Preparation method of fermented and enzymolyzed sour soybean milk through ultrasonic treatment

Abstract

The invention discloses a preparation method of ultrasonic treatment fermented enzymolysis sour soybean milk, and belongs to the technical field of food fermentation. In order to effectively improve the gel strength of the fermented soybean milk and improve the sensory quality of the fermented soybean milk, the invention provides the preparation method of the ultrasonic treatment fermented enzymolysis sour soybean milk, and favorable conditions are created for the actual production and industrial application of the fermented soybean milk through the combination of a biological dissociation technology and an ultrasonic technology. The main process comprises the following steps: (1) selecting soybeans, crushing, carrying out extrusion puffing pretreatment, and centrifuging after enzymolysis; (2) mixing soybean powder with the hydrolysate, and carrying out secondary enzymolysis; (3) primarily preparing a mixed solution after sterilization; (4) performing ultrasonic treatment, homogenizing, sterilizing and cooling; and (5) sterilizing and fermenting to obtain a finished product. According to the production process disclosed by the invention, the nutritional value and the gel strength of the fermented soybean milk are improved, and favorable conditions are created for actual production and industrial application of the fermented soybean milk. And better economic benefits are created.

Description

Technical Field

[0001] The invention belongs to the technical field of food fermentation, and in particular relates to a method for preparing sour soybean milk by ultrasonic treatment fermentation and enzymatic hydrolysis. Background Art

[0002] Lactobacillus plantarum is a type of lactic acid bacteria, with an optimal growth temperature of 30-35 degrees Celsius. It is anaerobic or facultative anaerobic. The strain is straight or curved rod-shaped, single, sometimes in pairs or chains, with an optimal pH of about 6.5. It is a homofermentative lactic acid bacteria. The difference between this bacterium and other lactic acid bacteria is that the number of live bacteria is relatively high, and it can produce a large amount of acid, so that the pH value in the water is stable and does not increase. Lactobacillus plantarum has many health benefits. It has a certain immune regulation effect; it has an inhibitory effect on pathogenic bacteria; it can reduce serum cholesterol levels and prevent cardiovascular diseases; maintain the balance of intestinal flora; promote the absorption of nutrients; relieve lactose intolerance and inhibit the formation of tumor cells.

[0003] There are many ways to modify soy protein, such as preheating, ultrasonic treatment, pH shift treatment, TG enzyme cross-linking, adding salt ions, etc. Among them, ultrasonic treatment mainly improves the gel properties of protein by regulating the protein aggregation behavior through the physical and chemical effects caused by the cavitation effect. This modification method has mild conditions, consumes less energy, is simple and quick to operate, and is an ideal way to modify protein. In recent years, many studies have shown that ultrasonic treatment of soy protein and fermentation treatment of soy protein can improve the gel properties of fermented soy protein products.

[0004] Soy milk is a high-quality plant protein beverage made from soybeans and other ingredients. It is widely popular because it contains proteins and unsaturated fatty acids that are easily absorbed by the human body, and it is rich in mineral salts and does not contain cholesterol. The hydrolyzate obtained by the aqueous enzyme method contains a large amount of protein polypeptides and essential amino acids, which can increase the content of polypeptides and essential amino acids in soybean powder, not only promoting human absorption, but also supplementing the essential amino acids in the human body, reducing the beany smell. However, the hydrolyzate obtained by the aqueous enzyme method exhibits a certain bitterness. Fermented soy milk is a kind of flavored beverage fermented from soybeans as the main raw material. After fermentation, the nutrients in soy milk are easily absorbed by the human body, and it has the effects of improving the intestinal environment, eliminating toxins, lowering cholesterol, improving immunity, and covering up bad flavors. However, the problems of severe whey precipitation, poor gelation, and unstable state during the fermentation of soy milk have always hindered the development of the fermented soy milk industry. Summary of the invention

[0005] The purpose of the present invention is to effectively improve the strong gelling ability of fermented soybean milk. In order to solve the above technical problems, the present invention provides a method for preparing ultrasonically treated fermented enzymatic acid soybean milk, wherein the fermented soybean milk is obtained after inoculating plant lactobacillus in soybean milk for fermentation. The fermentation is carried out by combining biological dissociation technology with ultrasonic technology, thereby improving the nutritional value and gelling properties of the fermented soybean milk and creating favorable conditions for the actual production and industrial application of the fermented soybean milk.

