Lactobacillus paracasei JM053 with low sugar content, low soybean fishy smell and the ability to convert soybean isoflavones, its fermented soybean milk and preparation method

Abstract

The present invention discloses a Lactobacillus paracasei JM053 with low sugar content, low soybean fishy smell and the ability to convert soybean isoflavones, as well as its fermented soybean milk and preparation method, belonging to the field of microbial technology. The Lactobacillus paracasei is preserved in the Guangdong Microbial Culture Collection Center, Guangzhou, with the preservation date being November 13, 2023 and the preservation number being GDMCC NO: 64011. Under low sugar conditions in the present invention, the content of soybean isoflavone aglycone in the soybean milk treated with β-glucosidase immobilized on bamboo cellulose carrier is significantly increased. The soybean milk obtained in the present invention is treated with β-glucosidase immobilized on bamboo cellulose carrier under the condition of 2.5-3.5% sucrose addition amount, which can reduce the contents of 1-octen-3-ol, 2-pentylfuran and nonanal, and has the strongest ability to convert soybean isoflavones. The present invention lays a foundation for the preparation of a new type of fermented soybean milk with low sugar content, low soybean fishy smell and rich in soybean isoflavone aglycone content.

Description

Technical Field

[0001] The present invention relates to a Lactobacillus paracasei JM053 with low sugar content, low soybean fishy smell and the ability to convert soybean isoflavones, its fermented soybean milk and preparation method, belonging to the field of microbial technology. Background Art

[0002] Fermented soybean milk is made by sterilizing raw soybean milk and then fermenting it with probiotics. It contains nutrients such as soybean isoflavones, but its conjugated glycoside form is difficult to be absorbed and utilized by the body. Only when it is converted into the free aglycone form does it have high biological activity. Improving the conversion rate of free aglycone is still a problem to be solved at present. At the same time, soybean milk has substances such as 1-octen-3-ol, 2-pentylfuran and nonanal, which make soybean milk present a fishy smell of soybeans, affecting the sensory quality of soybean milk and making it unacceptable to some people. Therefore, it is necessary to propose a preparation method of soybean milk with strong ability to convert soybean isoflavone aglycone and low soybean fishy smell.

[0003] Sucrose is an essential component added to fermented soybean milk, but a high sucrose addition amount may affect the body's blood sugar level, resulting in some people being less likely to accept soybean milk with a high sucrose addition amount. Along with the change of people's concept of paying attention to healthy diet, and there are few soybean milk products with a low sucrose addition amount in the current market. Therefore, it is important to propose a low-sugar fermented soybean milk and its preparation method, to ensure the flavor quality of soybean milk under the condition of low-sugar fermentation, and at the same time have a high content of soybean isoflavone aglycone, providing a research basis for the industrialization of fermented soybean milk with low sugar, low soybean fishy smell and high nutritional components. Summary of the Invention

[0004] The purpose of the present invention is to provide a Lactobacillus paracasei JM053 with low sugar content, low soybean fishy smell and the ability to convert soybean isoflavones.

[0005] At the same time, the purpose of the present invention is to provide a fermented soybean milk of Lactobacillus paracasei JM053 with low sugar content, low soybean fishy smell and the ability to convert soybean isoflavones, which has low sugar content, low soybean fishy smell and high nutritional components.

[0006] At the same time, the purpose of the present invention is to provide a preparation method of fermented soybean milk, which uses Lactobacillus paracasei JM053 for fermentation and adopts an ultrasonic-assisted bamboo cellulose carrier immobilized β-glucosidase enzymatic hydrolysis method for treatment, significantly increasing the content of soybean isoflavone aglycone in soybean milk.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] Lacticaseibacillus paracasei JM053 with low sugar content, low soybean fishy smell and the ability to convert soybean isoflavones. The Lacticaseibacillus paracasei is preserved in the Guangdong Microbial Culture Collection Center, Guangzhou. The preservation date is November 13, 2023, and the preservation number is GDMCC NO: 64011.

[0009] Fermented soybean milk of Lacticaseibacillus paracasei JM053. The content of soybean isoflavone aglycone in the fermented soybean milk reaches 97.29±3.56~98.75±3.82 μg / mL, and it has low sugar content and low soybean fishy smell.

[0010] The sucrose content is 2.5~3.5 wt%; the contents of 1-octen-3-ol, 2-pentylfuran and nonanal are 0.23±0.03~0.37±0.04%, 0.12±0.01~0.25±0.03% and 0.09±0.01~0.16±0.01% respectively.

