Microbial agents for fermenting low-nitrite and low-sodium sauerkraut and methods for preparing sauerkraut.
By using a compound inoculant of Leuconostoc mesenteroides and Lactobacillus plantarum to ferment sauerkraut, the problem of high nitrite content in traditional sauerkraut has been solved, achieving a low nitrite and low salt fermentation effect, thus improving the safety and taste of the product.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JILIN AGRICULTURAL UNIV
- Filing Date
- 2026-03-26
- Publication Date
- 2026-06-26
AI Technical Summary
Traditional pickled vegetables have high nitrite content during fermentation, which leads to unstable product quality, affects health, and restricts industrial development.
Fermentation was carried out using a compound microbial agent of Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705. By controlling the fermentation conditions and adding appropriate amounts of salt and sugar, the nitrite content was reduced and the crisp texture was maintained.
It effectively degrades nitrite content to ≤4 mg/kg, with a nitrite degradation rate of 63.8% after fermentation. It also achieves low-salt fermentation, improving product safety and sensory quality.
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Figure CN122278660A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of microbial fermentation and food processing technology, specifically, it relates to a microbial agent for fermenting low-nitrite and low-sodium sauerkraut and a method for preparing sauerkraut. Background Technology
[0002] Northeastern sauerkraut is a unique pickled food from northern China. It is made from fresh cabbage fermented with lactic acid bacteria in the presence of salt. Northeastern sauerkraut is characterized by its crisp, sour taste, bright color, pure aroma, and ability to sober one up and cut through greasiness. Rich in organic acids, probiotics, and other bioactive components, it is a healthy food beneficial to the human body. Sauerkraut offers numerous health benefits, such as maintaining digestive health, lowering cholesterol, anti-cancer properties, antioxidant effects, and immune regulation, making it popular among consumers. However, the natural fermentation process of sauerkraut is difficult to control. During pickling, bacteria such as Enterobacteriaceae and Flavobacterium on the vegetable raw materials and fermentation containers can secrete nitrate reductase, reducing nitrates in the vegetables to nitrites. This can easily lead to excessive nitrite levels, resulting in unstable product quality and potentially harming human health. These issues have hindered the large-scale production and industrialization of Northeastern sauerkraut, making it difficult for fermented vegetable foods in my country to gain widespread public acceptance.
[0003] Lactic acid bacteria (LAB) are a type of Gram-positive bacteria characterized by lactic acid as their main metabolic product. The lactic acid produced lowers the pH of fermented products, inhibits harmful microorganisms, and thus extends shelf life. Furthermore, it reduces nitrite residue by promoting nitrite reduction. To compensate for the shortcomings of natural fermentation, the use of lactic acid bacteria to ferment and prepare sauerkraut has become an important technical method.
[0004] Therefore, screening high-quality lactic acid bacteria and developing sauerkraut with simple production processes, low sodium chloride and nitrite content, and good sensory quality is particularly important for promoting the development of the traditional Northeast sauerkraut industry. Summary of the Invention
[0005] The purpose of this invention is to solve the problem of high nitrite content in traditional sauerkraut, and to provide a microbial agent for fermenting low-nitrite and low-sodium sauerkraut and a method for preparing sauerkraut. Using the microbial agent of this invention, low-salt fermentation can be achieved, and the sauerkraut prepared has a simple process, low nitrite content, and crisp taste.
[0006] The microbial agents used for fermenting low-nitrite and low-sodium sauerkraut are Leuconostoc mesenteroides LM701 with accession number CCTCC NO: M 20252807 and / or Lactobacillus plantarum LP705 with accession number CCTCC NO: M 20252808;
[0007] The ratio of Leuconostoc mesenteroides LM701 to Lactobacillus plantarum LP705 is 1~3:3~1.
[0008] The ratio is 1:2.
[0009] Application of microbial agents used for fermenting low-nitrite, low-sodium sauerkraut in the degradation of nitrite.
[0010] A method for producing low-nitrite, low-sodium sauerkraut includes:
[0011] 1) Remove the outer leaves of the Chinese cabbage and blanch it evenly in boiling water; then place it in a container;
[0012] 2) Add 2%~6% of the microbial agent for fermenting low-nitrite sauerkraut as described in claim 1, 1%~5% salt and 0.5%~4% sugar.
