Hansenula polymorpha and its use for improving the quality of kimchi

Abstract

This invention discloses a Hansgrohe Pasteurella multocida strain and its application in improving the quality of kimchi. This strain exhibits excellent fermentation performance, good acid and salt tolerance, and also possesses a certain gas-producing capacity, strong protease activity, and lipid-producing ability. Inoculating kimchi with this strain during fermentation can improve the flavor, aroma, and texture of the kimchi within the same fermentation time, effectively enhancing the quality of the kimchi.

Description

(I) Technical Field

[0002] This invention belongs to the field of microbial technology, specifically relating to a strain of Hansgrohe Pasteurella multocida with strong fermentation performance and its application in improving the quality of kimchi. (II) Background Technology

[0004] Kimchi is primarily made from fresh vegetables such as cabbage, mustard greens, and radishes, fermented through the action of microorganisms like lactic acid bacteria and yeast. Studies have shown that microbial fermentation not only helps vegetables retain their original nutrients but also creates a unique flavor. Other reports indicate that kimchi has various physiological functions, including regulating the intestinal environment, promoting growth and development, alleviating intestinal inflammation, and lowering cholesterol. Mustard greens are often used in kimchi fermentation; during fermentation, they develop a distinctive savory aroma that aids digestion and enhances appetite. Furthermore, mustard greens are rich in isothiocyanates, giving them a spicy flavor and a crisp texture, thus possessing high nutritional value.

[0005] In Ningbo and Taizhou, Zhejiang Province, there exists a unique type of fermented pickled vegetable with a distinctive pungent flavor, commonly known as "fragrant for miles." Its unique taste and flavor have made it a favorite among local consumers. However, as people's living standards improve, consumers have higher expectations for the quality and flavor of pickled vegetables. To enhance the flavor, pickling companies may add extra spices, but this can easily lead to overly complex odors that mask the original taste. Furthermore, artificial food additives such as flavorings and fragrances, crucial components of food processing, are increasingly less accepted by consumers. Low-temperature, slow fermentation can also produce a richer, more mellow, and milder flavor, but the longer fermentation time can lead to excessively high production costs. Flavor is a crucial evaluation indicator for pickled vegetables, and its quality is closely linked to the overall quality of the product. Therefore, how to improve the flavor and quality of pickled vegetables in a healthy and green environment while ensuring cost-effectiveness is a question worthy of research and discussion.

[0006] Microorganisms are a key factor in kimchi fermentation. While bacteria are the primary microorganisms, yeast plays a secondary but crucial role. They typically become active in the mid-to-late stages of fermentation, forming a dynamic interaction with the lactic acid bacteria that dominate the fermentation process. Yeast produces small amounts of gas and organic alcohols, produces lipids, and has a strong ability to utilize reducing sugars, which helps improve the flavor and texture of kimchi, while also adapting to the high-salt, high-acid environment. During fermentation, the physicochemical indicators, sensory and taste characteristics of co-fermentation with yeast and lactic acid bacteria are superior to those of lactic acid bacteria and other bacteria, and it also produces more acid, resulting in kimchi with a better taste. Yeast can also promote the growth and reproduction of certain lactic acid bacteria. Currently, the microbial community structure and fermentation strains of "Qianli Piaoxiang" kimchi are still unclear, making it difficult to control the quality of the kimchi. Kimchi fermentation is a high-salt, high-acid environment, and introduced strains may not necessarily have good fermentation characteristics. The yeast native to kimchi, through long-term natural selection, has stronger environmental adaptability and is more suitable for inoculation and fermentation.

[0007] Therefore, using successfully fermented fragrant kimchi as a sample source, and screening out yeasts with excellent fermentation performance, is of great practical significance for improving the flavor of kimchi and solving the problem of kimchi quality fluctuations caused by differences in spices. (III) Summary of the Invention

[0009] The purpose of this invention is to provide a Hansgrohe Pasteurella 523Y2 strain and its application in improving the quality of fermented kimchi. This strain exhibits excellent fermentation performance, good acid and salt tolerance, and also possesses a certain gas-producing capacity, strong protease activity, and lipid-producing ability. Inoculating kimchi with this strain during fermentation can improve the flavor, aroma, and texture of the kimchi within the same fermentation time, effectively enhancing the quality of the kimchi.

