Composite probiotic fermentation inoculant

Abstract

The invention discloses a composite probiotic fermentation inoculant, and belongs to the technical field of fermentation. The lactobacillus plantarum and the lactobacillus brevis are mixed to prepare the leavening agent, the leavening agent and the barley wort are used for fermentation of the pickled Chinese cabbages together, and the obtained pickled Chinese cabbage product is uniform and bright in color, glossy and free of white webs on the surface; the fragrance is rich, pleasant and free of abnormal smell; the taste is crisp and tender, free of looseness and erosion, sour, fresh, pure and delicious. After the raw material Chinese cabbage is inoculated with the leavening agent and fermented at 20 DEG C for 10 days, the total acid content of the pickled Chinese cabbage can reach 3 g / kg or above, the nitrite content is reduced to 0.2 mg / kg or below, at the moment, the pickled Chinese cabbage is appropriate in acidity and low in nitrite, the pickled Chinese cabbage is superior to pickled Chinese cabbages obtained through natural fermentation and pickled Chinese cabbages obtained through single strain fermentation, the fermentation speed is increased, and the pickled Chinese cabbage quality is improved; the method is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of fermentation technology, specifically to a compound probiotic fermentation agent. Background Technology

[0002] Traditional sauerkraut uses Chinese cabbage and radish as its main ingredients, developing its unique sour taste and flavor through natural fermentation. During its growth, Chinese cabbage absorbs large amounts of nitrogen fertilizer or nitrogen from the soil. Microorganisms on the surface of the cabbage or in the fermentation environment convert this nitrogen into nitrates. During the pickling process, these nitrates are further converted into nitrites by microorganisms, making the accumulation of nitrites in sauerkraut an unavoidable problem. Traditional sauerkraut fermentation generally relies on a natural process, which leads to instability in flavor, fermentation time, and the content of the harmful substance nitrite.

[0003] With the improvement of living standards and the modernization of the food industry, traditional home-style fermentation of sauerkraut in jars is gradually being replaced by industrial production. In sauerkraut production, the trend is shifting from natural fermentation to direct inoculation with microbial agents. The application of specialized microbial agents allows for better control of the microbial community, improving fermentation efficiency and product quality. Developing specialized microbial agents suitable for sauerkraut has become crucial for improving sauerkraut production processes. Summary of the Invention

[0004] In view of the above-mentioned prior art, the purpose of this invention is to provide a compound probiotic fermentation agent.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a compound probiotic fermentation agent comprising components with the following live bacteria ratio: *Lactobacillus plantarum* : *Lactobacillus brevis* = (0.5-5):(0.5-5); The aforementioned Lactobacillus plantarum ( Lactobacillus plantarum The accession number is CCTCC AB 2022276; the *Lactobacillus brevis* (… Lactobacillus brevis The accession number is CCTCC DB 20081547.

[0006] Furthermore, the number of viable bacteria in the fermentation agent shall not be less than 1×10⁻⁶. 6 CFU / g.

[0007] A second aspect of the present invention provides a method for fermenting sauerkraut, comprising the following steps: After pre-treating the Chinese cabbage, barley malt juice, salt water, and the aforementioned compound probiotic fermentation agent are added, and the finished sauerkraut is obtained after sealed fermentation. The preparation method of barley malt extract is as follows: Take barley that has sprouted within 10 days, mix it with water at a mass ratio of 1:(5-10), and then pulp it. The filtrate obtained after filtration is barley malt juice.

[0008] Further, the pretreatment process is as follows: Select fresh Chinese cabbage with bright color, intact leaves, and no pests or diseases. Clean the outer leaves, break the cabbage into several pieces along the stem, wash it with clean water, drain the surface water, and then cut the cabbage into even thin strips of 0.5-5cm.

[0009] Furthermore, take finely shredded cabbage from different parts, mix it with barley malt juice and NaCl brine until it covers the cabbage by 5-20 cm, wherein the mass ratio of the finely shredded cabbage, barley malt juice and brine is (2-10):(0.5-5):(2-10).

