A composition for reducing beany flavor and use thereof, a fermentation medium for lactobacillus plantarum

Abstract

The present application relates to the field of microbial fermentation, in particular to a composition for reducing beany flavor and application thereof, and a fermentation medium for lactobacillus plantarum. The present application provides a composition for reducing beany flavor, which comprises streptococcus thermophilus, lactobacillus bulgaricus and lactobacillus plantarum; wherein the mass ratio of the streptococcus thermophilus, the lactobacillus bulgaricus and the lactobacillus plantarum is 2.2-2.6:0.4-0.8:0.04-0.1; the lactobacillus plantarum has a preservation number of CCTCC AB 206133, and the composition can further comprise a sweetener. The present application can fundamentally solve the problem of beany flavor residue by using the three kinds of bacteria and the specific sweetener, and can improve the curd state of soybean yogurt.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microbial fermentation, in particular to a composition for reducing beany flavor and application thereof, and a fermentation medium for Lactobacillus plantarum. BACKGROUND

[0002] Soybean yogurt is made from soybean as raw material without adding any animal ingredients such as milk, etc., and is fermented by lactic acid bacteria. It is suitable for lactose intolerance, vegetarians, and environmental ethicists. Soybean is rich in high-quality protein, which is the only complete protein similar to mammalian protein, and its amino acid score can also be comparable to animal and whey protein. In addition to providing eight essential amino acids for the human body, the hydrolysate of soybean can reduce the total cholesterol concentration in the body. In addition, the physiological efficacy of soy isoflavones increases after fermentation, enhancing the body's antioxidant capacity.

[0003] Soybean has the characteristics of not containing lactose and cholesterol. Milk protein is mainly casein, which is composed of individual molecules with a relative molecular mass of 20-25 kDa. Soybean protein is mainly globulin, and soybean globulin is composed of 2S, 7S, 11S, and 15S proteins. The relative molecular weight of 11S protein is 360 kDa. Therefore, there is a big difference between soybean protein and milk protein in terms of protein type and protein relative molecular weight. This difference leads to defects in the sensory quality of soybean yogurt and milk yogurt. The main problems include the following two aspects: 1. Soybean yogurt has a series of undesirable flavors such as beany flavor and sour taste; 2. The texture of soybean yogurt is not delicate, and the coagulation state presents a "tofu-like" microstructure with high hardness and poor water holding capacity.

[0004] Currently, researchers have used the following methods to mask or cover the undesirable flavors of soybean yogurt and improve the sensory quality of the product in terms of flavor and texture: 1. Mixing milk with soy milk and then fermenting with lactic acid bacteria; 2. Pretreating soybean raw materials; 3. Adding fruits such as blueberries and mangoes, herbs, and flower plants directly to soybean yogurt; 4. Using Lactobacillus rhamnosus, Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus bulgaricus, Streptococcus thermophilus, and Keifir bacteria as fermentation agents to treat soy milk; However, the soybean yogurt prepared by these methods has complex raw materials, strains, and processes, and mainly reduces beany flavor by masking and covering. The product still has defects in flavor and coagulation state. SUMMARY

[0005] In order to solve the above problems, the application provides a composition for reducing soybean odor and application thereof, and a fermentation medium for Lactobacillus plantarum.

[0006] In order to achieve the above object, the application provides the following technical scheme.

[0007] The application provides a composition for reducing soybean odor, wherein the effective components of the composition include a fermentation agent and a sweetening agent.

[0008] Preferably, the bacterial activity of the Streptococcus thermophilus is 1x10 9 ~ 1x10 10 CFU / mL, the bacterial activity of the Lactobacillus bulgaricus is 1x10 9 ~ 1x10 10 CFU / mL, and the bacterial activity of the Lactobacillus plantarum is 1x10 9 ~ 1x10 10 CFU / mL.

[0009] Preferably, the sweetening agent includes a prebiotic or white granulated sugar, and the prebiotic includes inulin.

[0010] Preferably, when the composition includes the sweetening agent, the mass ratio of the Streptococcus thermophilus, the Lactobacillus bulgaricus, the Lactobacillus plantarum and the sweetening agent is 2.2~2.6:0.4~0.8:0.04~0.1:3~10.

[0011] The application provides application of the composition in reducing soybean odor in a soybean fermentation product.

[0012] The application provides a method for reducing soybean odor in a soybean product, which includes the following steps.

[0013] The fermentation substrate is mixed with the sweetening agent and the fermentation agent in sequence.

[0014] Preferably, the volume-mass ratio of the fermentation substrate, the sweetening agent and the fermentation agent is 100mL:3~10g:2.6~3.5g.

[0015] Preferably, the fermentation time is 8-12h and the temperature is 35-38℃.

[0016] The present application provides a soybean fermentation product prepared by the method, wherein the volume percentage of hexanal is 0.09%-0.12%, the volume percentage of pentanol is 0.3%-0.35%, the volume percentage of benzaldehyde is 0.29%-0.39%, the volume percentage of 1-octen-3-ol is 7%-7.41%, the volume percentage of 2-pentylfuran is 0.17%-0.23%, and the volume percentage of octanol is 0.16%-0.21%.

[0017] The present application provides a fermentation medium for culturing Lactobacillus plantarum, which comprises the following components at the following concentrations:

[0018] 40-50g / L of soybean protein isolate, 10-15g / L of inulin, 4.5-5.0g / L of sodium acetate anhydrous, 1.8-2.0g / L of diammonium hydrogen citrate, 0.8-1.0mL / L of Tween 80, 1.8-2.0g / L of K2HPO4, 0.5-0.6g / L of MgSO4·7H2O, and 0.2-0.25g / L of MnSO4·H2O;

[0019] The Lactobacillus plantarum has a preservation number of CCTCC AB 206133.

