Compound lactic acid bacteria for fermenting pickled potherb mustard as well as preparation method and application of compound lactic acid bacteria

Abstract

The invention discloses compound lactic acid bacteria for fermenting pickled potherb mustard as well as a preparation method and application of the compound lactic acid bacteria, and belongs to the technical field of food processing. In order to solve the problems of long fermentation time, limited temperature adaptability, large edible salt addition amount, high nitrite content, difficulty in anaerobic fermentation control and the like of the potherb mustard, the invention provides special efficient compound lactic acid bacteria for fermenting the potherb mustard, and the compound lactic acid bacteria comprise lactobacillus pentosus, leuconostoc mesenteroides and streptococcus thermophilus. The bacterial liquid of lactobacillus paracasei and bifidobacterium bifidum and the compound lactic acid bacteria are used for fermenting potherb mustard, so that the fermentation time can be shortened, the temperature adaptability can be improved, the dosage of edible salt can be reduced, the nitrite content of a finished product can be reduced, the fermentation flavor can be enriched, the fermentation stability can be improved, and the fermentation cost can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to a composite lactic acid bacteria for fermenting Chinese mustard greens sauerkraut and a preparation method and application thereof. Background Art

[0002] Traditional sauerkraut is a vegetable fermented food made by soaking fresh vegetables in a certain concentration of salt water and fermenting them through the natural lactic acid bacteria attached to the surface of the vegetables. Sauerkraut is rich in carbohydrates, vitamins, beneficial trace elements and active lactic acid bacteria. It is nutritious, has a unique sour and fragrant smell and a crisp and refreshing taste. It can not only be used as a side dish, but also has the characteristics of strengthening the stomach and digestion. It is a high-quality traditional fermented food and is therefore deeply loved by consumers in my country.

[0003] As one of the representatives of traditional Chinese pickles, Chinese mustard greens not only has a long history, but also contains a wealth of health-preserving methods. Chinese mustard greens are not only a delicious dish, but also a food full of nutrition and health benefits. It is rich in vitamins, dietary fiber and antioxidants, and has many functions such as enhancing immunity, promoting digestion, reducing inflammation, and lowering cholesterol. With the improvement of people's health awareness, the demand for Chinese mustard greens pickles is growing.

[0004] However, the traditional Chinese mustard sauerkraut production process is still at the stage of natural fermentation in small workshops, with backward technology and many problems, such as a long fermentation cycle, which usually takes 20 to 30 days; in order to inhibit the growth of harmful bacteria and prevent the Chinese mustard from spoiling during the fermentation process, fermentation is mainly concentrated in winter, so the adaptability to temperature is relatively limited; since a large amount of salt (about 15%) needs to be added to pickle vegetables in the production of sauerkraut, the salt content is too high and the nitrite content is also high, which is not good for health. In addition, unlike the traditional fermentation process of Chinese cabbage and cabbage, no additional water is added during the natural fermentation of Chinese mustard for immersion pickling, and most of the time it is directly exposed to the air, which makes it impossible to effectively control the anaerobic fermentation process, which easily leads to the proliferation of harmful bacteria. At the same time, the quality stability of Chinese mustard sauerkraut is also poor, and the flavor of the sauerkraut is often insufficient and there is a peculiar smell, and the color and taste are not satisfactory.

[0005] In recent years, some companies that have achieved large-scale production have gradually begun to add composite bacterial agents to the process of making sauerkraut with Chinese cabbage as the raw material. This method can significantly speed up the fermentation speed and improve the fermentation quality. However, there are relatively few studies on composite lactic acid bacteria for fermenting Chinese mustard sauerkraut. Due to the difference in the fermentation of Chinese mustard sauerkraut and Chinese cabbage sauerkraut, there are almost no composite lactic acid bacteria products on the market that are particularly suitable for fermented Chinese mustard sauerkraut. Therefore, it is particularly important to develop a highly efficient composite lactic acid bacteria specifically for Chinese mustard sauerkraut and clarify its application process in order to shorten the fermentation time, improve temperature adaptability, reduce the amount of edible salt and nitrite content, reduce costs and improve the stability of the fermentation process. Summary of the invention

[0006] In order to solve the problems of long fermentation time of Chinese mustard greens sauerkraut, limited temperature adaptability, large amount of edible salt added, high nitrite content, and difficult to control anaerobic fermentation, the present invention provides a special high-efficiency composite lactic acid bacteria for fermenting Chinese mustard greens sauerkraut and a preparation method thereof. Fermenting Chinese mustard greens with the composite lactic acid bacteria can not only solve the above-mentioned technical problems, but also enrich the fermentation flavor, improve the fermentation stability, and reduce the fermentation cost.