[0010] Furthermore, the mass fraction of the NaCl brine is (0.5-5) wt%.

[0011] Furthermore, the mass ratio of finely shredded cabbage to compound probiotic fermentation agent is 5 kg: (0.5-4) g.

[0012] Furthermore, the fermentation temperature is 7-30℃, the fermentation process is anaerobic, and the fermentation time is 5-30 days.

[0013] A third aspect of the present invention provides the application of the aforementioned compound probiotic fermentation agent in improving the quality of sauerkraut. Furthermore, the improvement of sauerkraut quality includes at least one of the following (i)-(iii): (i) Improve the sensory evaluation score of pickled cabbage; (ii) Increase the total acid content of pickled vegetables; (iii) Reduce the nitrite content of pickled vegetables.

[0014] The beneficial effects of this invention are: This invention prepares a starter culture by mixing *Lactobacillus plantarum* and *Lactobacillus brevis*, which is then used together with barley malt extract for sauerkraut fermentation. The resulting sauerkraut product has a uniform, bright, and glossy color, without any white residue on the surface; it has a rich, pleasant aroma without any abnormal odor; and it has a crisp and tender texture, without being loose or mushy, with a pure, fresh, and delicious flavor. After inoculating the raw cabbage with the starter culture and fermenting at 20°C, the total acid content of the sauerkraut can reach over 3g / kg, while the nitrite content can be reduced to below 0.2 mg / kg. At this point, the sauerkraut has suitable acidity and low nitrite content, superior to sauerkraut obtained through natural fermentation or fermentation using a single strain of bacteria. This invention improves both the fermentation speed and the quality of the sauerkraut, making it suitable for industrial production. Detailed Implementation

[0015] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0016] To enable those skilled in the art to better understand the technical solution of this application, the technical solution of this application will be described in detail below with reference to specific embodiments.

[0017] The test materials used in the embodiments of the present invention, unless otherwise specified, are all conventional test materials in the art and can be purchased through commercial channels.

[0018] The bacteria used in this invention are as follows: Lactobacillus plantarum ( Lactobacillus plantarum ), with accession number CCTCC AB 2022276; Lactobacillus brevis ( Lactobacillus brevis ), with accession number CCTCC DB 20081547; Example 1: Making Sauerkraut Preparation of barley malt extract Take 1 kg of barley that has sprouted within 3 days, add 8 kg of water, blend into a pulp, pass through four layers of gauze, collect the filtrate, sterilize at 121℃ for 20 minutes to obtain barley malt juice.

[0019] Fermentation of sauerkraut Select fresh Chinese cabbages with bright color, intact leaves, and no pests or diseases. After a series of pretreatments (trimming, washing, draining, and cutting), they are bottled, infused with brine, sealed, and fermented to obtain the finished product. The detailed process is as follows: Select fresh Chinese cabbages, clean the outer leaves, break the cabbage into several pieces along the stem, wash them thoroughly with clean water, drain the surface water, and cut the cabbage into uniform thin strips of 0.5-1 cm. Ensure that the cabbage strips from different parts are evenly mixed. Use glass fermentation containers, and fill each bottle with 5 kg of the mixed cabbage strips. Add 0.8 kg of barley malt juice, then add 5 kg of 1.5% NaCl brine until the bottle is full (10 cm above the cabbage). Inoculate the fermentation agent with 2 g and mix well. Finally, a closed fermentation system is formed. Fermentation is carried out at 20℃ under anaerobic conditions.

[0020] The starter culture used was Lactobacillus plantarum and Lactobacillus brevis, with a viable count of 1×10⁻⁶. 7 CFU / g, with a live count ratio of Lactobacillus plantarum to Lactobacillus brevis of 1:1.