[0020] Beneficial effects: the present application provides a composition, wherein the effective components of the composition comprise a fermentation bacterium and a sweetening agent; the fermentation bacterium comprises Streptococcus thermophilus, Lactobacillus bulgaricus, and Lactobacillus plantarum; the mass ratio of Streptococcus thermophilus, Lactobacillus bulgaricus, and Lactobacillus plantarum is 2.2-2.6:0.4-0.8:0.04-0.1; and the Lactobacillus plantarum has a preservation number of CCTCC AB 206133. In the fermentation bacterium, the strains produce a large amount of enzymes in the metabolic process. At the beginning, the soybean odor substances are tightly combined with soybean proteins through hydrogen bonds and other non-covalent bonds. In the fermentation process, the pH is reduced due to acid production, and the spatial structure of soybean proteins is changed due to the action of the produced proteases, thereby destroying the non-covalent bonds and releasing the soybean odor substances. The soybean proteins are more easily decomposed and metabolized by lactic acid bacteria, thereby fundamentally eliminating the soybean odor. The sweetening agent effectively reduces the sour taste produced after the fermentation of yogurt. The bacterium and the sweetening agent are used together, thereby fundamentally solving the problem of soybean odor in the soybean fermentation product. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows.

[0022] Figure 1 Products for control 1, control 2, experiment 3, experiment 1 and experiment 2;

[0023] Figure 2 Sensory evaluation radar chart for experiments 1-3, controls 1-2;

[0024] Figure 3 GC-MS determination results of bean odor substances for experiments 1-3, controls 1-2. DETAILED DESCRIPTION

[0025] Unless otherwise specified, the components required by the present application can be obtained by routine purchase by those skilled in the art.

[0026] The present application provides a composition for reducing bean odor, wherein the effective components of the composition include a fermentation bacterium and a sweetening agent; the fermentation bacterium includes Streptococcus thermophilus, Lactobacillus bulgaricus and Lactobacillus plantarum; the preservation number of the Lactobacillus plantarum is CCTCC AB 206133; and the mass ratio of the Streptococcus thermophilus, the Lactobacillus bulgaricus and the Lactobacillus plantarum is 2.2-2.6:0.4-0.8:0.04-0.1.

[0027] In terms of mass parts, the fermentation bacterium of the present application includes 2.2-2.6 parts of Streptococcus thermophilus, and more preferably 2.2-2.4 parts. The bacterial activity of the Streptococcus thermophilus of the present application is preferably 1×10 9 -1×10 10 CFU / mL, and more preferably 1×10 10 CFU / mL.

[0028] In terms of mass parts of Streptococcus thermophilus, the fermentation bacterium of the present application includes 0.4-0.8 parts of Lactobacillus bulgaricus, and more preferably 0.5-0.7 parts. The bacterial activity of the Lactobacillus bulgaricus of the present application is preferably 1×10 9 -1×10 10 CFU / mL, and more preferably 1×10 10 CFU / mL.

[0029] In terms of mass parts of Streptococcus thermophilus, the fermentation bacterium of the present application includes 0.04-0.1 parts, and more preferably 0.04 parts or 0.1 parts. The bacterial activity of the Lactobacillus plantarum of the present application is preferably 1×10 9 -1×10 10 CFU / mL, and more preferably 9×10 9 CFU / mL.

[0030] The source of the Streptococcus thermophilus, Lactobacillus bulgaricus and Lactobacillus plantarum is not particularly limited in the present application, and can be purchased by a person skilled in the art; in the specific embodiments of the present application, the Lactobacillus bulgaricus is preferably purchased from Xi'an Juxingyuan Biotechnology Co., Ltd., the Streptococcus thermophilus is preferably purchased from Xi'an Juxingyuan Biotechnology Co., Ltd., and the Lactobacillus plantarum is preferably purchased from China Center for Type Culture Collection (CCTCC). The Lactobacillus bulgaricus and Streptococcus thermophilus in the present application can be inquired from the website "https: / / shop6l225l84078n1.1688.com / page / offerlist_148775094.htm?spm=a2615.2177701.autotrace-categorySmall.3.5f3b738etgqRVu&sortType=wangpu_score". The Streptococcus thermophilus, Lactobacillus bulgaricus and Lactobacillus plantarum in the present application are preferably in the form of freeze-dried powder.

[0031] The present application also provides a preparation method of Lactobacillus plantarum freeze-dried powder, which comprises the following steps: centrifuging a Lactobacillus plantarum fermentation liquor, mixing the obtained bacterial body with a protective agent, and freeze-drying to obtain the Lactobacillus plantarum freeze-dried powder.

[0032] The present application preferably centrifuges the Lactobacillus plantarum fermentation liquor. The rotation speed of centrifugation is preferably 8000 rpm, and the time is preferably 10 min. The preparation method of the Lactobacillus plantarum fermentation liquor preferably comprises the following steps: inoculating Lactobacillus plantarum into MRS culture medium for culture to obtain activated Lactobacillus plantarum seed liquor; inoculating the activated Lactobacillus plantarum seed liquor into a fermentation culture medium for fermentation culture to obtain the Lactobacillus plantarum fermentation liquor.

[0033] The present application preferably inoculates Lactobacillus plantarum into MRS culture medium for culture to obtain activated Lactobacillus plantarum. The culture temperature is preferably 30-35℃, the culture time is preferably 24-36 h, and the culture time is preferably 26-34 h, more preferably 28-32 h. The MRS culture medium preferably comprises the following components at the following concentrations: peptone 10 g / L, yeast extract 5 g / L, beef infusion powder 10 g / L, glucose 20 g / L, anhydrous sodium acetate 5.0 g / L, dihydrogen ammonium citrate 2.0 g / L, Tween 80 1.0 mL / L, K2HPO4 2.0 g / L, MgSO4·7H2O 0.58 g / L and MnSO4·H2O 0.25 g / L. The inoculation amount of the Lactobacillus plantarum is preferably 2-3 circles.

