Lactic acid bacteria product, preparation method thereof and application in food preservation

Abstract

The present invention relates to a lactic acid bacteria product, a preparation method thereof, and an application thereof in food preservation. The lactic acid bacteria product comprises fermentation metabolites obtained by co-fermentation of Lactobacillus plantarum, Lactobacillus delbrueckii subsp. lactis, and Streptococcus salivarius thermophilus subsp., and a plant extract. By combining the lactobacillus and Streptococcus salivarius thermophilus subsp. in a scientific ratio and adding the plant extract with natural antibacterial effect, the antibacterial efficacy is synergistically improved, the preservation effect is enhanced, and the nutritional value of the food is improved, thereby increasing the probiotic function.

Description

Technical Field

[0001] The present invention belongs to the technical field of microbial fermentation, and in particular relates to a lactic acid bacteria product, a preparation method thereof, and an application thereof in food preservation. Background Art

[0002] During production, transportation, and storage, food is susceptible to environmental influences and can spoil, leading to foodborne illnesses and food poisoning. Furthermore, food spoilage wastes resources and causes significant economic losses worldwide. Therefore, adding appropriate preservatives to food has become an essential process to extend its shelf life and ensure its quality.

[0003] Currently, chemical preservatives are widely used in the food processing industry to preserve and maintain food. However, chemical preservatives have numerous drawbacks, and the use of many preservatives is subject to certain restrictions. Natural biological preservative technology uses natural organisms and their metabolites as core raw materials, inhibiting the growth of microorganisms by adding them directly or after extraction, fermentation, enzymatic conversion, or other treatments. Lactic acid bacteria are recognized as safe food-grade microorganisms. Lactic acid bacteria and their metabolites can not only inhibit the growth of pathogenic bacteria and extend the shelf life of products, but also have beneficial functions such as lowering blood lipids, regulating human immunity, and adjusting the gastrointestinal tract, and have broad application prospects.

[0004] Due to their abundant availability and low cost, plant extracts contain a rich array of chemical components, including phenols, flavonoids, aldehydes, and volatile oils. These substances not only achieve a preservative effect by disrupting cell walls and membranes, inhibiting protein function, binding to genetic material, and suppressing cellular respiration, but also have health benefits such as lowering blood lipids and blood pressure, anti-aging, and tumor prevention. Reports indicate that plant-based preservatives are already being used in a variety of foods, including animal, aquatic, plant-based, and flour-based foods.

[0005] However, the current natural biological preservation technology still has problems such as complicated fermentation technology, single antibacterial substance, narrow antibacterial spectrum and limited application scope. Summary of the Invention

[0006] The present invention addresses the challenges of current natural biological preservation technologies, including complex fermentation techniques, a single antibacterial substance, a narrow antibacterial spectrum, and limited application. The present invention provides a lactic acid bacteria product, a preparation method thereof, and its application in food preservation. The lactic acid bacteria product of the present invention is simple to prepare, and the antibacterial substances act synergistically to enhance antibacterial efficacy and maintain freshness. It also improves the nutritional value of food and enhances its probiotic properties, resulting in a wide range of applications.

[0007] Specifically, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides a lactic acid bacteria product, characterized in that the lactic acid bacteria product comprises fermentation metabolites of Lactobacillus plantarum, Lactobacillus delbrueckii subsp. lactis and Streptococcus salivarius subsp. thermophilus, and a plant extract.

[0009] Preferably, the lactic acid bacteria product is characterized in that the Lactobacillus plantarum is Lactobacillus plantarum Ali.Plateau.LP.VIII strain, which is deposited in the China Center for Type Culture Collection (CCTCC) with a deposit number of CCTCC NO: M 2022068;

[0010] The Lactobacillus delbrueckii subsp. lactis is the Dangxiong LBⅧ strain of Lactobacillus delbrueckii subsp. lactis, which is deposited in the China Center for Type Culture Collection (CCTCC) with a deposit number of CCTCC NO: M 2023396.

[0011] The thermophilic Streptococcus salivarius subsp. thermophilus is the thermophilic Streptococcus salivarius subsp. thermophilus Jiacha.ST-685 strain, which is deposited in the China Center for Type Culture Collection (CCTCC) with a deposit number of CCTCC NO: M 20231495.

[0012] Preferably, the lactic acid bacteria product is characterized in that the plant extract is selected from one or more of Zanthoxylum bungeanum extract, Ophiopogon japonicus extract, Leonurus japonicus extract, Forsythia suspensa extract, Star anise extract and Fennel extract.

[0013] In a second aspect, the present invention provides a method for preparing the lactic acid bacteria product, characterized in that the method comprises:

[0014] (1) Lactobacillus plantarum Ali.Plateau.LP.VIII, Lactobacillus delbrueckii subsp. lactis Dangxiong LBVIII and Streptococcus salivarius thermophilic subsp. Jiacha.ST-685 are inoculated into a fermentation medium for fermentation;

[0015] (2) centrifuging the fermentation broth obtained in step (1), taking the supernatant, and rotary evaporating the supernatant to obtain a concentrated solution;

[0016] (3) The concentrated solution obtained in step (2) and the plant extract are compounded and then inactivated.

[0017] Preferably, the method for preparing the lactic acid bacteria product is characterized in that, in step (1), the viable cell count of Lactobacillus plantarum Ali.Plateau.LP.VIII is 5×10 5 -1×10 6 CFU / g;

[0018] and / or, the viable cell count of Lactobacillus delbrueckii subspecies lactis Dangxiong LBⅧ is 5×10 5 -1×10 6 CFU / g;

[0019] and / or, the viable cell count of Streptococcus salivarius thermophilic subspecies Jiacha.ST-685 is 5×10 5 -1×10 6 CFU / g.

[0020] Preferably, the method for preparing the lactic acid bacteria product is characterized in that, in step (1), Lactobacillus plantarum Ali.Plateau.LP.VIII, Lactobacillus delbrueckii subsp. lactis Dangxiong LBVIII and Streptococcus salivarius subsp. thermophilic Jiacha.ST-685 are each inoculated into the fermentation medium at a volume percentage of 1-5%.

[0021] Preferably, the method for preparing the lactic acid bacteria product is characterized in that, in step (1), the fermentation temperature is 30-42°C;

[0022] Preferably, the fermentation time is 24-48h;

[0023] Further preferably, the fermentation medium is selected from MRS medium.

[0024] Preferably, the method for preparing the lactic acid bacteria product is characterized in that, in step (2), the centrifugal speed is 6000-8000 r / min;

[0025] and / or, the centrifugation time is 10-15 min;

[0026] Preferably, the rotary evaporation temperature is 50-60°C;

[0027] More preferably, the volume is concentrated by rotary evaporation to 1 / 2-1 / 10 of the original volume.

[0028] Preferably, the method for preparing the lactic acid bacteria product is characterized in that, in step (3), the plant extract is added to the concentrated solution at a mass percentage of 0.1-0.5%;

[0029] Preferably, the inactivation temperature is 80-100°C;

[0030] More preferably, the inactivation time is 20-30 min.

