Method for shallow fermentation of brassica napobrassica

Abstract

The invention relates to the technical field of brassica napobrassica, in particular to a method for slightly fermenting brassica napobrassica, which comprises the following steps: performing primary fermentation by using a complex microbial inoculant, and then performing secondary fermentation at low temperature by using a Weissella fusiformis microbial inoculant. The method can shorten the fermentation period and improve the production efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of kohlrabi, and in particular to a method for shallowly fermenting kohlrabi. Background Art

[0002] Pickled kohlrabi is a traditional pickled vegetable made from mustard or kohlrabi (turnip) through pickling and fermentation processes. The edible part of mustard is mainly the tuberous root, which is rich in dietary fiber, polysaccharides, vitamins, polyphenols and flavonoids. It also has good health benefits for the human body, and has the effects of clearing away heat and detoxification, diuresis, promoting digestion and relieving fatigue. However, fresh mustard has a strong spicy taste and does not taste good when eaten directly, so it is often diced and pickled before eating. The pickled kohlrabi has a dense texture, less water, and more cellulose. It has a strong sauce aroma and umami flavor, and a crisp and tender taste. It is an excellent product for meals and is deeply loved by consumers.

[0003] Kohlrabi is mostly produced by natural fermentation and pure manual processing. At present, there are many problems in the kohlrabi fermentation process, such as the long fermentation cycle, the traditional air-drying method generally takes several weeks, the high-salt fermentation speed is slow, resulting in low production efficiency; the quality of natural fermentation is uncontrollable, and the nitrite content is easy to accumulate to a high level in the early stage of fermentation, which is potentially harmful to human health; the aroma is insufficient after fermentation, and the color and crispness are difficult to maintain during the long fermentation process, affecting the product quality, etc., which is not conducive to the industrial production and processing of kohlrabi. Summary of the invention

[0004] The purpose of the present invention is to provide a method for shallow fermentation of kohlrabi, so as to solve the technical problems in the prior art of long natural fermentation cycle, large loss of nutrients during natural air drying, slow high-salt fermentation speed and low production efficiency.

[0005] The invention discloses a method for shallowly fermenting kohlrabi, comprising the following steps:

[0006] After the first fermentation using the composite bacterial agent, the second fermentation is carried out at low temperature using the fused Weissella bacterial agent.

[0007] Furthermore, the composite bacterial agent is prepared by Lactobacillus pentosus and Kazakhstan oligosporic yeast.

[0008] Furthermore, the Lactobacillus pentosus is preserved in the General Microbiology Center of the China Committee for Culture Collection of Microorganisms. The preservation time is July 15, 2016, and the preservation number is CGMCC No: 12793. The address of the preservation unit is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences. This strain is salt-tolerant (≥8%), temperature-tolerant (15 - 45°C), acid-tolerant (pH ≤ 4), and can rapidly ferment to produce acid (≥0.7%), shortening the product ripening time, inhibiting the growth of harmful microorganisms, and blocking the formation of nitrite.

[0009] Furthermore, the Kazachstania exigua is preserved in the General Microbiology Center of the China Committee for Culture Collection of Microorganisms. The preservation time is July 15, 2016, and the preservation number is CGMCC No: 12791. The address of the preservation unit is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences. This strain can produce alcohol and ester aromatic substances, and has a strong degradation ability for esters such as allyl isothiocyanate.

[0010] Furthermore, the Weissella confusa is preserved in the General Microbiology Center of the China Committee for Culture Collection of Microorganisms. The preservation time is November 15, 2021, and the preservation number is CGMCC No: 23918. The address of the preservation unit is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences. This strain produces bacteriocin and has an antibacterial effect on Escherichia coli; it can increase the amino acid content and enhance the fermentation flavor; it has antioxidant properties and weak acid production, which is beneficial to preventing over-acidification and post-acidification of fermented vegetables.

[0011] Furthermore, the preparation method of the composite bacterium agent is as follows: Mix the bacterial mud of Lactobacillus pentosus and Kazachstania exigua at a ratio of 2 - 3:1 - 1.5, and add 5 - 10% of protective agent milk powder, 3 - 7% of trehalose, and 0.5 - 1.5% of glycerol to make a stable bacterium agent. The viable bacteria count in the bacterium agent is 4×10 9 CFU / g - 7×10 9 CFU / g.