[0013] 3) Sealed fermentation.
[0014] After blanching, remove the wilted leaves and roots from the Chinese cabbage and cut it into strips about 3-5 mm long and 1-2 mm wide.
[0015] The salt content is 1%, and the sugar content is 0.5%.
[0016] The fermentation process was carried out at room temperature for 5 days.
[0017] The bacterial agent is prepared by the following method: Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705 are inoculated into MRS liquid medium and cultured for 24 h. After centrifugation at 6500 r / min for 10 minutes, the supernatant is discarded and the precipitate is retained. The precipitate is resuspended with sterile PBS and washed twice. The mixture is then used to prepare a bacterial suspension.
[0018] The beneficial effects of this invention are as follows:
[0019] 1. The Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705 screened in this invention have significant inhibitory effects on the production of Escherichia coli, Staphylococcus aureus and Salmonella, which can effectively inhibit the growth of harmful bacteria in sauerkraut fermentation and ensure the fermentation effect.
[0020] 2. The *Leuconostoc mesenteroides* LM701 and *Lactobacillus plantarum* LP705 screened in this invention both have good nitrite degradation capabilities. The nitrite content in the prepared sauerkraut is ≤4 mg / kg, and the nitrite degradation rate of the sauerkraut after fermentation reaches over 63.8%. The nitrite content in the 1% salt concentration group is 2.69 mg / kg. Attached Figure Description
[0021] Figure 1 Microscopic images of Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705.
[0022] Figure 2 Phylogenetic tree diagram of Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705.
[0023] Figure 3 Acid resistance results of Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705.
[0024] Figure 4 Salt tolerance results of Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705.
[0025] Figure 5 Figure showing the nitrite tolerance of Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705.
[0026] Figure 6 The antibacterial effect of Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705.
[0027] Figure 7 Figures showing the nitrite content and pH value of fermented sauerkraut with different inoculation ratios, and sensory evaluation results.
[0028] Figure 8 The results of nitrite content and pH value and sensory evaluation of fermented sauerkraut with different inoculation amounts are shown in the figure.
[0029] Figure 9 Figures showing the nitrite content and pH value of fermented sauerkraut at different salt concentrations, and sensory evaluation results.
[0030] Figure 10 Figures showing the nitrite content and pH value of fermented sauerkraut with different sugar concentrations, and sensory evaluation results. Detailed Implementation
[0031] Example 1: Isolation, screening, identification, and fermentation characteristics analysis of strains
[0032] 1. Initial screening
[0033] Weigh 1 g of naturally fermented sauerkraut sample from Northeast China and add 9 mL of sterile water to make 10 -1 Diluent, then serially diluted to 10.-2 ~10 -6 100 μL of each concentration dilution was spread onto MRS solid medium containing 2% calcium carbonate, with three replicates for each concentration, and incubated at 37°C for 48 h. After 48 h, colonies with obvious calcium dissolution zones and lactic acid bacteria morphology were picked for microscopic examination. Strains conforming to lactic acid bacteria morphology were transferred to fresh, clean MRS solid medium using the streak plate method and incubated at 37°C for 48 h. The above process was repeated 3-4 times until the colonies on the streak plates had uniform morphology, thus completing the strain isolation.
[0034] 2. Secondary screening
[0035] (1) Determination of nitrite degradation capacity
[0036] The initially screened strains were inoculated into MRS liquid medium and subcultured three times for activation. The activated strains were then inoculated into nitrite medium at a 2% inoculum and incubated at 37°C for 24 h, and the residual nitrite in the medium was measured.
[0037] Nitrite medium: Prepare a 100 mg / L sodium nitrite solution, filter it through a 2.5 μm filter to sterilize it, and add it to sterilized MRS medium at a volume ratio of 1:9 and mix well.