[0031] Preferably, the method for preparing the lactic acid bacteria product is characterized in that, after step (3), a drying step is further included;

[0032] Preferably, drying is selected from spray drying;

[0033] More preferably, the drying temperature is 130-190°C.

[0034] In a third aspect, the present invention provides a lactic acid bacteria product prepared by the preparation method.

[0035] In a fourth aspect, the present invention provides the use of the lactic acid bacteria product in food preservation and freshness preservation.

[0036] Preferably, the application is characterized in that the food is selected from fruits and vegetables, baked pastries, fresh meat or pre-prepared dishes.

[0037] Preferably, the application is characterized in that the lactic acid bacteria product is added to food by soaking, spraying or as an additive.

[0038] Beneficial effects of the present invention:

[0039] The lactic acid bacteria product of the present invention utilizes a scientifically formulated combination of Lactobacillus and Streptococcus salivarius subsp. thermophilus, along with the addition of a plant extract with natural antibacterial properties, to synergistically enhance antibacterial efficacy and preserve freshness. This product also improves the nutritional value of food and enhances its probiotic properties. It is suitable for a variety of applications, including preserving fruits and vegetables, baking pastries, fresh meat, and prepared dishes.

[0040] Culture collection information

[0041] The Streptococcus salivarius subsp. thermophilus Jiacha.ST-685 strain provided by the present invention was deposited in the China Center for Type Culture Collection (CCTCC) on August 17, 2023, with a deposit number of CCTCC NO: M 20231495, and the deposit address is: Wuhan University, Wuhan, China, Postal Code: 430072; Telephone: (027)-68754052.

[0042] The Lactobacillus plantarum Ali.Plateau.LP.VIII strain provided by the present invention was deposited with the China Center for Type Culture Collection on January 13, 2022, with a deposit number of CCTCC NO: M 2022068. The deposit address is: Wuhan University, Wuhan, China, Postal Code: 430072; Telephone: (027) 68754052. The strain has been disclosed in patent application publication number CN115838654A.

[0043] The Lactobacillus delbrueckii subsp. lactis Dangxiong LBⅧ strain provided by the present invention was deposited with the China Center for Type Culture Collection on March 23, 2023, with a deposit number of CCTCC NO: M 2023396. The deposit address is: Wuhan University, Wuhan, China, Postal Code: 430072; Telephone: (027) 68754052. This strain has been disclosed in patent application publication number CN116948884A. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The effect of mixed culture of Lactobacillus plantarum Ali.Plateau.LP.VIII, Lactobacillus delbrueckii subspecies DangxiongLBVIII and Streptococcus salivarius thermophilic subspecies Jiacha.ST-685 on growth in Example 3; A is the effect of mixed culture of Lactobacillus plantarum Ali.Plateau.LP.VIII and Streptococcus salivarius thermophilic subspecies Jiacha.ST-685 on growth; B is the effect of mixed culture of Lactobacillus delbrueckii subspecies Dangxiong LBVIII and Streptococcus salivarius thermophilic subspecies Jiacha.ST-685 on growth.

[0045] Figure 2 This is a diagram showing the anti-corrosion status of bread in Application Example 2. DETAILED DESCRIPTION

[0046] The technical solutions of the present invention are further described in detail below with reference to specific embodiments and comparative examples, but the present invention is not limited to the following technical solutions.

[0047] In some specific embodiments, the present invention provides a lactic acid bacteria product, which includes fermentation metabolites of Lactobacillus plantarum, Lactobacillus delbrueckii subsp. lactis and Streptococcus salivarius subsp. thermophilus, and a plant extract.

[0048] The plant lactobacillus is the Lactobacillus plantarum Ali.Plateau.LP.VIII strain, which was isolated from yak milk from herders' homes in the Ali region of Tibet and is a natural wild-type strain. The strain was identified as Lactobacillus plantarum by 16S rDNA and named Lactobacillus plantarum Ali.Plateau.LP.VIII. The strain was deposited in the China Center for Type Culture Collection on January 13, 2022, with a deposit number of CCTCC NO:M2022068. The strain has been disclosed in a patent application with publication number CN115838654A. Lactobacillus plantarum is recorded in the "List of Probiotics that Can Be Used in Health Foods" and has food safety attributes.

[0049] The Lactobacillus delbrueckii subsp. lactis strain Dangxiong LBVIII was isolated from naila (milk) produced by herders in Dangxiong County, Tibet, and is a naturally occurring wild strain. The strain's isolation and identification methods are disclosed in patent application publication number CN116948884A. Naila, a belt-shaped dairy product unique to northern Tibet and made from yak milk, has been listed as a regional intangible cultural heritage.

[0050] The thermophilic Streptococcus salivarius subsp. thermophilus is the Jiacha.ST-685 strain of Streptococcus salivarius subsp. thermophilus, which was screened from yogurt collected by herders in Jiacha County, Shannan City, Tibet, and obtained by the following method:

[0051] 1) Take 25g of yogurt from herders’ home in Jiacha County, Shannan City, Tibet, and mix it with 225mL of sterile saline to obtain a uniform sample solution. The sample solution was diluted in a gradient manner, and 10 -3 , 10 -4 , 10 -5 , 10 -6 The dilution of the concentration was spread on MRS medium plates for culture. After culture at 32℃ for 48h, colonies grew on the MRS medium.

[0052] 2) Initial screening of bacterial strains

[0053] According to the standard colony characteristics of thermophilic Streptococcus salivarius subspecies, single colonies were picked for separation and purification in MRS medium and continued to be cultured at 37°C. The separation and purification were repeated for no less than three times to obtain purified colonies.

[0054] 3) Acid production experiment

[0055] Individual colonies obtained from the initial screening were cultured on MRS agar plates containing 0.2% CaCO₃. After incubation at 32°C for 48 hours, the colonies were observed for the formation of clear zones around them. Colonies with strong acid production and large clear zones were selected for further isolation and purification. On MRS agar, colonies typically grow as round or nearly round, milky white or off-white colonies with a smooth surface, small size, and slightly irregular edges.

[0056] 4) Gram staining

[0057] The strain obtained by repeated screening was subjected to Gram staining. If the staining was typical Gram positive, the strain obtained was the target strain. Under a microscope, the cells were spherical, with a diameter of approximately 0.5-1.0 μm, without flagella, without spore formation, and without motility.

[0058] 5) Identification of strains

[0059] The isolated and purified strain was Gram-positive, H2O2 catalase-negative, acid-producing, and non-gas-producing. 16S rDNA gene sequencing was performed, and the results were compared with the NCBI GenBank database for homology analysis. The results showed that the strain was Streptococcus salivarius subsp. thermophilus.