[0034] After obtaining the activated Lactobacillus plantarum, the activated Lactobacillus plantarum is inoculated into a fermentation medium for fermentation culture to obtain a Lactobacillus plantarum fermentation liquor. The fermentation time is preferably 18-36 h, further preferably 24-35 h, still preferably 26-34 h, and more preferably 28-32 h; the temperature is preferably 32-37℃, and more preferably 34-36℃; and the fermentation culture mode is preferably anaerobic static culture. The inoculation amount of the activated Lactobacillus plantarum seed liquor is preferably 3%-8% of the volume of the fermentation medium, and more preferably 4%-6%.

[0035] The fermentation medium preferably comprises the following components at the following concentrations: soybean protein isolate 40-50 g / L, inulin 10-15 g / L, sodium acetate anhydrous 4.5-5.0 g / L, diammonium hydrogen citrate 1.8-2.0 g / L, Tween 80 0.8-1.0 mL / L, K2HPO4 1.8-2.0 g / L, MgSO4·7H2O 0.5-0.6 g / L, and MnSO4·H2O 0.2-0.25 g / L, and still preferably soybean protein isolate 42-48 g / L, inulin 12-18 g / L, sodium acetate anhydrous 5.0 g / L, diammonium hydrogen citrate 2.0 g / L, Tween 80 1.0 mL / L, K2HPO4 2.0 g / L, MgSO4·7H2O 0.58 g / L, and MnSO4·H2O 0.25 g / L, and more preferably soybean protein isolate 44-46 g / L, inulin 14-16 g / L, sodium acetate anhydrous 5.0 g / L, diammonium hydrogen citrate 2.0 g / L, Tween 80 1.0 mL / L, K2HPO4 2.0 g / L, MgSO4·7H2O 0.58 g / L, and MnSO4·H2O 0.25 g / L; in a specific embodiment of the present application, the fermentation medium preferably comprises the following components at the following concentrations: soybean protein isolate 40 g / L, inulin 10 g / L, sodium acetate anhydrous 5.0 g / L, diammonium hydrogen citrate 2.0 g / L, Tween 80 1.0 mL / L, K2HPO4 2.0 g / L, MgSO4·7H2O 0.58 g / L, and MnSO4·H2O 0.25 g / L. The pH of the fermentation medium is preferably 6.8-7.0. The viable cell count of the Lactobacillus plantarum fermentation liquor is preferably 4×10 9 CFU / mL-10×10 9 CFU / mL, i.e. 4×10 9 CFU / mL-1×10 10 CFU / mL, and still preferably 6×10 9 CFU / mL-9×10 9 CFU / mL, more preferably 7×10 9 CFU / mL-8×10 9CFU / mL.

[0036] After the centrifugation, the present application also preferably pre-freezes the wet bacteria obtained after the centrifugation; the pre-freezing time is preferably 12h, and the temperature is preferably -20℃.

[0037] After the pre-freezing, the present application preferably mixes the obtained bacteria with a protective agent, and then vacuum freeze-dries to obtain the freeze-dried powder of Lactobacillus plantarum. The mass-volume ratio of the bacteria and the protective agent in the present application is 1g:1-2mL. The protective agent in the present application preferably comprises the following components at the following concentrations: skimmed milk powder 10-15g / 100mL, trehalose 3-6g / 100mL, and sodium glutamate 3-5g / 100mL, and more preferably, skimmed milk powder 12-14g / 100mL, trehalose 4-5g / 100mL, and sodium glutamate 7-9g / 100mL; in a specific embodiment of the present application, the protective agent preferably comprises the following components at the following concentrations: skimmed milk powder 10g / 100mL, trehalose 5g / 100mL, and sodium glutamate 4g / 100mL. The protective agent preferably uses water as the solvent.

[0038] The freeze-drying in the present application preferably comprises pre-freezing and vacuum freeze-drying; the pre-freezing temperature is preferably -80℃, and the time is preferably 12h; the vacuum degree of the vacuum freeze-drying is preferably 1.3-13Pa, the time is preferably 30h, and the temperature is preferably -10--50℃.

[0039] The composition in the present application comprises a sweetener; the sweetener comprises a prebiotic or white granulated sugar; the prebiotic preferably comprises inulin, and more preferably, inulin; the mass ratio of the Streptococcus thermophilus, Lactobacillus bulgaricus, Lactobacillus plantarum, and the sweetener in the present application is preferably 2.2-2.6:0.4-0.8:0.04-0.1:8-10, and more preferably, 2.2-2.4:0.4-0.8:0.04-0.1:3-10, and more preferably, 2.2-2.4:0.4-0.8:0.04-0.1:3, 2.2-2.4:0.4-0.8:0.04:9, or 2.2-2.4:0.4-0.8:0.1:9. The use of the bacteria agent and the sweetener in the present application can fundamentally solve the problem of soybean fermentation product soybean smell.

[0040] When the sweetener comprises white granulated sugar, the mass ratio of the Streptococcus thermophilus, Lactobacillus bulgaricus, Lactobacillus plantarum, and white granulated sugar is preferably 2.2-2.6:0.4-0.8:0.04-0.1:3, and more preferably, 2.2-2.4:0.4-0.8:0.04-0.1:3. The white granulated sugar in the present application can adjust the taste of the product and slow down the sour taste generated after the fermentation of yogurt.