[0012] Furthermore, the preparation method of the composite bacterium agent is as follows: Mix the bacterial mud of Lactobacillus pentosus and Kazachstania exigua at a ratio of 2:1, and add 5% of protective agent milk powder, 3% of trehalose, and 1% of glycerol to make a stable bacterium agent. The viable bacteria count in the bacterium agent is 5×10 9 CFU / g.

[0013] Further, the method for preparing the sludge of Lactobacillus pentosus is to inoculate Lactobacillus pentosus into MRS broth medium and culture it at 37 °C for 18 - 24 hours until the cell concentration reaches 10 8 -10 9 CFU / mL, and then centrifuge to obtain the sludge.

[0014] Further, the method for preparing the sludge of Kazachstania exigua is to inoculate Kazachstania exigua into YPD medium and culture it at 25 °C for 18 - 24 hours until the cell concentration reaches 10 7 -10 8 CFU / mL, and then centrifuge to obtain the sludge.

[0015] Further, the method for preparing the Weisella confusa inoculant is as follows: inoculate Weisella confusa into MRS broth medium until the cell concentration reaches 10 8 -10 9 CFU / mL, collect the cells, wash them, and then make them into a cell suspension.

[0016] Further, the Weisella confusa is cultured at 37 °C for 18 - 24 hours.

[0017] Further, the washing is performed 2 - 3 times with sterile physiological saline.

[0018] Further, staged dehydration is performed before the primary fermentation.

[0019] Further, the staged dehydration is carried out by combining vacuum dehydration and hot air assistance.

[0020] Further, for the staged dehydration, first use vacuum dehydration until the water content drops to 70%, then transfer the vacuum - dehydrated turnips to hot air drying until the water content is about 50%.

[0021] Further, for the vacuum dehydration, the vacuum degree is controlled between 0.05 MPa and - 0.1 MPa, and the dehydration time is 30 - 40 minutes.

[0022] Further, the temperature for hot air drying is 40 - 60 °C.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. The method of the present invention can shorten the fermentation cycle and improve production efficiency;

[0025] 2. Compared with traditional natural air - drying, the staged dehydration significantly shortens the air - drying time and is beneficial to retaining the texture and nutritional components of turnips;

[0026] 3. Inoculation fermentation can quickly ferment to produce acid, shorten the product ripening time, inhibit the growth of harmful microorganisms, block the formation of nitrite, effectively reduce the nitrite content, and improve the edible safety of turnips;

[0027] 4. Increase the aroma of turnips after fermentation, maintain the color and crispy texture of turnips, and improve the edible value;

[0028] 5. Add lactic acid bacteria to inhibit miscellaneous bacteria, prevent post-acidification, and extend the shelf life. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0030] Figure 1 It is the sensory evaluation score chart of the embodiment of the present invention.

[0031] Figure 2 It is the total acid content chart of the embodiment of the present invention.

[0032] Figure 3 It is the nitrite content chart of the embodiment of the present invention.

[0033] Figure 4 It is the essential amino acid content chart of the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments.

[0035] Example 1

[0036] A method for shallow fermentation of turnips is disclosed in this embodiment, including the following steps:

[0037] Inoculate Lactobacillus pentosus CGMCC No: 12793 into MRS broth medium and culture it at 37 °C for 20 hours until the cell concentration reaches 10 9 CFU / mL, and centrifuge to obtain cell sludge; inoculate Kazachstania exigua CGMCC No: 12791 into YPD medium and culture it at 25 °C for 18 hours until the cell concentration reaches 10 8CFU / mL, and the bacterial sludge was obtained by centrifugation. The bacterial sludge of Lactobacillus pentosus and Kazachstania exigua was mixed at a ratio of 2:1, and 5% milk powder, 3% trehalose, and 1% glycerol as protective agents were added to prepare a stable bacterial agent. The viable count in the bacterial agent was 5.28×10 9 CFU / g. Weissella confusa CGMCC No: 23918 was inoculated into MRS broth medium and cultured at 37 °C for 18 hours until the cell concentration reached 10 8 CFU / mL. The cells were collected and washed 2 - 3 times with sterile normal saline to prepare a cell suspension.

[0038] (1) Raw material selection and cleaning: Fresh turnips without pests and diseases were selected as raw materials. The turnips were rinsed with clean water to remove the sediment and impurities on the surface.