[0060] The DNA sequence of the 16s rRNA of the thermophilic Streptococcus Jiacha.ST-685 strain is shown in SEQ ID NO: 1:

[0061] TGGCTCCAAAAGGTTACCTCACCGACTTCGGGTGTTACAAACTCTCGT

[0062] GGTGTGACGGGCGGTGTGTACAAGGCCCGGGAACGTATTCACCGCGGC

[0063] GTGCTGATCCGCGATTACTAGCGATTCCGACTTCATGTAGGCGAGTTGC

[0064] AGCCTACAATCCGAACTGAGATTGGCTTTAAGAGATTAGCTCGCCGTCA

[0065] CCGACTCGCAACTCGTTGTACCAACCATTGTAGCACGTGTGTAGCCCAG

[0066] GTCATAAGGGGCATGATGATTTGACGTCATCCCCACCTTTCCTCCGGTTTA

[0067] TTACCGGCAGTCTCGCTAGAGTGCCCAACTGAATGATGGCAACTAACAA

[0068] TAGGGGTTGCGCTCGTTGCGGGACTTAACCCAACATCTCACGACACGA

[0069] GCTGACGACAACCATGCACCACCTGTCACCGATGTACCGAAGTAACTT

[0070] TCTATCTCTAGAAATAGCATCGGGATGTCAAGACCTGGTAAGGTTCTTC

[0071] GCGTTGCTTCGAATTAAACCACATGCTCCACCGCTTGTGCGGGCCCCCG

[0072] TCAATTCCTTTGAGTTTCAACCTTGCGGTCGTACTCCCCAGGCGGAGTG

[0073] CTTAATGCGTTAGCTTCGGCACTGAATCCCGGAAAGGATCCAACACCTA

[0074] GCACTCATCGTTTACGGCGTGGACTACCAGGGTATCTAATCCTGTTCGC

[0075] TCCCCACGCTTTCGAGCCTCAGCGTCAGTTACAGACCAGAGAGCCGCT

[0076] TTCGCCACCGGTGTTCCTCCATATATCTACGCATTTCACCGCTACACATG

[0077] GAATTCCACTCTCCCCTTCTGCACTCAAGTTTGACAGTTTCCAAAGCGA

[0078] ACTATGGTTGAGCCACAGCCTTTAACTTCAGACTTATCAAACCGCCTGC

[0079] GCTCGCTTTACGCCCAATAAATCCGGACAACGCTCGGGACCTACGTATT

[0080] ACCGCGGCTGCTGGCACGTAGTTAGCCGTCCCTTTCTGGTAAGCTACCG

[0081] TCACAGTGTGAACTTTCCACTCTCACACCCGTTCTTGACTTACAACAGA

[0082] GCTTTACGATCCGAAAACCTTCTTCACTCACGCGGCGTTGCTCGGTCAG

[0083] GGTTGCCCCCATTGCCGAAGATTCCCTACTGCTGCCTCCCGTAGGAGTC

[0084] TGGGCCGTGTCTCAGTCCCAGTGTGGCCGATCACCCTCTCAGGTCGGCT

[0085] ATGTATCGTCGCCTAGGTGAGCCATTACCTCACCTACTAGCTAATACAAC

[0086] GCAGGTCCATCTTGTAGTGGAGCAATTGCCCCTTTCAAATAAATGACAT

[0087] GTGTCATCCATTGTTATGCGGTATTAGCTATCGTTTCCAATAGTTATCCCC

[0088] CGCTACAAGGCAGGTTACCTACGCGTTACTCACCCGTTCGCAACTCATC

[0089] CAAGAAGAGCAAGCTCCTCTCTTCAGCGTTCTACTTGCATGTATTAGGC

[0090] ACGCCGCCAGCGTC

[0091] The strain was deposited in the China Center for Type Culture Collection (CCTCC) on August 17, 2023, with the deposit number CCTCC NO: M20231495. The deposit address is: Wuhan University, Wuhan, China, Postal Code: 430072; Telephone: (027)-68754052.

[0092] All three strains are isolated from highland dairy products and are naturally safe. Lactobacillus plantarum Ali.Plateau.LP.VIII has strong acid production and a broad antibacterial spectrum, exhibiting strong antibacterial activity against Escherichia coli, Staphylococcus aureus, and molds. Lactobacillus delbrueckii subsp. lactis Dangxiong LBVIII exhibits strong DPPH and hydroxyl radical scavenging abilities and possesses high antioxidant activity. Streptococcus salivarius thermophilus subsp. Jiacha.ST-685 rapidly metabolizes lactic acid, formate, and CO2, which promote lactobacillus growth. Lactobacillus plantarum, Lactobacillus delbrueckii subsp. lactis, and Streptococcus salivarius thermophilus are all listed in the "List of Edible Strains."

[0093] The lactic acid bacteria product of the present invention scientifically combines Lactobacillus and Streptococcus salivarius thermophilus subspecies, which have different degrees of promoting the antiseptic and fresh-keeping functions, and adds plant extracts with natural antibacterial effects, thereby further synergistically improving the antibacterial efficacy and enhancing the fresh-keeping effect. At the same time, it can improve the nutritional value of food and increase the probiotic function.

[0094] The lactic acid bacteria product of the present invention has a wide range of applications and is suitable for a variety of application scenarios such as fruit and vegetable preservation, baked pastries, fresh meat and pre-prepared dishes. When the lactic acid bacteria product is applied to the preservation of fruits and vegetables, it can not only effectively inhibit the corruption of fruits and vegetables and extend the shelf life, but also maintain the moisture content of fruits and vegetables during the storage period and enhance the antioxidant capacity of fruits and vegetables. When the lactic acid bacteria product is applied to the preservation of baked pastries, it can significantly prolong the mold time and improve the texture of bread during storage. When the lactic acid bacteria product is applied to the preservation of pre-prepared dishes, it can better control the production of volatile basic nitrogen and the rancidity of oils and fats, and the addition of the lactic acid bacteria product will not change the flavor of the food itself.

[0095] The Lactobacillus plantarum CICC 24194 mentioned in the examples of the present invention is a purchased standard strain that produces Class IIa bacteriocins and can be used for antibacterial performance testing and starter culture development.

[0096] The Lactobacillus delbrueckii subsp. lactis CICC 25164 mentioned in the examples of the present invention is a purchased standard strain.

[0097] Unless otherwise specified, the various reagents and instruments used in the Examples and Comparative Examples of the present invention are conventional commercially available products. The sources of the instruments and reagents used in the Examples and Comparative Examples of the present invention are shown in Table 1 below.

[0098] Table 1

[0099]

[0100]

[0101]

[0102] Example 1 Lactobacillus plantarum strain characteristics

[0103] 1. Acid production capacity determination

[0104] Glycerol tubes of Lactobacillus plantarum Ali.Plateau.LP.VIII and a control strain, Lactobacillus plantarum CICC 24194, were removed from a -80°C freezer, thawed at room temperature, and inoculated into test tubes containing 10 mL of MRS liquid culture medium at a 2% (v / v) ratio. The strains were then statically incubated at 37°C for 12 hours for strain activation. The activated Lactobacillus plantarum Ali.Plateau.LP.VIII and Lactobacillus plantarum CICC 24194 strains were inoculated into 10 mL of sterilized MRS liquid culture medium at a pH of 6.60 at a 2% (v / v) ratio, incubated at 37°C under anaerobism for 24 hours, and centrifuged at 10,000 rpm for 10 minutes at 4°C. The pH of the fermentation supernatant was directly measured using a pH meter. At the same time, the titratable acidity was determined according to the national standard GB / T5413.34-2010, and the acidity of the lactic acid bacteria fermentation broth was expressed in degrees Gilles (°T), that is, 1 mL of the fermentation broth consumed for every 100 mL was a concentration of 0.1 mol·L –1 The NaOH solution is equivalent to 1°T. The results are shown in Table 2.

