repeated twice. The supernatant was taken, water was added to dissolve the precipitate, and the mixture was dialyzed overnight in a dialysis bag. The mixture was then freeze-dried in a vacuum tube to obtain soy protein isolate. Step 2: Glycosylation of soy protein isolate 17 g of soy protein isolate and 8 g of modified xanthan gum were added to distilled water and mixed, stirred at 24°C for 1.5 h, then heated in a water bath at 85°C for 3.5 h, cooled to room temperature, centrifuged at 6500 r / min for 20 min, and the supernatant was collected to obtain the soy protein isolate glycosylation product; Step 3: Preparation of soy protein powder 12 g of glycosylated product of isolated soybean protein and 14 g of laver polysaccharide were added to distilled water, the temperature was raised to 55°C, stirred for 40 min, allowed to stand for 1.5 h, and spray-dried with an inlet air temperature of 130°C and an outlet air temperature of 55°C to obtain soybean protein powder.

[0022] Example 3 Step 1: Extraction of soy protein isolate 20 g of soybeans were removed from the impurities, washed, and dried, then crushed and sieved. 222 mL of distilled water was added, the pH value was adjusted to 10, the mixture was heated in a water bath at 50° C., stirred at 800 r / min for 50 min, and centrifuged at 5500 r / min for 20 min. This operation was repeated three times to obtain a supernatant. The pH value of the supernatant was adjusted to 5, the mixture was heated in a water bath at 50° C., and centrifuged at 6500 r / min for 20 min. This operation was repeated three times. The supernatant was taken, water was added to dissolve the precipitate, and the mixture was dialyzed overnight with a dialysis bag. The mixture was then freeze-dried in a vacuum vacuum to obtain soy protein isolate. Step 2: Glycosylation of soy protein isolate 22 g of soy protein isolate and 10 g of modified xanthan gum were added to distilled water and mixed, stirred at 26°C for 2 h, then heated in a water bath at 90°C for 4 h, cooled to room temperature, centrifuged at 7500 r / min for 25 min, and the supernatant was collected to obtain the soy protein isolate glycosylation product; Step 3: Preparation of soy protein powder 18 g of glycosylated product of soybean protein isolate and 21 g of laver polysaccharide were added to distilled water, the temperature was raised to 55°C, stirred for 50 minutes, allowed to stand for 2 hours, and spray-dried with an inlet air temperature of 140°C and an outlet air temperature of 60°C to obtain soybean protein powder.

[0023] Example 4 Step 1: Extraction of soy protein isolate 25 g of soybeans were removed from the impurities, washed, and dried, then crushed and sieved. 300 mL of distilled water was added, the pH value was adjusted to 11, the mixture was heated in a water bath at 60° C., stirred at 1000 r / min for 60 min, and centrifuged at 6000 r / min for 25 min. This operation was repeated three times to obtain a supernatant. The pH value of the supernatant was adjusted to 6, the mixture was heated in a water bath at 60° C., and centrifuged at 8000 r / min for 25 min. This operation was repeated three times. The supernatant was taken, water was added to dissolve the precipitate, and the mixture was dialyzed overnight in a dialysis bag. The mixture was then freeze-dried in a vacuum oven to obtain soy protein isolate. Step 2: Glycosylation of soy protein isolate 25 g of soy protein isolate and 12 g of modified xanthan gum were added to distilled water and mixed, stirred at 28°C for 3 h, then heated in a water bath at 95°C for 5 h, cooled to room temperature, centrifuged at 8000 r / min for 30 min, and the supernatant was collected to obtain the soy protein isolate glycosylation product; Step 3: Preparation of soy protein powder 21 g of glycosylated soy protein isolate and 25 g of laver polysaccharide were added to distilled water, the temperature was raised to 60°C, stirred for 60 minutes, allowed to stand for 3 hours, and spray-dried with an inlet air temperature of 150°C and an outlet air temperature of 70°C to obtain soy protein powder.