[0006] The preparation method of the present invention is as follows:

[0007] (1) selecting clean soybeans free of impurities, peeling and removing the embryos, crushing and passing through a 200-mesh sieve, and performing extrusion puffing pretreatment after crushing, mixing the puffed material with water, adding alkaline protease to the mixture for enzymatic hydrolysis, and centrifuging to obtain a hydrolyzate;

[0008] (2) mixing the soybean powder with the hydrolyzate, adding alkaline protease thereto for secondary enzymolysis, the enzymolysis time being 1.5 to 2.0 hours, then adjusting the pH of the mixed solution, and then adding acidic protease for synergistic enzymolysis, the enzymolysis time being 1.5 to 2.0 hours;

[0009] (3) After enzymatic hydrolysis, the enzymatic hydrolyzed soy milk is obtained by high temperature sterilization, and 3.0% to 3.5% by mass of sucrose and 2.0% to 2.5% by mass of prebiotics are added to the enzymatic hydrolyzed soy milk to obtain an initial mixed solution;

[0010] (4) the initially mixed solution is subjected to ultrasonication, homogenization, sterilization and cooling to obtain a soymilk mixture;

[0011] (5) adding 2.5% to 3.2% by mass of a Lactobacillus plantarum fermentation agent to the soymilk mixture for fermentation, wherein the acidity at the end of the fermentation is 45 to 48°T.

[0012] It is further defined that in step (1), the moisture content of the material is 15.8%, the sleeve temperature is 95.5° C., the mold hole diameter is 20 mm, and the centrifugal conditions are 2000 rpm, 4° C., and 10 min.

[0013] It is further defined that in step (2), the mixing ratio of the soybean powder and the hydrolyzate is 1:8 (w / v), and the pH of the mixed solution is adjusted to 5.6.

[0014] It is further defined that the high temperature sterilization conditions in step (3) are 98-100° C., 10-15 min, and the prebiotic is inulin.

[0015] It is further defined that the ultrasonic conditions in step (4) are 400-600W for 15-30min, and the homogenization conditions are 50MPa-60MPa for 2-3min.

[0016] It is further defined that the fermentation temperature in step (5) is 32° C.-37° C., and the fermentation time is 6 h to 8 h.

[0017] Beneficial effects: The fermented soybean milk provided by the present invention is fermented by whole plants, has strong gelling property, and has no beany, bitter and unpleasant smell. The production process uses the biodissociation technology combined with the ultrasonic fermentation technology, and comprehensively utilizes the hydrolyzate of soybean water enzymatic method as an auxiliary material to improve the nutritional value and sensory characteristics of the fermented soybean milk, while creating favorable conditions for the actual production and industrial application of the fermented soybean milk, and creating better economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the process diagram of ultrasonic treatment and fermentation enzymatic hydrolysis of sour soy milk. Specific embodiments

[0019] The Lactobacillus plantarum fermentation culture was purchased from Shandong Zhongke Jiayi Biotechnology Co., Ltd.

[0020] The soybeans selected in the present invention are Beidahuang soybeans, which are purchased commercially.

[0021] Example 1.

[0022] A method for preparing soymilk by ultrasonic fermentation and enzymatic hydrolysis, characterized in that the preparation method is as follows:

[0023] (1) Clean soybeans free of impurities are selected, peeled and germinated, crushed and passed through a 200-mesh sieve, and then subjected to extrusion puffing pretreatment to make the moisture content of the material 15.8%, the sleeve temperature is 95.5° C., the die hole diameter is 20 mm, the puffed material is mixed with water, alkaline protease is added to the mixture for enzymatic hydrolysis, and centrifuged to obtain a hydrolyzate, and the centrifugation conditions are 2000 rpm, 4° C., and 10 min;

[0024] (2) The soybean powder and the hydrolyzate were mixed at a mixing ratio of 1:8 (w / v), alkaline protease was added thereto for secondary enzymolysis, and the enzymolysis time was 1.5 h, and then the pH of the mixed solution was adjusted to 5.6, and then acidic protease was added for synergistic enzymolysis, and the enzymolysis time was 2.0 h;

[0025] (3) After enzymatic hydrolysis, the enzymatic hydrolyzed soy milk is obtained by high temperature sterilization at 98° C. for 15 min, and 3.0% by mass of sucrose and 2.5% by mass of prebiotic inulin are added to the enzymatic hydrolyzed soy milk to obtain an initial mixed solution;

[0026] (4) the initially mixed solution is subjected to ultrasonication, homogenization, sterilization and cooling to obtain a soymilk mixture, wherein the ultrasonication condition is 400W for 30min and the homogenization condition is 50MPa for 3min;

[0027] (5) adding 2.5% by mass of a Lactobacillus plantarum starter to the soymilk mixture for fermentation at a temperature of 37° C. for 6 h and an acidity of 46° T at the end of the fermentation.

[0028] Example 2.

