Lactobacillus plantarum capable of producing exopolysaccharides and application of lactobacillus plantarum in preparation of texture-enhanced fermented vegetables

Abstract

The invention provides lactobacillus plantarum capable of producing exopolysaccharides and application of the lactobacillus plantarum in preparation of texture-enhanced fermented vegetable products, and belongs to the technical field of fermented food processing, and the preservation number of the lactobacillus plantarum is GDMCC NO: 63769. The invention also provides a preparation method of the fermented vegetables. The preparation method comprises the following steps: 1) mixing the pretreated vegetables with the salt brine to obtain a vegetable salt brine mixture; and (2) inoculating lactobacillus plantarum SAAS-B-MRS-20230301-5 into the vegetable salt brine mixture, and carrying out fermentation, so as to obtain the fermented vegetables. The lactobacillus plantarum with high exopolysaccharide yield is used for preparing the fermented vegetables, so that the industrial problem of texture deterioration of quickly fermented vegetable products can be more conveniently and quickly solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fermented food processing, and particularly relates to a Lactiplantibacillus plantarum producing exopolysaccharide and its application in the preparation of texture-enhanced fermented vegetable products. Background Art

[0002] Fermented vegetables are popular cooking condiments and side dishes among consumers. Traditional fermented vegetables are usually prepared by mixing fresh vegetables with brine or old mother brine in a pickling jar, sealing the jar at room temperature, and fermenting for 5 - 14 days through the microorganisms carried by the vegetables themselves or by inoculating with a starter culture to obtain a fermented and mature product with a sour and fragrant taste. The growth and metabolic activities of microorganisms are necessary processes for the formation of the quality of fermented vegetables. While endowing fermented vegetables with good quality, they will also damage the vegetable tissues through mechanical invasion due to the large reproduction of fermenting microorganisms. In addition, the cell wall degrading enzyme systems produced by microorganisms can also degrade the vegetable tissue structure. The physical and chemical effects caused by excessive microorganism reproduction can both damage the vegetable tissue, resulting in a soft texture of the finished product, which greatly affects the sensory acceptance of consumers. Therefore, the development of texture softening control technology suitable for fermented vegetables has important practical significance for the industrial development.

[0003] To solve the problem of soft texture of fermented foods, existing research mainly focuses on strategies such as blanching and sterilizing to inactivate enzymes or using additives such as calcium chloride to strengthen the microstructure of plant tissues. The hot processing of blanching inevitably causes losses of vegetable flavor and nutrients such as probiotics; while the addition of additives goes against the current concept of zero addition and pure natural in the consumer market. In recent years, active substances have gradually been applied to the food field, mainly focusing on the attachment of macromolecular colloids such as polysaccharides and proteins on the plant surface, which can form a natural protective film from a physical perspective and effectively slow down the texture deterioration of vegetables caused by microbial invasion and oxygen contact. However, the addition of exogenous polysaccharides and proteins requires additional costs on the one hand, and on the other hand, it will also complicate the process and may affect the fermentation process and product flavor. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a Lactiplantibacillus plantarum producing exopolysaccharide and its application in the preparation of texture-enhanced fermented vegetable products; by using Lactiplantibacillus plantarum with high exopolysaccharide production to prepare fermented vegetables, the present invention can more conveniently and quickly solve the industrial problem of texture deterioration of fast-fermented vegetable products.

[0005] The present invention provides a Lactiplantibacillus plantarum SAAS-B-MRS-20230301-5, with the preservation number GDMCC NO:63769.

[0006] The present invention provides a Lactobacillus plantarum bacterial agent, including the Lactobacillus plantarum SAAS-B-MRS-20230301-5; the concentration of the Lactobacillus plantarum SAAS-B-MRS-20230301-5 is 10 6 ~10 9 CFU / mL or 10 6 ~10 9 CFU / g.

[0007] The present invention provides the application of the Lactobacillus plantarum SAAS-B-MRS-20230301-5 or the Lactobacillus plantarum bacterial agent in the preparation of texture-strengthened fermented vegetables.

[0008] The present invention provides a method for preparing fermented vegetables, including the following steps:

[0009] 1) Mix the pretreated vegetables with brine to obtain a vegetable-brine mixture;

[0010] 2) After inoculating the Lactobacillus plantarum SAAS-B-MRS-20230301-5 into the vegetable-brine mixture, carry out fermentation to obtain fermented vegetables.