[0021] Example 2: Making Sauerkraut Fresh Chinese cabbage with bright color, intact leaves, and no pests or diseases was selected. After a series of pretreatments (trimming, washing, draining, and cutting), it was bottled, infused with brine, sealed, and fermented to obtain the finished product. The detailed process is as follows: Fresh Chinese cabbage was selected, and the outer leaves were cleaned. The cabbage was broken into several pieces along the stem, washed thoroughly with clean water, drained, and then cut into uniform thin strips of 0.5–1 cm. The cabbage strips from different parts were ensured to be evenly mixed. Fermentation containers made of glass were used, with 5 kg of the mixed cabbage strips placed in each bottle. 0.8 kg of the barley malt juice prepared in Example 1 was added, followed by 5 kg of 1.5% NaCl brine until the bottle was full (10 cm above the cabbage). 2 g of starter culture was inoculated into the fermentation tank and mixed evenly. A closed fermentation system was then formed. Anaerobic fermentation was carried out at 20°C.

[0022] The starter culture used was Lactobacillus plantarum and Lactobacillus brevis, with a viable count of 1×10⁻⁶. 7 CFU / g, with a live count ratio of Lactobacillus plantarum to Lactobacillus brevis of 1:2.

[0023] Example 3: Making Sauerkraut Fresh Chinese cabbage with bright color, intact leaves, and no pests or diseases was selected. After a series of pretreatments (trimming, washing, draining, and cutting), it was bottled, infused with brine, sealed, and fermented to obtain the finished product. The detailed process is as follows: Fresh Chinese cabbage was selected, and the outer leaves were cleaned. The cabbage was broken into several pieces along the stem, washed thoroughly with clean water, drained, and then cut into uniform thin strips of 0.5–1 cm. The cabbage strips from different parts were ensured to be evenly mixed. Fermentation containers made of glass were used, with 5 kg of the mixed cabbage strips placed in each bottle. 0.8 kg of the barley malt juice prepared in Example 1 was added, followed by 5 kg of 1.5% NaCl brine until the bottle was full (10 cm above the cabbage). 2 g of starter culture was inoculated into the fermentation tank and mixed evenly. A closed fermentation system was then formed. Anaerobic fermentation was carried out at 20°C.

[0024] The starter culture used was Lactobacillus plantarum and Lactobacillus brevis, with a viable count of 1×10⁻⁶. 7 CFU / g, with a live count ratio of Lactobacillus plantarum to Lactobacillus brevis of 2:1.

[0025] Comparative Example 1 The difference between this comparative example and Example 1 is that this comparative example does not use external feeding for fermentation, but uses natural (non-inoculated) fermentation, and does not use barley malt extract. The specific steps are as follows: Select fresh Chinese cabbages with bright color, intact leaves, and no pests or diseases. After a series of pretreatments (trimming, washing, draining, and cutting), they are bottled, infused with brine, sealed, and fermented to obtain the finished product. The detailed process is as follows: Select fresh Chinese cabbages, clean the outer leaves, break the cabbage into several pieces along the stem, wash them thoroughly with clean water, drain the surface water, and cut the cabbage into uniform thin strips of 0.5-1 cm. Ensure that the cabbage strips from different parts are evenly mixed. Use glass fermentation containers, divide each container into 5 kg of the mixed cabbage strips, and pour in 5.8 kg of 1.5% NaCl brine until the container is full (10 cm above the cabbage). Finally, a closed fermentation system is formed, and anaerobic fermentation is carried out at 20℃.

[0026] Comparative Example 2 The difference between this comparative example and Example 1 is that the starter used in this comparative example contains only Lactobacillus plantarum and does not use barley malt extract. The specific steps are as follows: Select fresh Chinese cabbages with bright color, intact leaves, and no pests or diseases. After a series of pretreatments (trimming, washing, draining, and cutting), they are bottled, infused with brine, sealed, and fermented to obtain the finished product. The detailed process is as follows: Select fresh Chinese cabbages, clean the outer leaves, break the cabbage into several pieces along the stem, wash them thoroughly with clean water, drain the surface water, and cut the cabbage into uniform thin strips of 0.5-1 cm. Ensure that the cabbage strips from different parts are evenly mixed. Use glass fermentation containers, divide each container into 5 kg of the mixed cabbage strips, and pour in 5.8 kg of 1.5% NaCl brine until the container is full (10 cm above the cabbage). Finally, a closed fermentation system is formed, and anaerobic fermentation is carried out at 20℃.