[0039] (2) Raw material sterilization: The washed turnips were irradiated under an ultraviolet lamp for 35 minutes to sterilize the microorganisms on the surface of the turnips.

[0040] (3) Step - by - step dehydration: A combination of vacuum dehydration and hot - air assistance was adopted. First, a vacuum dehydrator was used for preliminary dehydration. The vacuum degree was controlled at 0.08 MPa, and the dehydration time was 35 minutes until the moisture content dropped to about 70%. The turnips after vacuum dehydration were transferred to a hot - air dryer, and the temperature was controlled at 50 °C and dried until the moisture content was about 50%.

[0041] (4) Primary fermentation: The dehydrated turnips were placed in a clean ceramic jar, 6% salt was added, and they were mixed well. Then, a compound bacterial agent was added at 1.5% of the total mass of the turnips. The ceramic jar was inverted for fermentation, and the fermentation environment temperature was controlled at 30 °C for 3 days.

[0042] (5) Secondary low - temperature fermentation: The turnips that had completed primary fermentation were taken out of the ceramic jar, 0.8% rock sugar and 1% Weissella confusa bacterial agent were added, and they were mixed well and then placed in a fermentation tank for fermentation at 6 °C for 3 days.

[0043] (6) Cleaning, air - drying, and seasoning: The fermented turnips were simply rinsed with clean water, air - dried at 25 °C for 1.5 hours, shredded, and seasoned with 1.5% chili powder, 0.8% Chinese prickly ash, 0.3% star anise, 0.5% monosodium glutamate, 0.2% white sesame seeds, etc. to obtain the finished turnip product 1.

[0044] Example 2

[0045] Lactobacillus pentosus CGMCC No: 12793 was inoculated into MRS broth medium and cultured at 37 °C for 20 hours until the cell concentration reached 10 9CFU / mL, centrifuged to obtain bacterial sludge; Kazakhstan oligosporic yeast CGMCC No: 12791 was inoculated into YPD medium and cultured at 25°C for 18 hours until the bacterial concentration reached 10 8 CFU / mL, and centrifuged to obtain bacterial sludge. The bacterial sludge of Lactobacillus pentosus and Kazakhstan yeast oligosporus was mixed in a ratio of 1:2, and 5% protective milk powder, 3% trehalose, and 1% glycerol were added to prepare a stable bacterial agent. The number of viable bacteria in the bacterial agent was 5.28×10 9 CFU / g. Inoculate the fused Weissella CGMCC No: 23918 into MRS broth medium and culture at 37°C for 18 hours until the bacterial concentration reaches 10 8 CFU / mL, collect the bacteria, wash them 2-3 times with sterile saline to prepare a bacterial suspension.

[0046] (1) Raw material selection and cleaning: Select fresh, pest-free kohlrabi as the raw material. Rinse the kohlrabi with clean water to remove surface sand and impurities.

[0047] (2) Sterilization of raw materials: Place the cleaned kohlrabi under ultraviolet light for 35 minutes to sterilize the microorganisms on the surface of the kohlrabi.

[0048] (3) Segmented dehydration: A combination of vacuum dehydration and hot air assistance is used. First, use a vacuum dehydrator for preliminary dehydration, with the vacuum degree controlled at 0.08 MPa and the dehydration time at 35 minutes, until the moisture content drops to about 70%. Transfer the vacuum-dehydrated kohlrabi to a hot air dryer, control the temperature at 50°C, and dry it to a moisture content of about 50%.

[0049] (4) Primary fermentation: Place the dehydrated kohlrabi in a clean ceramic jar, add 6% salt, mix thoroughly, then add a composite bacterial agent at 1.5% of the total mass of the kohlrabi, turn the ceramic jar upside down for fermentation, control the fermentation environment temperature at 30°C, and ferment for 3 days.

[0050] (5) Secondary low-temperature fermentation: Take the kohlrabi that has matured in the first fermentation out of the pottery jar, add 0.8% crystal sugar and 1% fused Weissella inoculum, mix well, and place in a fermentation tank to ferment at 6°C for 3 days.

[0051] (6) Cleaning, air-drying, and seasoning: The fermented kohlrabi is simply rinsed with clean water, air-dried at 25° C. for 1.5 hours, cut into strips, and seasoned with 1.5% chili powder, 0.8% prickly ash, 0.3% star anise, 0.5% monosodium glutamate, 0.2% white sesame, etc., to obtain the kohlrabi finished product 2.

