Lactobacillus plantarum MA1 and application thereof in fermentation of low-salt yellow lantern chilli sauce

Abstract

The invention provides lactobacillus plantarum MA1 and application thereof in fermentation of low-salt yellow lantern chilli sauce. The lactobacillus plantarum MA1 is preserved in the Guangdong Microbial Culture Collection Center GDMCC on July 4, 2025, the preservation address is the 5th floor of the building 59, No. 100 Courtyard, Xianlie Middle Road, Guangzhou, the preservation number is GDMCC No: 66640, and the lactobacillus plantarum MA1 is classified and named as Lactiplantibacillus plantarum. The method has both technical innovation and industrial universality, synchronously realizes flavor jump, safety enhancement and process standardization under the low-salt condition for the first time, and provides a reusable solution for the salt reduction technology of the fermented condiment.

Description

Technical Field

[0001] This invention belongs to the field of microbial fermentation technology and relates to Lactobacillus plantarum MA1 and its application in the fermentation of low-salt yellow lantern chili sauce. Background Technology

[0002] Hainan Yellow Lantern Chili (Capsicum chinense), also known as Emperor Chili or Yellow Chili, is a herbaceous plant belonging to the genus Capsicum in the Solanaceae family. It is a rare and unique local chili variety endemic to Hainan Province. It is highly branched, with alternate, simple leaves that are entire or slightly wavy. The fruit hangs downwards, resembling a lantern. Hainan Yellow Lantern Chili is rich in nutrients, containing not only essential minerals such as phosphorus, calcium, and iron, but also various amino acids, proteins, and high levels of fiber. Rich in capsaicin, its fruit is spicy, beautiful in color, and has a distinctive aroma. It is generally not eaten directly but is chopped, pickled, and fermented to make Yellow Lantern Chili Sauce, primarily used as a condiment in Hainan Province. Traditional Hainan Yellow Lantern Chili Sauce relies on an open-air natural fermentation process. The method involves washing and drying the Yellow Lantern Chili, removing the stems, chopping it, mixing it with salt and other ingredients, and then bottling it for natural fermentation. This process has three inherent defects: the amount of salt added is highly arbitrary (usually >10%), resulting in excessively high salinity of the product and significant batch-to-batch quality fluctuations; the fermentation process is uncontrollable, the open environment is susceptible to contamination by miscellaneous bacteria, the risk of nitrite accumulation is increased, and the formation of key flavor substances is unstable, especially ester aroma components (such as ethyl acetate for fruit aromas) are easily inhibited by salinity, which greatly hinders the development of the industry.

[0003] The food industry is currently actively promoting technological upgrades that "reduce salt without sacrificing flavor." Studies show that when salt content exceeds 10%, the content of ethyl acetate, a core flavor compound in yellow lantern chili sauce, drops sharply by more than 85% (from 83.95 mg / kg to <6 mg / kg), directly weakening the product's fruity aroma. While existing low-salt fermentation technologies (salt addition ≤8%) can reduce the product's saltiness, they still carry the risk of microbial proliferation, producing harmful metabolites such as biogenic amines, or excessive accumulation of carboxylic acids, which can easily produce a putrid odor and reduce palatability. Furthermore, commercial bacterial strains have poor metabolic adaptability to the unique substrates of yellow lantern chili (such as high capsaicin and special glycoside precursors), resulting in low colonization efficiency and insufficient flavor transformation after inoculation. Therefore, developing low-salt, high-quality fermentation technology has become an urgent need for the upgrading of the yellow lantern chili sauce industry. Summary of the Invention

[0004] Based on the above technical problems, the purpose of this invention is to provide Plant Lactobacillus MA1 and its application in the fermentation of low-salt yellow lantern chili sauce.

[0005] The technical solution adopted by this invention to achieve its technical objectives is as follows:

[0006] This invention provides Lactiplantibacillus plantarum MA1, which was deposited on July 4, 2025 at the Guangdong Provincial Microbial Culture Collection Center (GDMCC), located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, with accession number GDMCC No: 66640 and classification name: Lactiplantibacillus plantarum.

[0007] This invention also provides the application of the above-mentioned Lactobacillus plantarum MA1 in the fermentation of low-salt yellow lantern chili sauce.

[0008] Preferably, the plant lactobacillus MA1 is used for low-salt yellow lantern chili sauce fermentation at a salinity of ≤5%.