[0011] Method for preparing fermented soybean milk, comprising the following steps:

[0012] Step 1: Add 2.5~3.5 wt% of sterilized sucrose to soybean milk, shake and mix evenly, then inoculate the bacterial liquid of Lacticaseibacillus paracasei JM053 with a total viable count of 1×10 7 ~1×10 9 CFU / mL, ferment at 37~40 °C until the pH at the end of fermentation is 4.40~4.60 to obtain fermented soybean milk;

[0013] Step 2: Treat the fermented soybean milk under the following conditions: carry out the treatment at an ultrasonic power of 200~250 W, a reaction temperature of 50~55 °C, a pH of 5.0~5.3, an enzyme addition amount of 7~9 wt%, and the enzyme is β-glucosidase immobilized on bamboo cellulose carrier for 45~60 min; after the reaction, carry out a boiling water bath for 5~10 min to inactivate the enzyme, and wait until it cools to room temperature to obtain the finished fermented soybean milk.

[0014] Preferably, the preparation method of β-glucosidase immobilized on bamboo cellulose carrier is as follows: dissolve 7-8 g of bamboo cellulose in 60-80 mL of a solution composed of dimethyl sulfoxide and acetone, with the volume ratio of dimethyl sulfoxide to acetone being 3:4, and drop the solution into ice water drop by drop to prepare bamboo cellulose particles. Subsequently, keep the bamboo cellulose particles in 100-120 mL of 0.15-0.20 mol / L NaOH solution at 40-50 °C for 70-90 min. After taking them out, place them in 50-60 mL of 2.5-3% glutaraldehyde solution and keep them at 95-100 °C for 55-60 min. Take out the bamboo cellulose carrier for standby; dissolve 40-50 mg of β-glucosidase in 40-50 mL of 0.1-0.15 mol / L phosphate buffer solution to prepare an enzyme solution, and place the bamboo cellulose carrier in it and keep it at low temperature for at least 18 h. Subsequently, filter the filtrate for standby to obtain β-glucosidase immobilized on bamboo cellulose carrier.

[0015] Preferably, the specific surface area of the bamboo cellulose carrier is 2.57-2.69 m 2 / g.

[0016] Preferably, the low temperature condition is 1-4 °C.

[0017] Application of Lactobacillus paracasei JM053 in fermented soybean milk with low sugar, low soybean bean flavor and high daidzein content.

[0018] Application of fermented soybean milk in healthy foods.

[0019] The present invention has the following beneficial effects:

[0020] Under the low sugar condition of the present invention, the content of daidzein in the soybean milk treated with β-glucosidase immobilized on bamboo cellulose carrier is significantly increased, reaching 97.29±3.56-98.75±3.82 μg / mL.

[0021] The soybean milk obtained by the present invention is treated with β-glucosidase immobilized on bamboo cellulose carrier under the condition of 3% sucrose addition amount, which can reduce the contents of 1-octen-3-ol, 2-pentylfuran and nonanal, and has the strongest ability to convert soybean isoflavones. The present invention lays a foundation for the preparation of novel fermented soybean milk with low sugar, low soybean bean flavor and high daidzein content.

[0022] The present invention also provides a preparation method of β-glucosidase immobilized on bamboo cellulose carrier, and the obtained immobilized enzyme is used to treat fermented soybean milk. Description of the Drawings

[0023] Figure 1 Shows the influence of β-glucosidase immobilized on bamboo cellulose carrier of the present invention on the content of daidzein in fermented soybean milk;

[0024] Figure 2 The effect of immobilizing β-glucosidase on the bamboo cellulose carrier of the present invention on the content of 1-octen-3-ol in fermented soymilk;

[0025] Figure 3 The effect of immobilizing β-glucosidase on the bamboo cellulose carrier of the present invention on the content of 2-pentylfuran in fermented soymilk;