[0105] Table 2 Acid production capacity of Lactobacillus plantarum

[0106]

[0107] Lactic acid bacteria produce acid during their growth, causing the pH of the fermentation broth to decrease and the acidity to increase. Compared to the control strain, Lactobacillus plantarum CICC 24194, the fermentation supernatant of Lactobacillus plantarum Ali.Plateau.LP.VIII had a significantly lower pH and higher acidity, indicating its stronger acid-producing ability.

[0108] 2. Determination of antibacterial ability

[0109] The antibacterial activity of the strains was determined by the double-layer agar diffusion method, and Escherichia coli, Staphylococcus aureus and fungi were used as indicator bacteria.

[0110] (1) Add 10 mL of 2 g / 100 mL water agar medium to a sterilized plate. After the water agar solidifies, place it in a sterilized Oxford cup to prepare a water agar plate.

[0111] (2) Add 1 ml of NB agar medium cooled to 50 °C and 10 6 -10 7 The indicator bacteria Escherichia coli and Staphylococcus aureus at 10 CFU / mL were fully mixed and poured into the prepared water agar plates respectively to obtain plates containing the indicator bacteria Escherichia coli and Staphylococcus aureus.

[0112] (3) Add 1 ml of PDA agar medium cooled to 50 °C with a viable count of 10 6 -10 7 CFU / mL of mold, mix thoroughly and pour into the prepared water agar plate to obtain a plate containing mold.

[0113] (4) After the plate culture medium containing the indicator bacteria Escherichia coli, Staphylococcus aureus, and mold solidified, the Oxford cup was removed and 100 μL of bacterial suspension of Lactobacillus plantarum Ali.Plateau.LP.VIII and Lactobacillus plantarum CICC 24194 was added to the wells, respectively. The plates were incubated at 37°C for 24 h, and the diameter of the inhibition zone (mm) was observed and measured. The results are shown in Table 3.

[0114] Table 3 Antibacterial ability of Lactobacillus plantarum

[0115]

[0116] In Table 3, the antibacterial effects of Lactobacillus plantarum Ali.Plateau.LP.VIII on Escherichia coli, Staphylococcus aureus, and mold were better than those of the control strain Lactobacillus plantarum CICC 24194, demonstrating its strong antibacterial ability.

[0117] Example 2 Characteristics of Lactobacillus germanica subsp. lactis

[0118] 1. DPPH free radical scavenging activity assay

[0119] The activated Lactobacillus delbrueckii subspecies Dangxiong LBⅧ and Lactobacillus delbrueckii subspecies CICC 25164 strains were inoculated at a 2% (v / v) inoculum into 10 ml of MRS liquid culture medium with a pH of 6.60 after sterilization, cultured under anaerobic conditions at 37°C for 24 hours, and then centrifuged at 10000 r / min for 10 minutes at 4°C to collect the bacterial sludge, which was re-dissolved with sterile physiological saline to obtain a bacterial suspension. 2 ml (OD 600A sample (with a sample concentration of 0.9-1) was mixed with 1 mL of a 0.2 mmol / L DPPH-anhydrous ethanol solution and allowed to react in the dark at 37°C for 30 minutes. After the reaction, the sample was centrifuged at 6000 rpm for 10 minutes. The supernatant was collected and the absorbance (A1) was measured at 517 nm. A blank control group used an equal volume of anhydrous ethanol instead of the DPPH-anhydrous ethanol solution, while a control group used an equal volume of distilled water instead of the sample solution. An equal volume of the distilled water-anhydrous ethanol mixture was used for blank zero adjustment. The DPPH free radical is a synthetic free radical whose alcohol solution appears purple. In the presence of antioxidants, the DPPH free radical is scavenged, resulting in a lighter solution color and a decreased absorbance at 517 nm. The change in absorbance is proportional to the extent of free radical scavenging.

[0120] The DPPH free radical scavenging rate was calculated according to formula (1), and the results are shown in Table 4:

[0121]

[0122] Where: A0 is the absorbance of the blank group; A1 is the absorbance of the sample group; A2 is the absorbance of the control group.

[0123] 2. Hydroxyl Radical Scavenging Activity Assay

[0124] 1 mL each of 5 mmol / L ferrous sulfate solution, 5 mmol / L salicylic acid ethanol solution, and 3 mmol / L hydrogen peroxide solution were added to a 10 mL stoppered test tube, and 2 mL of bacterial suspensions (OD 2) of Lactobacillus delbrueckii subsp. lactis Dangxiong LBⅧ and Lactobacillus delbrueckii subsp. lactis CICC 25164 were inoculated into the stoppered test tubes respectively. 600 The value is 0.9-1), and distilled water is added to the scale to 10ml, and the reaction is carried out in a 37℃ water bath for 15min, and then centrifuged at 6000r / min for 10min. The supernatant is taken and the absorbance is measured at a wavelength of 510nm. The blank group is replaced by an equal volume of distilled water instead of the sample solution. The Fenton reaction is carried out using ferrous sulfate solution and hydrogen peroxide solution to generate hydroxyl radicals: H2O2+Fe 2+ = OH + H2O + Fe 3+ When salicylic acid is added to the reaction system, the hydroxyl radicals generated by the Fenton reaction react with salicylic acid to produce 2,3-dihydroxybenzoic acid, which has a specific absorption wavelength of 510 nm. Adding a substance with hydroxyl radical scavenging properties to the reaction system reduces the amount of hydroxyl radicals produced, thereby reducing the amount of colored compounds produced. Hydroxyl radicals are commonly found in organisms.

[0125] The hydroxyl radical scavenging rate was calculated according to formula (2), and the results are shown in Table 4:

[0126]

[0127] Where: A0 is the absorbance of the blank group; A1 is the absorbance of the sample group.

[0128] Table 4 Antioxidant activity of Lactobacillus delbrueckii strains

[0129]

[0130] In Table 4, Lactobacillus delbrueckii subsp. lactis Dangxiong LBⅧ has strong DPPH free radical scavenging ability and hydroxyl free radical scavenging ability, and has high antioxidant activity.