[0011] Preferably, the inoculation amount of the Lactobacillus plantarum SAAS-B-MRS-20230301-5 in step 2) is 0.5-5% (w / v).

[0012] Preferably, the Lactobacillus plantarum SAAS-B-MRS-20230301-5 is inoculated in the form of a bacterial suspension, and the concentration of the inoculated bacterial suspension is 10 6 ~10 9 CFU / mL.

[0013] Preferably, the temperature of the fermentation in step 2) is 25-37°C, the humidity of the fermentation is 36-72%, and the fermentation time is 40-120 h.

[0014] Preferably, the ratio of the pretreated vegetables to brine in step 1) is 1 g:(1-3) ml.

[0015] Preferably, the number of microorganisms in the pretreated vegetables is ≤300 CFU / g.

[0016] Preferably, the total acid of the fermented vegetables is 0.4%-1.0%.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a Lactiplantibacillus plantarum SAAS-B-MRS-20230301-5, which has the property of high extracellular polysaccharide production, and the total polysaccharide content in the prepared fermented vegetables is 33-53 mg / L.

[0018] The present invention utilizes the property of high extracellular polysaccharide production of the Lactiplantibacillus plantarum SAAS-B-MRS-20230301-5 and applies it to the preparation of fermented vegetables; the Lactiplantibacillus plantarum SAAS-B-MRS-20230301-5 of the present invention can form a natural protective film from a physical perspective through the attachment of macromolecular colloid substances - polysaccharides on the plant surface, effectively slowing down the destruction of the vegetable microstructure caused by microbial invasion; in addition, the water retention property of the polysaccharide can inhibit the loss of water in the vegetable tissue, thereby maintaining the rigid structural state of the vegetable tissue and keeping the texture of the fermented vegetables. The polysaccharide produced by the Lactiplantibacillus plantarum SAAS-B-MRS-20230301-5 also has certain antibacterial properties, which can inhibit the growth of spoilage bacteria during storage and extend the shelf life of the fermented vegetables.

[0019] By using the Lactiplantibacillus plantarum with high extracellular polysaccharide production as a starter and applying it to the preparation of fermented vegetables, the present invention can more conveniently and quickly solve the industrial problem of texture deterioration of rapid fermented vegetable products without the need to add additional active substances. Description of the Drawings

[0020] Figure 1 It is the 16S rDNA sequence diagram of the Lactiplantibacillus plantarum SAAS-B-MRS-20230301-5 provided by the present invention;

[0021] Figure 2 It is the comparison result of the total polysaccharide content of the fermented vegetables prepared by different treatment groups in Example 3 of the present invention

[0022] Figure 3 It is the scanning electron microscope comparison diagram of the fermented vegetables prepared by different treatment groups in Example 3 of the present invention;

[0023] Figure 4 It is the comparison diagram of the hardness, crispness and chewiness of the fermented vegetable products obtained by different treatment groups in Example 3 of the present invention.

[0024] Biological Deposit Description

[0025] Lactiplantibacillus plantarum SAAS-B-MRS-20230301-5 was deposited in the Guangdong Provincial Culture Collection of Microorganisms, with the deposit number GDMCC NO: 63769, the deposit date of September 4, 2023, and the deposit address at the 5th Floor, Building 59, No. 100 Compound, Xianlie Middle Road, Guangzhou, Institute of Microbiology, Guangdong Academy of Sciences. Detailed implementation manners

[0026] The present invention provides a Lactiplantibacillus plantarum SAAS-B-MRS-20230301-5, with the deposit number GDMCC NO: 63769. In the present invention, the Lactiplantibacillus plantarum was isolated from the fermented vegetable brine in Chengdu City, Sichuan Province. Through sequencing analysis, its 16S rDNA sequence is as Figure 1 shown. The sequenced sequence was subjected to nucleic acid sequence alignment in NCBI, and the results showed that the nucleic acid sequence similarity with Lactiplantibacillus plantarum was as high as 100%. It was named Lactobacillus plantarum SAAS-B-MRS-20230301-5 and deposited in the Guangdong Provincial Culture Collection of Microorganisms, with the deposit number GDMCC NO: 63769.