[0024] Comparative Example 1 Step 1: Extraction of soy protein isolate 20 g of soybeans were removed from the impurities, washed, and dried, then crushed and sieved. 222 mL of distilled water was added, the pH value was adjusted to 10, the mixture was heated in a water bath at 50° C., stirred at 800 r / min for 50 min, and centrifuged at 5500 r / min for 20 min. This operation was repeated three times to obtain a supernatant. The pH value of the supernatant was adjusted to 5, the mixture was heated in a water bath at 50° C., and centrifuged at 6500 r / min for 20 min. This operation was repeated three times. The supernatant was taken, water was added to dissolve the precipitate, and the mixture was dialyzed overnight with a dialysis bag. The mixture was then freeze-dried in a vacuum vacuum to obtain soy protein isolate. Step 2: Preparation of soy protein powder 22 g of soy protein isolate and 10 g of modified xanthan gum were added to distilled water and stirred at 26°C for 2 h. The mixture was then heated in a water bath at 90°C for 4 h. The mixture was cooled to room temperature and centrifuged at 7500 r / min for 25 min. The supernatant was taken to obtain the glycosylation product of soy protein isolate. The mixture was spray-dried at an inlet air temperature of 140°C and an outlet air temperature of 60°C to obtain soy protein powder.

[0025] Comparative Example 2 Step 1: Extraction of soy protein isolate 20 g of soybeans were removed from the impurities, washed, and dried, then crushed and sieved. 222 mL of distilled water was added, the pH value was adjusted to 10, the mixture was heated in a water bath at 50° C., stirred at 800 r / min for 50 min, and centrifuged at 5500 r / min for 20 min. This operation was repeated three times to obtain a supernatant. The pH value of the supernatant was adjusted to 5, the mixture was heated in a water bath at 50° C., and centrifuged at 6500 r / min for 20 min. This operation was repeated three times. The supernatant was taken, water was added to dissolve the precipitate, and the mixture was dialyzed overnight with a dialysis bag. The mixture was then freeze-dried in a vacuum vacuum to obtain soy protein isolate. Step 2: Preparation of soy protein powder 18 g of soy protein isolate and 21 g of laver polysaccharide were added to distilled water, the temperature was raised to 55°C, stirred for 50 minutes, allowed to stand for 2 hours, and spray-dried with an inlet air temperature of 140°C and an outlet air temperature of 60°C to obtain soy protein powder.

[0026] test a. Effects on cell viability The soy protein powder prepared in Examples 1 to 4 and Comparative Examples 1 to 2 was prepared into a 250 μg / mL solution, and 0.1 mL to 15 mL of DMEM medium containing 8% fetal bovine serum was added. After immersion for 24 h, the solution was centrifuged, and the supernatant was taken. DMEM medium containing 8% fetal bovine serum was added and diluted. Rat osteoblasts were cultured. Second-generation cells were taken and diluted at 1×10 3 Cells / mL were inoculated in a 96-well culture plate, 100 μL per well, and cultured for 24 h. The negative control group was a DMEM medium containing 8% fetal bovine serum. After two days of culture, 25 μL of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) was added. After 2 h, 200 μL of dimethyl sulfoxide was added and shaken. The absorbance value Y in Examples 1 to 4 and Comparative Examples 1 to 2 was measured at a wavelength of 490 nm using an enzyme-linked immunosorbent assay (ELISA) to calculate the relative cell proliferation rate (RGR) (%). RGR = Y value of the experimental group / Y value of the negative control group × 100%. The safety of the soy protein powder was judged in this way. The results are shown in the following table:

[0027] As can be seen from the above table, the soy protein powders prepared in Examples 1 to 4 and Comparative Examples 1 and 2 of the present invention have good safety and are suitable for use as nutritional health products.

[0028] b. Stability test: The soy protein powders prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were placed at room temperature and pressure and a relative humidity of 60% RH for 80 days, and the changes in the appearance of the soy protein powders were observed. The test results are shown below:

[0029] It can be seen from the above table that the soy protein powder prepared in Examples 1 to 4 of the present invention has good stability and is easy to store. The soy protein powder in Comparative Example 1 is prepared by glycosylation-modified soy protein and does not produce electrostatic adsorption with laver polysaccharide, so its stability is poor; the soy protein powder in Comparative Example 2 is prepared by soy protein and laver polysaccharide without glycosylation modification and has poor stability.