[0041] When the sweetener comprises prebiotics, the mass ratio of the Streptococcus thermophilus, Lactobacillus bulgaricus, Lactobacillus plantarum and prebiotics is preferably 2.2-2.6:0.4-0.8:0.04-0.1:8-10, and is more preferably 2.2-2.4:0.4-0.8:0.04-0.1:8-10, and is more preferably 2.2-2.4:0.4-0.8:0.04:9 or 2.2-2.4:0.4-0.8:0.1:9. The inulin in the present application is a fructan with the dual functions of dietary fiber and prebiotics, and is also a polysaccharide. The polysaccharide as a sweetener can reduce the calorie of soybean yogurt by replacing high-carbohydrate white sugar, so that the inulin can completely replace white sugar as a sweetener. Due to the water binding capacity and gel network capacity, the fermented soybean yogurt has a delicate curd and less whey separation, and the texture is improved. In addition, the quality of the soybean yogurt is further optimized, and the growth and reproduction of lactic acid bacteria are promoted, the activity of lactic acid bacteria is improved, and the fermentation time is shortened. The product is detected by a third party, and the number of viable lactic acid bacteria is 1.9 x 10 9 CFU / mL, which is much larger than 1 x 10 6 CFU / mL, which is much larger than 1 x 10

[0042] Based on the advantages of the above-mentioned composition, the present application provides the use of the composition in the above technical solution for reducing the beany flavor in a soybean fermented product, and the soybean fermented product comprises soybean yogurt. The soy product obtained by using the composition provided by the present application is detected, and the results show that the content of beany flavor substances in the soy product is significantly reduced.

[0043] The present application provides a method for reducing the beany flavor in a soybean fermented product, which comprises the following steps:

[0044] The fermentation substrate is sequentially mixed with a sweetener and a fermentation agent for fermentation.

[0045] The present application sequentially mixes a fermentation substrate with a sweetener and a fermentation agent for fermentation. The fermentation substrate in the present application preferably comprises soybean milk. The preparation method of the soybean milk in the present application preferably comprises the following steps: after the soybean is boiled, it is immediately passed through a 200-mesh sieve to obtain soybean milk.

[0046] The volume-mass ratio of the fermentation substrate, the sweetener and the fermentation agent in the present application is preferably 100 mL:3-10 g:2.6-3.5 g, and more preferably 100 mL:3 g:3.1 g, 100 mL:3 g:3.04 g, 100 mL:9 g:3.1 g or 100 mL:9 g:3.04 g. The fermentation time in the present application is preferably 8-12 h, and is more preferably 8-12 h, and is more preferably 10 h; and the temperature is preferably constant at 35-38℃, and is more preferably constant at 36℃.

[0047] The fermentation substrate is mixed with the sweetener, and the mixture is preferably pasteurized; the pasteurization time is preferably 25-35 min, more preferably 28-32 min; the temperature is preferably 75-85℃, more preferably 80-82℃.

[0048] After the pasteurization, the pasteurized material is mixed with the fermentation agent; the mixing method is not limited, and any method known to those skilled in the art can be used.

[0049] After the fermentation, the fermented product is preferably subjected to a post-ripening treatment; the post-ripening time is preferably 8-12 h, more preferably 9-11 h; the temperature is preferably 0-4℃, more preferably 1-3℃.

[0050] The present application provides a soybean fermentation product prepared by the method described above, wherein the volume percentage of hexanal is 0.09%-0.12%, the volume percentage of pentanol is 0.3%-0.35%, the volume percentage of benzaldehyde is 0.29%-0.39%, the volume percentage of 1-octene-3-alcohol is 7%-7.41%, the volume percentage of 2-pentyl furan is 0.17%-0.23%, and the volume percentage of octanol is 0.16%-0.21%. The soybean fermentation product preferably comprises soybean yogurt. The pentanol is preferably 1-pentanol, and the octanol is preferably 1-octanol.

[0051] The application further provides a fermentation medium for culturing Lactobacillus plantarum, which comprises the following components in the following concentrations: soybean protein isolate 40-50 g / L, inulin 10-20 g / L, sodium acetate anhydrous 4.5-5.0 g / L, diammonium hydrogen citrate 1.8-2.0 g / L, Tween 80 0.8-1.0 mL / L, K2HPO4 1.8-2.0 g / L, MgSO4·7H2O 0.5-0.6 g / L and MnSO4·H2O 0.2-0.25 g / L, preferably soybean protein isolate 42-48 g / L, inulin 12-18 g / L, sodium acetate anhydrous 5.0 g / L, diammonium hydrogen citrate 2.0 g / L, Tween 80 1.0 mL / L, K2HPO4 2.0 g / L, MgSO4·7H2O 0.58 g / L and MnSO4·H2O 0.25 g / L, more preferably soybean protein isolate 44-46 g / L, inulin 14-16 g / L, sodium acetate anhydrous 5.0 g / L, diammonium hydrogen citrate 2.0 g / L, Tween 80 1.0 mL / L, K2HPO4 2.0 g / L, MgSO4·7H2O 0.58 g / L and MnSO4·H2O 0.25 g / L; the Lactobacillus plantarum has a preservation number of CCTCC AB 206133. The pH value of the fermentation medium is preferably 6.8-7.0.

[0052] The fermentation medium is more suitable for Lactobacillus plantarum and can meet the nutrient requirements of Lactobacillus plantarum in the fermentation process. The fermentation medium provided by the application is obtained by replacing glucose with inulin as a carbon source and replacing organic nitrogen source with soybean protein isolate on the basis of MRS medium; the Lactobacillus plantarum obtained by culturing in the fermentation medium has a viable cell count of 4×10 9 CFU / mL-10×10 9 CFU / mL.

[0053] In order to further illustrate the application, the technical solutions provided by the application are described in detail below in combination with the drawings and examples, but they should not be understood as limiting the protection scope of the application.

[0054] Example 1

[0055] Lactobacillus plantarum was inoculated into MRS medium and cultured at 32°C for 24h to obtain activated Lactobacillus plantarum seed liquid; the MRS medium was composed of the following components with the following concentrations: peptone 10g / L, yeast extract 5g / L, beef infusion powder 10g / L, glucose 20g / L, anhydrous sodium acetate 5.0g / L, diammonium hydrogen citrate 2.0g / L, Tween 80 1.0mL / L, K2HPO4 2.0g / L, MgSO4·7H2O 0.58g / L, and MnSO4·H2O 0.25g / L; the preservation number of Lactobacillus plantarum was CCTCC AB 206133.