[0052] Example 3

[0053] Lactobacillus pentosus CGMCC No: 12793 was inoculated into MRS broth medium and cultured at 37°C for 20 hours until the bacterial concentration reached 10 9 CFU / mL, centrifuged to obtain bacterial sludge; Kazakhstan oligosporic yeast CGMCC No: 12791 was inoculated into YPD medium and cultured at 25°C for 18 hours until the bacterial concentration reached 10 8 CFU / mL, and centrifuged to obtain bacterial sludge. The bacterial sludge of Lactobacillus pentosus and Oligospora Kazakhstan Saccharomyces cerevisiae was mixed in a ratio of 2:1, and 5% protective milk powder, 3% trehalose, and 1% glycerol were added to prepare a stable bacterial agent. The number of viable bacteria in the bacterial agent was 5.28×10 9 CFU / g. Inoculate the fused Weissella CGMCC No: 23918 into MRS broth medium and culture at 37°C for 18 hours until the bacterial concentration reaches 10 8 CFU / mL, collect the bacteria, wash them 2-3 times with sterile saline to prepare a bacterial suspension.

[0054] (1) Raw material selection and cleaning: Select fresh, pest-free kohlrabi as the raw material. Rinse the kohlrabi with clean water to remove surface sand and impurities.

[0055] (2) Sterilization of raw materials: Place the cleaned kohlrabi under ultraviolet light for 45 minutes to sterilize the microorganisms on the surface of the kohlrabi.

[0056] (3) Segmented dehydration: A combination of vacuum dehydration and hot air assistance is used. First, use a vacuum dehydrator for preliminary dehydration, with the vacuum degree controlled at 0.05 MPa for 40 minutes until the moisture content drops to about 70%. Transfer the vacuum-dehydrated kohlrabi to a hot air dryer, control the temperature at 60°C, and dry it to a moisture content of about 50%.

[0057] (4) Primary fermentation: Place the dehydrated kohlrabi in a clean ceramic jar, add 5% salt, mix thoroughly, then add a composite bacterial agent at 1% of the total mass of the kohlrabi, turn the ceramic jar upside down for fermentation, control the fermentation environment temperature at 35°C, and ferment for 3 days.

[0058] (5) Secondary low-temperature fermentation: Take the kohlrabi that has matured in the first fermentation out of the pottery jar, add 1% crystal sugar and 0.6% fused Weissella inoculum, mix well and place in a fermentation tank, and ferment at 8°C for 3 days.

[0059] (6) Cleaning, air-drying, and seasoning: Rinse the fermented kohlrabi with clean water, air-dry at 27° C. for 1 hour, cut into strips, and season with 1.5% chili powder, 0.8% pepper, 0.3% star anise, 0.5% monosodium glutamate, 0.2% white sesame, etc., to obtain the kohlrabi finished product 3.

[0060] Example 4

[0061] The method steps of Example 1 were used for the preparation of turnips, with the only difference being that Lactobacillus pentosus with the preservation number CGMCC No: 12793 was replaced by Lactobacillus plantarum CDMCC No: 60196. The bacterial agent was prepared according to the method in Example 1, and the finally obtained turnips were numbered as finished product 4.

[0062] Example 5

[0063] The method steps of Example 1 were used for the preparation of turnips, with the only difference being that Weissella confusa with the preservation number CGMCC No: 23918 was replaced by Leuconostoc mesenteroides GDMCC No: 60197. The bacterial agent was prepared according to the method in Example 1, and the finally obtained turnips were numbered as finished product 5.

[0064] Example 6

[0065] Production of traditional turnips

[0066] (1) Fresh and pest-free turnips were selected as raw materials. The roots were removed, and they were washed with normal-temperature clear water to remove impurities.

[0067] (2) Air-dried naturally for 20 days.

[0068] (3) Washed and pickled in a pool with 7% salt for 15 days.

[0069] (4) The turnips were cut and then subjected to soaking and desalting treatment.

[0070] (5) The soaked vegetables were pressed to remove water.

[0071] (6) Mixed with seasonings, and the finished turnips 6 could be obtained.