[0010] The technical solution adopted in this invention is:

[0011] This invention provides a Hansgrohe Pasteurella multocida strain ( Debaryomyces hansenii 523Y2, deposited at the China General Microbiological Culture Collection Center on February 2, 2026, with accession number CGMCC No. 39137, address: No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing.

[0012] The Hansgrohe Pasteurella 523Y2 strain of this invention exhibits a colony shape that, when observed with the naked eye, is round, white, moist, smooth, and has neat edges.

[0013] The present invention also provides an application of the Hansgrohe Pasteurella 523Y2 in improving the quality of kimchi, wherein the raw material of the kimchi is mustard greens.

[0014] Furthermore, the application method is as follows: wash and drain the raw materials of fresh kimchi, cut them into pieces of appropriate size and place them in a kimchi jar, add brine with a mass concentration of 2-4%, mix, inoculate with Hansgrohe Pasteurella 523Y2, seal, and ferment at 25-35℃ for 2-4 months (preferably 3 months).

[0015] Furthermore, the volume of brine added is 1-2 mL / g based on the mass of the drained kimchi raw material, preferably 1.2 mL / g; the brine concentration is preferably 3%.

[0016] Furthermore, the Hansgrohe Pasteurella 523Y2 was inoculated as a sterile saline suspension of wet cells at a concentration of 1.0 × 10⁻⁶ cells / mL. 7 -2.0×10 7 The inoculation amount is 1-5 mL / 100g based on the weight of the kimchi raw material, preferably 2 mL / 100g.

[0017] Furthermore, the wet bacterial cells are prepared as follows: Hansgrohe Pasteurella 523Y2 is inoculated onto a PDA solid medium plate, activated and cultured at 25°C for 48 hours, then inoculated into PDB liquid medium and cultured at 28°C for 36 hours. The inoculated medium is then inoculated at a volume concentration of 2% into the PDB liquid medium and cultured at 28°C in a shaker until the OD600nm reaches 1. The culture solution is then centrifuged at 4°C and 5000 rpm for 10 minutes, the supernatant is removed, and the bacterial cells are washed three times with sterile physiological saline. The wet bacterial cells are collected and suspended in an equal volume of sterile physiological saline to prepare a bacterial suspension, which is used as a mother starter for kimchi fermentation.

[0018] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

[0019] For the first time, Hansgrohe Pasteurella 523Y2 was screened from the "Qianlipiaoxiang" kimchi brine. It exhibits good growth performance, strong salt and acid tolerance, and can withstand a salinity of approximately 14%. It can grow in PDB liquid medium at pH 3.5 and demonstrates good fermentation performance.

[0020] After fermentation with Hansgrohe Pasteurella 523Y2 strain, the free amino acid content in kimchi increased by 26.82%. Except for a slight decrease in threonine, the contents of other amino acids remained unchanged or increased. Furthermore, the absolute content of volatile flavor compounds increased significantly, particularly alcohols and sulfur-containing compounds. Among them, (R)-(-)-2-butanol possessed a mild fusel oil aroma and alcoholic fragrance, ethyl octanoate contributed a wine-like aroma, making the kimchi flavor more mellow and rich, and dimethyl disulfide provided a hint of scallion and vegetable aromas. These substances are characteristic flavor compounds of kimchi and play a significant role in its flavor formation. Therefore, Hansgrohe Pasteurella 523Y2 can significantly improve the quality and flavor of kimchi and has good application potential in the fermentation of "Qianli Piaoxiang" kimchi. (iv) Description of the attached drawings

[0022] Figure 1 Colony diagram of strain 523Y2.

[0023] Figure 2 Cell morphology diagram of strain 523Y2.

[0024] Figure 3 Phylogenetic tree of strain 523Y2.

