Flavor-oriented compound starter culture of lactic acid bacteria for pickled mustard and application thereof

Abstract

This invention discloses a flavor-oriented lactic acid bacteria compound fermentation agent for mustard green kimchi and its application, relating to the field of food fermentation technology. The invention screens a strain of *Lactobacillus pentosaccharide* with excellent flavor from traditional kimchi and combines it with a strain of *Lactobacillus plantarum* with high-efficiency acid production and nitrite degradation capabilities to form a compound fermentation agent. When applied to mustard green kimchi, this compound fermentation agent significantly shortens the fermentation cycle to 5 days, reduces nitrite content to below 1 mg / kg, and significantly enhances the pleasant flavor attributes of kimchi, such as floral, fresh, and cucumber aromas, by promoting the formation of key aroma-active compounds such as β-ionone, phenylethyl alcohol, and (E,Z)-2,6-nonadienal, achieving the highest sensory preference score. This invention provides an efficient and reliable solution for the standardized production and flavor-oriented enhancement of high-quality kimchi.

Description

Technical Field

[0001] This invention relates to a flavor-oriented lactic acid bacteria compound fermentation agent for mustard green kimchi and its application, belonging to the technical field of fermented kimchi. Background Technology

[0002] Pickled vegetables, a traditional fermented vegetable product with a long history, are loved by consumers. Among them, pickled vegetables made from mustard greens are rich in a variety of flavor precursors, which, after being transformed by microorganisms, can form a unique flavor, making them a popular traditional fermented food in China.

[0003] Currently, the production and processing of kimchi mainly relies on natural fermentation. This process utilizes the natural microbial community attached to the surface of vegetables as the driving force for fermentation. However, natural fermentation has significant limitations: long fermentation cycle: relying on the natural succession of wild fungi results in slow fermentation speed and low production efficiency; large fluctuations in product quality: due to the unstable composition of the natural microbial community, it is significantly affected by factors such as raw materials and the environment, leading to poor consistency in flavor, texture, and safety between different batches of products, making it difficult to achieve standardized production; prominent safety hazards: it is impossible to effectively control the growth of miscellaneous bacteria and potential pathogenic microorganisms, which easily leads to product spoilage and deterioration, and high levels of harmful substances such as nitrites are easily produced during the fermentation process.

[0004] To overcome the shortcomings of natural fermentation, inoculation fermentation technology has emerged. This technology involves artificially adding specific lactic acid bacteria as a starter culture, aiming to achieve precise control over the fermentation process. Existing research on inoculation fermentation technology has confirmed that it can significantly shorten the fermentation cycle, improve product consistency, and enhance safety.

[0005] However, existing inoculation fermentation technologies still have significant shortcomings, the core issue being the bias in strain selection strategies. Currently, lactic acid bacteria screening generally uses physicochemical indicators such as acid production capacity and nitrite degradation capacity as the main, or even sole, screening criteria, while flavor quality is only used as an auxiliary evaluation parameter, lacking a systematic flavor-oriented screening process. This results in kimchi produced through inoculation fermentation generally having a single flavor and lacking complexity, with its flavor profile falling short of the complexity of traditional naturally fermented kimchi, making it difficult to meet consumers' demands for high-quality flavor.

[0006] Although some studies have attempted to improve flavor through mixed-strain fermentation, the construction of these strain combinations is not based on prior flavor-oriented screening, resulting in limited and untargeted improvement effects. Furthermore, existing methods for evaluating kimchi flavor are largely limited to simple volatile substance detection or subjective sensory assessment, making it difficult to accurately identify the active substances that truly contribute to the overall flavor. This fails to provide precise targets for flavor-oriented strain screening.