[0056] The activated Lactobacillus plantarum seed liquid was inoculated into fermentation medium and cultured at 32°C for 24h to obtain Lactobacillus plantarum fermentation liquid; the inoculation amount was 3% (v / v); the viable cell count of the fermentation liquid was 9×10 9 CFU / mL, wherein the fermentation medium was composed of the following components with the following concentrations: soybean protein isolate 40g / L, inulin 10g / L, anhydrous sodium acetate 5.0g / L, diammonium hydrogen citrate 2.0g / L, Tween 80 1.0mL / L, K2HPO4 2.0g / L, MgSO4·7H2O 0.58g / L, and MnSO4·H2O 0.25g / L; the pH of the fermentation medium was 6.8-7.0.

[0057] Comparative Example 1

[0058] Lactobacillus plantarum was inoculated into MRS medium and cultured at 32°C for 24h to obtain activated Lactobacillus plantarum; the MRS medium was composed of the following components with the following concentrations: peptone 10g / L, yeast extract 5g / L, beef infusion powder 10g / L, glucose 20g / L, anhydrous sodium acetate 5.0g / L, diammonium hydrogen citrate 2.0g / L, Tween 80 1.0mL / L, K2HPO4 2.0g / L, MgSO4·7H2O 0.58g / L, and MnSO4·H2O 0.25g / L; the pH of the MRS medium was 6.8-7.0; the preservation number of Lactobacillus plantarum was CCTCC AB 206133.

[0059] The activated Lactobacillus plantarum was inoculated into MRS medium and cultured at 32°C for 24h to obtain Lactobacillus plantarum fermentation liquid; the inoculation amount was 3% (v / v); the viable cell count of the fermentation liquid was 1.2×10 9CFU / mL, wherein the MRS culture medium is composed of the following components with the following concentrations: peptone 10 g / L, yeast extract 5 g / L, beef infusion powder 10 g / L, glucose 20 g / L, sodium acetate anhydrous 5.0 g / L, diammonium hydrogen citrate 2.0 g / L, Tween 80 1.0 mL / L, K2HPO4 2.0 g / L, MgSO4·7H2O 0.58 g / L, and MnSO4·H2O 0.25 g / L, and the pH of the MRS culture medium is 6.8-7.0.

[0060] Comparative Example 1-1

[0061] The same as the steps of Example 1, except that the concentrations of the components in the fermentation medium are different, specifically, the activated Lactobacillus plantarum seed liquid is inoculated into the fermentation medium and cultured at 32°C for 24 h, and the inoculation amount is 3% (v / v), to obtain a Lactobacillus plantarum fermentation liquid, and the viable cell count of the fermentation liquid is 3.5×10 9 CFU / mL, wherein the fermentation medium is composed of the following components with the following concentrations: soybean protein isolate 35 g / L, inulin 20 g / L, sodium acetate anhydrous 5.0 g / L, diammonium hydrogen citrate 2.0 g / L, Tween 80 1.0 mL / L, K2HPO4 2.0 g / L, MgSO4·7H2O 0.58 g / L, and MnSO4·H2O 0.25 g / L, and the pH of the fermentation medium is 6.8-7.0.

[0062] Comparative Example 1-2

[0063] The same as the steps of Example 1, except that the concentrations of the components in the fermentation medium are different, specifically, the activated Lactobacillus plantarum seed liquid is inoculated into the fermentation medium and cultured at 32°C for 24 h, and the inoculation amount is 3% (v / v), to obtain a Lactobacillus plantarum fermentation liquid, and the viable cell count of the fermentation liquid is 3.0×10 9 CFU / mL, wherein the fermentation medium is composed of the following components with the following concentrations: soybean protein isolate 30 g / L, inulin 20 g / L, sodium acetate anhydrous 5.0 g / L, diammonium hydrogen citrate 2.0 g / L, Tween 80 1.0 mL / L, K2HPO4 2.0 g / L, MgSO4·7H2O 0.58 g / L, and MnSO4·H2O 0.25 g / L, and the pH of the fermentation medium is 6.8-7.0.

[0064] As can be seen from Example 1 and Comparative Example 1, the viable cell count of Lactobacillus plantarum cultured by using the fermentation medium screened in the present application is high.

[0065] Preparation Example

[0066] The preparation steps of the Lactobacillus plantarum freeze-dried powder are as follows:

[0067] Lactobacillus plantarum was inoculated into MRS medium and incubated at 32°C for 24h to obtain activated Lactobacillus plantarum seed liquid; the MRS medium was composed of the following components with the following concentrations: peptone 10g / L, yeast extract 5g / L, beef infusion powder 10g / L, glucose 20g / L, sodium acetate anhydrous 5.0g / L, di-ammonium hydrogen citrate 2.0g / L, Tween 80 1.0mL / L, K2HPO4 2.0g / L, MgSO4·7H2O 0.58g / L, and MnSO4·H2O 0.25g / L; the preservation number of Lactobacillus plantarum was CCTCC AB 206133.

[0068] The activated Lactobacillus plantarum seed liquid was inoculated into fermentation medium and fermented at 32°C for 24h to obtain Lactobacillus plantarum fermentation liquid; the inoculation amount was 3% (v / v); the viable cell count of the fermentation liquid was 9×10 9 CFU / mL, wherein the fermentation medium was composed of the following components with the following concentrations: soybean protein isolate 40g / L, inulin 10g / L, sodium acetate anhydrous 5.0g / L, di-ammonium hydrogen citrate 2.0g / L, Tween 80 1.0mL / L, K2HPO4 2.0g / L, MgSO4·7H2O 0.58g / L, and MnSO4·H2O 0.25g / L; the pH of the fermentation medium was 6.8-7.0.