[0025] Figure 4 Growth curve of strain 523Y2.

[0026] Figure 5 Salt tolerance curve of strain 523Y2.

[0027] Figure 6 Acid tolerance curve of strain 523Y2. (V) Detailed Implementation Methods

[0029] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto:

[0030] PDA solid culture medium: 300.0g potato, 20.0g glucose, 20.0g agar, 0.1g chloramphenicol, distilled at 1000mL, sterilized at 121℃ for 20min.

[0031] PDB liquid culture medium: 300.0g potato, 20.0g glucose, 0.1g chloramphenicol, distilled at 1000mL, sterilized at 121℃ for 20min.

[0032] Bengal Red Culture Medium: 5.0g protein, 10.0g glucose, 1.0g potassium dihydrogen phosphate, 0.5g anhydrous magnesium sulfate, 20.0g agar, 0.033g Bengal Red, 0.1g chloromycin, dissolved in 1000mL distilled water, sterilized at 121℃ for 20min.

[0033] In this embodiment of the invention, the mustard stem refers to the stem of the mustard plant near the ground. Brassica juncea (L.)Czern.), an annual herbaceous plant belonging to the genus Brassica in the family Brassicaceae.

[0034] Example 1: Preparation of "Fragrance Spreading for Miles" Pickled Vegetables

[0035] Fresh mustard green stems were washed in running tap water, drained, and cut into appropriate sizes. They were then blanched in boiling water and allowed to cool. 1.2 kg of mustard green stems were weighed and placed in a 3L kimchi jar, along with 1% (by weight of mustard green stems) of chili peppers and 1% (by weight of mustard green stems). A 3% brine solution was added to cover the mustard green stems, the jar was sealed, and the mixture was left to ferment at room temperature (25-30℃) for 3 months. After fermentation, a trained team scored the color, texture, aroma, and taste of the fermented kimchi according to Table 1. Kimchi with a total score greater than 70 was defined as excellent fermented kimchi and used as samples for subsequent bacterial strain isolation.

[0036] Table 1 Scoring Criteria

[0037]

[0038] Example 2: Screening and identification of Hansgrohe Pasteurella multocida 523Y2

[0039] 1. Initial screening:

[0040] The "Qianli Piaoxiang" pickled vegetable liquid screened in Example 1 was serially diluted 10-fold with sterile physiological saline, and 10 μL of the solution was taken. 0 (i.e., the original solution), 10 -2 10 -3 Two dilutions, 100 μL each, were evenly spread onto Bengal Red agar plates using a sterile spreader. After incubation at 28°C for 72 h, typical yeast colonies were picked and repeatedly streaked onto PDA solid agar plates, incubated at 28°C for 72 h, and finally, single colonies were obtained and designated as strains 523Y2, 523Y7, and 523Y16. The samples were then frozen in 20% glycerol.

[0041] 2. Secondary screening:

[0042] (1) Using a sterile inoculation loop, pick up a loopful of bacterial culture from the glycerol tube frozen in step 1 and streak it onto a PDA solid medium plate. After incubating at 28°C for 72 h, pick up a loopful of single colony in a test tube containing PDB liquid medium, mix well, and incubate at 28°C for 48 h. Measure the bacterial density (OD600nm) of the sample at 24 h and 48 h respectively. The results are shown in Table 2.

[0043] (2) Take the activated culture medium after 48 hours of culture in step (1) at an inoculation amount of 2% by volume, adjust the OD600nm to 1 with sterile water, and add it to the PDB liquid culture medium containing the Duchenne duct. Culture at 28℃ for 72 hours. Observe the gas production of the Duchenne duct every 12 hours to make a preliminary judgment on the gas production capacity of the yeast. The results are shown in Table 2.

[0044] (3) Take the activated culture medium after 48h of culture in step (1) and adjust the OD600nm to 1 with sterile water. Spread it evenly on the Bengal Red medium with 1.5% skim milk powder and place it in an incubator at 28℃ for 72h. Observe whether a transparent ring appears around the colony every 24h. The presence of a transparent ring indicates that the strain has protease activity. The results are shown in Table 2.