[0009] More preferably, the *Lactobacillus plantarum* MA1 has a relative abundance of >34.73% under low-salt conditions, making it the absolutely dominant bacterial group and able to inhibit contamination by other bacteria.

[0010] Preferably, the inoculum amount of *Lactobacillus plantarum* MA1 is 5%, the fermentation temperature is 25-35℃, and the fermentation time is 5 days.

[0011] This invention also provides a fermentation process for low-salt yellow lantern chili sauce, comprising: crushing fresh yellow lantern chilies, adding 5% edible salt and 10% rice wine by mass ratio, inoculating with a 5% suspension of Lactobacillus plantarum MA1, stirring evenly, sealing and bottling, and fermenting at 25-35℃ for 5 days to obtain low-salt yellow lantern chili sauce.

[0012] Preferably, the alcohol content of the rice wine is 26% v / v.

[0013] Preferably, the bacterial suspension has an OD600 of 0.5.

[0014] The present invention also provides a low-salt yellow lantern chili sauce, which is prepared by the above-mentioned fermentation process.

[0015] Preferably, the low-salt yellow lantern chili sauce contains esters accounting for >61.5%, ethyl hexanoate >8 mg / kg, nitrite content <1.9 mg / kg, and lactic acid >1500 mg / 100g.

[0016] The main innovative points of this invention include:

[0017] 1) Development of specific functional strains: Lactiplantibacillusplantarum MA1 was isolated and obtained. This strain showed specific adaptation ability to yellow lantern pepper matrix at ≤5% salinity, with a relative abundance of >34.73%, and was strongly positively correlated with the synthesis of 20 flavor substances. Inoculation of yellow lantern pepper fermentation process with lactic acid bacteria.

[0018] (ii) Targeted regulation of low salt and high ester: Through MA1 inoculation and fermentation, lactic acid production was increased by 180% (1646.84mg / 100g vs 589.39mg / 100g) under salinity ≤5%, and the proportion of esters was >61.5%, of which ethyl hexanoate was >8mg / kg, effectively solving the defect of insufficient fruit aroma in low salt fermentation.

[0019] (iii) Targeted inhibition of pathogenic bacteria: MA1 inhibits Klebsiella pneumoniae through niche competition, ensuring the safety of low-salt fermentation.

[0020] (iv) Process standardization system: Establish a combination of parameters for salt addition, inoculation amount, and temperature to form a quality control standard with the content of characteristic flavor substances as the indicator.

[0021] The beneficial effects of the present invention are:

[0022] This invention achieves a breakthrough in low-salt, high-ester fermentation, solving the fundamental defects of traditional processes. The amount of salt added is reduced by more than 70%, and the nitrite content of the product is stable at <1.9mg / kg (compliant with GB 2762-2022 standard), completely solving the health risks and excessive saltiness caused by high salt content.

[0023] The open-ended fermentation was transformed into a directed and controllable process. The relative abundance of strain MA1 in a low-salt environment was >34.73% (compared to <5% in the control group during natural fermentation), forming an absolutely dominant microbial community, inhibiting contamination by other microorganisms, and increasing the fermentation success rate from less than 60% to 98%.

[0024] Targeted enhancement of key flavor compounds and reshaping the flavor characteristics of low-salt products: After inoculation with MA1 fermentation, the proportion of ester compounds reached 61.5% (NF in the naturally fermented group was only 18.1%), ethyl hexanoate was >8mg / kg, the overall sensory score was better than that of the inoculated fermentation group, and palatability was significantly improved.

[0025] Through process standardization and efficiency improvement, MA1 inoculation fermentation reaches its peak flavor (1646.84 mg / 100g lactic acid yield) in 5 days (D5) at 25-35℃, while traditional natural fermentation requires 10-15 days. Quantitative quality control standards have been established, with ethyl hexanoate content >8 mg / kg and lactic acid >1500 mg / 100g as core indicators, to achieve precise flavor control.

[0026] This invention combines technological innovation with industrial applicability, achieving for the first time a simultaneous improvement in flavor, enhanced safety, and standardized process under low-salt conditions, providing a reusable solution for salt reduction technology in fermented condiments. Attached Figure Description

[0027] Figure 1 Composition and relative abundance of microbial strains in yellow lantern chili sauce at different salt addition levels.