[0038] Methods for detecting nitrite:
[0039] Take 0.1 mL of bacterial culture and place it in a 5 mL centrifuge tube. Add 0.5 mL of saturated borax solution, 0.2 mL of potassium ferrocyanide solution, and 0.2 mL of zinc acetate solution in sequence. Then add 4 mL of ultrapure water, mix well, and centrifuge at 4000 r / min for 10 min. Take 3 mL of the supernatant and add it to a 10 mL colorimetric tube. Add 1 mL of p-aminobenzenesulfonic acid solution, shake well, and let stand in the dark for 5 min. Then add 0.5 mL of naphthylethylenediamine hydrochloride solution, and make up to 6 mL with ultrapure water. Shake well and let stand in the dark for 10 min. Zero the tube and measure the absorbance at a wavelength of 538 nm. The residual amount of nitrite in the bacterial culture is calculated according to formula (1):
[0040] (1)
[0041] In formula (1): X1 is the sodium nitrite content in the bacterial solution (mg / kg); m2 is the mass of sodium nitrite in the sample solution (μg); m3 is the mass of the sample (g); V1 is the volume of the sample solution (mL); V0 is the total volume of the sample treatment solution (mL). (The "×1000" in the formula is a "formal notation" for unit conversion, which has no numerical meaning, but allows the testers to directly substitute the original test data of μg (m2) and g (m3), and the calculation result is directly the mg / kg required by the national standard, which simplifies the practical steps and is the conventional way of writing food physicochemical testing.)
[0042] The degradation rate of nitrite by lactic acid bacteria is calculated according to formula (2):
[0043] (2)
[0044] In formula (2): R is the nitrite degradation rate (%); X0 is the nitrite content in the initial culture medium (mg / kg); X1 is the nitrite content in the bacterial culture after culture (mg / kg).
[0045] (2) Determination of acid production capacity
[0046] The initially screened strains were inoculated into MRS liquid medium and subcultured and activated three times. The OD value was adjusted to 1.0, and the strains were inoculated into MRS liquid at a 2% inoculation rate. The cultures were then incubated at 37°C for 24 h, and the pH value and total acid content were measured.
[0047] Determination of total acid: Take 1 mL of bacterial culture and add sterile water to 10 mL, add 2 drops of phenolphthalein solution, and titrate the sample solution with 0.05 mol / L NaOH solution until it turns light pink and does not fade within 30 seconds. Calculate the acid content of the sample solution based on the volume of NaOH solution consumed. Repeat the process three times in parallel and take the average value. Use distilled water as a control. The total acid content is calculated according to formula (3):
[0048] (3)
[0049] In the formula: X2 is the total acid content (g / L); C is the NaOH concentration (mol / L); V1 is the volume of NaOH consumed in the sample titration (mL); V2 is the volume of NaOH consumed in the blank titration (mL); K is the acid conversion factor, 0.09 for lactic acid; F is the sample solution dilution factor; V is the sample solution volume (mL).
[0050] Table 1. Nitrite-reducing and acid-producing capabilities of the secondary-screened strains
[0051] strain number pH NIT degradation rate (%) Total acidity (g / L) LM701 4.48 <![CDATA[91.96%±0.02 b ]]> <![CDATA[10.43±0.20 b ]]> SC-2 4.31 <![CDATA[32.18%±0.05 e ]]> <![CDATA[6.60±0.08 f ]]> SC-3 4.29 <![CDATA[92.86%±0.003 ab ]]> <![CDATA[7.25±0.11 e ]]> SC-4 4.28 <![CDATA[84.76%±0.003 c ]]> <![CDATA[7.55±0.04 d ]]> LP705 3.87 <![CDATA[96.16%±0.004 a ]]> <![CDATA[14.10±0.13 a ]]> SC-6 4.30 <![CDATA[84.27%±0.03 c ]]> <![CDATA[7.63±0.04 d ]]> SC-7 4.49 <![CDATA[72.71%±0.02 d ]]> <![CDATA[8.80±0.28 c ]]>
[0052] 3. Identification of 16S rRNA
[0053] Of the seven selected strains, strains LM701 and LP705, which exhibit both strong nitrite degradation and acid production capabilities, were identified by microscopic examination and 16S rRNA gene sequencing. The results are as follows: Figure 1-2 As shown, strain LM701 was identified as Leuconostoc mesenteroides, and strain LP705 was identified as Lactobacillus plantarum.
[0054] On December 8, 2025, the following samples were deposited at the China Center for the Preservation of Cultures, located at Wuhan University, Wuhan, China: *Leuconostoc mesenteroides* LM701 (CCTCC NO: M 20252807) and *Lactobacillus plantarum* LP705 (CCTCC NO: M 20252808).