[0007] In order to solve the above technical problems and achieve corresponding technical effects, the present invention specifically provides the following technical solutions:

[0008] The first object of the present invention is to provide a composite lactic acid bacteria for fermenting Chinese mustard sauerkraut, the composite lactic acid bacteria comprising a bacterial solution of Lactobacillus pentosus, a bacterial solution of Leuconostocmesenteroides, a bacterial solution of Streptococcus thermophilus, a bacterial solution of Lactobacillus paracasei and a bacterial solution of Bifidobacterium bifidum, wherein the viable count of each bacterial solution is 0.8×10 9 ~1.0×10 9 cfu / mL; the volume ratio of the Lactobacillus pentosus bacterial solution, the Leuconostoc mesenteroides bacterial solution, the Streptococcus thermophilus bacterial solution, the Lactobacillus paracasei bacterial solution and the Bifidobacterium bifidum bacterial solution is (3-8):(1-3):(1-2):(1-2):(1-2).

[0009] In one embodiment of the present invention, the Lactobacillus pentosus has a preservation number of CGMCC 1.2707, the Leuconostoc mesenteroides has a preservation number of CGMCC 1.578, the Streptococcus thermophilus has a preservation number of CGMCC 1.1855, the Lactobacillus paracasei has a preservation number of CGMCC 1.121, and the Bifidobacterium bifidum has a preservation number of CGMCC 1.5090.

[0010] The second object of the present invention is to provide a method for preparing the above-mentioned composite lactic acid bacteria, the preparation method comprising the following steps:

[0011] (1) Lactobacillus pentosus, Leuconostoc mesenteroides, Streptococcus thermophilus, Lactobacillus paracasei and Bifidobacterium bifidum were inoculated into a solid culture medium and activated at 25° C. to 37° C. for 1 to 3 days;

[0012] (2) The activated strains obtained in step (1) were inoculated into liquid culture medium and cultured at 25°C to 37°C for 1 to 3 days until the number of viable bacteria in the bacterial solution of each strain reached 0.8×10 9 ~1.0×10 9 cfu / mL;

[0013] (3) inoculating the bacterial liquid of each bacterial species obtained in step (2) into a liquid culture medium, respectively, and expanding and culturing at 25° C. to 37° C. for 1 to 3 days to obtain a single lactic acid bacteria liquid for use;

[0014] (4) The five single lactic acid bacteria solutions obtained in step (3) are uniformly mixed according to the volume ratio of Lactobacillus pentosus solution, Leuconostoc mesenteroides solution, Streptococcus thermophilus solution, Lactobacillus paracasei solution and Bifidobacterium bifidum solution of (3-8): (1-3): (1-2): (1-2): (1-2) to obtain composite lactic acid bacteria.

[0015] In one embodiment of the present invention, the solid culture medium in step (1) is MRS solid culture medium.

[0016] In one embodiment of the present invention, the liquid culture medium in step (2) and step (3) is MRS liquid culture medium.

[0017] In one embodiment of the present invention, the inoculation amount of the expanded culture in step (3) is 5% by volume of the liquid culture medium.

[0018] The third object of the present invention is to provide a method for fermenting Chinese mustard greens sauerkraut using the composite lactic acid bacteria, the method comprising the following steps:

[0019] S1. After being aired, cleaned, washed, blanched and air-dried, the Chinese mustard is placed in a container, a layer of edible salt is sprinkled on each layer of Chinese mustard, and the Chinese mustard is compacted, wherein the amount of edible salt added is 0% to 4% of the weight of the Chinese mustard;

[0020] S2. Add 20-40 mL of the composite lactic acid bacteria per kg of Chinese mustard to the bottom of the container, and seal and ferment at 0-35° C. for 2-7 days.

[0021] In one embodiment of the present invention, the drying is to dry the Chinese mustard greens for 1-3 days until the weight reaches 65%-70% of the original weight.

[0022] In one embodiment of the present invention, the blanching is performed in 100° C. boiling water for 20 seconds.

[0023] The fourth object of the present invention is to provide sauerkraut obtained by the above method.

[0024] Beneficial effects of the present invention:

[0025] 1. The composite lactic acid bacteria liquid for fermenting Chinese mustard sauerkraut provided by the present invention has the characteristics of high activity, fast fermentation start-up speed, and wide temperature adaptability. The number of live bacteria in the sauerkraut fermentation liquid is not less than 0.8×10 9 cfu / mL, the fermentation time is shortened by more than 75% compared with the traditional method, and fermentation production can be carried out in all seasons.

[0026] 2. The composite lactic acid bacteria provided by the present invention are used to ferment Chinese mustard, which can reduce the pH value of the sauerkraut fermentation environment during the fermentation process, and can effectively inhibit the reproduction of yeast and harmful bacteria, thereby preventing the sauerkraut from spoiling and the generation of sauerkraut odor; the final product obtained by fermentation has rich flavor, crisp taste, and better taste than traditional naturally fermented sauerkraut.

