Preparation method of enzymolysis soybean protein high-solubility soybean milk powder

Abstract

The invention relates to a preparation method of enzymolysis soybean protein high-solubility soybean milk powder. The invention discloses a method for preparing high-solubility soybean milk powder through enzymolysis of soybean protein, and belongs to the technical field of soybean milk powder processing. In order to solve the problems that soybean milk powder is not suitable for brewing due to caking in the brewing process, and further the taste of consumers in the eating process is influenced, the invention provides a preparation method of high-solubility soybean milk powder, which mainly comprises the steps of soaking, pulping, enzymolysis, enzyme deactivation, high-pressure homogenization, spray drying and the like. Wherein the soybean protein in the soybean milk is hydrolyzed by mainly adopting an enzymolysis mode, and the molecular weight of the protein is reduced, so that the solubility of the protein is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of soybean milk powder processing, and mainly relates to a preparation method of soybean milk powder with high solubility by hydrolyzing soybean protein in soybean milk through multi-enzyme composite catalytic reaction. Background Art

[0002] As an important plant protein resource, soybean has a protein content of up to 40%. It also contains rich minerals, vitamins, dietary fiber and a variety of bioactive substances. It is an indispensable source of high-quality nutritious food for humans. As a high-quality protein, soybean protein is widely used as an ingredient for various nutritious foods or directly processed into high-protein nutritious foods. As a new category of soybean processed products, instant soybean powder has an increasingly strong market demand due to its rich nutrition, instant dissolution, easy preparation, and convenience. It is deeply loved by consumers. At present, the most commonly used method for preparing soybean milk powder is the traditional wet process, which generally involves soaking soybeans, blanching, grinding, separation, and boiling the slurry, and then concentrating, homogenizing and spray drying to obtain soybean milk powder. However, the soy milk powder obtained by traditional process technology has poor solubility, so the soy milk protein is treated by biological enzyme method to obtain higher quality soybean powder.

[0003] Single enzyme has certain limitations in improving the properties of products. Therefore, the present invention adopts multi-enzyme composite catalysis, selects two biological enzymes to modify soybean milk protein in turn, and then spray-dries it into soybean milk powder. It improves catalytic activity and catalytic effect through dual enzymatic catalysis, and decomposes protein into smaller molecules, thereby improving the solubility of soybean milk powder. Among them, alkaline protease belongs to the protease of microbial origin, which can hydrolyze soybean protein (soy protein isolate or soybean protein concentrate, etc.) into soybean polypeptides. It is an endoenzyme that improves the solubility and functional properties of soybean protein and has strong hydrolysis ability. Flavor protease has both endoenzyme activity and exoenzyme activity, which can more fully hydrolyze soybean protein and improve its solubility, making up for the deficiency of single alkaline protease.

[0004] The purpose of the present invention is to prepare a soybean milk powder with high solubility by performing a multi-enzyme composite catalytic reaction on soybean milk before spray drying and using two proteases in combination with the perspectives of nutrition, health and high-quality food development. Summary of the invention

[0005] The novel high-solubility soybean milk powder prepared by the invention solves the problems of low solubility and easy agglomeration of traditional soybean milk powder, and hydrolyzes soybean milk protein by using two proteases in sequence to reduce the size of protein particles and improve the fluidity of soybean milk powder to meet the needs of consumers; and provides a method for preparing soybean milk powder which is easy to dissolve and brew and has good solubility.

[0006] To solve the above problems, the present invention is implemented through the following technical solutions:

[0007] A method for preparing high-solubility soybean milk powder, the method comprising the following steps:

[0008] Step 1: Select soybeans with uniform particles, soak them at 25°C in a ratio of 3:1 (dry soybeans: water, w / w) for 12 hours, drain the water, add ultrapure water in a ratio of soybeans: water = 1:7, grind the soaked soybeans, and grind the soybeans with a high-speed blender for 3 minutes to obtain soy milk;

[0009] Step 2: First, adjust the temperature of the ground soy milk in step 1 to 50°C and pH = 9, add alkaline protease at an enzyme amount of 3000U / g (per unit / substrate weight), perform enzymolysis for 3.5 hours, and after the enzymolysis is completed, perform a 95°C water bath for 15 minutes to inactivate the enzyme; then adjust the temperature to 50°C and pH = 6.5, add flavor protease at an enzyme amount of 3000U / g (per unit / substrate weight), perform enzymolysis for 3.5 hours, and after the enzymolysis is completed, perform a 95°C water bath for 15 minutes to inactivate the enzyme to obtain an enzymolyzate.