[0055] Example 2: Fermentation characteristics analysis of strains LM701 and LP705
[0056] 1. Analysis of acid resistance characteristics
[0057] Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705 were activated for 2-3 generations, respectively. 2% inoculum was added to MRS liquid medium adjusted to different pH values (3.5, 4.5, 5.5, 6.5) with NaOH (1 mol / L) and HCl (1 mol / L) solutions, respectively. Triple-samples were prepared and incubated at 30℃ and 37℃ for 24 h, respectively. After 24 h, absorbance was measured at 600 nm. The survival rate of the strains was obtained after normalization. Results are as follows: Figure 3 As shown, at pH 3.5, the survival rates of *Leuconostoc mesenteriae* LM701 and *Lactobacillus plantarum* LP705 were 16.05% and 26.85%, respectively; at pH 4.5, the survival rates were 56.5% and 94.3%, respectively; at pH 5.5, the survival rates were 93.88% and 98.3%, respectively; and at pH 6.5, the survival rates were 91.48% and 96.05%, respectively. These results indicate that both target strains exhibit strong acid tolerance and stable, good fermentation performance under the critical pH 4.5 acid stress conditions during the sauerkraut fermentation period.
[0058] 2. Salt tolerance characteristics analysis
[0059] Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705 were activated for 2-3 generations, respectively. 2% inoculum was added to MRS liquid medium adjusted to different concentrations (2%, 3%, 4%, 5%, 6%) with NaCl. Triple-sample preparations were performed, and the samples were incubated at 30℃ and 37℃ for 24 h, respectively. After 24 h, absorbance was measured at 600 nm. The survival rate of the strains was obtained after normalization. Results are as follows: Figure 4As shown, at a salt concentration of 2%, the survival rates of *Leuconostoc mesenteriae* LM701 and *Lactobacillus plantarum* LP705 were 91.6% and 97.09%, respectively; at 3%, the survival rates were 81.73% and 93.39%, respectively; at 4%, the survival rates were 69.07% and 90.8%, respectively; at 5%, the survival rates were 56.54% and 89.76%, respectively; and at 6%, the survival rates remained at 53.8% and 83.24%, respectively. The 6% salt concentration represents the critical threshold for salt tolerance growth, under which both target strains exhibited strong growth capabilities.
[0060] 3. Analysis of nitrite tolerance characteristics
[0061] Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705 were activated for 2-3 generations, respectively. 2% inoculum was added to MRS liquid medium adjusted to different gradients (50 μg / mL, 100 μg / mL, 150 μg / mL, 200 μg / mL, 300 μg / mL, 400 μg / mL) with NaNO2. Triple-samples were prepared and incubated at 30℃ and 37℃ for 24 h, respectively. Absorbance was measured at 600 nm after 24 h. The survival rate of the strains was obtained after normalization. Results are as follows: Figure 5 As shown, at 50 μg / mL, the survival rates of *Leuconostoc mesenteriae* LM701 and *Lactobacillus plantarum* LP705 were 96.04% and 98.7%, respectively; at 100 μg / mL, the survival rates were 88.38% and 97.84%, respectively; at 150 μg / mL, the survival rates were 76.94% and 96.94%, respectively; at 200 μg / mL, the survival rates were 71.6% and 96.48%, respectively; at 300 μg / mL, the survival rates were 64.4% and 90.78%, respectively; and at 400 μg / mL, the survival rates were 58.71% and 82.92%, respectively. Under sodium nitrite stress of 200 μg / mL, the strains still exhibited good growth capacity and could grow and reproduce normally in fermentation systems containing this concentration of nitrite. This provides a physiological basis for the strains to continuously play a role in nitrite degradation and ensure the smooth progress of fermentation during sauerkraut fermentation.
[0062] 4. Analysis of antibacterial properties
[0063] Indicator bacterial suspension: Escherichia coli, Salmonella, and Staphylococcus aureus were inoculated separately into LB cells.