[0027] The present invention also provides a Lactiplantibacillus bacterial agent, including the Lactiplantibacillus plantarum SAAS-B-MRS-20230301-5 described above; the concentration of the Lactiplantibacillus plantarum SAAS-B-MRS-20230301-5 is 10 6 ~10 9 CFU / mL or 10 6 ~10 9 CFU / g. The present invention has no special limitation on the cultivation method of the Lactiplantibacillus plantarum SAAS-B-MRS-20230301-5, and the conventional strain cultivation methods in the art can be used. Preferably, the Lactiplantibacillus plantarum SAAS-B-MRS-20230301-5 is subjected to liquid activation culture, preferably using MRS liquid medium. In the present invention, the Lactiplantibacillus bacterial agent is a liquid bacterial agent or a solid bacterial agent.

[0028] The present invention also provides the application of the Lactiplantibacillus plantarum SAAS-B-MRS-20230301-5 or the Lactiplantibacillus bacterial agent described above in the preparation of texture-strengthened fermented vegetables.

[0029] The present invention provides a method for preparing fermented vegetables, comprising the following steps: 1) mixing the pretreated vegetables with salt brine to obtain a vegetable-salt brine mixture; 2) inoculating the vegetable-salt brine mixture with the Lactobacillus plantarum SAAS-B-MRS-20230301-5, and then carrying out fermentation to obtain fermented vegetables.

[0030] In the present invention, the pretreated vegetables are mixed with salt brine to obtain a vegetable-salt brine mixture; the ratio of the pretreated vegetables to the salt brine is preferably 1 g:(1-3) ml, and more preferably 1 g:(1.5-2.5) ml. In the present invention, the number of microorganisms in the pretreated vegetables is preferably ≤300 CFU / g.

[0031] In the present invention, the vegetables are pretreated to obtain pretreated vegetables. The present invention has no special limitation on the pretreatment, and the pretreatment steps of fermented vegetables in the art can be adopted; in the specific implementation process of the present invention, the pretreatment preferably includes the steps of removing impurities, cutting, washing, disinfecting, washing and draining. In the present invention, it is preferred to remove the impurities and inedible parts of the vegetables, and then carry out cutting. The cutting is preferably carried out according to the type of vegetables, and is preferably cut into blocks, strips or other shapes; after cutting, washing is carried out; then disinfection is carried out. The disinfection is preferably carried out by soaking in a hypochlorous acid disinfectant solution. The concentration of hypochlorous acid in the hypochlorous acid disinfectant solution is preferably 80-120 mg / L, and more preferably 100 mg / L; the disinfection time is preferably 2-4 min, more preferably 3 min. The purpose of disinfection is to control the number of microorganisms in the vegetables, and preferably control the number of microorganisms ≤300 CFU / g; in the present invention, after the disinfection, it is preferably rinsed with clean water for 3 min and drained for standby.

[0032] The present invention has no special limitation on the type of the vegetables, and the conventional vegetable types in the art can be adopted; preferably, it includes any one or several of carrots, red-skinned white radishes, white radishes, celery, cowpeas, young gingers, peppers, green vegetables, Chinese onions, garlic, water radishes, beautiful heart radishes, mustards, and onions.

[0033] The present invention has no special limitation on the raw materials and preparation method of the brine, and the raw materials and preparation method of the brine conventional in the field of fermented vegetables can be adopted. In the specific implementation process of the present invention, the raw materials of the brine preferably include star anise, Chinese prickly ash, chili peppers, ginger, table salt, glucose and water; more preferably include 0.5-2% (w / v) star anise, 2-4% (w / v) Chinese prickly ash, 0.5-2% (w / v) chili peppers, 1-2% (w / v) ginger, 2-4% (w / v) table salt, 3-5% (w / v) glucose and the balance of water. In the present invention, the raw materials are preferably mixed, boiled, cooled and filtered to obtain the brine. In the present invention, the boiling time is preferably 30-60 min, more preferably 35-45 min; the filtration is preferably filtration with gauze, and the gauze is preferably 150-300 mesh gauze. In the present invention, the capsaicin content in the brine is preferably 0.5-2.0 mg / L, and the glucosinolate content is preferably 0.1-0.3 μmol / mL.

[0034] After obtaining the brine mixture in the present invention, the obtained vegetable brine mixture is inoculated with the Lactobacillus plantarum SAAS-B-MRS-20230301-5, and fermented to obtain fermented vegetables.