[0028] Figure 2 Gram-stained microscopic image of Lactobacillus plantarum MA1.

[0029] Figure 3 Phylogenetic tree of Lactobacillus plantarum MA1.

[0030] Figure 4 Changes in nitrite content in fermented yellow lantern chili sauce in the naturally fermented group (NF) and the inoculated fermented group (IF).

[0031] Figure 5 Changes in volatile flavor components of fermented yellow lantern chili sauce in the naturally fermented (NF) and inoculated fermented (IF) groups.

[0032] Figure 6 Sensory evaluation analysis of fermented yellow lantern chili sauce in the natural fermentation group (NF) and inoculated fermentation group (IF). Detailed Implementation

[0033] The present invention will now be described in detail with reference to specific embodiments. The following specific embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way.

[0034] Example

[0035] (1) Design of experimental and control groups

[0036] Inoculation and Fermentation Group (Experimental Group): Lactiplantibacillus plantarum MA1 was activated to prepare a bacterial suspension. Fresh yellow lantern peppers were crushed, and 5% of the bacterial suspension, 5% of edible salt, and 10% Hainan traditional rice wine (26% v / v) were added at the specified mass ratio. After thorough mixing, the mixture was sealed and bottled. Fermentation was carried out at a constant temperature of 30℃ in the dark. IF indicates the experimental group; IF0, IF5, IF10, IF15, and IF20 represent the sample names on days 0, 5, 10, 15, and 20 of fermentation, respectively.

[0037] Natural fermentation group (control group): Fresh yellow lantern peppers were crushed and mixed with 5% edible salt and 10% Hainan traditional rice wine (26% v / v) by weight. The mixture was then sealed and bottled. Fermentation was carried out at a constant temperature of 30℃ in the dark. NF represents the control group, and NF0, NF5, NF10, NF15, and NF20 represent the sample names on days 0, 5, 10, 15, and 20 of fermentation, respectively.

[0038] (2) Index Measurement

[0039] The nitrite content was determined according to the method of GB / T 5009.33-2016; the organic acid was determined by high performance liquid chromatography; the volatile components of Huangdenglong chili sauce were analyzed by gas chromatography-mass spectrometry (GC-MS); and a sensory evaluation panel was organized to evaluate the four core indicators of Huangdenglong chili sauce: color, flavor, texture and taste.

[0040] I. Effects of different salt addition amounts on the microbial community structure of naturally fermented YCS (Yellow Lantern Chili Sauce)

[0041] Fresh yellow lantern peppers were crushed and then mixed with different percentages of edible salt and 10% Hainan traditional rice wine (26% v / v). The mixture was stirred thoroughly and then sealed in jars. Fermentation was carried out for 5 days at a constant temperature of 30℃ in the dark. SP0, SP5, SP10, SP15, and SP20 represent samples with salt additions of 0%, 5%, 10%, 15%, and 20%, respectively.

[0042] like Figure 1 As shown, among the yellow lantern chili sauce samples with different salt additions, the relative abundance of *Klebsiella michiganensis* in SP10 was 9.12%, indicating that it began to exhibit salt tolerance in the community. *Klebsiella michiganensis* was the dominant species in both SP15 and SP20, with relative abundances of 15.33% and 4.39%, respectively. This indicates that *Klebsiella michiganensis* can not only survive normally in high-salt (salt content greater than 10%) fermentation environments but can also become a dominant species. The main dominant species in SP5 were *Lactobacillus plantarum* and *Companilactobacillus farciminis*, with relative abundances of 34.73% and 7.74%, respectively, while the relative abundance of *Klebsiella michiganensis* was 0.12%. The probiotics inhibited *Klebsiella michiganensis* through niche competition, ensuring the safety of low-salt fermentation.

[0043] A correlation analysis was conducted between key flavor compounds and core microorganisms in Yellow Lantern Chili Sauce. Lactiplantibacillus plantarum showed a strong positive correlation with 20 flavor compounds, including ethyl acetate, hexyl acetate, acetic acid, isoamyl acetate, amyl acetate, propyl acetate, diethyl succinate, 3-mercaptohexyl acetate, ethyl 3-phenylpropionate, ethyl 2-hydroxy-4-methylvalerate, 1-octen-3-one, and 2,3-butanedione.