[0045] (4) Take an inoculum of 2% by volume after 48 hours of culturing in step (1), adjust the OD600nm to 1 with sterile water, and add it to PDB liquid medium. Incubate at 28℃ for 48 hours to obtain the fermentation broth. The total ester content in the fermentation broth was determined by reflux saponification. The specific steps are as follows: Add 4 mL of fermentation broth to a 150 mL Erlenmeyer flask, add 36 mL of ultrapure water, add 2-4 drops of phenolphthalein indicator, titrate with 0.1 mol / L NaOH aqueous solution until a faint red color appears, then accurately add 25 mL of 0.1 mol / L NaOH aqueous solution, reflux saponify in a boiling water bath for 0.5 hours, cool, and immediately titrate with 0.1 mol / L HCl aqueous solution until the red color just disappears. Record the volume of HCl consumed. The results are shown in Table 2.

[0046] Table 2. Fermentation performance test results of each strain

[0047]

[0048] Among them, strain 523Y2 exhibits good growth ability, certain gas production capacity, strong protease activity, and lipid production capacity. Therefore, strain 523Y2 was selected as the optimal fermentation strain.

[0049] 3. Identification of strain 523Y2

[0050] Morphological identification: Strain 523Y2 was streaked onto PDA solid medium plates and incubated at 28°C for 72 h. A loopful of a single colony was then picked and transferred to a test tube containing PDB liquid medium, mixed thoroughly, and incubated at 28°C for 48 h to obtain an activated bacterial solution. 100 μL of the activated bacterial solution was spread onto PDA solid medium plates and incubated at 28°C for 72 h. Colony morphology was observed visually, and cell morphology was observed under a light microscope. The colony and cell morphology of strain 523Y2 are shown below. Figure 1 , Figure 2 As shown, the colonies appear to be round, white, moist, smooth, and with neat edges when observed with the naked eye.

[0051] Molecular identification: The selected strain 523Y2 was inoculated into test tubes containing PDB liquid medium and cultured in a shaker at 28°C for 36 hours. Cells were then harvested. DNA was extracted using a fungal genomic DNA extraction kit. Using this DNA as a template, ITS rDNA amplification was performed using universal fungal primers: forward primer ITS1 5'-TCCGTAGGTGAACCT GCGG-3'; reverse primer ITS4 5'-TCCTCCGCTTATTGAT ATGC-3'. After passing PCR testing, the PCR products were sent to Beijing Qingke Biotechnology Co., Ltd. for sequencing. Homology was compared using BLAST, and a phylogenetic tree was constructed using MEGA10.0. Figure 3 As shown.

[0052] The ITS rDNA sequence (SEQ ID NO.1) was introduced into NCBI for BLAST homology comparison. The results showed that strain 523Y2 was similar to *Pasteurella multocida*. Debaryomyces hansenii The similarity reached 99.84%. Based on morphological characteristics, strain 523Y2 was identified as... Debaryomyces hansenii It was named Hansgrohe Pasteurella ( Debaryomyces hansenii 523Y2, deposited at the China General Microbiological Culture Collection Center (CGMCC) on February 2, 2026, with accession number CGMCC No. 39137, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing.

[0053] ITS rDNA sequence of strain 523Y2:

[0054] .

[0055] Example 3: Fermentation performance test of strain 523Y2

[0056] 1. Growth curve determination

[0057] Growth capacity is an important parameter for evaluating fermentation strains, and growth curves can provide a direct understanding of the growth patterns of the bacteria.

[0058] Strain strain 523Y2 was inoculated onto PDA solid medium plates and activated at 28°C for 72 hours. Then, it was inoculated into PDB liquid medium and incubated at 28°C for 36 hours. Finally, it was inoculated into PDB liquid medium at a 2% (v / v) inoculum concentration and incubated on a shaker at 28°C for 48 hours. Samples were taken every 2 hours during the incubation period to determine the bacterial density (OD600nm). The results are as follows: Figure 4 As shown.