[0035] In the present invention, the inoculation amount of the Lactobacillus plantarum SAAS-B-MRS-20230301-5 is preferably 0.5-5% (w / v), more preferably 1-3% (w / v), and still more preferably 2% (w / v). In the present invention, the Lactobacillus plantarum SAAS-B-MRS-20230301-5 is inoculated in the form of a bacterial suspension, and the concentration of the inoculated bacterial suspension is preferably 10 6 ~10 9 CFU / mL, more preferably 10 7 ~10 8 CFU / mL. In the present invention, the fermentation temperature is preferably 25-37 °C, more preferably 28-32 °C, and most preferably 30 °C; the fermentation humidity is preferably 36-72%, more preferably 40-60%; in the present invention, the fermentation time is preferably 40-120 h, preferably 45-100 h; the fermentation time is preferably determined by the total acid content of the fermented vegetables, and the fermentation ends when the total acid of the fermented vegetables is preferably 0.4%-1.0%, more preferably 0.6-0.9%, and most preferably 0.8%. After the fermentation ends in the present invention, fermented vegetables are obtained; the present invention preferably further includes the process of packaging the fermented vegetables, and the present invention has no special limitation on the packaging, and the conventional packaging methods in the art can be adopted.

[0036] The hardness, crispness, chewiness and microscopic structure characteristics of the fermented vegetables prepared by the present invention are significantly improved compared with conventional fermented vegetables, and the problem of texture deterioration of fermented vegetable products is well solved.

[0037] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0038] The culture media involved in the following embodiments are as follows:

[0039] MRS liquid medium (1L): peptone 10g, beef extract powder 8g, yeast extract powder 4g, glucose 20g, dipotassium hydrogen phosphate 2g, diammonium hydrogen citrate 2g, sodium acetate 5g, magnesium sulfate 0.2g, manganese sulfate 0.04g, Tween-80 1g, add water to a constant volume of 1000 mL, pH value 5.7 ± 0.2.

[0040] MRS solid medium (1L): peptone 10g, beef extract powder 8g, yeast extract powder 4g, glucose 20g, dipotassium hydrogen phosphate 2g, diammonium hydrogen citrate 2g, sodium acetate 5g, magnesium sulfate 0.2g, manganese sulfate 0.04g, Tween-80 1g, agar addition amount is 1.5%, add water to a constant volume of 1000 mL, pH value 5.7 ± 0.2.

[0041] Example 1

[0042] Screening and identification of Lactobacillus plantarum

[0043] The specific steps are as follows:

[0044] Taking the fermented vegetable brine from Chengdu City, Sichuan Province as a sample, taking 5 mL of brine, centrifuging, adding it to 5 mL of PBS (adding 0.05% cysteine), mixing and performing gradient dilution, selecting the gradient dilution solution of 10 -5 ~10 -7 and coating it on the MRS solid medium, and culturing at 37 °C for 48 h. Picking typical colonies into the solid medium for streak purification, placing them in an inverted culture at 37 °C in an incubator for 48 h, picking single colonies and inoculating them into 5 mL of liquid medium, culturing in an incubator at 37 °C for 16 - 18 h, taking 1.5 mL of the bacterial solution and centrifuging at 6000 r / min for 3 min to remove the supernatant, adding 1 mL of 30% sterile glycerol for preservation, and at the same time leaving a portion of 1.5 mL of the bacterial cells centrifuged, removing the supernatant and resuspending with sterile water for strain identification.

[0045] When screening the strains, first observe the single colony drawing phenomenon to initially judge the polysaccharide production performance, then inoculate into the fermented vegetables to observe the viscosity. After initially determining the candidate strains, then measure the polysaccharide content of the culture for precise screening.

[0046] A strain with excellent polysaccharide-producing performance was screened. After sequencing analysis, its 16S rDNA sequence is as Figure 1 shown. The sequenced sequence was subjected to nucleic acid sequence alignment in NCBI, and the result showed that the nucleic acid sequence similarity with Lactobacillus plantarum was as high as 100%. It was named Lactobacillus plantarum SAAS-B-MRS-20230301-5 and deposited in the Guangdong Provincial Culture Collection Center of Microorganisms with the deposit number GDMCC NO: 63769.

[0047] Example 2

[0048] The specific steps for culturing Lactobacillus plantarum SAAS-B-MRS-20230301-5 are as follows:

[0049] Lactobacillus plantarum SAAS-B-MRS-20230301-5 was inoculated into MRS liquid medium and cultured at 37 °C for 16 h. Then, the bacterial liquid was aspirated and transferred into fresh MRS liquid medium at an inoculation amount of 2% (v / v). After culturing under the same conditions for 12 h, the bacterial cells were centrifuged at 8000 r / min for 15 min, washed with 0.9% physiological saline (containing cysteine hydrochloride at a concentration of 0.4 g / L), centrifuged again at 8000 r / min for 10 min to collect the bacterial cells, resuspended with 30% glycerol solution, and a resuspension was prepared and stored at -80 °C for later use.