[0026] Figure 4 The present invention shows the effect of immobilizing β-glucosidase on the content of nonanal in fermented soy milk by using the bamboo cellulose carrier. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] In the present invention, the strain is isolated from traditional fermented dairy products in the laboratory, wherein the low-sugar, low-beany smell Lactobacillus paracasei JM053 (Lacticaseibacillus paracasei JM053) with the ability to convert soybean isoflavones is deposited in Guangdong Microbiological Culture Collection Center (GDMCC No: 64011), address: 5th Floor, Building 59, No. 100, Xianlie Middle Road, Guangzhou, and the preservation date is November 13, 2023. The method for preparing fermented soy milk using Lactobacillus paracasei JM053 with low sugar, low beany smell and the ability to convert soybean isoflavones comprises the following steps: using Lactobacillus paracasei JM053 isolated from traditional dairy products to ferment soy milk, adding 8% (equivalent to 8% of the weight of soy milk) sterilized sucrose to the soy milk, shaking and mixing, and then inoculating the bacterial solution (the total number of viable bacteria is 1×10 7 CFU / mL), fermented at 37°C until the pH at the fermentation end point is 4.50, and fermented soy milk is obtained. The fermented soy milk processing conditions are: ultrasonic power 210W, reaction temperature 50°C, pH=5.1, enzyme addition amount 8% (equivalent to 8% of the weight of the fermented soy milk), reaction time 45min. After the reaction is completed, the enzyme is inactivated in a boiling water bath for 6min, and the finished fermented soy milk is obtained after cooling to room temperature.

[0030] Preparation of bamboo cellulose carrier-immobilized β-glucosidase: 7.35 g of bamboo cellulose was dissolved in 60 mL of a solvent consisting of dimethyl sulfoxide: acetone (3:4), and the solution was dripped into ice water drop by drop to prepare bamboo cellulose particles, which were then kept in 120 mL of a 0.15 mol / L NaOH solution at 45 ° C for 80 min. After being taken out, they were finally placed in 60 mL of a 2.6% glutaraldehyde solution at 100 ° C for 55 min. The bamboo cellulose carrier was taken out for use, and its specific surface area was measured to be 2.69 m2 Dissolve 40 mg of β-glucosidase in 40 mL of 0.1 mol / L phosphate buffer to prepare an enzyme solution, and place the bamboo cellulose carrier in it and store it at a low temperature (2 °C) for 18 h, then filter the filtrate for standby. That is, the β-glucosidase immobilized on the bamboo cellulose carrier is obtained.

[0031] The preparation method of 2.6% glutaraldehyde solution is as follows: Add 10 mL of 26% glutaraldehyde solution to 90 mL of double-distilled water, and stir evenly to obtain it.

[0032] Application of Lactobacillus paracasei JM053 in fermented soy milk with low sugar, low soybean fishy smell and high content of soy isoflavone aglycone.

[0033] Application of the fermented soy milk of this example in health foods.

[0034] I. Materials and Methods

[0035] 1. Determination of the content of soy isoflavone aglycone in soy milk

[0036] Take 3 mL of fermented soy milk and place it in a 10 mL volumetric flask, make up the volume with 85% methanol solution, take an appropriate amount of the solution and centrifuge it at 8000 r / min for 15 min, and take the supernatant and filter it with a 0.45 μm filter membrane. Use high performance liquid chromatography for determination. Chromatographic conditions: Chromatographic column: C 18 Chromatographic column (250 mm × 4.6 mm, 5 μm), mobile phase A: acetonitrile, mobile phase B: 0.1% formic acid solution. The gradient elution program is as follows: 0 min, 90% B; 0 - 8 min, B linearly changes from 90% to 84%; 8 - 22 min, B linearly changes from 84% to 78%; 22 - 30 min, B linearly changes from 78% to 70%; 30 - 50 min, B is maintained at 70%; 50 - 55 min, B linearly changes from 70% to 20%; 55 - 58 min, B linearly changes from 20% to 90%; 58 - 60 min, B is maintained at 90%. Flow rate: 1.0 mL / min, detection wavelength: 260 nm, column temperature: 40 °C, injection volume: 10 μL, and determine the contents of daidzein and genistein in soy milk.

[0037] 2. Determination of soybean fishy smell substances in soy milk

[0038] Take 5 mL of the sample and add it to a headspace vial. Incubate at 40 °C for 10 min. Extract with an extraction head at 40 °C for 30 min. Determine the beany odor substances using gas chromatography-mass spectrometry (GC-MS). GC-MS chromatographic conditions: DB-5MSUI capillary column (60 m × 0.25 mm, 0.25 μm). Desorb the extraction head in the injection port (250 °C) for 6 min: initial temperature 35 °C, hold for 5 min, increase to 120 °C at a rate of 4 °C / min, hold for 2 min, then increase to 250 °C at a rate of 10 °C / min, hold for 8 min. The carrier gas (He) flow rate is 1.0 mL / min, and splitless injection is used. Quantitative analysis is performed by area normalization method.