[0131] Example 3 Effect of mixed culture of Lactobacillus and Streptococcus salivarius on growth

[0132] 1. Preparation of Cell-Free Supernatant (CFS) of Lactobacillus plantarum, Lactobacillus delbrueckii subsp. lactis, and Streptococcus salivarius subsp. thermophilus

[0133] Lactobacillus plantarum Ali.Plateau.LP.VIII, Lactobacillus delbrueckii subsp. lactis Dangxiong LBVIII and Streptococcus salivarius thermophilic subsp. Jiacha.ST-685 activated for 2-3 generations were inoculated into MRS broth culture medium sterilized at high temperature, with an inoculum amount of 2% (v / v). After culturing for 12 hours, the fermentation broth was centrifuged at 10,000 r / min and 4°C for 10 minutes, and the supernatant was collected. After filtering through a 0.22 μm microporous filter membrane, the supernatant obtained was Lactobacillus plantarum Ali.Plateau.LP.VIII cell-free supernatant (LP.VIII CFS), Lactobacillus delbrueckii subsp. lactis Dangxiong LBVIII cell-free supernatant (LBVIII CFS) and Streptococcus salivarius thermophilic subsp. Jiacha.ST-685 cell-free supernatant (ST685 CFS).

[0134] 2. Effect of mixed culture of Lactobacillus plantarum, Lactobacillus delbrueckii subsp. lactis, and Streptococcus salivarius subsp. thermophilus on growth

[0135] Lactobacillus plantarum, Streptococcus salivarius thermophilus subsp. salivarius and their cell-free supernatants were inoculated into high-temperature sterilized MRS broth culture medium, including the following samples: (1) LP.Ⅷ: only Lactobacillus plantarum Ali.Plateau.LP.Ⅷ was inoculated; (2) ST685: only Streptococcus salivarius thermophilus subsp. Jiacha.ST-685 was inoculated; (3) LP.Ⅷ+ST685 was inoculated CFS: inoculated with the cell-free supernatant of Lactobacillus plantarum Ali.Plateau.LP.VIII and Streptococcus salivarius thermophilus Jiacha.ST-685; (4) LP.VIII CFS+ST685: inoculated with the cell-free supernatant of Lactobacillus plantarum Ali.Plateau.LP.VIII and Streptococcus salivarius thermophilus Jiacha.ST-685; (5) LPVIII+ST685: inoculated with Lactobacillus plantarum Ali.Plateau.LP.VIII and Streptococcus salivarius thermophilus Jiacha.ST-685. The total inoculation amount of each sample was 2% (v / v), wherein the volume ratio of the two components in each sample was 1:1. Results are shown in Figure 1 Figure A shows that the addition of thermophilic Streptococcus thermophilus subsp. Jiacha.ST-685 significantly promoted the growth of Lactobacillus plantarum Ali.Plateau.LP.Ⅷ, and the metabolites were closely related to the synergistic effect between the strains.

[0136] Lactobacillus delbrueckii subsp. lactis, Streptococcus salivarius thermophilus subsp. lactis and their cell-free supernatant were activated for 2-3 generations and inoculated into high-temperature sterilized MRS broth culture medium, including the following samples: (1) LBⅧ: only Lactobacillus delbrueckii subsp. lactis Dangxiong LBⅧ was inoculated; (2) ST685: only Streptococcus salivarius thermophilus subsp. Jiacha.ST-685 was inoculated; (3) LBⅧ+ST685CFS: inoculated with Lactobacillus delbrueckii subsp. lactis Dangxiong LBⅧ and cell-free supernatant of Streptococcus salivarius thermophilus subsp. Jiacha.ST-685; (4) LBⅧCFS+ST685: inoculated with Lactobacillus delbrueckii subsp. lactis Dangxiong LBⅧ and cell-free supernatant of Streptococcus salivarius thermophilus subsp. Jiacha.ST-685; (5) LBⅧ+ST685: inoculated with Lactobacillus delbrueckii subsp. lactis Dangxiong LB VIII and Streptococcus salivarius thermophilus subspecies Jiacha.ST-685. The total inoculum volume of each sample was 2% (v / v), wherein the ratio of the two components in each sample was 1:1. Figure 1 Figure B shows that the addition of thermophilic Streptococcus thermophilus subsp. Jiacha.ST-685 significantly promoted the growth of Lactobacillus delbrueckii subsp. lactis Dangxiong LBⅧ, and the metabolites were closely related to the synergistic effect between the strains.

[0137] Lactobacillus (Lactobacillus plantarum and Lactobacillus delbrueckii subsp. lactis) has a strong ability to decompose protein and can produce a variety of amino acids, providing nutrients for Streptococcus thermophilus; at the same time, substances such as lactic acid, formate, and CO2 produced by the rapid metabolism of Streptococcus thermophilus can become growth stimulants for Lactobacillus, promoting the growth of Lactobacillus.

[0138] Example 4 Preparation of lactic acid bacteria products

[0139] 1. Fermentation: Take out the glycerol tubes of Lactobacillus plantarum, Lactobacillus delbrueckii subsp. lactis, and Streptococcus salivarius thermophilus subsp. from a -80°C freezer, thaw at room temperature, and inoculate them into test tubes containing 10 mL of MRS liquid culture medium at a ratio of 2% (v / v). Incubate statically in a 37°C incubator for 12 hours to activate the strains. Activate Lactobacillus plantarum Ali.Plateau.LP.VIII, Lactobacillus delbrueckii subsp. lactis Dangxiong LBVIII, and Streptococcus salivarius thermophilus Jiacha.ST-685 in sterilized MRS culture medium at a ratio of 2% (v / v), wherein the ratio of viable bacteria of each bacterium is 2:2:1, i.e., the viable count of Lactobacillus plantarum Ali.Plateau.LP.VIII is 1×10 6 CFU / g, the number of viable bacteria of Lactobacillus germanium subspecies Dangxiong LBⅧ is 1×10 6 CFU / g, the number of viable bacteria of Streptococcus salivarius thermophilic subspecies Jiacha.ST-685 was 5×10 5 CFU / g, and fermented in a 37°C incubator for 24 h to obtain the fermentation broth.

[0140] 2. Post-treatment: centrifuge the fermentation broth at 6000 r / min for 10 minutes to obtain a supernatant; perform rotary evaporation on the supernatant at 50° C. and concentrate it to 1 / 2 of its original volume to obtain a concentrated solution; add 0.1% by mass of Zanthoxylum bungeanum extract to the concentrated solution, mix well, and sterilize and inactivate at 80° C. for 30 minutes to obtain an inactivated solution; spray dry the sterilized and inactivated fermentation broth at a drying temperature of 150° C. to obtain a lactic acid bacteria product.

[0141] Example 5 Preparation of lactic acid bacteria products

[0142] 1. Fermentation: Take out the glycerol tubes of Lactobacillus plantarum, Lactobacillus delbrueckii subsp. lactis, and Streptococcus salivarius thermophilus subsp. from a -80°C freezer and immediately place them in a 37°C water bath. After the liquid in the glycerol tubes has completely melted, inoculate them into a test tube containing 10 mL of MRS liquid culture medium at a ratio of 1% (v / v). Incubate them statically in a 37°C incubator for 12 hours to activate the strains. Activate Lactobacillus plantarum Ali.Plateau.LP.VIII, Lactobacillus delbrueckii subsp. lactis Dangxiong LBVIII, and Streptococcus salivarius thermophilus Jiacha.ST-685 at a ratio of 1% (v / v) each into sterilized MRS culture medium, wherein the ratio of viable bacteria of each strain is 1:1:1, i.e., the viable bacteria count of Lactobacillus plantarum Ali.Plateau.LP.VIII is 1×10 6 CFU / g, the number of viable bacteria of Lactobacillus delbrueckii subspecies Dangxiong LBⅧ is 1×10 6 CFU / g, the number of viable bacteria of Streptococcus salivarius thermophilic subspecies Jiacha.ST-685 is 1×10 6 CFU / g, and fermented in a 30°C incubator for 48 h to obtain the fermentation broth.