[0050] Example 3

[0051] Using Lactobacillus plantarum SAAS-B-MRS-20230301-5 to prepare texture-strengthened fermented vegetables

[0052] The specific steps are as follows:

[0053] (1) Vegetable pretreatment: Remove impurities and inedible parts from red-skinned white radishes, then cut the vegetables into pieces, strips or other shapes, wash them, and set aside. The vegetables were disinfected with a disinfectant that can form hypochlorous acid for 3 min, and the microbial count of the vegetables was controlled ≤ 300 CFU / g; then rinsed with clean water for 3 min and drained for later use;

[0054] (2) Preparation of brine: Weigh 1% (w / v) star anise, 2% (w / v) Chinese prickly ash, 1% (w / v) chili peppers, 2% (w / v) ginger, 3% (w / v) table salt, and 4% (w / v) glucose, add purified water to dissolve them fully, heat and boil for 40 min, cool the boiled brine to room temperature, and filter it through a 300-mesh gauze to obtain the brine.

[0055] (3) Preparation of vegetable-brine mixture: Mix the pretreated vegetables obtained in step (1) with the brine obtained in step (2) at a ratio of 1:2 (w / v) to obtain the vegetable-brine mixture.

[0056] (4) Preparation of the working fermentation broth of Lactobacillus plantarum SAAS-B-MRS-20230301-5: Pick Lactobacillus plantarum SAAS-B-MRS-20230301-5 and inoculate it into MRS liquid medium. After culturing at 37 °C for 24 h, inoculate it again into MRS liquid medium at an inoculation amount of 2% and culture at 37 °C for 24 h to obtain a bacterial solution. Centrifuge to obtain a bacterial cell precipitate, wash it twice with 0.9% sterile physiological saline, and then redissolve it in sterile water to obtain a working fermentation broth with a concentration of 1×10 7 CFU / mL.

[0057] (5) Fermentation culture: Add the working fermentation broth prepared in step (4) to the vegetable-brine mixture obtained in step (3) at a ratio of 2% (w / v), control the temperature at 30 °C, and ferment for 2 days until the total acid is 0.8% to obtain texture-strengthened fermented vegetables as the experimental group.

[0058] Blank control group: Do not inoculate additional strains

[0059] Conventional inoculant group: Replace the strain in the experimental group with SAAS-B-MRS-20230301-11 (SAAS-B-MRS-20230301-11 is another polysaccharide-producing strain obtained during the screening of Lactobacillus plantarum SAAS-B-MRS-20230301-5).

[0060] Measure the total polysaccharide content, vegetable texture profile (hardness, crispness, chewiness), and microscopic structure characteristics of the experimental group, blank control group, and conventional inoculant group respectively. The specific measurement methods are as follows:

[0061] (1) Determination of total polysaccharide content: The texture-strengthened fermented vegetables were dried and ground into powder. Take 2 g and place it in a 250 mL beaker, add 100 mL of water, heat it in a water bath, boil for 1 hour, cool to room temperature, then make up the water to the scale of 100 mL, mix well and filter to obtain the filtrate. Precipitate polysaccharide: Accurately pipette 5.0 mL of the above filtrate into a 50 mL centrifuge tube, add 20 mL of 80% ethanol solution, mix well, let it stand in a refrigerator at 4°C for 1 hour, centrifuge at 4000 r / min for 10 min, and discard the supernatant. Dissolve the residue in water and make up the volume to 25 mL to obtain the extracted total polysaccharide; Determination of total polysaccharide content: Take 2 mL of the extracted total polysaccharide solution, add 1 mL of 5% phenol reagent, quickly add 5 mL of concentrated sulfuric acid, shake well, heat in a water bath for 15 min, cool, and measure the absorbance at 490 nm with a UV spectrophotometer. Calculate the content of the extracted total polysaccharide using glucose as the standard substance.

[0062] (2) Determination of texture profile (hardness, crispness, chewiness): Using a texture analyzer, select the P36 probe, in the TPA mode, the pre-test, test, and post-test speeds are 1 mm / s, 1 mm / s, and 2 mm / s respectively, and the compression ratio is 50%. Record the hardness, crispness, and chewiness data feedback by the instrument.