[0044] II. Isolation and Identification of Functional Strains

[0045] The core bacterial strain *Lactiplantibacillus plantarum* was isolated and screened from yellow lantern chili sauce to obtain the specific functional strain *Lactiplantibacillus plantarum* MA1. This strain exhibited specific adaptation ability to the yellow lantern chili sauce matrix at ≤5% salinity. Gram staining microscopic images and phylogenetic trees of *Lactiplantibacillus plantarum* MA1 are shown below. Figure 2 and Figure 3 .like Figure 2 As shown, after Gram staining, *Lactobacillus plantarum* MA1 appears purple under a microscope, indicating it is a Gram-positive bacterium; the bacteria are rod-shaped, small, and arranged in short chains.

[0046] Lactiplantibacillus plantarum MA1 was deposited on July 4, 2025, at the Guangdong Provincial Microbial Culture Collection Center (GDMCC), located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, with accession number GDMCC No: 66640 and classification name: Lactiplantibacillus plantarum.

[0047] III. Fermentation Process of Low-Salt Yellow Lantern Chili Sauce

[0048] Lactiplantibacillus plantarum MA1, isolated and preserved in our laboratory, was used as the core functional strain. Seed culture was prepared by activation and propagation on MRS liquid medium. Before use, the bacterial culture preservation tube was removed and slowly thawed. Activation: In a sterile laminar flow hood, 100 μL of the thawed bacterial culture was inoculated into a test tube containing 10 mL of sterile MRS liquid medium and incubated at 37°C for 24 h (first generation). Propagation: The first generation culture was transferred at a 2% (v / v) inoculation rate to a 500 mL Erlenmeyer flask containing 100 mL of sterile MRS medium and incubated at 37°C for 18-24 h (second generation). Seed culture preparation: The second generation culture was then transferred at a 2% (v / v) inoculation rate to a 1000 mL Erlenmeyer flask containing 500 mL of sterile MRS medium and incubated at 37°C for 16-18 h. The culture medium is centrifuged to remove the liquid culture medium, and then the bacterial precipitate is diluted with sterile water (OD600 = 0.5) to obtain the seed culture.

[0049] Fresh yellow lantern chilies are crushed using a crusher, then 5% edible salt and 10% Hainan traditional rice wine (26% v / v alcohol) are added by weight. A 5% (w / w) bacterial suspension (OD600 = 0.5) is inoculated, and the mixture is stirred thoroughly before sealing and bottling. Fermentation is carried out at 30℃ for 5 days to obtain low-salt yellow lantern chili sauce. The fermentation temperature can be between 25 and 35℃. IV. Changes in nitrite content in fermented yellow lantern chili sauce.

[0050] like Figure 4 As shown, the nitrite content in the naturally fermented group (NF) remained relatively stable throughout the fermentation process, starting at 3.09 mg / kg on day 0, then slowly rising to 3.52 mg / kg on day 5, before slowly decreasing to 2.97 mg / kg. Overall, the fluctuations were small, indicating a dynamic equilibrium between nitrite formation and degradation in the naturally fermented group. The initial nitrite content in the inoculated fermentation group (IF) was 3.13 mg / kg, similar to that of the naturally fermented group (NF), but it rapidly decreased to 1.33 mg / kg on day 5, a significant drop, reaching its lowest value of 0.56 mg / kg on day 15. After the start of fermentation, the nitrite content in the inoculated fermentation group (IF) was consistently significantly lower than that in NF. This suggests that fermentation with *Lactobacillus plantarum* MA1 has a significant effect on nitrite degradation, possibly related to its enhanced metabolic activity or the production of nitrite reductase. In contrast, the naturally fermented group relied solely on the metabolism of environmental microorganisms, resulting in lower nitrite removal efficiency. Inoculation fermentation process shows a significant advantage in controlling nitrite accumulation, especially in key fermentation stages (such as D15), where it can significantly reduce the accumulation of this substance and ensure food safety.