[0030] c. Indirect ELISA method to detect the IgE (immunoglobulin E) binding ability of soy protein powder to determine the allergenicity of soy protein powder The soy protein powder prepared in Examples 1 to 4 and Comparative Examples 1 to 2 was prepared into a 250 μg / mL solution, which was added to an ELISA plate, 0.2 mL was added to each well, and an untreated soy protein isolate solution was set as a control group. After culturing for 24 h, the plate was washed with phosphate buffer 3 times, each time for 3 min, and then 100 μL of 5% bovine serum albumin was added dropwise to each well. The plate was incubated at 37 ° C for 1 h, washed with phosphate buffer 3 times, each time for 3 min, and rabbit anti-soybean diluted 1:1600 was added. 100 μL of globulin serum was added to each well and incubated at 37°C for 1 hour. Then 100 μL / well of HRP (horseradish peroxidase)-labeled goat anti-rabbit IgE antibody diluted 1:5000 was added and incubated at 37°C for 1 hour. The cells were washed 3 times with phosphate buffer, 3 minutes each time, and 100 μL / well of DAB (3,3-diaminobenzidine) colorimetric solution was added and incubated at 37°C for 15 minutes. After incubation and color development, 2 mol / mL of sulfuric acid stop solution was added and the cells were placed in a microplate reader. The OD value (absorbance value) was detected at a wavelength of 450 nm. The formula is: IgE binding capacity (%) = OD W / OD Q ×100%, where OD W is the OD value of the experimental group, OD Q is the OD value of the control group. The test results are shown in the following table:

[0031] It can be seen from the above table that the soy protein powder prepared in Examples 1 to 4 of the present invention has low allergenicity and can meet the edible needs of allergic people. Comparative Example 1 directly prepares soy protein powder from the glycosylation product of soy protein isolate. Although the allergenicity of soy protein powder is reduced after glycosylation modification, it is unable to utilize the anti-allergic effect of laver polysaccharide to form a synergistic anti-allergic effect, so the test results are poor. The soy protein powder of Comparative Example 2 is prepared from soy protein and laver polysaccharide, and the soy protein is not modified by glycosylation, so the test results are also relatively poor.

[0032] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing soybean protein powder, characterized in that: The following steps are involved: Step 1: Extraction of soy protein isolate The soybeans are removed from impurities, washed, and dried, then crushed and sieved, distilled water is added, the pH value is adjusted to alkaline, the temperature of the water bath is 40-60° C., stirring is carried out at 500-1000 r / min for 30-60 min, and the mixture is centrifuged at a speed of 5000-6000 r / min for 10-25 min, and the operation is repeated 1-3 times to obtain a supernatant, the pH value of the supernatant is adjusted to acidic, the temperature of the water bath is 40-60° C., centrifuged at a speed of 5000-8000 r / min for 10-25 min, and the operation is repeated 1-3 times, the supernatant is collected, water is added to dissolve the precipitate, dialyzed overnight with a dialysis bag, and then freeze-dried in a vacuum to obtain soy protein isolate; Step 2: Preparation of modified xanthan gum Add xanthan gum to distilled water, raise the temperature to 40-50°C, stir evenly, add arginine and catalytic components, raise the temperature again, react for 4-6 hours, cool and separate the product to obtain modified xanthan gum; Step 3: Glycosylation of soy protein isolate Soy protein isolate and modified xanthan gum are added to distilled water and mixed, stirred at 22-28°C for 1-3 hours, then reacted in a water bath for 3-5 hours, cooled to room temperature, centrifuged at 6000-8000 r / min for 15-30 minutes, and the supernatant is collected to obtain a glycosylated product of soy protein isolate; Step 4: Preparation of soy protein powder Add the glycosylated product of isolated soybean protein and laver polysaccharide into distilled water, raise the temperature to 50-60° C., stir for 30-60 minutes, let stand for 1-3 hours, and spray dry to obtain soybean protein powder.

2. The method for preparing soybean protein powder according to claim 1, wherein In step 1, the liquid-to-solid ratio of distilled water to soybeans is 10-12:

1.

3. The method for preparing soybean protein powder according to claim 1, wherein In step 1, the alkaline pH is 8-11, and the acidic pH is 3-6.

4. The method for preparing soybean protein powder according to claim 1, wherein In step 2, the catalytic component is Novozym435 immobilized lipase.

5. The method for preparing soybean protein powder according to claim 1, wherein In step 2, the temperature is raised again to 60-75°C.

6. The method for preparing soybean protein powder according to claim 1, wherein In step 3, the mass ratio of the soy protein isolate to the modified xanthan gum is 2-2.5:1-1.

4.

7. The method for preparing soybean protein powder according to claim 1, wherein In step 4, the mass ratio of the glycosylated product of the isolated soybean protein to the laver polysaccharide is 1-1.8:1-2.

8. The method for preparing soybean protein powder according to claim 1, wherein In step 4, the spray drying conditions are as follows: the inlet air temperature is 120-150°C and the outlet air temperature is 50-70°C.

9. A method for preparing soybean protein powder, characterized in that: The method according to claim 1 is used to prepare the product.

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