[0072] Experimental example 1: Sensory comparison of samples

[0073] Randomly selected 10 professional sensory personnel to score the color, fragrance, taste, and texture of finished products 1 - 6. The five-point preference scale method was used for evaluation, where "1" means very dislike and unacceptable; "2" means dislike; "3" means neither like nor dislike; "4" means like; "5" means very like. The results are as Figure 1As shown, the overall sensory score of the finished product 1 is higher than that of the finished products 2-6, and the taste score is the highest, indicating that the pickled turnips made according to Example 1 are not much different from those made by traditional processes, and have better color, fragrance, taste, and texture. The overall sensory score of the finished product 1 is higher than that of the finished product 5, indicating that the pickled turnips made with Weissella confusa used in the present invention have better color, flavor, taste, and texture than those made with Leuconostoc mesenteroides. The overall sensory score of the finished product 4 is the lowest, indicating that fermenting dried radishes with Lactobacillus plantarum will result in too high acidity and post-acidification, which has a greater impact on the taste. The fragrance scores of the finished products 1, 3, 4, and 5 are all greater than that of the finished product 6, indicating that an appropriate amount of Kazachstania exigua is beneficial to enhancing the aroma of fermented pickled turnips; while the fragrance score of the finished product 2 is the lowest because too high a quantity of Kazachstania exigua will result in a large amount of ethanol produced during fermentation, giving the finished product an alcoholic taste.

[0074] Experimental Example 2: Comparison of total acid content

[0075] Total acid is an important physical and chemical parameter in the production of pickled turnips, which not only affects the sensory quality but also reflects the maturity of pickled turnips. According to the national standard determination method, the total acid concentrations of the finished products 1-5 at 1, 3, 5, 7, and 9 days of fermentation were measured, and the results are as Figure 2 shown. At the same time, the total acid content of the finished product 6 was also measured for reference. The total acid concentration of the finished product 6 is 0.78 g / 100 g. The total acid of the finished product 2 has the slowest growth rate, the finished product 4 has the fastest growth rate and the highest total acid content, indicating that the fast fermentation rate of Lactobacillus plantarum leads to too high acidity of pickled turnips; the total acid of the finished product 5 still has a small increase in the later stage, indicating that Leuconostoc mesenteroides has no obvious effect on inhibiting post-acidification; the fermentation rate of the finished product 1 is fast and the acidity is moderate, and the total acid content tends to be stable after maturity, which is consistent with the total acid concentration of the finished product 6, indicating that the pickled turnips made according to Example 1 have the best effect, quickly reach the acidity of pickled turnips by traditional processes in a short time, and there is no post-acidification phenomenon, and the acidity remains stable.

[0076] Experimental Example 3: Comparison of nitrite content

[0077] As Figure 3 can be seen, no nitrite was detected in the finished products 1 and 3 at the time of fermentation maturity, the nitrite contents of the finished products 2, 4, and 5 are relatively low, and the nitrite content of the finished product 6 is relatively high, approaching the national limit standard (20 mg / kg), with a certain risk of nitrite exceeding the standard. It can be seen that the method used in the present invention can effectively block the formation of nitrite and ensure the edible safety of pickled turnips.

[0078] Experimental Example 4: Comparison of amino acid content

[0079] Essential amino acids refer to amino acids that the human body needs but cannot synthesize on its own or the synthesis rate cannot meet the body's needs. There are a total of 9 essential amino acids, namely lysine, tryptophan, phenylalanine, methionine, threonine, isoleucine, leucine, valine, and histidine, among which histidine is essential for infants. In this test, the contents of 8 amino acids except methionine were determined, and the results are as Figure 4 shown. The amino acid contents of finished products 1-5 are all higher than that of finished product 6, and the content of finished product 1 is the highest.

[0080] Experimental Example 5: Comparison of the number of coliform bacteria

[0081] Coliform bacteria are one of the commonly used indicator bacteria for food contamination both at home and abroad. The detection of coliform bacteria in food indicates a high possibility of being contaminated by pathogenic bacteria (such as Salmonella, Shigella, pathogenic Escherichia coli). If the coliform bacteria in food seriously exceed the standard, it will destroy the nutritional components of the food, making the food lose its edible value; it will also accelerate the spoilage of the food and may endanger human health. The number of coliform bacteria in finished products 1-6 is shown in Table 1. Among them, the number of coliform bacteria in finished product 6 is relatively high, and coliform bacteria also exist in finished product 5, indicating that Leuconostoc mesenteroides has no inhibitory effect on coliform bacteria. No coliform bacteria were detected in 1-4, proving that Weissella confusa has an inhibitory effect on coliform bacteria.