[0069] After the Lactobacillus plantarum fermentation liquid was centrifuged at 8000rpm for 10min, the obtained wet bacteria were pre-frozen at -20°C for 12h; after the pre-frozen bacteria were mixed with a protective agent, they were pre-frozen at -80°C for 12h; then, the bacteria were vacuum freeze-dried for 30h to obtain Lactobacillus plantarum freeze-dried powder; the mass-volume ratio of the bacteria and the protective agent was 1g:1-1:2mL; the protective agent was composed of the following components with the following concentrations: skimmed milk powder 10g / 100mL, trehalose 5g / 100mL, and sodium glutamate 4g / 100mL; water was used as the solvent.

[0070] Lactobacillus bulgaricus freeze-dried powder was purchased from Xi'an Juren Original Biotechnology Co., Ltd.

[0071] Streptococcus thermophilus freeze-dried powder was purchased from Xi'an Juren Original Biotechnology Co., Ltd.

[0072] The following examples all used the Lactobacillus plantarum freeze-dried powder prepared in the preparation example, and the purchased Lactobacillus bulgaricus freeze-dried powder and Streptococcus thermophilus freeze-dried powder.

[0073] Example 2

[0074] The composition for reducing beany flavor was composed of fermentation bacteria and prebiotics; the fermentation bacteria were composed of 0.6g of Lactobacillus bulgaricus freeze-dried powder, 2.4g of Streptococcus thermophilus freeze-dried powder, and 0.1g of Lactobacillus plantarum freeze-dried powder; the prebiotics was 9g of inulin.

[0075] The soybean was boiled and immediately passed through a 200-mesh sieve to obtain soybean milk.

[0076] The obtained soybean milk was prepared as a base of 100 mL, and no milk was added; the soybean milk was mixed with inulin first, and then a fermentation agent was added after pasteurization at 80°C for 30 min, followed by fermentation in a thermostat at 36°C for 10 h, and then post-ripening at 4°C for 8 h to obtain soybean yogurt, and the viable count of lactic acid bacteria in the soybean yogurt was 1.6 x 10 9 CFU / mL, which was recorded as Experiment 1.

[0077] Example 3

[0078] The composition for reducing the soybean odor consisted of a fermentation agent and a prebiotic, wherein the fermentation agent consisted of 0.6 g of Lactobacillus bulgaricus freeze-dried powder, 2.4 g of Streptococcus thermophilus freeze-dried powder, and 0.04 g of Lactobacillus plantarum freeze-dried powder, and the prebiotic was 9 g of inulin;

[0079] The soybean was boiled and immediately passed through a 200-mesh sieve to obtain soybean milk.

[0080] The obtained soybean milk was prepared as a base of 100 mL, and no milk was added; the soybean milk was mixed with inulin first, and then a fermentation agent was added, followed by fermentation in a thermostat at 36°C for 10 h, pasteurization at 80°C for 30 min, and then post-ripening at 4°C for 8 h to obtain soybean yogurt, and the viable count of lactic acid bacteria in the soybean yogurt was 1.9 x 10 9 CFU / mL, which was recorded as Experiment 2.

[0081] Example 4

[0082] The soybean was boiled and immediately passed through a 200-mesh sieve to obtain soybean milk.

[0083] The obtained soybean milk was prepared as a base of 100 mL, and no milk was added; the soybean milk was mixed with 3 g of white sugar first, and then a fermentation agent was added after pasteurization at 80°C for 30 min, wherein the fermentation agent consisted of 0.6 g of Lactobacillus bulgaricus freeze-dried powder, 2.4 g of Streptococcus thermophilus freeze-dried powder, and 0.04 g of Lactobacillus plantarum freeze-dried powder, followed by fermentation in a thermostat at 36°C for 10 h, and then post-ripening at 4°C for 8 h to obtain soybean yogurt, and the viable count of lactic acid bacteria in the soybean yogurt was 1.5 x 10 9 CFU / mL, which was recorded as Experiment 3.

[0084] Comparative Example 2

[0085] The soybean was boiled and immediately passed through a 200-mesh sieve to obtain soybean milk.

[0086] The soy milk prepared in 100 mL was used as a base without adding any milk; the soy milk was mixed with 3 g of white sugar, pasteurized at 80 °C for 30 min, and then 0.02 g of a fermentation agent was added, wherein the fermentation agent was a commercially available bacteria purchased from Jiangsu Haote Food Technology Co., Ltd., the commercially available bacteria included Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus plantarum, Lactobacillus rhamnosus, Streptococcus thermophilus, Lactobacillus casei and Bifidobacterium, and then the fermentation was performed in a thermostat at 36 °C for 10 h, and then the post-ripening was performed at 4 °C for 8 h, to obtain soy yogurt, and the viable count of lactic acid bacteria was 8.5 × 10 8 CFU / mL, denoted as Control 1.

[0087] Comparative Example 3

[0088] The soybean was boiled and then sieved through a 200-mesh sieve to obtain soy milk.

[0089] The soy milk prepared in 100 mL was used as a base without adding any milk; the soy milk was mixed with 3 g of white sugar, pasteurized at 80 °C for 30 min, and then 0.02 g of a fermentation agent was added, wherein the fermentation agent was a commercially available bacteria purchased from Jiangsu Haote Food Technology Co., Ltd., the commercially available bacteria included Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus plantarum, Lactobacillus rhamnosus, Streptococcus thermophilus, Lactobacillus casei and Bifidobacterium, and then the fermentation was performed in a thermostat at 36 °C for 10 h, and then the post-ripening was performed at 4 °C for 8 h, to obtain soy yogurt, and the viable count of lactic acid bacteria was 8.5 × 10 8 CFU / mL, denoted as Control 1.

[0090] Comparative Example 4

[0091] The preparation steps of the Lactobacillus plantarum freeze-dried powder were as follows:

[0092] The Lactobacillus plantarum was inoculated into MRS medium and cultured at 32 °C for 24 h to obtain activated Lactobacillus plantarum seed liquid; wherein the MRS medium was composed of the following components at the following concentrations: peptone 10 g / L, yeast extract 5 g / L, beef infusion powder 10 g / L, glucose 20 g / L, anhydrous sodium acetate 5.0 g / L, dihydrogen ammonium citrate 2.0 g / L, Tween 80 1.0 mL / L, K2HPO4 2.0 g / L, MgSO4·7H2O 0.58 g / L and MnSO4·H2O 0.25 g / L, and the preservation number of the Lactobacillus plantarum was CCTCC AB 206133.