[0007] Therefore, there is an urgent need in this field for a new technical solution that can fundamentally improve flavor as the core objective and establish a complete system from strain screening to flavor evaluation in order to develop a special fermentation agent that can ensure safety and efficiency while giving kimchi a rich, pleasant and stable flavor. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing natural fermentation and inoculation fermentation technologies for kimchi, and to provide a flavor-oriented screening-based compound lactic acid bacteria starter culture and its application. Specifically, this invention aims to address the problem that existing inoculation fermentation technologies, due to their overemphasis on physicochemical indicators in screening criteria, result in kimchi with a single flavor profile and a gap compared to traditional naturally fermented kimchi. This invention provides a compound starter culture that can synergistically improve the flavor quality and food safety of kimchi, achieving a short fermentation cycle, low nitrite content, and prominent key pleasant flavors. It establishes a complete technical system from flavor-oriented strain screening to precise analysis of key flavor substances, providing a solution for the targeted development of high-quality kimchi.

[0009] The first technical solution provided by this invention is a strain of Lactobacillus pentosus ( Lactiplantibacillus pentosus JNC003.002 was deposited on March 11, 2026 at the China Center for Type Culture Collection, located at Wuhan University, No. 299 Bayi Road, Wuchang District, Wuhan City, Hubei Province, with accession number CCTCC NO:M 202642.

[0010] The second technical solution provided by the present invention is a microbial agent containing Lactobacillus pentosus JNC003.002 as described in the first technical solution.

[0011] The third technical solution provided by this invention is a compound fermentation agent containing *Lactobacillus pentosus* and *Lactobacillus plantarum*. These two strains achieve synergistic effects through functional complementarity.

[0012] In some embodiments, the Lactobacillus pentosus is Lactobacillus pentosus JNC003.002 as described in the first technical solution. This strain was obtained through flavor-oriented screening and can significantly improve the flavor preference of kimchi and promote the formation of pleasant flavors such as floral and fresh aromas.

[0013] In some embodiments, the *Lactobacillus plantarum* is *Lactobacillus plantarum* JNC003.001, whose accession number is CCTCC NO:2024447, and which was deposited at the China Center for Type Culture Collection on March 18, 2024, and which has the ability to produce acid and degrade nitrite efficiently.

[0014] In some embodiments, the ratio of viable Lactobacillus pentosus to Lactobacillus plantarum is (0.5-2):1, with the most preferred ratio being 1:1.

[0015] In some embodiments, the fermenting agent may be in the form of lyophilized bacterial powder, liquid fermenting agent, or other conventional formulations in the art.

[0016] The method for constructing the composite fermentation agent of the present invention includes the following key steps: a) Flavor-oriented initial screening: Lactic acid bacteria were isolated from high-quality traditional kimchi and inoculated into a mustard leaf-simulated fermentation system. Sensory preference was used as the primary indicator for screening to obtain candidate strains with excellent flavor.

[0017] b) Functional combination: The selected strains with excellent flavor are combined with a functionally complementary strain.

[0018] The fourth technical solution provided by the present invention is a method for preparing pickled mustard greens, wherein the method involves introducing the compound fermentation agent described in the third technical solution into a fermentation system containing mustard green leaves to prepare pickled mustard greens.

[0019] In some embodiments, the total inoculum amount of the fermenting agent is 5%-10% (v / w) of the mustard leaf mass, preferably 7.5% (v / w). When using a mixture of two strains, a 1:1 ratio is preferred.

[0020] In some embodiments, the inoculated mustard leaves are fermented in a fermentation broth containing 2%-4% (w / v) glucose and 2%-4% (w / v) sodium chloride at 25-35°C for 3-7 days.

[0021] Furthermore, the solid-liquid ratio was 1:4, and fermentation was carried out at 30°C for 5 days.

[0022] Furthermore, the compound fermentation agent is inoculated with a liquid culture medium, which is a prepared food-grade culture medium. After inoculation with the strains, the mixture is cultured in a shaker at 37°C for 24 hours.

[0023] The fifth technical solution provided by the present invention is a method for enhancing the flavor of mustard greens kimchi, wherein the method involves fermenting mustard green leaves with the compound fermenting agent described in the third technical solution to prepare mustard greens kimchi.

[0024] In some embodiments, the flavor compound includes β-ionone, phenylethanol, (E,Z)-2,6-nonadienal, etc.

[0025] The sixth technical solution provided by this invention is the application of Lactobacillus pentosus JNC003.002 described in the first technical solution, the microbial preparation described in the second technical solution, or the compound fermentation agent described in the third technical solution in improving the quality of pickled mustard greens.