[0059] Depend on Figure 4It can be seen that from 0 to 16 hours, strain 523Y2 was in the lag phase, with slow growth; after 16 hours, it entered the logarithmic growth phase, with rapid increase in cell number; after 28 hours, growth slowed down, and it began to enter the stationary phase. Therefore, strain 523Y2 has good growth ability.

[0060] 2. Salt tolerance

[0061] Strain strain 523Y2 was inoculated onto PDA solid medium plates and activated at 28°C for 72 h. Then, it was inoculated into PDB liquid medium and incubated at 28°C for 36 h. Finally, it was inoculated at a 2% (v / v) inoculum into PDB liquid medium supplemented with 0%, 2%, 4%, 6%, 8%, 10%, 12%, and 14% NaCl (i.e., salt concentrations) and incubated at 28°C for 48 h. The OD600nm value of the bacterial culture was measured, and the results are as follows: Figure 5 As shown.

[0062] Depend on Figure 5 It can be seen that strain 523Y2 is less inhibited when the salt concentration is between 2% and 6%; when the salt concentration is increased to 8%, the OD600nm is around 0.77; and when the salt concentration is increased to above 8%, strain 523Y2 is significantly inhibited, but still grows. This indicates that strain 523Y2 has strong salt tolerance, and can grow slowly even at a salt concentration of 14%.

[0063] 3. Acid resistance

[0064] Strain 523Y2 was inoculated onto PDA solid medium plates and activated at 28°C for 72 h. Then, it was inoculated into PDB liquid medium and incubated at 28°C for 36 h. Finally, it was inoculated at a volume concentration of 2% into PDB liquid media at pH 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, and 6.0, and incubated on a shaker at 28°C for 48 h. The bacterial density (OD600nm) of each culture was then measured. The results are as follows: Figure 6 As shown.

[0065] Depend on Figure 6 It can be seen that when the pH is less than 3.0, strain 523Y2 can hardly grow normally; when the pH rises to 4, the OD600nm is around 0.54; when the pH rises to 5, strain 523Y2 is less inhibited; and when the pH rises above 5.5, strain 523Y2 can grow normally. This indicates that strain 523Y2 has strong acid resistance and can grow slowly at a pH of 3.5.

[0066] Example 4: Wet mycelium of strain 523Y2

[0067] Strain strain 523Y2 was inoculated onto PDA solid medium plates and activated at 28°C for 72 h. Then, it was inoculated into PDB liquid medium and incubated at 28°C for 36 h. Next, it was inoculated into PDB liquid medium at a 2% (v / v) inoculum concentration and incubated at 28°C on a shaker until the OD600nm value reached 1. The culture was then centrifuged at 4°C and 5000 rpm for 10 min, the supernatant was discarded, and the cells were washed three times with sterile physiological saline. The wet cells were collected and finally resuspended in an equal volume of sterile physiological saline to prepare a bacterial suspension with a cell concentration of 1.0 × 10⁻⁶. 7 CFU / mL, used as a starter culture for kimchi fermentation.

[0068] Example 5: Application of Hansgrohe Pasteurella 523Y2 in the fermentation of mustard stems

[0069] 1. Preparation of pickled vegetables: Wash and drain fresh mustard stems, cut them into appropriately sized pieces, and place them in a pickling jar. Add 3% brine at a ratio of 1g:1.2mL, mix, and inoculate with the bacterial suspension prepared in Example 4 (1.0×10⁻⁶) at a ratio of 100g mustard weight to 2mL bacterial suspension volume. 7 The experimental group consisted of CFU / mL, while the uninoculated natural fermentation group served as the blank control group. After sealing, the mixture was fermented at 25-35℃ for 3 months.