[0143] 2. Post-treatment: centrifuge the fermentation broth at 6000 r / min for 10 minutes to obtain a supernatant; perform rotary evaporation on the supernatant at 60°C and concentrate it to 1 / 10 of the original volume to obtain a concentrate; add 0.5% by mass of Ophiopogon japonicus extract to the concentrate, mix well, and sterilize at 100°C for 20 minutes to obtain an inactivated solution; spray dry the sterilized and inactivated fermentation broth at a drying temperature of 130°C to obtain a lactic acid bacteria product.

[0144] Example 6 Preparation of lactic acid bacteria products

[0145] 1. Fermentation: Take out the glycerol tubes of Lactobacillus plantarum, Lactobacillus delbrueckii subsp. lactis, and Streptococcus salivarius thermophilus from a -80°C refrigerator and immediately place them in a 37°C water bath. After the liquid in the glycerol tubes has completely melted, inoculate them into a test tube containing 10 mL of MRS liquid culture medium at a ratio of 5% (v / v), and culture them statically in a 42°C incubator for 24 hours for strain activation. Activated Lactobacillus plantarum Ali.Plateau.LP.VIII, Lactobacillus delbrueckii subsp. lactis Dangxiong LBVIII, and Streptococcus salivarius thermophilus Jiacha.ST-685 are each inoculated into sterilized MRS culture medium at a ratio of 5% (v / v), wherein the ratio of viable bacteria of each strain is 2:1:2, that is, the viable bacteria count of Lactobacillus plantarum Ali.Plateau.LP.VIII is 1×10 6 CFU / g, the number of viable bacteria of Lactobacillus germanium subspecies Dangxiong LBⅧ is 5×10 5CFU / g, the number of viable bacteria of Streptococcus salivarius thermophilic subspecies Jiacha.ST-685 is 1×10 6 CFU / g, and fermented in a 37°C incubator for 24 h to obtain the fermentation broth.

[0146] 2. Post-treatment: centrifuge the fermentation broth at 6000 r / min for 10 minutes to obtain a supernatant; perform rotary evaporation on the supernatant at 50° C. and concentrate it to 1 / 10 of the original volume to obtain a concentrated solution; add 0.1% by mass of Leonurus japonicus extract to the concentrated solution, mix well, and sterilize and inactivate at 80° C. for 30 minutes to obtain an inactivated solution; spray dry the sterilized and inactivated fermentation broth at a drying temperature of 130° C. to obtain a lactic acid bacteria product.

[0147] Example 7 Preparation of lactic acid bacteria products

[0148] 1. Fermentation: Take out the glycerol tubes of Lactobacillus plantarum, Lactobacillus delbrueckii subsp. lactis, and Streptococcus salivarius thermophilus subsp. from a -80°C refrigerator and immediately place them in a 37°C water bath. After the liquid in the glycerol tubes has completely melted, inoculate them into a test tube containing 10 mL of MRS liquid culture medium at a ratio of 2% (v / v). Incubate them statically in a 37°C incubator for 12 hours to activate the strains. Inoculate the activated Lactobacillus plantarum Ali.Plateau.LP.VIII, Lactobacillus delbrueckii subsp. lactis Dangxiong LBVIII, and Streptococcus salivarius thermophilus Jiacha.ST-685 at a ratio of 2% (v / v) each into sterilized MRS culture medium, wherein the ratio of viable bacteria of each strain is 1:1:2, that is, the viable bacteria count of Lactobacillus plantarum Ali.Plateau.LP.VIII is 5×10 5 CFU / g, the number of viable bacteria of Lactobacillus germanium subspecies Dangxiong LBⅧ is 5×10 5 CFU / g, the number of viable bacteria of Streptococcus salivarius thermophilic subspecies Jiacha.ST-685 is 1×10 6 CFU / g, and fermented in a 37°C incubator for 24 h to obtain the fermentation broth.

[0149] 2. Post-treatment: centrifuge the fermentation broth at 8000 r / min for 10 minutes to obtain a supernatant; perform rotary evaporation on the supernatant at 60°C and concentrate it to 1 / 10 of the original volume to obtain a concentrated solution; add 0.5% by mass of Forsythia suspensa extract to the concentrated solution, mix well, and sterilize at 100°C for 20 minutes to obtain an inactivated solution; spray dry the sterilized and inactivated fermentation broth at a drying temperature of 130°C to obtain a lactic acid bacteria product.

[0150] Comparative Example 1

[0151] Compared with Example 1, no Zanthoxylum bungeanum extract was added, and the rest was the same as Example 1.

[0152] Comparative Example 2

[0153] Compared with Example 1, Lactobacillus plantarum Ali.Plateau.LP.VIII, Lactobacillus delbrueckii subsp. lactis DangxiongLBVIII and Streptococcus salivarius thermophilus subsp. Jiacha.ST-685 were inoculated into sterilized MRS medium at a ratio of 6:1:2, i.e., the number of viable bacteria of Lactobacillus plantarum Ali.Plateau.LP.VIII was 6×10 6 CFU / g, the number of viable bacteria of Lactobacillus germanium subspecies Dangxiong LBⅧ is 5×10 5 CFU / g, the number of viable bacteria of Streptococcus salivarius thermophilic subspecies Jiacha.ST-685 is 1×10 6 CFU / g, and the rest are the same as in Example 1.

[0154] Experimental Example 1

[0155] 1. Determination of antibacterial ability and pH value of different lactic acid bacteria products

[0156] The antibacterial activities of the different lactic acid bacteria preparations prepared in Examples 4-7 and Comparative Examples 1-2 were determined using a double-layer agar diffusion method, with Escherichia coli, Staphylococcus aureus, and molds being used as indicator bacteria.

[0157] (1) Add 10 mL of 2 g / 100 mL water agar medium to a sterilized plate. After the water agar solidifies, place it in a sterilized Oxford cup to prepare a water agar plate.

[0158] (2) Add 1 ml of NB agar medium cooled to 50 °C and 10 6 -10 7 The indicator bacteria Escherichia coli and Staphylococcus aureus at 10 CFU / mL were fully mixed and poured into the prepared water agar plates respectively to obtain plates containing the indicator bacteria Escherichia coli and Staphylococcus aureus.

[0159] (3) Add 1 ml of PDA agar medium cooled to 50 °C with a viable count of 10 6 -10 7 CFU / mL of mold, mix thoroughly and pour into the prepared water agar plate to obtain a plate containing mold.