[0010] Step 3: The enzymatic hydrolysate is homogenized by two-stage homogenization, the first-stage homogenization pressure is 30MPa, the second-stage homogenization pressure is 20MPa, and the homogenization temperature is 60°C. The homogenized liquid is sprayed into the drying chamber at a pressure of 10MPa for spray drying, the feed temperature is 175°C, and the discharge temperature is 65°C. Finally, the finished soybean powder is obtained. The present invention has the following beneficial effects:

[0011] 1. The combined action of the two enzymes in the present invention plays a vital role in the preparation of highly soluble soybean milk powder. The combined catalysis of the two enzymes enables them to exert maximum biological activity.

[0012] 2. Enzymatic reactions are mild, environmentally friendly and efficient. Enzymatic hydrolysis is a promising way to modify proteins, and the products prepared will not cause harm to health. In addition, peptides with a wider range of activities can be prepared after enzymatic hydrolysis, and these peptides are also an important material basis for the biological activity of enzymatic hydrolysis products. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Attached Figure 1 The process route diagram of the present invention;

[0014] Attached Figure 2 Implementation case finished product diagram;

[0015] Attached Figure 3 Conduct case potential analysis;

[0016] Attached Figure 4 Implementation case fluorescence spectroscopy analysis;

[0017] Attached Figure 5 Implementation Case Fourier Transform Infrared Spectroscopy;

[0018] Attached Figure 6 Implementation case SDS-PAGE gel electrophoresis analysis; DETAILED DESCRIPTION

[0019] Example 1: (1) Select soybeans with uniform particles, soak them at 25°C in a ratio of 3:1 (dry soybeans: water, w / w) for 12 hours, drain the water, add ultrapure water in a ratio of soybeans: water = 1:7 to grind the soaked soybeans, and grind the soybeans with a high-speed mixer for 3 minutes to obtain soybean milk. (2) Adjust the temperature and pH of the soybean milk, do not add any enzymes, stir for 3.5 hours, and heat at 95°C for 15 minutes. (3) The homogenization method adopts two-stage homogenization, the first-stage homogenization pressure is 30MPa, the second-stage homogenization pressure is 20MPa, and the homogenization temperature is 60°C. The homogenized liquid is sprayed into the drying chamber at a pressure of about 10MPa for spray drying, the feed temperature is 175°C, and the discharge temperature is 65°C. Finally, the finished soybean powder is obtained.

[0020] Example 2: (1) Select soybeans with uniform particles, soak them at 25°C in a ratio of 3:1 (dry soybeans: water, w / w) for 12 hours, drain the water, add ultrapure water in a ratio of soybeans: water = 1:7 to grind the soaked soybeans, and grind the soybeans with a high-speed mixer for 3 minutes to obtain soybean milk. (2) Adjust the soybean milk temperature to 50°C and pH = 9, add alkaline protease, the enzyme amount is 3000U / g (per unit / substrate weight), stir for 3.5 hours, and inactivate the enzyme at 95°C for 15 minutes. (3) The homogenization method adopts two-stage homogenization, the first-stage homogenization pressure is 30MPa, the second-stage homogenization pressure is 20MPa, and the homogenization temperature is 60°C. The homogenized liquid is sprayed into the drying chamber at a pressure of about 10MPa for spray drying, the feed temperature is 175°C, and the discharge temperature is 65°C. Finally, the finished soybean powder is obtained.

[0021] Example 3: (1) Select soybeans with uniform particles, soak them at 25°C in a ratio of 3:1 (dry soybeans: water, w / w) for 12 hours, drain the water, add ultrapure water in a ratio of soybeans: water = 1:7 to grind the soaked soybeans, and grind the soybeans with a high-speed mixer for 3 minutes to obtain soybean milk. (2) Adjust the soybean milk temperature to 50°C and pH = 6.5, add flavor protease, the enzyme amount is 3000U / g (per unit / substrate weight), stir for 3 hours, and inactivate the enzyme at 95°C for 15 minutes. (3) The homogenization method adopts two-stage homogenization, the first-stage homogenization pressure is 30MPa, the second-stage homogenization pressure is 20MPa, and the homogenization temperature is 60°C. The homogenized liquid is sprayed into the drying chamber at a pressure of about 10MPa for spray drying, the feed temperature is 175°C, and the discharge temperature is 65°C. Finally, the finished soybean powder is obtained.