[0039] II. Experimental Results

[0040] 1. Effect of β-glucosidase immobilized on bamboo cellulose carrier on the content of soy isoflavone aglycones in soymilk fermented by Lactobacillus paracasei JM053

[0041] The content of soy isoflavone aglycones in fermented soymilk is expressed as the total content of daidzein and genistein. As Figure 1 shown, compared with group A, the content of soy isoflavone aglycones in the soymilk fermented by Lactobacillus paracasei JM053 in group B can reach 45.63 ± 0.22 μg / mL, indicating that Lactobacillus paracasei JM053 has a certain ability to convert soy isoflavone aglycones in soymilk. However, compared with groups B and C, the content of soy isoflavone aglycones in the soymilk treated with β-glucosidase immobilized on bamboo cellulose carrier in group D can reach 90.07 ± 3.26 μg / mL, indicating that the content of soy isoflavone aglycones in soymilk can be significantly increased after treatment with ultrasound-assisted β-glucosidase immobilized on bamboo cellulose carrier. Soy isoflavone aglycones can provide supplementary nutrients for the human body and are beneficial to absorption, providing a theoretical basis for the development of functional soymilk.

[0042] Figure 1 In, A: unfermented soymilk group (add 8% sterilized sucrose to soymilk, shake well to obtain); B: JM053 fermented soymilk group (add 8% sterilized sucrose to soymilk, shake well, then inoculate the bacterial solution (total viable count is 1×10 7 CFU / mL), ferment at 37 °C until the fermentation end point pH is 4.50 to obtain fermented soymilk); C: β-glucosidase + JM053 fermented soymilk group (add 8% sterilized sucrose to soymilk, shake well, then inoculate the bacterial solution (total viable count is 1×10 7(CFU / mL), ferment at 37 °C until the pH at the end of fermentation is 4.50 to obtain fermented soy milk. The treatment conditions of the fermented soy milk are as follows: perform the treatment under the conditions of an ultrasonic power of 210 W, a reaction temperature of 50 °C, pH = 5.1, an amount of β-glucosidase added of 8%, and a reaction time of 45 min. After the reaction, carry out a boiling water bath for 6 min to inactivate the enzyme, and wait until it cools to room temperature to obtain it); D: Group of adding β-glucosidase immobilized on bamboo cellulose carrier + JM053 fermented soy milk (that is, add 8% of sterilized sucrose to soy milk, shake and mix well, and then inoculate the bacterial solution (the total viable count is 1×10 7 (CFU / mL), ferment at 37 °C until the pH at the end of fermentation is 4.50 to obtain fermented soy milk. The treatment conditions of the fermented soy milk are as follows: perform the treatment under the conditions of an ultrasonic power of 210 W, a reaction temperature of 50 °C, pH = 5.1, an amount of β-glucosidase immobilized on bamboo cellulose carrier of 8%, and a reaction time of 45 min. After the reaction, carry out a boiling water bath for 6 min to inactivate the enzyme, and wait until it cools to room temperature to obtain it).

[0043] 2. Effect of β-glucosidase immobilized on bamboo cellulose carrier on the content of beany flavor substances in fermented soy milk by Lactobacillus paracasei JM053

[0044] Polyunsaturated fatty acids in soy milk are oxidized to form hydroperoxides, which are then degraded into volatile substances such as aldehydes and furans, thus forming a beany flavor. After fermentation by probiotics, the content of beany flavor substances in soy milk will be reduced, which is beneficial for human acceptance. As Figure 2 shown in Figures 3 and 4, compared with other control groups, the content of beany flavor substances such as 1-octen-3-ol, 2-pentylfuran, and nonanal in the soy milk in Group D treated with ultrasonic-assisted β-glucosidase immobilized on bamboo cellulose carrier was significantly reduced, indicating that after treatment with ultrasonic-assisted β-glucosidase immobilized on bamboo cellulose carrier, the beany flavor substances in soy milk can be reduced, which is beneficial for improving the quality of fermented soy milk.

[0045] Figure 2 In Figures 3 and 4, the grouping of Group A, Group B, Group C, and Group D is the same as the grouping in Figure 1 .