[0070] 2. pH Measurement of Kimchi: The finished kimchi fermentation liquid was taken and measured directly using a pH meter. The kimchi inoculated with Hansgrohe Pasteurella 523Y2 had a pH of 6.23 after fermentation, which was not significantly different from naturally fermented kimchi (pH=6.2). Generally, kimchi is considered mature when the pH of the fermentation liquid is less than 4.0, but a small amount of kimchi may have a pH greater than 4.0 due to different production processes and fermentation microorganisms. Qianli Piaoxiang kimchi, compared to ordinary kimchi, has a higher pH and a weaker or even no sour taste. This also indicates that inoculating with Hansgrohe Pasteurella 523Y2 does not change the type and characteristics of the kimchi.

[0071] 3. Determination of total acidity in kimchi: Accurately measure 10 mL of fermentation broth and add it to a 100 mL volumetric flask. Add water to the mark and mix well. Filter with filter paper or absorbent cotton and reserve the filtrate. Accurately pipette 25 mL of the filtrate into a 100 mL Erlenmeyer flask, add a few drops of phenolphthalein indicator, and titrate with 0.1 mol / L sodium hydroxide aqueous solution until a pink color initially appears and does not fade within 0.5 min, which is the endpoint. Record the titration volume of sodium hydroxide aqueous solution consumed. The total acid content in the sample is expressed as lactic acid, in grams per liter (g / L).

[0072] The total acid content of kimchi inoculated with Hansgrohe Pasteurella 523Y2 was 1.2 g / L after fermentation, which was slightly higher than that of the naturally fermented group (0.64 g / L).

[0073] 4. Determination of amino acid content: Centrifuge 1 mL of fermentation broth at 12000 r / min for 10 min at 4℃, and then filter through a 0.22 μm filter membrane. Analyze the filtrate using an automated amino acid analyzer to determine the free amino acid content. The free amino acid content is expressed in mg / L, and the results are shown in Table 3.

[0074] Table 3. Types and contents of amino acids in kimchi

[0075]

[0076] The types and content of free amino acids in kimchi directly affect its flavor. As shown in Table 3, a total of 13 amino acids were found in kimchi. Among them, aspartic acid and glutamic acid are umami amino acids and are the main sources of umami flavor in kimchi. The aspartic acid content in kimchi fermented with Hansgrohe Pasteurella 523Y2 was higher than that in naturally fermented kimchi, indicating that inoculation with Hansgrohe Pasteurella 523Y2 helps to improve the umami flavor of kimchi. Meanwhile, except for a slight decrease in threonine content, the contents of glutamic acid, cysteine, tyrosine, lysine, and proline remained basically unchanged, while the contents of other amino acids increased. Overall, the free amino acid content increased by 26.82% after inoculation with Hansgrohe Pasteurella 523Y2, which helps to improve the overall flavor of kimchi.

[0077] 5. Sensory Evaluation: A sensory evaluation team composed of trained members from the kimchi factory scored the color, texture, aroma, and taste of the fermented kimchi with different treatments according to the sensory scoring criteria in Table 1. Due to differences in kimchi production processes and fermentation microorganisms, the sensory scoring criteria differed significantly from those of most other kimchi products, as shown in Table 4.

[0078] Table 4 Sensory Scores of Kimchi

[0079]

[0080] Kimchi inoculated with Hansgrohe Pasteurella 523Y2 did not show significant differences in color compared to naturally fermented kimchi, but its scores in texture, aroma, and taste were significantly higher, and its overall sensory score was also significantly higher. This indicates that Hansgrohe Pasteurella 523Y2 can significantly improve the sensory quality of kimchi.

[0081] 6. Determination of volatile flavor compounds in kimchi: Take 2g of fermentation broth and add it to a 20mL headspace vial, along with 0.72g of NaCl and 100μL of 0.6mg / mL methyl octanoate aqueous solution (as internal standard). Use a GC-MS system to detect volatile flavor compounds. First, the CDVB / CAR / PDMS fiber head is adsorbed in the headspace vial at 40℃ for 30min, then inserted into the GC-MS injection port for desorption at 250℃ for 5min. Split ratio: 40:1, carrier gas: He, flow rate: 1mL / min.