[0027] 3. The Chinese mustard greens sauerkraut fermentation process provided by the present invention uses a composite lactic acid bacteria solution for fermentation, and the nitrite content of the final product is significantly reduced. In the sauerkraut fermentation process, the Chinese mustard greens are blanched in 100°C boiling water for 20 seconds and then air-dried, which effectively maintains the bright color and crisp and tender taste of the Chinese mustard greens.

[0028] 4. By using the composite lactic acid bacteria and Chinese mustard sauerkraut fermentation method provided by the present invention, the fermented sauerkraut final product has good sensory quality, low salt content (as low as 0.2%), low pH (3.18-3.32), extremely low nitrite content of 0.39-0.67 mg / kg, high organic acid content of 20.11-21.14 g / kg, greatly shortened fermentation time to 2-7 days; and significantly improved batch stability of the final product.

[0029] 6. Fermenting Chinese mustard with the composite lactic acid bacteria provided by the present invention can enrich the fermentation flavor, shorten the fermentation time, expand the fermentation temperature, reduce the cultivation cost, and improve the fermentation stability, which completely solves the shortcomings of high-dose edible salt addition, high nitrite content, mixed flavor of the final product, light sour taste, high cost of supplementing composite bacterial agents, low number of viable bacteria, and poor quality stability in the traditional fermentation process.

[0030] 7. The composite lactic acid bacteria provided by the present invention is used for fermentation of Chinese mustard sauerkraut, and the effect of enriching the flavor of the sauerkraut can be achieved without adding any exogenous preservatives, spices and seasonings during the fermentation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a picture of the Chinese mustard pickle product obtained by fermentation in Example 4 of the present invention. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below in conjunction with specific examples and drawings. The following examples are convenient for better understanding of the present invention, but are not intended to limit the present invention. The experimental methods in the following examples are conventional methods unless otherwise specified. The drugs, reagents, and materials used in the following examples can be purchased through commercial channels unless otherwise specified.

[0033] The culture medium involved in the present invention is as follows:

[0034] MRS medium was purchased from Qingdao Haibo Biotechnology Co., Ltd.

[0035] The strains used in the present invention are as follows:

[0036] Lactobacillus pentosus with a preservation number of CGMCC 1.2707, Leuconostoc mesenteroides with a preservation number of CGMCC 1.578, Streptococcus thermophilus with a preservation number of CGMCC 1.1855, Lactobacillus paracasei with a preservation number of CGMCC 1.121 and Bifidobacterium bifidum with a preservation number of CGMCC 1.5090 were all purchased from China General Microbiological Culture Collection Administration Center.

[0037] Example 1: Preparation of composite lactic acid bacteria for fermenting Chinese mustard greens sauerkraut

[0038] The method for preparing a composite lactic acid bacteria for fermenting Chinese mustard greens sauerkraut comprises the following steps:

[0039] (1) MRS solid culture medium was dispensed into test tubes, with 3 mL dispensed into each test tube; Lactobacillus pentosus, Leuconostoc mesenteroides, Streptococcus thermophilus, Lactobacillus paracasei and Bifidobacterium bifidum were activated by puncture method, inoculated onto the solid culture medium in the test tubes, and cultured at 25° C. for 3 days.

[0040] (2) The MRS liquid culture medium was divided into 250 mL conical flasks, 50 mL per bottle, and sterilized by high pressure steam at 121° C. for 15 min for standby use; the activated strains obtained in step (1) were transferred to conical flasks containing MRS liquid culture medium and cultured at 25° C. for 3 days until the number of viable bacteria in the bacterial solution of each lactic acid bacteria strain reached 0.8×10 9 cfu / mL.

[0041] (3) Expansion of bacterial strains and culture: The activated bacterial culture of each bacterial strain was transferred to a corresponding container at a dosage ratio of 5% (v / v), and the container contained 60% volume of MRS liquid culture medium. The culture was cultured at 37° C. for 2 days to obtain a single lactic acid bacteria culture for use.

[0042] (4) The five lactic acid bacteria liquids obtained by culturing in step (3) are uniformly mixed in a volume ratio of 3:1:1:1:1:1 among Lactobacillus pentosus liquid, Leuconostoc mesenteroides liquid, Streptococcus thermophilus liquid, Lactobacillus paracasei liquid and Bifidobacterium bifidum liquid to obtain a composite lactic acid bacteria for fermenting Chinese mustard sauerkraut.

[0043] Example 2: Preparation of composite lactic acid bacteria for fermenting Chinese mustard greens sauerkraut

[0044] The method for preparing a composite lactic acid bacteria for fermenting Chinese mustard greens sauerkraut comprises the following steps:

[0045] (1) MRS solid culture medium was dispensed into test tubes, with 3 mL dispensed into each test tube; Lactobacillus pentosus, Leuconostoc mesenteroides, Streptococcus thermophilus, Lactobacillus paracasei and Bifidobacterium bifidum were activated by puncture method, inoculated onto the solid culture medium in the test tubes, and cultured at 35° C. for 2 days.