[0093] The activated Lactobacillus plantarum seed liquid was inoculated into a fermentation medium and fermented at 32 °C for 24 h, and the inoculation amount was 3% (v / v), to obtain Lactobacillus plantarum fermentation liquid, and the viable count was preferably 3.0 × 10 9CFU / mL, wherein the fermentation medium consists of the following components at the following concentrations: soybean protein isolate 30 g / L, inulin 20 g / L, sodium acetate anhydrous 5.0 g / L, diammonium hydrogen citrate 2.0 g / L, Tween 80 1.0 mL / L, K2HPO4 2.0 g / L, MgSO4·7H2O 0.58 g / L, and MnSO4·H2O 0.25 g / L, and the pH of the fermentation medium is 6.8-7.0.

[0094] The Lactobacillus plantarum fermentation broth is centrifuged at 8000 rpm for 10 min, the obtained wet bacteria are pre-frozen at -20°C for 12 h, the pre-frozen bacteria are mixed with a protective agent, pre-frozen at -80°C for 12 h, and then vacuum freeze-dried for 30 h to obtain the Lactobacillus plantarum freeze-dried powder, wherein the mass-volume ratio of the bacteria and the protective agent is 1 g:1-1:2 mL, and the protective agent consists of the following components at the following concentrations: skim milk powder 10 g / 100 mL, trehalose 5 g / 100 mL, and sodium glutamate 4 g / 100 mL, and water is used as the solvent.

[0095] The soybean is boiled and immediately sieved through a 200-mesh sieve to obtain soybean milk; 100 mL of the prepared soybean milk is used as a base without adding any milk; the soybean milk is mixed with 3 g of white granulated sugar, pasteurized at 80°C for 30 min, and then fermented by adding a fermentation agent, wherein the fermentation agent consists of 0.6 g of Lactobacillus bulgaricus freeze-dried powder, 2.4 g of Streptococcus thermophilus freeze-dried powder, and 0.6 g of Lactobacillus plantarum freeze-dried powder; the fermentation is carried out in a thermostat at 36°C for 10 h, and then post-ripening is carried out at 4°C for 8 h to obtain soybean yogurt, wherein the viable count of Lactobacillus plantarum in the soybean yogurt is 1.0×10 9 CFU / mL, which is recorded as Control 3. Since the viable count of Lactobacillus plantarum is small, the amount of Lactobacillus plantarum freeze-dried powder needs to be increased during the experiment, but the effect is not good, so further sensory evaluation and odor detection are not carried out.

[0096] The sensory evaluation of the soybean yogurt prepared in experiments 1-3 and controls 1-2 is investigated 24 h after the soybean yogurt is obtained, mainly in terms of four indexes of organization state, color, odor, and taste, and the scoring standards are shown in Table 1, and the specific experimental process is as follows:

[0097] The number of investigators is 25;

[0098] The specific investigation method for sensory evaluation is as follows: 25 persons who have been professionally trained score the color, taste, organization state, and odor of the product respectively, each item adopts a 1-10 point system, and the average value of 25 persons is taken.

[0099] Table 1 Sensory evaluation scoring standards for soybean yogurt

[0100]

[0101]

[0102] The score results are shown in Table 2. Figure 2 Figure 2 The taste in Table 1 is the mouthfeel.

[0103] Table 2 shows the score results of the soy yogurts prepared in Examples 1-3 and Comparative Examples 1-2.

[0104]

[0105] The color and texture of the soy yogurts prepared in Examples 1-3 and Comparative Examples 1-2 are shown in Table 2. Figure 1 Figure 2 Figure 1 In Table 2, from left to right are Comparative Example 1, Comparative Example 2, Example 3, Example 1, and Example 2, respectively. Figure 1 As shown in Table 2, the soy yogurt prepared in Example 2 is light yellow, uniform in color, fine in texture, and has no whey separation; the soy yogurt prepared in Example 1 is light yellow, uniform in color, fine in texture, and has a small amount of whey separation; the soy yogurt prepared in Example 3 is light yellow, uniform in color, fine in texture, and has a small amount of whey separation; the soy yogurt prepared in Comparative Example 1 is light yellow, uneven in texture, in a form of a thin paste, and has a small amount of whey separation; and the soy yogurt prepared in Comparative Example 2 is light yellow, uneven in texture, in a form of a thin paste, and has a small amount of whey separation.

[0106] The smell investigation results are shown in Table 2. Figure 2 As shown in Table 2, the soy yogurt prepared in Example 3 has a very weak bean smell, the soy yogurt prepared in Example 1 has a slight chrysanthemum powder smell and no bean smell, and the soy yogurt prepared in Example 2 has a slight chrysanthemum powder smell and no bean smell; the soy yogurt prepared in Comparative Example 1 has a slightly rough mouthfeel, and the soy yogurt prepared in Comparative Example 2 has a bean smell.

[0107] The mouthfeel investigation results are shown in Table 2. Figure 2 As shown in Table 2, the soy yogurt prepared in Example 3 has a sour and sweet mouthfeel, the soy yogurt prepared in Example 1 has a sour and sweet mouthfeel, and the soy yogurt prepared in Example 2 has a sour and sweet mouthfeel; the soy yogurt prepared in Comparative Example 1 has a slightly rough mouthfeel, and the soy yogurt prepared in Comparative Example 2 has a slightly rough mouthfeel.

[0108] The content of the bean smell substance in the soy yogurts prepared in Examples 1-3 and Comparative Examples 1-2 was detected by the following method.