[0026] In some embodiments, the improvement of mustard green pickle quality includes at least one of the following effects: (1) Increase the content of flavor compounds in mustard green kimchi, including β-ionone, phenylethyl alcohol, (E,Z)-2,6-nonadienal, etc.; (2) Degrading nitrite in pickled mustard greens.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention significantly enhances the flavor and quality of mustard green kimchi: through flavor-oriented screening and compounding, kimchi prepared with the fermentation agent of this invention achieved the highest sensory preference score. It effectively promotes the formation of key pleasant aroma compounds such as β-ionone, phenylethyl alcohol, and (E,Z)-2,6-nonadienal, making the kimchi more prominent in sensory attributes such as floral, fresh, and cucumber aromas. Through the detection of volatile flavor substances and OAV calculations, the aroma-active compounds that contribute significantly to the overall flavor of the kimchi were precisely identified, providing clear targets for flavor-oriented design.

[0028] This invention simultaneously enhances the fermentation efficiency and safety of mustard greens: This invention can significantly shorten the fermentation cycle: The inoculated fermentation group can reduce the pH value to below 4.0 on the second day, reaching the maturity standard, while the naturally fermented group still has a pH value as high as 4.85 on the fifth day.

[0029] This invention can efficiently degrade nitrite: the inoculated fermentation group can reduce the nitrite content to below 1 mg / kg on the 3rd day, which is far below the national standard (20 mg / kg), while the natural fermentation group is still as high as 50.13 mg / kg on the 5th day, which significantly improves safety.

[0030] In summary, this invention improves the flavor and safety of pickled mustard greens and shortens fermentation time by inoculating with a compound fermentation agent. At the same time, the flavor-oriented strategy and the construction idea of ​​the compound fermentation agent can provide a reference for the quality improvement of other traditional fermented foods.

[0031] Preservation of biological materials A strain of Lactobacillus pentosus ( Lactiplantibacillus pentosus JNC003.002, taxonomic name is Lactiplantibacillus pentosus It was deposited on March 11, 2026 at the China Center for Type Culture Collection, located at Wuhan University, Wuhan, China (299 Bayi Road, Wuchang District, Wuhan, Hubei Province), with accession number CCTCC NO:M 2026423.

[0032] A strain of Lactobacillus plantarum ( Lactobacillus plantarum JNC003.001, taxonomic name is Lactobacillus plantarumIt was deposited on March 11, 2024 at the China Center for Type Culture Collection, located at Wuhan University, Wuhan, China (299 Bayi Road, Wuchang District, Wuhan, Hubei Province), with accession number CCTCC NO:M2024447, and has been published in patent CN118648722A. Attached Figure Description

[0033] Figure 1 Sensory evaluation scores for the seven lactic acid bacteria strains obtained from the initial screening.

[0034] Figure 2 The pH, total acidity, and nitrite content of four groups of kimchi (NF, ZF, WF, and MF) were measured.

[0035] Figure 3 The content of volatile flavor compounds in four groups of kimchi: NF, ZF, WF, and MF.

[0036] Figure 4 The flavor profiles of four groups of kimchi: NF, ZF, WF, and MF. Detailed Implementation

[0037] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0038] Raw materials used in the examples: The MRS agar medium in this embodiment of the invention is composed of the following components: 10 g peptone, 10 g beef extract, 5 g yeast powder, 20 g glucose, 2 g diammonium citrate, 5 g anhydrous sodium acetate, 0.1 g magnesium sulfate heptahydrate, 0.05 g manganese sulfate tetrahydrate, 2 g dipotassium hydrogen phosphate, 1 mL Tween-80, and 15 g agar powder are dissolved in 1000 mL distilled water and autoclaved at 121°C for 15 minutes before use.

[0039] The MRS liquid culture medium in this embodiment of the invention consists of the following components: 10 g tryptone, 10 g beef extract, 5 g yeast powder, 20 g glucose, 2 g diammonium citrate, 5 g anhydrous sodium acetate, 0.1 g magnesium sulfate heptahydrate, 0.05 g manganese sulfate tetrahydrate, 2 g dipotassium hydrogen phosphate, and 1 mL Tween-80, dissolved in 1000 mL distilled water and autoclaved at 121°C for 15 minutes before use.