[0046] (2) The MRS liquid culture medium was divided into 250 mL conical flasks, 50 mL per bottle, and sterilized by high pressure steam at 121° C. for 15 min for standby use; the activated strains obtained in step (1) were transferred to conical flasks containing MRS liquid culture medium and cultured at 37° C. for 1 day until the number of viable bacteria in the bacterial solution of each lactic acid bacteria strain reached 1.0×10 9 cfu / mL.

[0047] (3) Expansion of bacterial strains and culture: The activated bacterial culture of each bacterial strain was transferred to a corresponding container at a dosage ratio of 5% (v / v), and the container contained 60% volume of MRS liquid culture medium. The culture was cultured at 37° C. for 2 days to obtain a single lactic acid bacteria culture for use.

[0048] (4) The five lactic acid bacteria liquids obtained by culturing in step (3) are uniformly mixed in a volume ratio of 8:3:2:2:2, including Lactobacillus pentosus liquid, Leuconostoc mesenteroides liquid, Streptococcus thermophilus liquid, Lactobacillus paracasei liquid and Bifidobacterium bifidum liquid, to obtain a composite lactic acid bacteria for fermenting Chinese mustard sauerkraut.

[0049] Example 3: Preparation of composite lactic acid bacteria for fermenting Chinese mustard greens sauerkraut

[0050] The method for preparing a composite lactic acid bacteria for fermenting Chinese mustard greens sauerkraut comprises the following steps:

[0051] (1) The MRS solid culture medium was dispensed into test tubes, with 3 mL dispensed into each test tube; Lactobacillus pentosus, Leuconostoc mesenteroides, Streptococcus thermophilus, Lactobacillus paracasei and Bifidobacterium bifidum were activated by puncture method, inoculated onto the solid culture medium in the test tubes, and cultured at 30° C. for 2 days.

[0052] (2) The MRS liquid culture medium was divided into 250 mL conical flasks, 50 mL per bottle, and sterilized by high pressure steam at 121° C. for 15 min for standby use; the activated strains obtained in step (1) were transferred to conical flasks containing MRS liquid culture medium and cultured at 30° C. for 2 days until the number of viable bacteria in the bacterial solution of each lactic acid bacteria strain reached 0.9×10 9 cfu / mL.

[0053] (3) Expansion of bacterial strains and culture: The activated bacterial culture of each bacterial strain was transferred to a corresponding container at a dosage ratio of 5% (v / v), and the container contained 60% volume of MRS liquid culture medium. The culture was cultured at 37° C. for 2 days to obtain a single lactic acid bacteria culture for use.

[0054] (4) The five lactic acid bacteria liquids obtained by culturing in step (3) are uniformly mixed in a volume ratio of 5:2:1:2:1 for Lactobacillus pentosus liquid, Leuconostoc mesenteroides liquid, Streptococcus thermophilus liquid, Lactobacillus paracasei liquid and Bifidobacterium bifidum liquid to obtain a composite lactic acid bacteria for fermenting Chinese mustard sauerkraut.

[0055] Example 4: Fermentation of Chinese mustard greens with composite lactic acid bacteria

[0056] The method of fermenting Chinese mustard greens with the composite lactic acid bacteria obtained in Example 1 specifically comprises the following steps:

[0057] (1) Dry the Chinese mustard greens for 2 days until they are 65% of their original weight, remove impurities, wash, blanch in 100° C. boiling water for 20 seconds, air-dry, put into a jar, and compact the Chinese mustard greens.

[0058] (2) Add compound lactic acid bacteria to the bottom of the jar, add 20 mL of compound lactic acid bacteria solution per kilogram of Chinese mustard; seal and ferment at 15°C, and it can be eaten after 7 days of fermentation. The Chinese mustard pickled cabbage product is shown in the figure Figure 1 shown.

[0059] Example 5: Fermentation of Chinese mustard greens with composite lactic acid bacteria

[0060] The method of fermenting Chinese mustard greens with the composite lactic acid bacteria obtained in Example 2 specifically comprises the following steps:

[0061] (1) Dry the Chinese mustard greens for 1 day until they are 70% of their original weight, remove impurities, wash, blanch in 100°C boiling water for 20 seconds, and air-dry. Then, put them into a jar and sprinkle with edible salt that is 2% of the weight of the Chinese mustard greens. Sprinkle a layer of salt on each layer of vegetables and compact the Chinese mustard greens.

[0062] (2) Add compound lactic acid bacteria to the bottom of the jar, adding 40 mL of compound lactic acid bacteria solution per kilogram of Chinese mustard; seal and ferment at 25° C. The jar can be eaten after two days of fermentation.