[0082] Use a chromatographic column equipped with a DB-5MS column (30m) 0.25mm Volatile compounds were separated and detected using a GC-MS system with a sample size of 0.25 μm. The temperature program was as follows: 40 °C (1 min) to 76 °C (hold for 1 min) at 4 °C / min, 94 °C (hold for 1 min) at 2 °C / min, 114 °C (hold for 1 min) at 4 °C / min, 150 °C (hold for 1 min) at 5 °C / min, and 230 °C (hold for 5 min) at 10 °C / min. The injection temperature was 250 °C, and the mass spectrometry conditions were full scan acquisition mode, electron impact ionization (EI) source, electron energy 70 eV, ion source temperature 200 °C, quadrupole temperature 150 °C, and mass scan range m / z 29–650.

[0083] The results of the determination of volatile flavor compounds in fermented kimchi made with Hansgrohe Pasteurella 523Y2 are shown in Table 5.

[0084] Table 5. Types and relative contents of volatile components in kimchi

[0085]

[0086] The results showed that 19 volatile compounds were detected in kimchi fermented with Hansgrohe Pasteurella multocida 523Y2, compared to 21 in naturally fermented kimchi, mainly esters, sulfur-containing compounds, and alcohols. While the quantity and types of volatile flavor compounds were highly consistent between the two types, the content of these compounds was significantly increased in kimchi fermented with Hansgrohe Pasteurella multocida 523Y2. The most significant increase among alcohols was in (R)-(-)-2-butanol, which has a mild fusel oil flavor and alcoholic aroma. The increase in alcohol content enhanced the wine, floral, and rose aromas in the kimchi. Among esters, ethyl octanoate significantly increased, contributing a wine-like aroma and making the kimchi flavor more mellow and rich. Sulfur compounds play an important role in the flavor of fermented vegetables and are a major source of kimchi flavor. Inoculation fermentation can increase the content of sulfur-containing compounds, especially dimethyl disulfide, which can provide the kimchi with onion and vegetable aromas. Simultaneously, the content of octanoic acid also increased significantly, enhancing the characteristic flavor of the kimchi.

Claims

1. Hansgrohe Pasteurella multocida ( Debaryomyces hansenii 523Y2 is deposited at the China General Microbiological Culture Collection Center on February 2, 2026, with accession number CGMCC No. 39137.

2. The application of the Hansgrohe Pasteurella 523Y2 strain as described in claim 1 in improving the quality of kimchi.

3. The application as described in claim 2, characterized in that, The raw material for the pickled vegetables is mustard greens.

4. The application as described in claim 3, characterized in that, The application method is as follows: Wash and drain the fresh kimchi raw materials, cut them into pieces of appropriate size, place them in a kimchi jar, add brine with a mass concentration of 2-4%, mix, inoculate with Hansgrohe Pasteurella 523Y2, seal, and ferment at 25-35℃ for 2-4 months.

5. The application as described in claim 4, characterized in that, The amount of brine added is 1-2 mL / g based on the weight of the drained kimchi raw materials.

6. The application as described in claim 4, characterized in that, The *Pasteurella multocida* 523Y2 strain was inoculated as a sterile saline suspension of wet cells at a concentration of 1.0 × 10⁻⁶ cells / mL. 7 -2.0×10 7 CFU / mL, the inoculation amount is 1-5 mL / 100g based on the weight of the kimchi raw material.

7. The application as described in claim 4, characterized in that, The wet bacterial cells were prepared as follows: Hansgrohe Pasteurella 523Y2 was inoculated onto a PDA solid medium plate and activated at 25°C for 48 hours. Then, it was inoculated into PDB liquid medium and cultured at 28°C for 36 hours. The inoculation was then carried out at a volume concentration of 2% into the PDB liquid medium and cultured at 28°C in a shaker until the OD600nm reached 1. The culture solution was centrifuged at 4°C and 5000 rpm for 10 minutes, the supernatant was removed, and the bacterial cells were washed three times with sterile physiological saline. The wet bacterial cells were collected and suspended in sterile physiological saline to prepare a bacterial suspension.

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