[0027] Comparative Example 3 The difference between this comparative example and Example 1 is that the starter used in this comparative example contains only Lactobacillus brevis and does not use barley malt extract. The specific steps are as follows:

[0028] Select fresh Chinese cabbages with bright color, intact leaves, and no pests or diseases. After a series of pretreatments (trimming, washing, draining, and cutting), they are bottled, infused with brine, sealed, and fermented to obtain the finished product. The detailed process is as follows: Select fresh Chinese cabbages, clean the outer leaves, break the cabbage into several pieces along the stem, wash them thoroughly with clean water, drain the surface water, and cut the cabbage into uniform thin strips of 0.5-1 cm. Ensure that the cabbage strips from different parts are evenly mixed. Use glass fermentation containers, divide each container into 5 kg of the mixed cabbage strips, and pour in 5.8 kg of 1.5% NaCl brine until the container is full (10 cm above the cabbage). Finally, a closed fermentation system is formed, and anaerobic fermentation is carried out at 20℃.

[0029] Comparative Example 4 The difference between this comparative example and Example 1 is that this comparative example does not use external feeding for fermentation, but uses natural (non-inoculated) fermentation. The specific steps are as follows: Select fresh Chinese cabbages with bright color, intact leaves, and no pests or diseases. After a series of pretreatments (trimming, washing, draining, and cutting), they are bottled, infused with brine, sealed, and fermented to obtain the finished product. The detailed process is as follows: Select fresh Chinese cabbages, clean the outer leaves, break the cabbage into several pieces along the stem, wash them thoroughly with clean water, drain the surface water, and cut the cabbage into uniform thin strips of 0.5-1 cm. Ensure that the cabbage strips from different parts are evenly mixed. Use glass fermentation containers, and divide each container into 5 kg of the mixed cabbage strips. Add 0.8 kg of barley malt juice, and then add 5 kg of 1.5% NaCl brine until the container is full (10 cm above the cabbage). Finally, a closed fermentation system is formed, and anaerobic fermentation is carried out at 20℃.

[0030] Test case After 10 days of fermentation, the fermented products of Example 1 and Comparative Examples 1-4 were tested. The test items were sensory evaluation, total acid content and nitrite content in the sauerkraut.

[0031] 1. Sensory Evaluation: The sauerkraut products were evaluated based on four aspects: color and appearance, aroma, texture, and taste. The sensory evaluation team consisted of 25 food professionals familiar with food descriptive terms and evaluation standards. The scoring criteria were based on the national standard "GB 2714-2015 National Food Standard for Pickled Vegetables," as shown in Table 1. The final score was the sum of all scores (100 points).

[0032] Table 1 Sensory Evaluation Criteria 2. Determination of Total Acid Content in Sauerkraut: Grind 10.0g of sauerkraut into a paste, add purified water to a final volume of 100mL, and filter the mixture. Collect 40mL of the filtrate and titrate with 0.1mol / L NaOH, adding 2 drops of 10g / L phenolphthalein as an indicator, until the solution turns a faint pink. Record the volume of 0.1mol / L NaOH solution consumed as V1, in milliliters (mL). Blank: Replace the sample solution with the same volume of purified water, and record the volume of 0.1mol / L NaOH solution consumed as V2, in milliliters (mL). The formula for calculating the total acid content is as follows: X=[c×(V1-V2)]×k×F / m In the formula: X: Total acid content in the sample, in grams per kilogram (g / kg); c: Concentration of the sodium hydroxide standard titration solution, in moles per liter (mol / L); k: Conversion factor for acids (calculated for lactic acid, 0.090); F: Dilution factor of the solution; m: Mass of the sample, in grams (g); 3. Determination of nitrite content in pickled vegetables: The nitrite content was determined using a food nitrite content detection kit (Solepro, Beijing, China), and the unit is milligrams per kilogram (mg / kg).