[0046] 3. Effect of sucrose addition amount and β-glucosidase immobilized on bamboo cellulose carrier on the content of beany flavor substances in fermented soy milk by Lactobacillus paracasei JM053

[0047] As shown in Table 1, the effects of different enzyme treatments and sucrose addition amounts on the content of beany flavor substances in fermented soy milk were studied. Compared with groups H and I, the content of beany flavor substances in the soy milk treated with β-glucosidase immobilized on bamboo cellulose carrier in groups A, B, C, D, E, F, and G decreased. At the same time, under the treatment of different sucrose addition amounts in groups A, B, C, D, E, F, and G, the content of beany flavor substances in the soy milk in group B with 3% sucrose addition was the lowest, and the contents of 1-octen-3-ol, 2-pentylfuran, and nonanal were 0.23±0.03, 0.12±0.01, and 0.09±0.01%, respectively. This further indicated that under the condition of low sucrose addition fermentation, treating soy milk with β-glucosidase immobilized on bamboo cellulose carrier could reduce the content of beany flavor substances in it. Under this condition, the content of daidzein was measured to be 98.75±3.82 μg / mL, providing a basic research for the preparation of low-sugar and low-beany flavor soy milk.

[0048] In Table 1, A: adding immobilized enzyme (i.e., β-glucosidase immobilized on bamboo cellulose carrier) + adding 2% sugar; B: adding immobilized enzyme + adding 3% sugar; C: adding immobilized enzyme + adding 4% sugar; D: adding immobilized enzyme + adding 5% sugar; E: adding immobilized enzyme + adding 6% sugar; F: adding immobilized enzyme + adding 7% sugar; G: adding immobilized enzyme + adding 8% sugar; H: β-glucosidase + adding 3% sugar; I: β-glucosidase + adding 10% sugar.

[0049] The following Table 1 shows the data of the content of beany flavor substances in soy milk under different enzyme treatments and sucrose addition amounts.

[0050] Table 1 Content of beany flavor substances in soy milk under different enzymes and sucrose addition amounts

[0051]

[0052] That is, the preparation method of the fermented soy milk in this example is the process of group B in Table 1, that is:

[0053] The method for making fermented soy milk using Lactobacillus paracasei JM053 with low sugar, low beany flavor, and the ability to convert soy isoflavones: includes the following steps: Using Lactobacillus paracasei JM053 isolated from traditional dairy products to ferment soy milk. Add 3% (equivalent to 3% of the weight of soy milk) of sterilized sucrose to the soy milk, shake well, and then inoculate the bacterial liquid (the total viable count is 1×10 7(CFU / mL), ferment at 37 °C until the pH at the end of fermentation is 4.50 to obtain fermented soy milk. The treatment conditions for the fermented soy milk are as follows: perform treatment under the conditions of an ultrasonic power of 210 W, a reaction temperature of 50 °C, a pH of 5.1, an enzyme addition amount of 8% (equivalent to 8% of the weight of the fermented soy milk), and a reaction time of 45 min. After the reaction, carry out a boiling water bath for 6 min to inactivate the enzyme, and wait until it cools to room temperature to obtain the finished fermented soy milk.

[0054] Preparation of β-glucosidase immobilized on bamboo cellulose carrier: Dissolve 7.35 g of bamboo cellulose in a solvent composed of 60 mL of dimethyl sulfoxide:acetone (3:4), and dropwise add the solution into ice water to prepare bamboo cellulose particles. Subsequently, keep it at 45 °C in 120 mL of 0.15 mol / L NaOH solution for 80 min. After taking it out, finally place it in 60 mL of 2.6% glutaraldehyde solution and store it at 100 °C for 55 min. Take out the bamboo cellulose carrier for standby, and measure its specific surface area to be 2.69 m 2 / g. Dissolve 40 mg of β-glucosidase in 40 mL of 0.1 mol / L phosphate buffer solution to prepare an enzyme solution, and place the bamboo cellulose carrier in it and store it at a low temperature condition (2 °C) for 18 h. Subsequently, filter the filtrate for standby. Thus, β-glucosidase immobilized on bamboo cellulose carrier is obtained.

[0055] Example 2

[0056] Lacticaseibacillus paracasei JM053 with low sugar, low soy bean odor and the ability to convert soy isoflavones. The Lacticaseibacillus paracasei is preserved in the Guangdong Provincial Microbial Culture Collection Center, Guangzhou. The preservation date is November 13, 2023, and the preservation number is GDMCC NO: 64011.