[0160] (4) After the plate culture medium containing the indicator bacteria Escherichia coli, Staphylococcus aureus, and mold solidified, the Oxford cup was removed and 100 μL of the different lactic acid bacteria preparations prepared in Examples 4-7 and Comparative Examples 1-2 (the lactic acid bacteria preparations were rehydrated to a dry matter content of 5%) were added to the wells. The plates were incubated at 37°C for 24 h, and the diameters of the inhibition zones (mm) were observed and measured. The results are shown in Table 5.

[0161] The pH values ​​of the different lactic acid bacteria products prepared in Examples 4-7 and Comparative Examples 1-2 were measured using a pH meter. The results are shown in Table 5.

[0162] As shown in Table 5, the combined results of pH and inhibition zone measurements indicate that the lactic acid bacteria preparation obtained in Example 4 is the most preferred lactic acid bacteria preparation of the present invention. The combination of lactic acid bacteria and Streptococcus salivarius subsp. thermophilus in a specific ratio and the addition of 0.1% Zanthoxylum bungeanum extract significantly improved the antibacterial ability of the lactic acid bacteria preparation and enhanced its freshness preservation.

[0163] Table 5 pH and antibacterial ability results of different lactic acid bacteria products

[0164]

[0165] 2. Determination of the content of total reducing sugar, organic acid, protein and dietary fiber in the lactic acid bacteria prepared in Example 4

[0166] Total reducing sugar was determined according to the first method of GB 5009.7-2016 “National Food Safety Standard - Determination of Reducing Sugars in Foods”; organic acid content was determined according to GB 5009.157-2016 “National Food Safety Standard - Determination of Organic Acids in Foods”; protein content was determined according to GB 5009.5-2016 “National Food Safety Standard - Determination of Protein in Foods”; dietary fiber was determined according to GB 5009.88-2014 “National Food Safety Standard - Determination of Dietary Fiber in Foods”. The determination results are shown in Table 6.

[0167] Table 6 Nutritional composition of lactic acid bacteria products

[0168]

[0169] As shown in Table 6, the lactic acid bacteria preparation of Example 4 is low in sugar and rich in organic acids, protein, and dietary fiber. Its application in food can improve the nutritional value of the food and enhance its probiotic function. Therefore, the lactic acid bacteria preparations used in the following application examples were all obtained using the composition ratios and preparation methods of Example 4.

[0170] Application Example 1: Lactic acid bacteria products are used in fruit and vegetable preservation

[0171] Apple pieces (3 cm × 3 cm × 3 cm) and lettuce slices (5 cm × 5 cm) were soaked in 5% by mass of the lactic acid bacteria preparation prepared in Example 4 for 10 minutes. Untreated fruits and vegetables served as blank controls (CK). After treatment, the products were air-dried, sealed, and stored at room temperature. Indicators were measured every five days. The results are shown in Table 7 below.

[0172] The total colony count is determined according to the method in GB 4789.2-2016 "National Food Safety Standard - Determination of Total Colony Count for Food Microbiological Examination" and the unit is lg (CFU / mL).

[0173] The formula for calculating weight loss rate is as follows:

[0174]

[0175] Where: L is the weight loss rate, %; W1 is the mass of the sample before storage, g; W2 is the mass of the sample after storage, g.

[0176] The processed fruits, vegetables and lettuce were chopped and added to a pre-cooled 1% HCl-methanol solution. The mixture was thoroughly homogenized in a tissue homogenizer. The supernatant was then centrifuged and directly colorimetrically analyzed at a wavelength of 280 nm. The total phenol content was expressed as the absorbance per gram of fresh weight of fruit and vegetable tissue at a wavelength of 280 nm, i.e., OD 280 / g. The initial total phenolic contents of apple and lettuce were 1.11 and 0.30 OD respectively. 280 / g.

[0177] Table 7 Storage period test of fruits and vegetables

[0178]

[0179] After being treated with lactic acid bacteria products, the total colony count and weight loss rate of apples and lettuce decreased significantly, and the total phenol content increased slightly. This shows that adding lactic acid bacteria products can not only effectively inhibit the spoilage of fruits and vegetables and extend their shelf life; it can also maintain the moisture content of fruits and vegetables during the storage period and enhance the antioxidant capacity of fruits and vegetables.

[0180] Application Example 2: Lactic acid bacteria products are used to preserve baked pastries

[0181] Prepared bread slices were randomly divided and sprayed with 5% by weight of the lactic acid bacteria preparation prepared in Example 4. Untreated bread served as a blank negative control (CK), and 1g / kg of sorbic acid was added as a positive control. The bread was sealed and stored under constant temperature and humidity conditions (35°C, 85% humidity), and mold growth time was observed. On the third day of storage, the bread's hardness, elasticity, and viscosity were tested using a TA.XTC-18 texture analyzer with a TA / 36R cylindrical probe. The results are shown in Table 8.

[0182] Table 8 Bread storage period test

[0183]

[0184] After adding lactic acid bacteria products, the mold time is significantly prolonged. Figure 2 At the same time, the bread has a lower hardness, higher elasticity and stickiness, which improves the problem of deterioration of texture properties due to starch aging during storage.

[0185] Application Example 3: Lactic acid bacteria products are used to preserve pre-prepared dishes

[0186] Fresh pork was cleaned of blood stains, sliced, and washed with distilled water. 5% by weight of the lactic acid bacteria product prepared in Example 4 was added to the pork slices, mixed evenly, and seasonings were added and stir-fried until fragrant. The pork was vacuum-packed and pasteurized. A blank control experiment was also performed. The total colony count, volatile basic nitrogen, and acid value were measured on days 7, 14, and 28, respectively. The results are shown in Table 9.

[0187] The total colony count is determined according to the method in GB 4789.2-2016 "National Food Safety Standard - Determination of Total Colony Count for Food Microbiological Examination" and the unit is lg (CFU / mL).

[0188] Volatile basic nitrogen is determined by referring to the semi-micro nitrogen determination method in the "National Food Safety Standard - Determination of Volatile Basic Nitrogen in Food" (GB5009.228-2016).

[0189] The acid value was determined in accordance with the "Methods of Analysis for Hygienic Standards of Meat and Meat Products" (GB / T5009.044-2003).

[0190] After the samples were removed and allowed to cool to room temperature, they were immediately evaluated by 10 sensory evaluators, assessing the meat slices' color, aroma, flavor, and muscle elasticity, using a score ranging from 1 to 5. The scoring criteria are shown in Table 10. An overall score of 17 to 20 indicates freshness, 9 to 16 indicates good quality, and 8 or less indicates significant deterioration. The results are shown in Table 11.

[0191] Table 9 Meat slice storage period test

[0192]

[0193] Table 10 Sensory evaluation details

[0194]

[0195] Table 11 Sensory evaluation results

[0196]

[0197]

[0198] After adding lactic acid bacteria products, the total colony count of meat slices was significantly reduced during storage, the production of volatile basic nitrogen could be better controlled, and the meat could still maintain first-level freshness after 28 days of storage. The oil rancidity was rare, and the addition of lactic acid bacteria products did not affect the color, aroma and taste of the food itself.