[0063] Example 6: Fermentation of Chinese mustard greens with composite lactic acid bacteria

[0064] The method of fermenting Chinese mustard greens with the composite lactic acid bacteria obtained in Example 3 specifically comprises the following steps:

[0065] (1) Dry the Chinese mustard greens for 1.5 days until they are 67% of their original weight, remove impurities, wash, blanch in 100°C boiling water for 20 seconds, and air-dry. Then, put them into a jar and sprinkle with edible salt that is 4% of the weight of the Chinese mustard greens. Sprinkle a layer of salt on each layer of vegetables and compact the Chinese mustard greens.

[0066] (2) Add compound lactic acid bacteria to the bottom of the jar, adding 30 mL of compound lactic acid bacteria solution per kilogram of Chinese mustard; seal and ferment at 35° C. The jar can be eaten after 2 days of fermentation.

[0067] Comparative Example 1:

[0068] The traditional fermentation method of sauerkraut (without adding additional bacteria) includes the following steps:

[0069] Dry the Chinese mustard greens for 1 day until they are 70% of their original weight, remove impurities, wash, blanch in 100°C boiling water for 20 seconds, and air-dry. Then put them into a jar and sprinkle with edible salt that is 15% of the weight of the Chinese mustard greens. Sprinkle a layer of salt on each layer of vegetables, compact the Chinese mustard greens, and ferment them in a sealed container at 25°C. They can be eaten after 20 days of fermentation.

[0070] Comparative Example 2:

[0071] The fermentation of Chinese mustard pickle using Lactobacillus pentosus as the only bacterial species includes the following steps:

[0072] 1. Preparation of Lactobacillus pentosus bacterial solution

[0073] (1) The MRS solid culture medium was dispensed into test tubes, with 3 mL dispensed into each test tube; the Lactobacillus pentosus strain was activated by a puncture method, inoculated onto the solid culture medium in the test tube, and cultured at 35° C. for 2 days.

[0074] (2) The MRS liquid culture medium was divided into 250 mL conical flasks, 50 mL per flask, and sterilized by high pressure steam at 121°C for 15 min for use; the activated strain obtained in step (1) was transferred to a conical flask containing MRS liquid culture medium and cultured at 37°C for 1 day until the number of viable bacteria in the bacterial solution reached 1.0×10 9 cfu / mL.

[0075] (3) Expansion culture of bacterial strains and bacterial liquid: The activated bacterial liquid of the bacterial strains is transferred to a corresponding container at a dosage ratio of 5% (v / v), the container contains 60% volume of MRS, and cultured at 37° C. for 2 days to obtain a single lactic acid bacteria liquid for use.

[0076] 2. Use Lactobacillus pentosus bacterial liquid to ferment Chinese mustard sauerkraut

[0077] (1) Dry the Chinese mustard greens for 1 day until they are 70% of their original weight, remove impurities, wash, blanch in 100°C boiling water for 20 seconds, and air-dry. Then, put them into a jar and sprinkle with edible salt that is 2% of the weight of the Chinese mustard greens. Sprinkle a layer of salt on each layer of vegetables and compact the Chinese mustard greens.

[0078] (2) Add Lactobacillus pentosus bacterial solution to the bottom of the jar, add 40 mL of Lactobacillus pentosus bacterial solution per kilogram of Chinese mustard, and ferment at 25° C. The jar can be eaten after 5 days of fermentation.

[0079] Comparative Example 3:

[0080] The fermentation of Chinese mustard pickle using Leuconostoc mesenteroides as the only bacterial species includes the following steps:

[0081] 1. Preparation of Leuconostoc mesenteroides culture solution

[0082] (1) The MRS solid culture medium was dispensed into test tubes, with 3 mL dispensed into each test tube; the strain of Leuconostoc mesenteroides was activated by puncture method, inoculated into the solid culture medium in the test tube, and cultured at 35° C. for 2 days.

[0083] (2) The MRS liquid culture medium was divided into 250 mL conical flasks, 50 mL per flask, and sterilized by high pressure steam at 121°C for 15 min for use; the activated strain obtained in step (1) was transferred to a conical flask containing MRS liquid culture medium and cultured at 37°C for 1 day until the number of viable bacteria in the bacterial solution reached 1.0×10 9cfu / mL.

[0084] (3) Expansion culture of bacterial strains and bacterial liquid: The activated bacterial liquid of the bacterial strains is transferred to a corresponding container at a dosage ratio of 5% (v / v), the container contains 60% volume of MRS, and cultured at 37° C. for 2 days to obtain a single lactic acid bacteria liquid for use.

[0085] 2. Use the bacterial liquid of Leuconostoc mesenteroides to ferment Chinese mustard pickles

[0086] (1) Dry the Chinese mustard greens for 1 day until they are 70% of their original weight, remove impurities, wash, blanch in 100°C boiling water for 20 seconds, and air-dry. Then, put them into a jar and sprinkle with edible salt that is 2% of the weight of the Chinese mustard greens. Sprinkle a layer of salt on each layer of vegetables and compact the Chinese mustard greens.