[0064] In liquid culture medium, incubate at 37°C for 24 h, then adjust the concentration of sterile physiological saline to 10. 6CFU / mL. *Leuconostoc mesenteroides* LM701 and *Lactobacillus plantarum* LP705 were activated for 2-3 generations respectively, and inoculated into MRS liquid medium at a 2% inoculum volume. The cultures were incubated at 37°C for 24 h, and the bacterial concentration was adjusted to 10 CFU / mL with sterile physiological saline. 8 After reaching CFU / mL, centrifuge (4℃, 6000 r / min, 5 min) and collect the supernatant. Using the Oxford cup diffusion method, 100 μL of indicator bacterial solution is placed on the corresponding indicator bacterial medium and evenly spread on the plate surface. 150 μL of fermentation supernatant is added to the wells using a pipette. An equal volume of sterile water is used as a control. Each group has three replicates. Incubate at 37℃ upside down for 48 h. The size of the inhibition zone is measured using calipers, and the average value is taken. The inhibition zone size results are shown below. Figure 6 As shown in Table 2, Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705 have significant antibacterial effects against Escherichia coli, Staphylococcus aureus and Salmonella.
[0065] Table 2. Antibacterial effect of lactic acid bacteria
[0066] strain number Escherichia coli (mm) Staphylococcus aureus (mm) Salmonella (mm) LM701 13.33±0.08 12.17±0.08 16.83±0.10 LP705 16.50±0.15 16.17±0.08 19.33±0.15
[0067] Example 3: Effect of inoculation ratio on the quality of sauerkraut
[0068] 1. Select a Chinese cabbage of appropriate weight, remove the old leaves, and blanch the Chinese cabbage in boiling water for 30 seconds to remove dirt and harmful substances.
[0069] 2. After blanching the Chinese cabbage, remove the wilted leaves and roots, then cut it into strips about 3-5 mm long and 1-2 mm wide.
[0070] 3. Inoculate Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705 into MRS liquid medium and culture for 24 h. Centrifuge at 6500 r / min for 10 min, discard the supernatant and retain the precipitate. Resuspend the precipitate with sterile PBS and wash twice. Mix in ratios of 1:0, 1:1, 1:2, 1:3, 2:1, 3:1 and 0:1 to prepare bacterial suspensions.
[0071] 4. Add 3% salt, 1% sugar, and 2% of the bacterial suspension prepared in step 3 to the cabbage prepared in step 2.
[0072] 5. Seal and ferment the sample prepared in step 4 at room temperature (20-25°C) for 5 days.
[0073] Example 4: Effect of inoculum amount on the quality of sauerkraut
[0074] 1. Select a Chinese cabbage of appropriate weight, remove the old leaves, and blanch the Chinese cabbage in boiling water for 30 seconds to remove dirt and harmful substances.
[0075] 2. After blanching the Chinese cabbage, remove the wilted leaves and roots, then cut it into strips about 3-5 mm long and 1-2 mm wide.
[0076] 3. Inoculate Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705 into MRS liquid medium and culture for 24 h. Centrifuge at 6500 r / min for 10 min, discard the supernatant and retain the precipitate. Resuspend the precipitate with sterile PBS and wash twice. Mix them at a ratio of 1:2 to prepare a bacterial suspension.
[0077] 4. Add 3% salt and 1% sugar to the cabbage prepared in step 2.
[0078] 5. Inoculate the bacterial suspension prepared in step 3 into the sample prepared in step 4 at inoculation amounts of 2%, 3%, 4%, 5%, and 6%, and ferment in a sealed container at room temperature of 20-25°C for 5 days.
[0079] Example 5: Effect of different salt concentrations on the quality of pickled cabbage
[0080] 1. Select a Chinese cabbage of appropriate weight, remove the old leaves, and blanch the Chinese cabbage in boiling water for 30 seconds to remove dirt and harmful substances.
[0081] 2. After blanching the Chinese cabbage, remove the wilted leaves and roots, then cut it into strips about 3-5 mm long and 1-2 mm wide.
[0082] 3. Inoculate Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705 into MRS liquid medium and culture for 24 h. Centrifuge at 6500 r / min for 10 min, discard the supernatant and retain the precipitate. Resuspend the precipitate with sterile PBS and wash twice. Mix at a ratio of 1:2 to prepare a bacterial suspension.
[0083] 4. Add 1% sugar and 3% bacterial suspension prepared in step 3 to the cabbage prepared in step 2.
[0084] 5. Add 1%, 2%, 3%, 4%, and 5% salt to the samples prepared in step 4 respectively, and seal and ferment at room temperature (20-25℃) for 5 days.