[0029] A method for preparing soymilk by ultrasonic fermentation and enzymatic hydrolysis, characterized in that the preparation method is as follows:

[0030] (1) Clean soybeans free of impurities are selected, peeled and germinated, crushed and passed through a 200-mesh sieve, and then subjected to extrusion puffing pretreatment to make the moisture content of the material 15.8%, the sleeve temperature is 95.5° C., the die hole diameter is 20 mm, the puffed material is mixed with water, alkaline protease is added to the mixture for enzymatic hydrolysis, and centrifuged to obtain a hydrolyzate, and the centrifugation conditions are 2000 rpm, 4° C., and 10 min;

[0031] (2) mixing soybean powder and hydrolyzate at a mixing ratio of 1:8 (w / v), adding alkaline protease thereto for secondary enzymolysis for 2.0 h, then adjusting the pH of the mixed solution to 5.6, and then adding acidic protease for synergistic enzymolysis for 1.5 h;

[0032] (3) After enzymolysis, the enzymolyzed soy milk is obtained by high temperature sterilization at 100° C. for 10 min, and 3.5% by mass of sucrose and 2.0% by mass of prebiotic inulin are added to the enzymolyzed soy milk to obtain an initial mixed solution;

[0033] (4) The initially mixed solution is subjected to ultrasonication, homogenization, sterilization and cooling to obtain a soymilk mixture, wherein the ultrasonication condition is 600 W for 15 min, and the homogenization condition is 60 MPa for 2 min;

[0034] (5) adding 3.2% by mass of Lactobacillus plantarum fermentation agent to the soymilk mixture for fermentation at a temperature of 32° C. for 8 h and an acidity of 48° T at the end of fermentation.

[0035] The following experiment was used to verify the experimental effect: Example 2 was used to verify the experimental effect:

[0036] 1. The indicators are determined as follows:

[0037] 1. Sensory evaluation

[0038] Ten people anonymously test the wine under bright light, looking straight ahead and evaluating the wine in terms of color, flavor, and texture. The total score of the three indicators is 100. The higher the score, the better the effect. The tasting results are statistically analyzed.

[0039] 2. Coliform count

[0040] Adopt national standard method [GB4789.3]

[0041] 3. Gel strength and water holding capacity

[0042] The fermented sour soybean milk was cooled to 4° C. and allowed to stand for 8 hours, then the fermented sour soybean milk was taken out and its gel strength and water holding capacity were measured.

[0043] 2. Results Analysis

[0044] 1. Sensory evaluation

[0045]

[0046] 2. Coliform count

[0047] Escherichia coli <3 / 100ml; pathogenic bacteria shall not be detected.

[0048] 3. Gel strength and water holding capacity

[0049] Table 1 Gel strength and water holding capacity test results

[0050]

[0051] As shown in Table 1, the use of ultrasonic treatment to ferment enzymatic yogurt can significantly improve the gel strength and water holding capacity of fermented yogurt.

Claims

1. A method for preparing soymilk by ultrasonic fermentation and enzymatic hydrolysis, characterized in that: The preparation method is as follows: (1) selecting clean soybeans free of impurities, peeling and removing the embryos, crushing and passing through a 200-mesh sieve, and performing extrusion puffing pretreatment after crushing, mixing the puffed material with water, adding alkaline protease to the mixture for enzymatic hydrolysis, and centrifuging to obtain a hydrolyzate; (2) mixing the soybean powder with the hydrolyzate, adding alkaline protease thereto for secondary enzymolysis, the enzymolysis time being 1.5 to 2.0 hours, then adjusting the pH of the mixed solution, and then adding acidic protease for synergistic enzymolysis, the enzymolysis time being 1.5 to 2.0 hours; (3) After enzymatic hydrolysis, the enzymatic hydrolyzed soy milk is obtained by high temperature sterilization, and 3.0% to 3.5% by mass of sucrose and 2.0% to 2.5% by mass of prebiotics are added to the enzymatic hydrolyzed soy milk to obtain an initial mixed solution; (4) the initially mixed solution is subjected to ultrasonication, homogenization, sterilization and cooling to obtain a soymilk mixture; (5) adding 2.5% to 3.2% by mass of a Lactobacillus plantarum fermentation agent to the soymilk mixture for fermentation, wherein the acidity at the end of the fermentation is 45 to 48°T.

2. The preparation method according to claim 4, characterized in that: The moisture content of the material in step (1) is 15.8%, the sleeve temperature is 95.5°C, the mold hole diameter is 20 mm, and the centrifugal conditions are 2000 rpm, 4°C, and 10 min.

3. The preparation method according to claim 4, characterized in that: In step (2), the soybean powder and the hydrolyzate are mixed in a ratio of 1:8 (w / v), and the pH of the mixed solution is adjusted to 5.

6.

4. The preparation method according to claim 4, characterized in that: The high temperature sterilization conditions in step (3) are 98-100° C., 10-15 min, and the prebiotic is inulin.

5. The preparation method according to claim 4, characterized in that: The ultrasonic conditions in step (4) are 400-600W for 15-30min, and the homogenization conditions are 50MPa-60MPa for 2-3min.

6. The preparation method according to claim 4, characterized in that: The fermentation temperature in step (5) is 32° C.-37° C., and the fermentation time is 6 h to 8 h.

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