[0087] (2) Add 40 mL of Leuconostoc mesenteroides liquid to the bottom of the jar per kilogram of Chinese mustard, and seal and ferment at 25° C. The jar can be eaten after 7 days of fermentation.

[0088] Comparative Example 4:

[0089] The fermentation of Chinese mustard greens sauerkraut using Lactobacillus paracasei as the only bacterial species includes the following steps:

[0090] 1. Preparation of Lactobacillus paracasei bacterial liquid

[0091] (1) MRS solid culture medium was dispensed into test tubes, with 3 mL dispensed into each test tube; Lactobacillus paracasei strains were activated by puncture method, inoculated onto the solid culture medium in the test tubes, and cultured at 35° C. for 2 days.

[0092] (2) The MRS liquid culture medium was divided into 250 mL conical flasks, 50 mL per flask, and sterilized by high pressure steam at 121°C for 15 min for use; the activated strain obtained in step (1) was transferred to a conical flask containing MRS liquid culture medium and cultured at 37°C for 1 day until the number of viable bacteria in the bacterial solution reached 1.0×10 9 cfu / mL.

[0093] (3) Expansion culture of bacterial strains and bacterial liquid: The activated bacterial liquid of the bacterial strains is transferred to a corresponding container at a dosage ratio of 5% (v / v), the container contains 60% volume of MRS, and cultured at 37° C. for 2 days to obtain a single lactic acid bacteria liquid for use.

[0094] 2. Use Lactobacillus paracasei culture liquid to ferment Chinese mustard sauerkraut

[0095] (1) Dry the Chinese mustard greens for 1 day until they are 70% of their original weight, remove impurities, wash, blanch in 100°C boiling water for 20 seconds, and air-dry. Then, put them into a jar and sprinkle with edible salt that is 2% of the weight of the Chinese mustard greens. Sprinkle a layer of salt on each layer of vegetables and compact the Chinese mustard greens.

[0096] (2) Add Lactobacillus paracasei bacterial solution to the bottom of the jar, add 40 mL of Lactobacillus paracasei bacterial solution per kilogram of Chinese mustard, and ferment at 25° C. in a sealed container. The jar can be eaten after fermentation for 10 days.

[0097] Comparative Example 5:

[0098] The fermentation of Chinese mustard sauerkraut using a composite lactic acid bacteria strain consisting of Lactobacillus pentosus, Leuconostoc mesenteroides and Lactobacillus paracasei comprises the following steps:

[0099] 1. Preparation of compound lactic acid bacteria liquid

[0100] (1) MRS solid culture medium was dispensed into test tubes, with 3 mL dispensed into each test tube; Lactobacillus pentosus, Leuconostoc mesenteroides, and Lactobacillus paracasei were activated by puncture method, inoculated onto the solid culture medium in the test tubes, and cultured at 35° C. for 2 days.

[0101] (2) The MRS liquid culture medium was divided into 250 mL conical flasks, 50 mL per bottle, and sterilized by high pressure steam at 121° C. for 15 min for standby use; the activated strains obtained in step (1) were transferred to conical flasks containing MRS liquid culture medium and cultured at 37° C. for 1 day until the number of viable bacteria in the bacterial solution of each lactic acid bacteria strain reached 1.0×10 9 cfu / mL.

[0102] (3) Expansion of bacterial strains and culture: The activated bacterial culture of each bacterial strain was transferred to a corresponding container at a dosage ratio of 5% (v / v), and the container contained 60% volume of MRS liquid culture medium. The culture was cultured at 37° C. for 2 days to obtain a single lactic acid bacteria culture for use.

[0103] (4) The three lactic acid bacteria cultured in step (3) are uniformly mixed in a volume ratio of 8:3:2 for the Lactobacillus pentosus bacteria solution, the Leuconostoc mesenteroides bacteria solution, and the Lactobacillus paracasei bacteria solution, thereby obtaining a composite lactic acid bacteria for fermenting Chinese mustard sauerkraut.

[0104] 2. Use the compound lactic acid bacteria liquid composed of Lactobacillus pentosus, Leuconostoc mesenteroides and Lactobacillus paracasei to ferment Chinese mustard sauerkraut

[0105] (1) drying the Chinese mustard greens for 1 day until the weight is 70% of the original weight, removing impurities, washing, blanching in 100° C. boiling water for 20 seconds, air-drying, placing in a jar, and sprinkling with edible salt of 2% of the weight of the Chinese mustard greens, sprinkling a layer of salt on each layer of vegetables, and compacting the Chinese mustard greens;

[0106] (2) Add the composite lactic acid bacteria liquid to the bottom of the jar, add 40 mL of the composite lactic acid bacteria liquid per kilogram of Chinese mustard, and seal and ferment at 25° C. The jar can be eaten after 4 days of fermentation.