[0082] Table 1 Number of coliform bacteria

[0083] Number Quantity (CFU / g) Finished product 1 ＜10 Finished product 2 ＜10 Finished product 3 ＜10 Finished product 4 ＜10 Finished product 5 80 Finished product 6 350

[0084] Experimental Example 6: Shelf life comparison

[0085] The packaged finished products 1-6 were placed in a constant temperature incubator at 25°C for 30 days, and the swelling of pickled mustard tuber after packaging was observed. The results are shown in Table 2. Finished products 1 and 3 did not show swelling after being placed at 25°C for 30 days, finished product 4 showed swelling after 25 days, finished product 5 showed swelling after 20 days, and finished products 2 and 6 showed swelling only after 10 days. Since Kazachstania exigua has strong gas-producing ability, too high a quantity will cause swelling.

[0086] In summary, a method for lightly fermenting pickled mustard tuber provided by the present invention is used for pickled mustard tuber fermentation, with a fast fermentation speed, moderate acidity and no post-acidification, good quality of the finished product, no risk of nitrite, increased content of essential amino acids for the human body, longer shelf life compared to pickled mustard tuber made by the current traditional process, and high food safety.

[0087] Table 2 Shelf life experiment results

[0088]

[0089] The above are the implementation manners listed in this embodiment. However, this embodiment is not limited to the above optional implementation manners. Those skilled in the art can obtain many other implementation manners by arbitrarily combining the above manners. Anyone can obtain various other forms of implementation manners under the inspiration of this embodiment. The above specific implementation manners should not be construed as limiting the protection scope of this embodiment. The protection scope of this embodiment shall be subject to the definition in the claims, and the specification can be used to interpret the claims.

Claims

1. A method for lightly fermented turnips, characterized in that: It includes the following steps: After primary fermentation with a compound microbial agent, secondary fermentation is carried out at low temperature using Weissella confusa.

2. The method for pickled turnip with shallow fermentation according to claim 1, characterized in that: The compound microbial agent is prepared from Lactobacillus pentosus and Kazachstania exigua with few spores.

3. A method for lightly fermenting turnips according to claim 2, characterized in that: The Lactobacillus pentosus is preserved in the General Microbiology Center of the China Committee for Culture Collection of Microorganisms. The preservation time is July 15, 2016, and the preservation number is CGMCC No: 12793. The address of the preservation unit is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences.

4. A method for lightly fermented turnips according to claim 2, characterized in that: The Kazachstania exigua with few spores is preserved in the General Microbiology Center of the China Committee for Culture Collection of Microorganisms. The preservation time is July 15, 2016, and the preservation number is CGMCC No: 12791. The address of the preservation unit is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences.

5. A method for lightly fermented turnips according to any one of claims 1-4, characterized in that: The Weissella confusa is preserved in the General Microbiology Center of the China Committee for Culture Collection of Microorganisms. The preservation time is November 15, 2021, and the preservation number is CGMCC No: 23918. The address of the preservation unit is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences.

6. A method for lightly fermented turnips according to any one of claims 1-4, characterized in that: The preparation method of the compound bacterium agent is as follows: Mix the bacterial mud of Lactobacillus pentosus and Kazachstania exigua in a ratio of 2-3:1-1.5, and add 5-10% of protective agent milk powder, 3-7% of trehalose, and 0.5-1.5% of glycerol to make a stable bacterium agent, and the viable bacteria count in the bacterium agent is 4×10 9 CFU / g - 7×10 9 CFU / g.

7. A method for lightly fermenting turnips according to claim 3, characterized in that: The method for preparing the bacterial sludge of Lactobacillus pentosus is to inoculate Lactobacillus pentosus into MRS broth medium and culture it at 37 °C for 18 - 24 hours until the cell concentration reaches 10 8 -10 9 CFU / mL, and then centrifuge to obtain the bacterial sludge.

8. A method for lightly fermented turnips according to claim 5, characterized in that: The preparation method of the Weissella confusa bacterium agent is as follows: inoculate Weissella confusa into MRS broth medium to make the cell concentration reach 10 8 -10 9 CFU / mL, collect the cells, wash them, and then make a cell suspension.

9. A method for lightly fermenting turnips according to claim 1, characterized in that: Segmented dehydration is carried out before primary fermentation.

10. A lightly fermented turnip, characterized in that: It is prepared by the method for lightly fermented turnips according to any one of claims 1-9.

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