[0109] ​​​1. Solid phase microextraction of volatile substances in soy yogurt: 1 mL sample + 2 g NaCl was placed in a 20 mL headspace bottle. A DVB / CAR / PDMS fiber head 2 cm was used for SPME extraction, and the sample was incubated at 50℃ for 15 min, extracted for 30 min, and desorbed in the GC inlet for 5 min.

[0110] 2. GC-MS analysis: Instrument: Agilent 7890B-5977B gas chromatography-mass spectrometry (GC-MS); chromatographic column: DB-WAX (30 m x 0.25 mm x 0.25 μm); injection temperature: 250℃; no split; carrier gas: helium (99.999%); flow rate: 1 mL / min; column temperature: 40℃ for 5 min, increased to 220℃ at 5℃ / min, increased to 250℃ at 20℃ / min and maintained for 2.5 min; interface temperature: 260℃; ion source temperature: 230℃; quadrupole temperature: 150℃; ionization mode: EI+, 70 ev; scanning mode: full scan; mass range: 29-400;

[0111] The extraction and determination of volatile substances in the sample were performed in triplicate.

[0112] The detection results of the content of beany flavor substances in the soy yogurt prepared in experiments 1-3 and controls 1-2 are shown in Table 1 and Table 3. Figure 3 and Table 3.

[0113] Table 3 Detection results of the content of beany flavor substances in the soy yogurt prepared in experiments 1-3 and controls 1-2

[0114]

[0115] From Figure 3As known from Table 3, the soy yogurt prepared in Experiment 2 is determined by GC-MS to have the contents of the six beany taste substances hexanal, 1-pentanol, benzaldehyde, 1-octen-3-ol, 2-pentyl furan and 1-octanol as 0.09%, 0.35%, 0.39%, 7%, 0.17% and 0.18% respectively, the soy yogurt prepared in Experiment 1 is determined by GC-MS to have the volume percentage contents of the six beany taste substances hexanal, 1-pentanol, benzaldehyde, 1-octen-3-ol, 2-pentyl furan and 1-octanol as 0.1%, 0.31%, 0.28%, 7.41%, 0.22% and 0.16% respectively, the soy yogurt prepared in Experiment 3 is determined by GC-MS to have the volume percentage contents of the six beany taste substances hexanal, 1-pentanol, benzaldehyde, 1-octen-3-ol, 2-pentyl furan and 1-octanol as 0.12%, 0.3%, 0.29%, 7.36%, 0.23% and 0.21% respectively, the soy yogurt prepared in Control 1 is determined by GC-MS to have the contents of the six beany taste substances hexanal, 1-pentanol, benzaldehyde, 1-octen-3-ol, 2-pentyl furan and 1-octanol as 0.49%, 0.69%, 0.46%, 10.22%, 0.33% and 0.28% respectively, and the soy yogurt prepared in Control 2 is determined by GC-MS to have the contents of the six beany taste substances hexanal, 1-pentanol, benzaldehyde, 1-octen-3-ol, 2-pentyl furan and 1-octanol as 0.46%, 0.68%, 0.52%, 10.03%, 0.4% and 0.3% respectively. It can be seen that the content of beany taste substances in the soy yogurt prepared by the method provided in the present application is significantly reduced, and the problem of beany taste of soy yogurt is fundamentally solved.

[0116] As summarized above, the strain used in the composition of the present application can produce abundant enzymes in the metabolic process, which can change the molecular structure of the fishy taste substances and convert them into substances without fishy taste, thereby achieving the effect of fundamentally removing fishy taste. Moreover, the probiotics and prebiotics in the composition of the present application have a synergistic effect, and the number of live lactic acid bacteria in the soy yogurt prepared is 1.9 x 10 9 CFU / mL, which is much greater than 1 x 10 6 CFU / mL of the national standard T / WSJD 12-2020 "Plant Protein Beverage Plant Yogurt".

[0117] Although the present application has been disclosed with reference to the preferred embodiments as above, it is not intended to limit the present application, and any person skilled in the art can make various modifications and modifications without departing from the spirit and scope of the present application, and therefore the protection scope of the present application should be defined by the claims.

Claims

1. A method for reducing the beany taste in soy yogurt, characterized in that, The method consists of the following steps: The fermentation substrate is mixed with sweetener and fermentation agent in sequence for fermentation; The fermentation agent is composed of Streptococcus thermophilus, Lactobacillus bulgaricus, and Lactobacillus plantarum; the mass ratio of Streptococcus thermophilus, Lactobacillus bulgaricus, and Lactobacillus plantarum is 2.2~2.6:0.4~0.8:0.04~0.1; the preservation number of Lactobacillus plantarum is CCTCAB 206133; The bacterial count of the thermophilic streptococcus was 1 × 10⁻⁶. 9 ~1×10 10 CFU / mL, the bacterial activity of Lactobacillus bulgaricus is 1×10⁻⁶. 9 ~1×10 10 CFU / mL, the bacterial activity of Lactobacillus plantarum is 1×10⁻⁶. 9 ~1×10 10 CFU / mL; The sweetener is a prebiotic; the prebiotic is inulin. The mass ratio of Streptococcus thermophilus, Lactobacillus bulgaricus, Lactobacillus plantarum and sweetener is 2.2~2.6:0.4~0.8:0.04~0.1:3~10.

2. The method according to claim 1, characterized in that, The volume-to-mass ratio of the fermentation substrate, sweetener, and fermentation agent is 100 mL: 3~10 g: 2.6~3.5 g.

3. The method according to claim 1 or 2, characterized in that, The fermentation time is 8-12 hours, and the temperature is 35-38℃.

4. A fermented soybean product prepared by the method according to any one of claims 1 to 3, characterized in that, The fermented soybean product contains 0.09% to 0.12% hexanal by volume, 0.3% to 0.35% pentanol by volume, 0.29% to 0.39% benzaldehyde by volume, 7% to 7.41% 1-octen-3-ol by volume, 0.17% to 0.23% 2-pentylfuran by volume, and 0.16% to 0.21% octanol by volume.

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