[0040] The food-grade culture medium in this embodiment of the invention comprises the following components: 2.5 g of soybean protein, 2 g of food-grade glucose, 1 mL of tomato juice, and 0.5 g of food-grade dipotassium hydrogen phosphate, dissolved in 100 mL of deionized water. The soybean protein was purchased from Linyi Shansong Biological Products Co., Ltd.; the food-grade glucose and food-grade dipotassium hydrogen phosphate were purchased from Jiahe Food Industry Co., Ltd. In this application, unless otherwise specified, % refers to wt%, and all proportions are mass ratios; unless otherwise specified, all raw materials used are commercially available products.

[0041] Example 1: Screening and Identification of Flavor-Oriented Lactic Acid Bacteria From 12 commercially available samples of traditional mustard leaf kimchi with excellent flavor, kimchi broth was inoculated into MRS liquid medium at a 5% (v / v) inoculation rate and cultured at 37°C with shaking at 200 rpm for 24 hours. The culture was then diluted with sterile physiological saline and spread onto MRS solid medium containing calcium carbonate, and incubated statically at 37°C for 48 hours. Single colonies with obvious calcium dissolution zones were picked and repeatedly streaked for purification, and preliminary identification was performed by catalase test and Gram staining.

[0042] The isolated pure strain was inoculated into MRS liquid medium and cultured at 37°C until the bacterial concentration reached 1×10⁻⁶. 8 CFU / mL. A fermentation broth containing 2% (w / v) glucose and 3% (w / v) sodium chloride was prepared, boiled, cooled, and then homogenized with mustard leaves (solid-liquid ratio 1:4) to create a simulated fermentation system. Each strain was inoculated into the simulated system at an inoculum of 7.5% (v / v) and fermented at 30℃ for 5 days. After fermentation, a trained sensory evaluation team conducted preliminary screening, removing strains that produced off-flavors or had a bland taste. A nine-point preference rating system (1 for extremely dislike, 9 for very like) was used for quantitative evaluation. Seven strains with high preference were initially selected.

[0043] The above seven bacterial strains were inoculated into a real mustard leaf kimchi system (inoculation amount 7.5% (v / v), fermentation conditions as above). After fermentation maturity, its physicochemical properties were measured and sensory evaluation was performed. The results showed that all inoculated strains could reduce the pH of the kimchi to below 4.0 on the second day of fermentation and reduce the nitrite content to below 1 mg / kg on the third day. Sensory evaluation results are as follows. Figure 1 The results showed that strain JNC003.002 had the highest preference score and was therefore selected as the core strain with excellent flavor.

[0044] The selected strain JNC003.002 was identified by 16S rRNA gene sequencing. PCR amplification was performed using primers 27F (5'-AGAGTTTGATCCTGGCCTCA-3') and 1492R (5'-GGTTACCTTGTTACGACTT-3'), and the amplified products were purified and sequenced. The sequences were then compared with the NCBI database using BLAST, confirming the strain as *Lactobacillus pentosacchari*. Lactiplantibacillus pentosus (), deposited at the China Center for Type Culture Collection, located at No. 299 Bayi Road, Wuchang District, Wuhan City, Hubei Province, within the campus of Wuhan University, with accession number CCTCC NO:M 2026423.

[0045] Example 2: Construction and Application Effect Verification of Compound Fermentation Agent The flavorful Lactobacillus pentosaccharide JNC003.002 strain obtained from Example 1 was compared with a laboratory-preserved Lactobacillus plantarum strain JNC003.001, which has highly efficient acid production and nitrite degradation capabilities. Lactiplantibacillus plantarum JNC003.001 (CCTCC NO: M2024447) was used for compounding. The two strains were mixed at a 1:1 ratio of live cells to form a compound fermentation agent.