[0199] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A lactic acid bacteria product, characterized in that The lactic acid bacteria product includes fermentation metabolites obtained by co-fermentation of Lactobacillus plantarum, Lactobacillus delbrueckii subsp. lactis and Streptococcus salivarius subsp. thermophilus, and plant extracts; Wherein, the plant lactobacillus is plant lactobacillus ( Lactobacillus plantarum ) Ali.Plateau.LP.Ⅷ strain, deposit number is CCTCC NO: M 2022068; the Lactobacillus delbrueckii subspecies lactis is Lactobacillus delbrueckii subspecies lactis ( Lactobacillus delbrueckii subsp. lactis ) Dangxiong LBⅧ strain, deposit number is CCTCCNO: M 2023396; the thermophilic subspecies of Streptococcus salivarius is the thermophilic subspecies of Streptococcus salivarius ( Streptococcus salivarius subsp. thermophilus ) Jiacha.ST-685 strain, deposited with CCTCC NO: M20231495; Before co-fermentation, the number of viable bacteria of the plant lactobacillus Ali.Plateau.LP.VIII was 1×10 6 CFU / g; the viable count of the Lactobacillus delbrueckii subspecies Dangxiong LBⅧ is 1×10 6 CFU / g; the viable count of the thermophilic Streptococcus salivarius subspecies Jiacha.ST-685 is 5×10 5 CFU / g; The plant extract is Zanthoxylum bungeanum extract.

2. A method for preparing the lactic acid bacteria product according to claim 1, characterized in that: The method comprises: (1) Lactobacillus plantarum Ali.Plateau.LP.VIII, Lactobacillus delbrueckii subsp. lactis Dangxiong LBVIII and Streptococcus salivarius thermophilic subsp. Jiacha.ST-685 were inoculated into a fermentation medium and fermented together, wherein the preservation number of Lactobacillus plantarum Ali.Plateau.LP.VIII strain is CCTCC NO: M 2022068; the preservation number of Lactobacillus delbrueckii subsp. lactis Dangxiong LBVIII strain is CCTCC NO: M 2023396; the preservation number of Streptococcus salivarius thermophilic subsp. Jiacha.ST-685 strain is CCTCC NO: M 20231495; Before co-fermentation, the viable count of the plant lactobacillus Ali.Plateau.LP.VIII was 1×10 6 CFU / g; the viable count of the Lactobacillus delbrueckii subspecies Dangxiong LBⅧ is 1×10 6 CFU / g; the viable count of the thermophilic Streptococcus salivarius subspecies Jiacha.ST-685 is 5×10 5 CFU / g; (2) centrifuging the fermentation liquid obtained in step (1), taking the supernatant, and rotary evaporating the supernatant to obtain a concentrated solution; (3) The concentrated solution obtained in step (2) and the plant extract are compounded and then inactivated.

3. The method for preparing a lactic acid bacteria product according to claim 2, wherein: In step (1), Lactobacillus plantarum Ali.Plateau.LP.VIII, Lactobacillus delbrueckii subsp. lactis Dangxiong LBVIII and Streptococcus salivarius thermophilic subsp. Jiacha.ST-685 are inoculated into the fermentation medium at a volume percentage of 1-5%.

4. The method for preparing a lactic acid bacteria product according to claim 2, wherein: In step (1), the fermentation temperature is 30-42°C; and / or, the fermentation time is 24-48 hours; And / or, the fermentation medium is selected from MRS medium.

5. The method for preparing a lactic acid bacteria product according to claim 3, wherein: In step (1), the fermentation temperature is 30-42°C; and / or, the fermentation time is 24-48 hours; And / or, the fermentation medium is selected from MRS medium.

6. The method for preparing a lactic acid bacteria product according to claim 2, wherein: In step (2), the centrifugal speed is 6000-8000 r / min; And / or, the centrifugation time is 10-15 minutes.

7. The method for preparing a lactic acid bacteria product according to claim 3, wherein: In step (2), the centrifugal speed is 6000-8000 r / min; And / or, the centrifugation time is 10-15 minutes.

8. The method for preparing a lactic acid bacteria product according to claim 4, wherein: In step (2), the centrifugal speed is 6000-8000 r / min; And / or, the centrifugation time is 10-15 minutes.

9. The method for preparing a lactic acid bacteria product according to claim 2, wherein: In step (2), the rotary evaporation temperature is 50-60°C.

10. The method for preparing a lactic acid bacteria product according to claim 3, wherein: In step (2), the rotary evaporation temperature is 50-60°C.

11. The method for preparing a lactic acid bacteria product according to claim 4, wherein: In step (2), the rotary evaporation temperature is 50-60°C.

12. The method for preparing a lactic acid bacteria product according to claim 6, wherein: In step (2), the rotary evaporation temperature is 50-60°C.

13. The method for preparing a lactic acid bacteria product according to claim 2, wherein: In step (2), the volume is concentrated by rotary evaporation to 1 / 2-1 / 10 of the original volume.

14. The method for preparing a lactic acid bacteria product according to claim 3, wherein: In step (2), the volume is concentrated by rotary evaporation to 1 / 2-1 / 10 of the original volume.

15. The method for preparing a lactic acid bacteria product according to claim 4, wherein: In step (2), the volume is concentrated by rotary evaporation to 1 / 2-1 / 10 of the original volume.

16. The method for preparing a lactic acid bacteria product according to claim 6, wherein: In step (2), the volume is concentrated by rotary evaporation to 1 / 2-1 / 10 of the original volume.

17. The method for preparing a lactic acid bacteria product according to claim 9, wherein: In step (2), the volume is concentrated by rotary evaporation to 1 / 2-1 / 10 of the original volume.

18. The method for preparing a lactic acid bacteria product according to any one of claims 2 to 17, characterized in that: In step (3), the plant extract is added to the concentrate at a mass percentage of 0.1-0.5%.

19. The method for preparing a lactic acid bacteria product according to any one of claims 2 to 17, characterized in that: In step (3), the inactivation temperature is 80-100°C; and / or the inactivation time is 20-30 minutes.

20. The method for preparing a lactic acid bacteria product according to claim 18, wherein: In step (3), the inactivation temperature is 80-100°C; and / or the inactivation time is 20-30 minutes.

21. The method for preparing a lactic acid bacteria product according to any one of claims 2 to 17, wherein: The step (3) is followed by a drying step.

22. The method for preparing a lactic acid bacteria product according to claim 18, wherein: The step (3) is followed by a drying step.

23. The method for preparing a lactic acid bacteria product according to claim 19, wherein: The step (3) is followed by a drying step.

24. The method for preparing a lactic acid bacteria product according to claim 21, wherein: Drying is selected from spray drying.

25. The method for preparing a lactic acid bacteria product according to claim 21, wherein: The drying temperature is 130-190℃.

26. A lactic acid bacteria product prepared by the preparation method according to any one of claims 2 to 25.

27. Use of the lactic acid bacteria product according to claim 1 or 26 in food preservation.

28. The use according to claim 27, characterized in that The food is selected from fruits and vegetables, baked pastries, fresh meat or pre-prepared dishes.

29. The use according to claim 27 or 28, characterized in that Lactic acid bacteria products are added to food by soaking, spraying or as additives.

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