[0085] Example 6: Effect of different sugar concentrations on the quality of sauerkraut
[0086] 1. Select a Chinese cabbage of appropriate weight, remove the old leaves, and blanch the Chinese cabbage in boiling water for 30 seconds to remove dirt and harmful substances.
[0087] 2. After blanching the Chinese cabbage, remove the wilted leaves and roots, then cut it into strips about 3-5 mm long and 1-2 mm wide.
[0088] 3. Inoculate Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705 into MRS liquid medium and culture for 24 h. Centrifuge at 6500 r / min for 10 min, discard the supernatant and retain the precipitate. Resuspend the precipitate with sterile PBS and wash twice. Mix at a ratio of 1:2 to prepare a bacterial suspension.
[0089] 4. Add 1% salt and 3% of the bacterial suspension prepared in step 3 to the cabbage prepared in step 2.
[0090] 5. Add 0.5%, 1%, 2%, 3%, and 4% sugar to the samples prepared in step 4 respectively, and ferment them in a sealed container at room temperature (20-25°C) for 5 days.
[0091] Comparative Example: Preparation of Naturally Fermented Sauerkraut
[0092] 1. Select a Chinese cabbage of appropriate weight, remove the old leaves, and blanch the Chinese cabbage in boiling water for 30 seconds to remove dirt and harmful substances.
[0093] 2. After blanching the Chinese cabbage, remove the wilted leaves and roots, then cut it into strips about 3-5 mm long and 1-2 mm wide.
[0094] 3. Add 1% salt and 0.5% sugar to the cabbage prepared in step 2, and ferment in a sealed container at room temperature (20-25℃) for 5 days. The percentages mentioned above are the weight percentages of the cabbage and the additives.
[0095] Detection of nitrite content: The method is the same as in Example 1.
[0096] Sensory evaluation: A sensory evaluation team of 20 food science graduate students was invited to conduct a sensory evaluation of the pickled cabbage. The test environment was at room temperature. The evaluators evaluated the pickled cabbage in five aspects: acidity, crispness, umami, color, and viscosity. The total score was 100 points. The total score was obtained by summing the scores of each item for each sample.
[0097] The effect of different strain ratios on the fermentation effect of sauerkraut is as follows: Figure 7As shown, the nitrite content in the naturally fermented group was significantly higher than that in all inoculated groups, with a peak value close to 11 mg / kg. Among the different inoculation ratios (Lactobacillus plantarum LP705: Leuconostoc mesenteroides LM701), the nitrite content was 3.98 mg / kg in the 0:1 group, 2.83 mg / kg in the 1:1 group, 2.79 mg / kg in the 1:2 group, 2.85 mg / kg in the 1:3 group, 3.16 mg / kg in the 2:1 group, 3.28 mg / kg in the 3:1 group, and 3.7 mg / kg in the 1:0 group. The 1:2 inoculation ratio showed the best degradation effect. Although the nitrite content in the 0:1, 1:1, 1:3, 2:1, 3:1, and 1:0 groups was slightly higher than that in the 1:2 group, it was still significantly better than that in the naturally fermented group, indicating that the compound bacteria can effectively inhibit nitrite accumulation. In terms of sensory quality: ratios of 1:2, 3:1, and 1:3 showed outstanding performance in flavor and texture. Considering the ability to degrade nitrite, the final ratio of 1:2 was chosen to balance safety and sensory quality.
[0098] The effect of different inoculum amounts on the fermentation effect of sauerkraut is as follows: Figure 8 As shown, the nitrite content in the naturally fermented group was significantly higher than that in all inoculated groups, with a peak value close to 11 mg / kg. The residual nitrite content in the compound fermented sauerkraut was 2.92 mg / kg at 2% inoculation, 2.72 mg / kg at 3% inoculation, 3.08 mg / kg at 4% inoculation, 2.87 mg / kg at 5% inoculation, and 3 mg / kg at 6% inoculation. The nitrite content was lowest in the compound fermented sauerkraut with a 3% inoculation. In terms of sensory quality, the 3% inoculation group exhibited outstanding acidity, crispness, and umami flavor, with a relatively balanced color and viscosity.