[0022] Example 4: (1) Soybeans with uniform particles were selected, soaked at 25°C in a ratio of 3:1 (dry soybeans: water, w / w) for 12 hours, drained, and then ultrapure water was added to grind the soaked soybeans in a ratio of soybeans: water = 1:7, and the soybeans were grinded with a high-speed mixer for 3 minutes to obtain soybean milk. (2) The soybean milk temperature was adjusted to 50°C and pH = 9, alkaline protease was added, the enzyme amount was 3000U / g (per unit / substrate weight), stirred for 3.5 hours, and the enzyme was inactivated at 95°C for 15 minutes, then cooled to adjust the temperature to 50°C and pH = 6.5, flavor protease was added, the enzyme amount was 3000U / g (per unit / substrate weight), stirred for 3.5 hours, and the enzyme was inactivated at 95°C for 15 minutes (3) The homogenization method adopted a two-stage homogenization, the first-stage homogenization pressure was 30MPa, the second-stage homogenization pressure was 20MPa, and the homogenization temperature was 60°C. The homogenized liquid is sprayed into the drying chamber at a pressure of about 10 MPa for spray drying, with a feed temperature of 175°C and a discharge temperature of 75°C. Finally, the finished soybean powder is obtained.

[0023] Example 5: (1) Soybeans with uniform particles were selected, soaked at 25°C in a ratio of 3:1 (dry soybeans: water, w / w) for 12 hours, drained, and then ultrapure water was added to grind the soaked soybeans in a ratio of soybeans: water = 1:7, and the soybeans were grinded with a high-speed mixer for 3 minutes to obtain soybean milk. (2) The soybean milk temperature was adjusted to 50°C and pH = 6.5, flavor protease was added at an enzyme amount of 3000U / g (per unit / substrate weight), stirred for 3.5 hours, and enzyme was inactivated at 95°C for 15 minutes, then cooled to adjust the temperature to 50°C and pH = 9, alkaline protease was added at an enzyme amount of 3000U / g (per unit / substrate weight), stirred for 3.5 hours, and enzyme was inactivated at 95°C for 15 minutes (3) The homogenization method adopted a two-stage homogenization, with a first-stage homogenization pressure of 30MPa, a second-stage homogenization pressure of 20MPa, and a homogenization temperature of 60°C. The homogenized liquid is sprayed into the drying chamber at a pressure of about 10 MPa for spray drying, with a feed temperature of 175°C and a discharge temperature of 75°C. Finally, the finished soybean powder is obtained.

[0024] The hydrolysis degree of the bean powder obtained in the above-mentioned examples 1, 2, 3, 4 and 5 was measured, and the test results are shown in Table 1. The solubility, protein solubility index (PDI) and bulk density of the bean powder obtained in the above-mentioned examples 1, 2, 3, 4 and 5 were measured, and the test results are shown in Table 2:

[0025] Table 1 Degree of hydrolysis

[0026]

[0027]

[0028] Table 2 Solubility, protein solubility index (PDI), bulk density

[0029]

[0030] As can be seen from the above table, the soy flour prepared by different enzymatic hydrolysis methods has different hydrolysis degrees. Among them, the hydrolysis degree of implementation case 5 is the highest in which the flavor protease is first used for hydrolysis and then the alkaline protease is used for hydrolysis. The degree of cleavage of the protein peptide bonds during the hydrolysis process is the highest, which also makes the soy flour solubility of this process method the highest; the lower the PDI, the better the solubility. The PDI value of implementation case 5 is the smallest, the bulk density is the largest, and the solubility is the best; in addition, alkaline protease is added later to make its pH close to the isoelectric point of soybean protein (4.5), and the solubility is high; the solubility of the unhydrolyzed soy flour in implementation case 1 is the worst.