[0057] Method for making fermented soy milk using Lacticaseibacillus paracasei JM053 with low sugar, low soy bean odor and the ability to convert soy isoflavones: It includes the following steps: Use Lacticaseibacillus paracasei JM053 separated from traditional dairy products to ferment soy milk. Add 2.5% (equivalent to 2.5% of the weight of the soy milk) of sterilized sucrose to the soy milk, shake well and then inoculate the bacterial liquid (the total viable count is 1×10 9 CFU / mL), ferment at 40 °C until the pH at the end of fermentation is 4.40 to obtain fermented soy milk. The treatment conditions for the fermented soy milk are as follows: perform treatment under the conditions of an ultrasonic power of 200 W, a reaction temperature of 55 °C, a pH of 5.0, an enzyme addition amount of 7% (equivalent to 7% of the weight of the fermented soy milk), and a reaction time of 60 min. After the reaction, carry out a boiling water bath for 5 min to inactivate the enzyme, and wait until it cools to room temperature to obtain the finished fermented soy milk.

[0058] Preparation of β-glucosidase immobilized on bamboo cellulose carrier: Dissolve 7 g of bamboo cellulose in 80 mL of a solvent composed of dimethyl sulfoxide:acetone (3:4), and drop the solution into ice water drop by drop to prepare bamboo cellulose particles. Then, keep it in 100 mL of 0.20 mol / L NaOH solution at 40 °C for 70 min. After taking it out, finally place it in 50 mL of 2.5% glutaraldehyde solution and store it at 95 °C for 60 min. Take out the bamboo cellulose carrier for standby, and measure its specific surface area to be 2.57 m 2 / g. Dissolve 50 mg of β-glucosidase in 50 mL of 0.15 mol / L phosphate buffer to prepare an enzyme solution, and place the bamboo cellulose carrier in it and store it at a low temperature (1 °C) for 20 h. Then, filter the filtrate for standby. That is, β-glucosidase immobilized on bamboo cellulose carrier is obtained.

[0059] Application of Lactiplantibacillus paracasei JM053 of this example in fermented soy milk with low sugar, low soybean fishy smell and high daidzein content.

[0060] Application of the fermented soy milk of this example in healthy foods.

[0061] The daidzein content measured in this example is 97.29 ± 3.56 μg / mL, and the contents of 1-octen-3-ol, 2-pentylfuran and nonanal are 0.37 ± 0.04%, 0.25 ± 0.03% and 0.16 ± 0.01% respectively.

[0062] Example 3

[0063] Lactiplantibacillus paracasei JM053 with low sugar, low soybean fishy smell and the ability to convert soy isoflavones. The Lactiplantibacillus paracasei is preserved in the Guangdong Provincial Culture Collection Center of Microorganisms, Guangzhou, the preservation date is November 13, 2023, and the preservation number is GDMCC NO: 64011.

[0064] Method for making fermented soy milk using Lactiplantibacillus paracasei JM053 with low sugar, low soybean fishy smell and the ability to convert soy isoflavones: It includes the following steps: Use Lactiplantibacillus paracasei JM053 isolated from traditional dairy products to ferment soy milk. Add 3.5% (equivalent to 3.5% of the weight of soy milk) of sterilized sucrose to the soy milk, shake it evenly, and then inoculate the bacterial solution (the total viable bacteria count is 1×10 8(CFU / mL), ferment at 39 °C until the pH at the end of fermentation is 4.60 to obtain fermented soy milk. The treatment conditions for the fermented soy milk are as follows: carry out the treatment under the conditions of an ultrasonic power of 250 W, a reaction temperature of 52 °C, a pH of 5.3, an enzyme addition amount of 9% (equivalent to 9% of the weight of the fermented soy milk), and a reaction time of 55 min. After the reaction is completed, carry out a boiling water bath for 10 min to inactivate the enzyme. Wait until it cools to room temperature to obtain the finished fermented soy milk.