[0051] V. Changes in volatile flavor components of fermented yellow lantern chili sauce

[0052] The volatile components of the naturally fermented (NF) and inoculated fermented (IF) groups were analyzed using gas chromatography-mass spectrometry (GC-MS). The results are as follows: Figure 5As shown, comparing the two fermentation methods, the content of volatile aroma compounds in Hainan Yellow Lantern Chili Sauce inoculated with *Lactobacillus plantarum* MA1 significantly increased after fermentation. In the inoculated fermentation group, the content of most ester compounds was generally higher than that in the naturally fermented group at all fermentation time points, with ethyl hexanoate and ethyl isovalerate showing particularly significant increases. 4-Methylpentyl isovalerate, as the main lipid compound, had a relative content higher than 50 mg / kg in the inoculated fermentation group, reaching a peak of 64.91 mg / kg on day 15 of fermentation. In contrast, the content of 4-methylpentyl isovalerate in the naturally fermented group was consistently below 31 mg / kg, showing a significant difference. Furthermore, the relative content of ethyl hexanoate in the inoculated fermentation group was consistently higher than 8 mg / kg throughout the entire process, while it was consistently lower than 0.2 mg / kg in the naturally fermented group. The relative content of ethyl isovalerate in the inoculated fermentation group was also higher than that in the naturally fermented group. Ethyl hexanoate and ethyl isovalerate, as important ester compounds, synergistically contribute to the sweet fruity base of the sample.

[0053] VI. Quality Standards for Fermented Yellow Lantern Chili Sauce

[0054] Ethyl hexanoate is the main flavor component of strong-aroma baijiu, with unique fruit and pineapple aromas. Lactic acid is a characteristic product of lactic acid bacteria fermentation. Therefore, based on these two substances, a quantitative quality control standard is established, with ethyl hexanoate content >8mg / kg and lactic acid content >1500mg / 100g as the core indicators to achieve precise flavor control.

[0055] This process achieves product quality in 5 days that would normally take 10 days to ferment, thus shortening the fermentation time.

[0056]

[0057] VII. Sensory Evaluation and Analysis of Fermented Yellow Lantern Chili Sauce

[0058] Sensory changes in the naturally fermented (NF) and inoculated (IF) groups of yellow lantern peppers at different fermentation stages were analyzed, and the results are as follows: Figure 6 As shown in the diagram, in the initial stage (D0), the sensory scores of the two groups were similar. However, as fermentation progressed, the IF group outperformed the NF group in both aroma and taste. During fermentation from D5 to D15, NF outperformed IF in color and texture. Throughout the entire fermentation process, the IF group consistently scored higher than the NF group. Overall, the inoculated fermentation group demonstrated a more stable sensory advantage in the later stages of fermentation by enhancing aroma and taste.

[0059] Obviously, the above embodiments of the present invention are merely examples to illustrate the present invention more clearly, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all implementation methods here. Any obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. Lactiplantibacillus plantarum MA1, which was deposited on July 4, 2025 at the Guangdong Provincial Microbial Culture Collection Center (GDMCC), located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, with accession number GDMCC No: 66640 and classification name: Lactiplantibacillus plantarum.

2. The application of *Lactobacillus plantarum* MA1 as described in claim 1 in the fermentation of low-salt yellow lantern chili sauce.

3. The application according to claim 2, characterized in that, The plant lactobacillus MA1 was used to ferment low-salt yellow lantern chili sauce at a salinity of ≤5%.

4. The application according to claim 3, characterized in that, The plant lactobacillus MA1 has a relative abundance of >34.73% under low-salt conditions, making it the absolutely dominant bacterial group and able to inhibit contamination by other bacteria.

5. The application according to claim 2 or 3, characterized in that, The inoculum size of *Lactobacillus plantarum* MA1 was 5%; the fermentation temperature was 25–35°C; and the fermentation time was 5 days.

6. A fermentation process for a low-salt yellow lantern chili sauce, comprising: Fresh yellow lantern peppers are crushed, and 5% edible salt and 10% rice wine are added by weight. A bacterial suspension of 5% Lactobacillus plantarum MA1 is inoculated, stirred evenly, and then sealed and bottled. Fermentation is carried out at 25-35℃ for 5 days to obtain low-salt yellow lantern pepper sauce.

7. The fermentation process according to claim 6, characterized in that, The rice wine has an alcohol content of 26% v / v.

8. The fermentation process according to claim 6, characterized in that, The bacterial suspension has an OD600 of 0.

5.

9. A low-salt yellow lantern chili sauce, prepared by the fermentation process described in any one of claims 6 to 8.

10. The low-salt yellow lantern chili sauce according to claim 9, characterized in that, The low-salt yellow lantern chili sauce contains esters accounting for >61.5%, ethyl hexanoate >8mg / kg, nitrite content <1.9mg / kg, and lactic acid >1500mg / 100g.

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