[0063] (3) Determination of microscopic structure characteristics: Sample pretreatment: Cut the sample tissue into 4 - 5 small pieces (about 0.5 cm × 0.5 cm × 0.1 cm), then fix it with 4% glutaraldehyde for 24 h, and then wash the sample with phosphate buffer solution (pH 7.2) for 3 h, 10 min each time. Then dehydrate the sample with 25%, 50%, 75%, 95%, and 100% alcohol, dehydrate for 10 min at each gradient, and finally store it in 100% absolute ethanol and place it at 4°C for standby; Electron microscopy observation: Use liquid CO2 critical drying, coat the dried sample with gold particles, and then observe the sample with a scanning electron microscope under an electron acceleration voltage of 15 kV and high vacuum conditions.

[0064] The results of the total polysaccharide content are as Figure 2 shown. After fermentation at 30°C for 48 h, the total polysaccharide content of the blank control group was 7.96 mg / L; the total polysaccharide content of the experimental group was 35.62 mg / L; the total polysaccharide content of the conventional bacterial agent group was 11.39 mg / L.

[0065] The microscopic structure characteristics are as Figure 3 shown. In the experimental group, the pore sizes were relatively consistent, and the pore distribution was relatively uniform, without obvious aggregation or blank areas, the surface was relatively smooth, and the pore edges were relatively round; while in the conventional bacterial agent group, the pore sizes and shapes varied greatly, the pore distribution was uneven, and the surface roughness was higher, and the pore edges were sharper, showing more cracks and irregularities. Generally speaking, the experimental group had a more uniform and smooth pore structure, while the conventional bacterial agent group had a higher roughness and irregularity.

[0066] The results of the hardness, crispness, and chewiness of vegetables are as Figure 4 shown. The hardness, crispness, and chewiness of the blank control group were 11234 g, 11991 g, and 564 g respectively. After fermentation at 30 °C for 48 h, the hardness, crispness, and chewiness of the experimental group were 12951 g, 14506 g, and 726 g; the hardness, crispness, and chewiness of the conventional inoculant group were 11130 g, 11282 g, and 548 g.

[0067] The above results indicate that the exopolysaccharide of Lactobacillus plantarum SAAS-B-MRS-20230301-5 provided by the present invention has a protective effect on fresh vegetables under fermentation conditions and can be applied as a potential method for enhancing the quality of fermented vegetables.

[0068] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A Lactiplantibacillus plantarum SAAS-B-MRS-20230301-5, characterized in that, The preservation number is GDMCC NO: 63769.

2. A Lactobacillus plantarum bacterial agent, characterized in that, Including Lactobacillus plantarum SAAS-B-MRS-20230301-5 described in claim 1; the viable cell concentration of Lactobacillus plantarum SAAS-B-MRS-20230301-5 is 10 6 ~10 9 CFU / mL or 10 6 ~10 9 CFU / g.

3. Use of Lactobacillus plantarum SAAS-B-MRS-20230301-5 according to claim 1 or the Lactobacillus plantarum bacterial agent according to claim 2 in the preparation of texture-strengthened fermented vegetables.

4. A method for preparing fermented vegetables, characterized in that, Comprising the following steps: 1) Mixing the pretreated vegetables with brine to obtain a vegetable-brine mixture; 2) Inoculating the vegetable-brine mixture with Lactobacillus plantarum SAAS-B-MRS-20230301-5 according to claim 1 and then fermenting to obtain fermented vegetables.

5. The preparation method according to claim 4, characterized in that, The inoculation amount of Lactobacillus plantarum SAAS-B-MRS-20230301-5 in step 2) is 0.5-5% (w / v).

6. The preparation method according to claim 4 or 5, characterized in that, The Lactobacillus plantarum SAAS-B-MRS-20230301-5 is inoculated in the form of a bacterial suspension, and the concentration of the inoculated bacterial suspension is 10 6 ~10 9 CFU / mL.

7. The preparation method according to claim 4, characterized in that, The temperature of the fermentation in step 2) is 25-37 °C, the humidity of the fermentation is 36-72%, and the fermentation time is 40-120 h.

8. The preparation method according to claim 4, characterized in that, The ratio of the pretreated vegetables to brine in step 1) is 1 g: (1-3) ml.

9. The preparation method according to claim 4 or 8, characterized in that, The number of microorganisms in the pretreated vegetables is ≤ 300 CFU / g.

10. The preparation method according to claim 4, characterized in that, The total acid of the fermented vegetables is 0.4%-1.0%.

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