[0107] Comparative Example 6:

[0108] The fermentation of Chinese mustard sauerkraut using a composite lactic acid bacteria strain consisting of Lactobacillus pentosus, Leuconostoc mesenteroides, Lactobacillus paracasei and Lactobacillus plantarum comprises the following steps:

[0109] 1. Preparation of compound lactic acid bacteria liquid

[0110] (1) MRS solid culture medium was dispensed into test tubes, with 3 mL dispensed into each test tube; Lactobacillus pentosus, Leuconostoc mesenteroides, Lactobacillus paracasei and Lactobacillus plantarum were activated by puncture method, inoculated onto the solid culture medium in the test tubes, and cultured at 35° C. for 2 days.

[0111] (2) The MRS liquid culture medium was divided into 250 mL conical flasks, 50 mL per bottle, and sterilized by high pressure steam at 121° C. for 15 min for standby use; the activated strains obtained in step (1) were transferred to conical flasks containing MRS liquid culture medium and cultured at 37° C. for 1 day until the number of viable bacteria in the bacterial solution of each lactic acid bacteria strain reached 1.0×10 9 cfu / mL.

[0112] (3) Expansion of bacterial culture: The activated bacterial culture of each bacterial strain was transferred to the corresponding container at a dosage ratio of 5% (v / v), and the container contained 60% volume of MRS liquid culture medium. The culture was cultured at 37° C. for 2 days to obtain a single lactic acid bacteria culture for use.

[0113] (4) The four lactic acid bacteria cultured in step (3) are uniformly mixed in a volume ratio of 8:3:2:2 among Lactobacillus pentosus, Leuconostoc mesenteroides, Lactobacillus paracasei and Lactobacillus plantarum to obtain a composite lactic acid bacteria for fermenting Chinese mustard sauerkraut.

[0114] 2. Use the compound lactic acid bacteria liquid composed of Lactobacillus pentosus, Leuconostoc mesenteroides, Lactobacillus paracasei and Lactobacillus plantarum to ferment Chinese mustard sauerkraut

[0115] (1) drying the Chinese mustard greens for 1 day until the weight is 70% of the original weight, removing impurities, washing, blanching in 100° C. boiling water for 20 seconds, air-drying, placing in a jar, and sprinkling with edible salt of 2% of the weight of the Chinese mustard greens, sprinkling a layer of salt on each layer of vegetables, and compacting the Chinese mustard greens;

[0116] (2) Add the composite lactic acid bacteria liquid to the bottom of the jar, add 40 mL of the composite lactic acid bacteria liquid per kilogram of Chinese mustard, and seal and ferment at 25° C. The jar can be eaten after 4 days of fermentation.

[0117] Comparative Example 7:

[0118] The compound lactic acid bacteria widely used in the fermentation of pickled mustard greens on the market are used to ferment pickled mustard greens. Kimchi sauerkraut lactic acid bacteria fermentation powder was purchased from Beijing Chuanxiu Technology Co., Ltd. Its ingredients include Lactobacillus plantarum, Lactobacillus acidophilus, and Lactobacillus rhamnosus. The specific fermentation process is as follows:

[0119] (1) drying the Chinese mustard greens for 1 day until the weight is 70% of the original weight, removing impurities, washing, blanching in 100° C. boiling water for 20 seconds, air-drying, placing in a jar, and sprinkling with edible salt of 2% of the weight of the Chinese mustard greens, sprinkling a layer of salt on each layer of vegetables, and compacting the Chinese mustard greens;

[0120] (2) 1g The kimchi sauerkraut lactic acid bacteria fermentation powder is dissolved in 40 mL of sterile water to prepare a composite lactic acid bacteria solution, which is added to the bottom of a jar, with 40 mL added for every kilogram of Chinese mustard; the solution is sealed and fermented at 25°C and can be eaten after 3 days of fermentation.

[0121] In order to evaluate the fermentation effect of Examples 4-6 and each comparative example, the present invention measures and records the fermentation process parameters such as the number of viable cells in the liquid and the fermentation time, measures the pH, salt content, nitrite content, and total organic acid content in the fermented product, and is supplemented by sensory evaluation (see Table 2). The sensory evaluation of the Chinese mustard pickled vegetable products was carried out in terms of color, morphology, smell, taste, and flavor. The sensory evaluation personnel were 25 food professionals who were familiar with food description attributives and food evaluation standards. The scoring standards were formulated according to the national standard GB2714-2015 "National Standard for Pickled Vegetables" as shown in Table 1, and the final score was the sum of all score values ​​(100 points).