[0046] Taking mustard greens as an example, wash the mustard greens in clean water to remove mud, dust, and residual pesticides until the water is clear; remove yellow and rotten leaves from the vegetables; drain the vegetables to remove surface moisture and set aside for later use; prepare a fermentation liquid with a salt concentration of 2% (w / v) and a sugar concentration of 2% (w / v), and put the mustard greens into a fermentation liquid container at a ratio of 1:4 and seal it for fermentation at a constant temperature of 30℃.

[0047] Four methods were used to ferment mustard greens into kimchi: Natural fermentation group (NF): No additional microorganisms are inoculated; fermentation occurs naturally. The Lactobacillus plantarum inoculation group (ZF) was inoculated with Lactobacillus plantarum CCTCC NO:2024447 for fermentation at an inoculation rate of 7.5% (v / w) and a bacterial concentration of 1×10⁻⁶. 8 CFU / mL.

[0048] WF group inoculated with Lactobacillus pentosus: Fermentation was carried out by inoculating with Lactobacillus pentosus CCTCC NO:M 2026423 at an inoculation rate of 7.5% (v / w) and a bacterial concentration of 1×10⁻⁶. 8 CFU / mL.

[0049] Multi-strain inoculation group (MF): Simultaneous inoculation with 3.75% (v / w) *Lactobacillus plantarum* CCTCC NO:2024447 and 3.75% (v / w) *Lactobacillus pentosaccharide* CCTCC NO:M 2026423, for a total inoculation amount of 7.5% (v / w) and a bacterial concentration of 1×10⁻⁶. 8 CFU / mL.

[0050] 1. Determination of total acidity, pH value and nitrite content Determination of total acidity: The acid-base titration method is used in accordance with GB 12456-2021 "Determination of total acidity in food".

[0051] pH Measurement: The pH meter was calibrated by rinsing the electrode head with ultrapure water and wiping it clean with filter paper. It was then placed sequentially in standard buffer solutions with pH values ​​of 4.0, 6.86, and 9.18. After calibration, the slope should remain between 95% and 100%. Calibration was complete when three calibration points appeared on the display. 25g of pickled mustard greens were mixed with an equal volume of CO2-free water and homogenized in a tissue homogenizer. The homogenate was then transferred to an Erlenmeyer flask and allowed to cool to 25°C before measuring the pH value using a pH meter.

[0052] Determination of nitrite content: The nitrite content was determined according to Chinese National Standard GB5009.33-2016. For example... Figure 2 As shown, the pH of the MF and ZF groups dropped below 4.0 on day 2 of fermentation, while the pH of the NF group remained at 4.85 on day 5. The TTA content in the MF group reached a relatively high level on day 5. The MF, ZF, and WF groups all reduced the nitrite content to below 1 mg / kg on day 3 of fermentation, while the NF group still had a high nitrite content of 50.13 mg / kg on day 5. The changes in pH and TTA together indicate that inoculation with lactic acid bacteria for fermentation can effectively shorten the fermentation cycle, positively impact the formation of kimchi flavor, and enhance the safety of kimchi through rapid acid production.

[0053] 2. Analysis of volatile flavor compounds Volatile flavor compounds in different groups were analyzed by HS-SPME-GC-MS.

[0054] As shown in Table 1, a total of 83 volatile compounds were identified by GC-MS, classified into 9 categories according to their chemical structure, including 15 sulfur-containing compounds, 4 esters, 18 alcohols, 11 aldehydes, 10 ketones, 6 phenols, 6 acids, 6 heterocyclic compounds, and alkenes. 72, 68, 53, and 52 volatile compounds were detected in the NF, ZF, WF, and MF spectra of the samples, respectively. Figure 3As shown, the total concentration of volatile flavor compounds in the six groups of kimchi ranged from 2761.90 μg / kg to 1456.58 μg / kg. Sulfur-containing compounds accounted for the highest proportion, with isothiocyanates (ITCs) being the majority. These compounds have a pungent and irritating flavor and are characteristic flavor components of cruciferous vegetables. They mainly originate from the degradation products of naturally occurring glucosinolates (GSLs) in vegetables under the action of myrosinase. During the fermentation and further processing of kimchi, the vegetables are subjected to compression and osmotic pressure, leading to tissue damage. Endogenous myrosinase is released and activated, decomposing GSLs into ITCs, thiocyanates, and nitrile substances. In the early stages of kimchi fermentation, the pH is higher, and GSLs are mainly degraded into ITCs.