[0099] The effects of different salt concentrations on the fermentation effect of sauerkraut are as follows: Figure 9As shown, the nitrite content in the naturally fermented group was significantly higher than that in all inoculated groups, with a peak value approaching 11 mg / kg. Among different salt concentrations, the nitrite content was 2.69 mg / kg in the 1% salt concentration group, 3.13 mg / kg in the 2% salt concentration group, 3.29 mg / kg in the 3% salt concentration group, 3.27 mg / kg in the 4% salt concentration group, and 3.35 mg / kg in the 5% salt concentration group. In comparison, the 1% salt concentration group showed the best degradation effect, maximizing product safety. In terms of sensory quality, the 1%~3% salt concentrations exhibited a balanced performance, ensuring both rich flavor and avoiding the health risks associated with high salt content. Overall, 1% is the suitable salt concentration for sauerkraut fermentation in this invention, aligning with the industry's trend towards low-salt production while achieving good fermentation results and product quality.
[0100] The effects of different sugar concentrations on the fermentation effect of sauerkraut are as follows: Figure 10 As shown, the nitrite content in the naturally fermented group was significantly higher than that in all inoculated groups, with a peak value close to 11 mg / kg. Among different sugar concentrations, the nitrite content was 2.58 mg / kg in the 0.5% sugar concentration group, 3.06 mg / kg in the 1% sugar concentration group, 3.18 mg / kg in the 2% sugar concentration group, 2.94 mg / kg in the 3% sugar concentration group, and 2.96 mg / kg in the 4% sugar concentration group. Comparatively, the 0.5% sugar concentration group showed the best degradation effect. In terms of sensory quality, the 0.5%–2% sugar concentration exhibited a balanced performance, ensuring both rich flavor and avoiding the flavor imbalance caused by high sugar content. In summary, 0.5% is the suitable sugar concentration for sauerkraut fermentation in this invention, providing sufficient metabolic substrates for the strain while achieving good fermentation results and product quality, consistent with the flavor characteristics of traditional sauerkraut.
[0101] In summary, the improved method for screening lactic acid bacteria and fermenting sauerkraut according to this invention not only has low nitrite content, but also breaks through the bottlenecks of long fermentation cycle and low efficiency of traditional sauerkraut, while achieving a technological breakthrough of 1% low-salt fermentation.
Claims
1. Microbial agents used for fermenting low-nitrite, low-sodium sauerkraut, including: Leuconostoc mesenteroides LM701 with accession number CCTCC NO: M 20252807 and / or Lactobacillus plantarum LP705 with accession number CCTCC NO: M 20252808.
2. The microbial agent for fermenting low-nitrite and low-sodium sauerkraut according to claim 1, characterized in that: The ratio of Leuconostoc mesenteroides LM701 to Lactobacillus plantarum LP705 is 1~3:3~1.
3. The microbial agent for fermenting low-nitrite and low-sodium sauerkraut according to claim 2, characterized in that: The ratio is 1:
2.
4. Application of microbial agents used in fermenting low-nitrite and low-sodium sauerkraut in the degradation of nitrite.
5. A method for producing low-nitrite, low-sodium sauerkraut through fermentation, comprising: 1) Remove the outer leaves of the Chinese cabbage and blanch it evenly in boiling water; then place it in a container; 2) Add 2%~6% of the microbial agent for fermenting low-nitrite sauerkraut as described in claim 1, 1%~5% salt and 0.5%~4% sugar; 3) Sealed fermentation.
6. The method for producing low-nitrite, low-sodium sauerkraut according to claim 5, characterized in that: After blanching, remove the wilted leaves and roots from the Chinese cabbage and cut it into strips about 3-5 mm long and 1-2 mm wide.
7. The method for producing low-nitrite, low-sodium sauerkraut according to claim 6, characterized in that: The salt content is 1%, and the sugar content is 0.5%.
8. The production method for fermenting low-nitrite, low-sodium sauerkraut according to claim 7, characterized in that: The fermentation process was carried out at room temperature for 5 days.
9. The method for producing low-nitrite, low-sodium sauerkraut according to claim 5, 6, 7 or 8, characterized in that: The bacterial agent is prepared by the following method: Leuconostoc mesenteroides LM701 and Lactobacillus plantarum LP705 are inoculated into MRS liquid medium and cultured for 24 h. After centrifugation at 6500 r / min for 10 minutes, the supernatant is discarded and the precipitate is retained. The precipitate is resuspended with sterile PBS and washed twice. The mixture is then used to prepare a bacterial suspension.