[0031] Attached Figure 3 The zeta potential diagrams of Example 1, Example 2, Example 3, Implementation Case 4 and Implementation Case 5 are shown, among which the one with the highest absolute potential value is Implementation Case 5, i.e., the group of hydrolysis using flavor protease first and then using alkaline protease, which may be because the two enzyme treatments more fully promote the degradation of protein molecules, thereby causing more charged groups to be exposed, and the protein (hydrolysate) system with a high absolute zeta potential has strong intermolecular electrostatic repulsion, thereby improving the dispersibility and stability of the system. Therefore, the soymilk powder after the fifth treatment has the best dispersibility and stability.

[0032] Attached Figure 4 The fluorescence spectrum analysis diagrams of Example 1, Example 2, Example 3, Implementation Case 4 and Implementation Case 5 show that the maximum fluorescence intensity of the differently treated soymilk powders is all around 350nm. The fluorescence spectra of the soymilk powders after enzymatic hydrolysis with alkaline protease in Implementation Case 2, Implementation Case 4 and Implementation Case 5 all show a slight red shift. This may be because protease hydrolysis promotes the breakage of protein peptide chains, resulting in the exposure of aromatic amino acid residues wrapped in the protein, making them easier to dissolve.

[0033] Attached Figure 5 The Fourier transform infrared spectra of Example 1, Example 2, Example 3, Example 4 and Example 5 are shown in Figure 1. The FTIR spectrum can be used to provide information about the vibration of functional groups, wherein the hydrophobic region of the protein is mainly 2800-3000cm -1 , which is generated by CH stretching vibration. As shown in the figure, Example 2 shows a slight red shift after alkaline protease hydrolysis, and the hydrolyzate treated with composite enzymatic hydrolysis in Implementation Case 4 and Implementation Case 5 shows a blue shift, indicating that the hydrophobic region of the protein is affected by enzymatic hydrolysis; 3500-3000cm -1is the typical vibration frequency of the amide A band, which mainly produces stretching vibrations between OH and NH, thereby allowing hydrogen bonds to combine with other functional groups. As shown in the figure, the peak of the hydrolyzate soybean powder in Implementation Case 5 becomes wider and the peak intensity becomes stronger, which also indicates the destruction of the hydrogen bond structure during the hydrolysis process, the breaking of hydrogen bonds, and the decrease of molecular weight, thereby improving the solubility of the product.

[0034] Attached Figure 6 The SDS-PAGE gel electrophoresis diagrams of Example 1, Example 2, Example 3, Implementation Case 4 and Implementation Case 5 are used to analyze the molecular weight and distribution of soybean powder in the five groups of implementation cases. As shown in the figure, in Implementation Case 1, the bands in the range of 75-245kda are clear and obvious, and the unhydrolyzed soybean powder has a large molecular weight and poor solubility. In Example 2 and Implementation Case 5, there are no obvious bands after hydrolysis, the molecular weight is small, and there are residues at the injection port, indicating that there are smaller molecules not shown in the electrophoresis of large molecular weight, and the protein in the soybean powder has been decomposed into smaller molecules. The smaller the molecular weight, the higher the solubility, and the better the solubility. Among them, the electrophoresis band of Implementation Case 5 is the least obvious, the molecular weight is the smallest, the solubility is the largest, and the solubility is the best.

Claims

1. A method for preparing low anti-nutritional factor soymilk using ultrasonic technology, characterized in that: The method comprises the following steps: Step 1: remove impurities and soak the soybean raw material, the soaking solution is a sodium bicarbonate solution with a mass fraction of 0.4-0.6%; the material-liquid ratio of the soaking treatment is 1:3-1:5, the soaking temperature is 20-30°C, and the soaking time is 8-16h; Step 2: grinding the soaked soybeans obtained in step 1, wherein the ratio of soybeans to water is 1:7-1:11; preparing raw soy milk; Step 3: The raw soymilk obtained in step 2 is subjected to ultrasonic, filtration and high-pressure homogenization treatment in sequence to prepare a homogenized liquid; the ultrasonic frequency is 20000-30000 Hz; the ultrasonic power is 200-600 W, the ultrasonic time is 25-35 min, and the high-pressure homogenization pressure is 100-200 MPa; Step 4: The homogenized liquid obtained in step 3 is boiled and sterilized in sequence to prepare soymilk with low anti-nutritional factors; the high-temperature sterilization treatment is to heat the homogenized liquid to 95° C. and then keep it warm for 8 minutes.

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