[0055] Among the four groups of kimchi, allyl isothiocyanates (AITCs) were present in the highest concentration. Alcohols and aldehydes were also present in high amounts, forming important components of kimchi flavor. Aldehydes have a low odor threshold and can exhibit a variety of flavor characteristics, including floral, fruity, and woody aromas. Their formation may be related to lipid oxidation and Strecker degradation. Alcohols mainly include terpenoid alcohols (such as linalool) and aromatic alcohols (such as phenylethyl alcohol), typically possessing fruity, rose-like, and mildly spicy aromas. Terpenoid alcohols are generally believed to be produced by the degradation of terpene glycosides in the raw materials, while phenylethyl alcohol is mainly produced by phenylalanine through microbial metabolism. The concentrations were: 26.16 μg / kg in the NF group; 52.01 μg / kg in the ZF group; 41.99 μg / kg in the WF group; and 68.43 μg / kg in the MF group. The content of (E,Z)-2,6-nonadienal in the NF group was 3.37 μg / kg; the content of (E,Z)-2,6-nonadienal in the ZF group was 4.42 μg / kg; the content of (E,Z)-2,6-nonadienal in the WF group was 3.95 μg / kg; and the content of (E,Z)-2,6-nonadienal in the MF group was 4.81 μg / kg.

[0056] In addition, ketones generally have low odor thresholds; for example, β-ionone exhibits a typical violet fragrance. The content in the NF group was 5.12 μg / kg; in the ZF group, it was 6.23 μg / kg; in the WF group, it was 12.62 μg / kg; and in the MF group, it was 16.32 μg / kg. Among acids, acetic acid and lactic acid, as the main organic acids in fermented vegetables, are important sources of the sour taste in kimchi. However, short-chain fatty acids such as caprylic acid and hexanoic acid detected during natural fermentation exhibit strong sweaty and foot odors, which may be related to the metabolic pathways of alanine, leucine, or isoleucine by microorganisms in the natural fermentation system. Furthermore, other categories of substances, such as olefins, are present in low amounts, and due to their high odor thresholds, they are generally considered to contribute little to the overall flavor.

[0057] To further evaluate the contribution of aromatic active compounds, quantitative analysis was performed using existing standards based on the identification results of volatile flavor compounds in kimchi. OAV (Organic Acid Valve Volume) was used to determine the main aroma contributors. OAV is equal to the concentration of volatile flavor compounds divided by a threshold in water; compounds with OAV ≥ 1 are generally considered to contribute to the aroma characteristics of the sample. Table 3 lists the compounds with OAV ≥ 1 in four groups of kimchi.

[0058] These compounds include aldehydes (5), ketones (3), alcohols (5), sulfur-containing compounds (5), and heterocyclic compounds (2). The compound with the highest OAV value was 2-methoxy-3-(1-methylethyl)pyrazine, due to its extremely low threshold, which allows it to produce a strong flavor and aroma even at low concentrations, significantly impacting the overall flavor of the kimchi. Among the sulfur-containing compounds, allyl isothiocyanate and 4-isothiocyanate-1-butene had OAV values ​​greater than 1, consistent with the GCO results (Table 1), primarily contributing a spicy and pungent flavor profile, while dimethyl trisulfide mainly provided a cabbage flavor. In the MF group, phenethyl alcohol, linalool, and 4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-3-buten-2-one had significantly higher OAV values ​​than the other three groups, contributing a stronger floral, fresh, and vegetable flavor. Aldehydes, including decanal, octanal, nonanal, and (E,Z)-2,6-nonadienal, are significant aroma contributors to mustard greens and kimchi, imparting flavors of vegetables, citrus, and soap. Their high MF and OAV values ​​indicate a strong correlation between OAV and GC-O. However, among the aromatic active compounds identified by GCO, acids such as octanoic acid, hexanoic acid, and acetic acid have OAV values ​​less than 1 due to their high threshold values, reflecting the potential influence of the food matrix. Similarly, 4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2-butanone and 2-methoxy-3-(1-methylpropyl)pyrazine showed high OAV values ​​in the samples, but these may not have been captured during olfaction due to the fractionation of odor compounds.