[0033] The sensory evaluation results are shown in Table 2, and the physicochemical index determination results are shown in Table 3.

[0034] Table 2 Sensory Evaluation Results Based on sensory evaluation and the results in Table 2, the pickled cabbage leaves of Example 1 were light yellow, the stems were transparent white, the color was uniform, the acidity was moderate, and the taste was good, which met the industry standards. The pickled cabbage product of Example 1 scored the highest, which was better than the pickled cabbage of Comparative Example 1 and Comparative Example 4 obtained by natural fermentation, and the pickled cabbage of Comparative Example 2-Comparative Example 3 obtained by fermentation using a single strain of bacteria.

[0035] Table 3 Results of Physicochemical Indicators According to the results in Table 3, fermentation with the starter culture at 20℃ for 10 days can increase the total acid content of sauerkraut to over 3 g / kg and reduce the nitrite content to below 0.2 mg / kg. At this point, the sauerkraut has suitable acidity and low nitrite content, making it edible. This indicates that inoculation with the starter culture can improve the fermentation speed and the quality of sauerkraut, which is superior to the sauerkraut obtained by natural fermentation in Comparative Examples 1 and 4, as well as the sauerkraut obtained by fermentation using a single strain of bacteria in Comparative Examples 2 and 3.

[0036] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A compound probiotic fermentation agent, characterized in that, The component includes the following live bacteria ratio: Lactobacillus plantarum: Lactobacillus brevis = (0.5-5):(0.5-5); The aforementioned Lactobacillus plantarum ( Lactobacillus plantarum The accession number is CCTCC AB 2022276; the *Lactobacillus brevis* (… Lactobacillus brevis The accession number is CCTCC DB 20081547.

2. The compound probiotic fermentation agent according to claim 1, characterized in that, The number of viable bacteria in the starter culture shall not be less than 1×10⁻⁶ 6 CFU / g.

3. A method for fermenting sauerkraut, characterized in that, Includes the following steps: After pre-treating Chinese cabbage, barley malt juice, salt water, and the compound probiotic fermentation agent as described in claim 1 or 2 are added, and the finished sauerkraut is obtained after closed fermentation. The preparation method of barley malt extract is as follows: Take barley that has sprouted within 10 days, mix it with water at a mass ratio of 1:(5-10), and then pulp it. The filtrate obtained after filtration is barley malt juice.

4. The method for fermenting sauerkraut according to claim 3, characterized in that, The pretreatment process is as follows: Select fresh Chinese cabbage with bright color, intact leaves and no pests or diseases. Clean the outer leaves, break the cabbage into several pieces along the stem, wash it with clean water, drain the surface water, and then cut the cabbage into even thin strips of 0.5-5cm.

5. The method for fermenting sauerkraut according to claim 4, characterized in that, Take finely shredded cabbage from different parts, mix it with barley malt juice and NaCl salt water until the cabbage is submerged by 5-20 cm. The mass ratio of the shredded cabbage, barley malt juice and salt water is (2-10):(0.5-5):(2-10).

6. The method for fermenting sauerkraut according to claim 5, characterized in that, The mass fraction of the NaCl brine is (0.5-5) wt%.

7. The method for fermenting sauerkraut according to claim 5, characterized in that, The mass ratio of finely shredded cabbage to compound probiotic fermentation agent is 5 kg: (0.5-4) g.

8. The method for fermenting sauerkraut according to claim 5, characterized in that, The fermentation temperature is 7-30℃, the fermentation process is anaerobic, and the fermentation time is 5-30 days.

9. The application of the compound probiotic fermentation agent according to claim 1 or 2 in improving the quality of sauerkraut.

10. The application according to claim 9, characterized in that, The improvement of sauerkraut quality includes at least one of the following (i)-(iii): (i) Improve the sensory evaluation score of pickled cabbage; (ii) Increase the total acid content of pickled vegetables; (iii) Reduce the nitrite content of pickled vegetables.

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