[0065] Preparation of β-glucosidase immobilized on bamboo cellulose carrier: Dissolve 8 g of bamboo cellulose in a solvent composed of 70 mL of dimethyl sulfoxide:acetone (3:4), and drop the solution into ice water drop by drop to prepare bamboo cellulose particles. Then keep it at 50 °C in 110 mL of 0.18 mol / L NaOH solution for 90 min. After taking it out, finally place it in 55 mL of 3% glutaraldehyde solution and store it at 100 °C for 60 min. Take out the bamboo cellulose carrier for standby, and measure its specific surface area to be 2.62 m 2 / g. Dissolve 45 mg of β-glucosidase in 50 mL of 0.1 mol / L phosphate buffer solution to prepare an enzyme solution, and place the bamboo cellulose carrier in it and store it at a low temperature condition (4 °C) for 24 h. Then filter the filtrate for standby. That is, β-glucosidase immobilized on bamboo cellulose carrier is obtained.

[0066] Application of Lactobacillus paracasei JM053 in this example in fermented soy milk with low sugar, low soybean fishy smell and high content of soybean isoflavone aglycone.

[0067] Application of the fermented soy milk in this example in healthy foods.

[0068] The content of soybean isoflavone aglycone measured in this example is 98.12 ± 3.68 μg / mL, and the contents of 1-octen-3-ol, 2-pentylfuran and nonanal are 0.29 ± 0.03%, 0.21 ± 0.02%, 0.12 ± 0.02% respectively.

[0069] The above are only the preferred embodiments of the present invention. It should be noted that: for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. Lactobacillus paracasei with the ability to convert soy isoflavones ( Lacticaseibacillus paracasei ) JM053, characterized in that, The Lactobacillus paracasei is deposited in Guangdong Provincial Microbiological Culture Collection Center, Guangzhou, with a preservation date of November 13, 2023 and a preservation number of GDMCC NO: 64011.

2. the fermented soybean milk prepared by Lactobacillus paracasei JM053 according to claim 1, is characterized in that, The soy isoflavone aglycone content of fermented soy milk reaches 97.29~98.75μg / mL, and it is low in sugar and bean smell.

3. The fermented soybean milk according to claim 2, characterized in that The sucrose content is 2.5~3.5wt%; the contents of 1-octen-3-ol, 2-pentylfuran and nonanal are 0.23~0.37%, 0.12~0.25% and 0.09~0.16% respectively.

4. The method for producing fermented soybean milk according to claim 2 or 3, characterized in that: The following steps are involved: Step 1: Add 2.5-3.5 wt% sterilized sucrose to the soy milk, shake and mix, and then inoculate the bacterial solution of Lactobacillus paracasei JM053, with a total viable count of 1×10 7 ~1×10 9 CFU / mL, ferment at 37-40°C until the pH at the fermentation end point is 4.40-4.60, and obtain fermented soymilk; Step 2, treating the fermented soy milk, the treatment conditions are: ultrasonic power 200~250W, reaction temperature 50~55℃, pH=5.0~5.3, enzyme addition amount 7~9wt%, enzyme is β-glucosidase fixed on bamboo cellulose carrier, reaction time 45~60min; after the reaction is completed, boiling water bath 5~10min to inactivate the enzyme, and cooling to room temperature to obtain the finished fermented soy milk.

5. The method according to claim 4, characterized in that: The preparation method of bamboo cellulose carrier fixed β-glucosidase is as follows: 7-8 g of bamboo cellulose is dissolved in 60-80 mL of a solution consisting of dimethyl sulfoxide: acetone, the volume ratio of dimethyl sulfoxide to acetone is 3:4, and the solution is dripped into ice water drop by drop to prepare bamboo cellulose particles, then the bamboo cellulose particles are kept warm at 40-50°C for 70-90 min in 100-120 mL, 0.15-0.20 mol / L NaOH solution, taken out, placed in 50-60 mL, 2.5-3% glutaraldehyde solution at 95-100°C for 55-60 min, and the bamboo cellulose carrier is taken out for use; 40-50 mg of β-glucosidase is dissolved in 40-50 mL, 0.1-0.15 mol / L phosphate buffer to prepare an enzyme solution, and the bamboo cellulose carrier is placed therein and stored at low temperature for at least 18 h, then filtered, and the filtrate is used for use to obtain the bamboo cellulose carrier fixed β-glucosidase.

6. The method according to claim 5, characterized in that: The specific surface area of ​​bamboo cellulose carrier is 2.57~2.69m 2 / g.

7. The method according to claim 5, characterized in that: The low temperature condition is 1~4℃.

8. Application of Lactobacillus paracasei JM053 according to claim 1 in preparing fermented soymilk with low sugar, low beany flavor and high soy isoflavone aglycone content.

9. Use of the fermented soybean milk according to claim 2 or 3 in preparing healthy food.

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