[0122] Table 1 Sensory scoring standards for pickled cabbage

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[0124] Table 2 Comparison of fermentation effects of Chinese mustard greens obtained in the examples and comparative examples

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[0126] As can be seen from Table 2, the embodiments provided in the present invention achieve the effect of increasing the fermentation speed, reducing the salt content and nitrite content, and enriching the fermentation flavor by compounding multiple strains. Compared with Comparative Examples 1-7, the sauerkraut obtained by fermenting Chinese potherb mustard with the composite lactic acid bacteria provided by the present invention has a higher number of viable bacteria, a lower pH, a shorter fermentation time, and a better sensory evaluation of the final product, a significantly reduced salt content, a lower nitrite content, and a higher organic acid content than the sauerkraut obtained by natural fermentation, a single strain, and other composite lactic acid bacteria fermentation. These parameters show that the use of the composite lactic acid bacteria provided by the present invention can enable each strain to form a complementary fermentation advantage, significantly improving the shortcomings of slow fermentation speed of natural strains or single strains, and short fermentation duration. After many explorations, the present invention has obtained a suitable environment in which the composite strains can coexist well in the fermentation process of Chinese potherb mustard sauerkraut.

[0127] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A composite lactic acid bacteria for fermenting Chinese mustard sauerkraut, characterized in that: The samples included Lactobacillus pentosus, Leuconostoc mesenteroides, Streptococcus thermophilus, Lactobacillus paracasei and Bifidobacterium bifidum. The viable count of each sample was 0.8 × 10 9 ~1.0×10 9 cfu / mL; the volume ratio of the Lactobacillus pentosus bacterial solution, the Leuconostoc mesenteroides bacterial solution, the Streptococcus thermophilus bacterial solution, the Lactobacillus paracasei bacterial solution and the Bifidobacterium bifidum bacterial solution is (3-8):(1-3):(1-2):(1-2):(1-2).

2. The composite lactic acid bacteria according to claim 1, characterized in that The Lactobacillus pentosus has a preservation number of CGMCC 1.2707, the Leuconostoc mesenteroides has a preservation number of CGMCC 1.578, the Streptococcus thermophilus has a preservation number of CGMCC 1.1855, the Lactobacillus paracasei has a preservation number of CGMCC 1.121, and the Bifidobacterium bifidum has a preservation number of CGMCC 1.5090.

3. The method for preparing the composite lactic acid bacteria according to any one of claims 1 or 2, characterized in that: The steps include: (1) Lactobacillus pentosus, Leuconostoc mesenteroides, Streptococcus thermophilus, Lactobacillus paracasei and Bifidobacterium bifidum were inoculated into a solid culture medium and activated at 25° C. to 37° C. for 1 to 3 days; (2) The activated strains obtained in step (1) were inoculated into liquid culture medium and cultured at 25°C to 37°C for 1 to 3 days until the number of viable bacteria in the bacterial solution of each strain reached 0.8×10 9 ~1.0×10 9 cfu / mL; (3) inoculating the bacterial liquid of each bacterium obtained in step (2) into a liquid culture medium, and expanding the culture at 25° C. to 37° C. for 1 to 3 days to obtain a single lactic acid bacteria liquid for use; (4) The five single lactic acid bacteria solutions obtained in step (3) are uniformly mixed according to the volume ratio of Lactobacillus pentosus solution, Leuconostoc mesenteroides solution, Streptococcus thermophilus solution, Lactobacillus paracasei solution and Bifidobacterium bifidum solution of (3-8): (1-3): (1-2): (1-2): (1-2) to obtain composite lactic acid bacteria.

4. The preparation method according to claim 3, characterized in that: The solid culture medium in step (1) is MRS solid culture medium.

5. The preparation method according to claim 3, characterized in that: The liquid culture medium in step (2) and step (3) is MRS liquid culture medium.

6. The preparation method according to claim 3, characterized in that: The inoculation amount of the expanded culture in step (3) is 5% by volume of the liquid culture medium.

7. A method for fermenting Chinese mustard greens with the composite lactic acid bacteria according to any one of claims 1 or 2, characterized in that: The steps include: S1. After being aired, cleaned, washed, blanched and air-dried, the Chinese mustard is placed in a container, a layer of edible salt is sprinkled on each layer of Chinese mustard, and the Chinese mustard is compacted, wherein the amount of edible salt added is 0% to 4% of the weight of the Chinese mustard; S2. Add 20-40 mL of the composite lactic acid bacteria per kg of Chinese mustard to the bottom of the container, and seal and ferment at 0-35° C. for 2-7 days.

8. The method according to claim 7, characterized in that The drying step S1 is to dry the Chinese mustard greens for 1-3 days until the weight of the Chinese mustard greens is 65%-70% of the original weight.

9. The method according to claim 7, characterized in that: The blanching in S1 is performed in 100° C. boiling water for 20 seconds.

10. Pickled Chinese potherb mustard obtained by the method according to any one of claims 7 to 9.

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