[0059] Table 1. Volatile compounds in different groups of kimchi

[0060] Table 2. MF values ​​of odor-active compounds identified in kimchi by GC / O / MS

[0061] Table 3. Aromatic compounds in different groups of kimchi

[0062] Example 3: Sensory evaluation of kimchi quality A trained sensory evaluation team conducted sensory evaluations on each group of mustard green kimchi prepared in Example 2, constructed the flavor profile of the kimchi, and selected nine aroma descriptors, namely cabbage flavor, spicy and pungent flavor, sour flavor, fresh flavor, mellow flavor, herbal flavor, pungent flavor, cucumber flavor and floral flavor, to determine the flavor characteristics of the four groups of kimchi samples. Figure 4 As shown, the aroma characteristics of kimchi samples fermented with different microbial strains differ. It is evident that the flavor preference of the inoculated fermentation group is significantly higher than that of the naturally fermented group, with MF (fermented macadamia oleifera) showing the highest preference among the inoculated fermentation groups. MF exhibits the highest intensity of pleasant flavors such as floral, cucumber, mellow, fresh, and cabbage aromas, which explains its highest preference score. The NF group, due to substances like caproic acid and caprylic acid, has a significantly higher intensity of pungent odor than other groups, while its intensity of sour, fresh, mellow, and floral aromas is significantly lower than other groups, indicating that inoculation fermentation enhances the flavor of the kimchi.

[0063] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A strain of Lactobacillus pentosus ( Lactiplantibacillus pentosus JNC003.002, characterized in that, It was deposited at the China Center for Type Culture Collection on March 11, 2026, with accession number CCTCC NO:M 2026423.

2. A microbial inoculum containing Lactobacillus pentosus JNC003.002 as described in claim 1.

3. A compound fermentation agent, characterized in that, The compound fermentation agent comprises *Lactobacillus pentosus* and *Lactobacillus plantarum*, wherein *Lactobacillus pentosus* is *Lactobacillus pentosus* JNC003.002 as described in claim 1, and *Lactobacillus plantarum* is *Lactobacillus plantarum* (…). Lactobacillus plantarum JNC003.001, the Lactobacillus plantarum ( Lactobacillus plantarum The accession number of JNC003.001 is CCTCC NO:2024447.

4. The compound fermentation agent according to claim 3, characterized in that, The ratio of viable Lactobacillus pentosus to Lactobacillus plantarum is (0.5-2):

1.

5. A method for preparing pickled mustard greens, characterized in that, The method involves incorporating the compound fermenting agent described in any one of claims 3 to 4 into a fermentation system containing mustard leaves to prepare pickled mustard greens.

6. The method for preparing pickled mustard greens according to claim 5, characterized in that, The total inoculum amount of the fermenting agent is 5%-10% (v / w) of the mustard leaf mass.

7. The method for preparing pickled mustard greens according to claim 5, characterized in that, The inoculated mustard leaves were fermented in a fermentation broth containing 2%-4% (w / v) glucose and 2%-4% (w / v) sodium chloride at 25-35°C for 3-7 days.

8. A method for enhancing the flavor of mustard green kimchi compounds, characterized in that, The method involves fermenting mustard leaves with the compound fermenting agent described in any one of claims 3 to 4 to prepare pickled mustard greens, wherein the flavor compounds include β-ionone, phenylethanol, and (E,Z)-2,6-nonadienal.

9. The application of Lactobacillus pentosus JNC003.002 as described in claim 1, the microbial preparation as described in claim 2, or the compound fermentation agent as described in any one of claims 3 to 4 in improving the quality of pickled mustard greens.

10. The application according to claim 9, characterized in that, The improvement of the quality of pickled mustard greens includes at least one of the following effects: (1) Increase the content of flavor compounds in mustard green kimchi, including β-ionone, phenylethyl alcohol, (E,Z)-2,6-nonadienal, etc.; (2) Degrading nitrite in mustard pickles.

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