Lactobacillus plantarum INM3122 as well as preparation and application thereof

Abstract

The invention provides a strain of lactobacillus plantarum INM3122 and preparation and application thereof, the strain is lactobacillus plantarum, the strain is preserved in Guangdong Microbial Culture Collection Center on November 4, 2024, the preservation number is GDMCC No: 65411, and the preservation address is No. 59 building, No. 100 Courtyard, Xianlie Middle Road, Guangzhou City, Guangdong Province. The lactobacillus plantarum has the advantages that the texture quality of the cold-chain rice can be effectively improved, and the good taste characteristic of the rice can be maintained in the cold-chain storage process.

Description

TECHNICAL FIELD

[0001] The present application relates to a strain of Lactobacillus plantarum INM3122 and its preparation and application. BACKGROUND

[0002] In the process of cold-chain cooked rice, the interaction between water and heat and starch and protein components, including starch gelatinization and protein denaturation, is the core chemical change. Secondly, during the storage process, the completely gelatinized starch is cooled or slowly dehydrated and dried at low temperature, so that the hydrogen bonds of starch molecules recombine to form an ordered arrangement of crystalline structure, which is "regeneration" (β-ization, or aging, retrogradation). Amylose can complete the aging process within a few hours of rice cooling, while amylopectin is relatively slow. However, both will affect the texture of rice, such as the increase in hardness, which affects the sensory quality. In summary, the processes of starch gelatinization, aging and protein denaturation have a significant impact on the texture of rice, which is closely related to the rice variety, process and environmental factors.

[0003] The methods for controlling the texture quality of rice mainly include the following three points: 1) rice variety selection: the contents of amylose, amylopectin and protein are different among different rice varieties, and the hardness of rice generally increases with the increase of amylose content, such as the hardness of Can rice is greater than that of japonica rice. Related studies have shown that even among the same rice varieties, there are similar starch contents, but due to the different starch structures, it can still lead to differences in rice texture. Research has shown that the content and molecular size of medium and long chain amylose can determine the hardness quality of rice. In addition, protein, as the second component of rice, also affects the texture of rice. Studies have shown that the removal of surface proteins of rice particles can promote the thermal dissolution of starch, increase the content of amylose, and thus improve the viscosity of rice. Therefore, it is necessary to screen the variety of rice in order to obtain satisfactory texture quality. 2) Cooking method: such as processing technology, including traditional steam cooking, microwave heating, electric rice cooker cooking, pressure cooking, high hydrostatic pressure method and other thermal and non-thermal treatment methods; soaking method, water-rice ratio control can make the rice gelatinization complete within a suitable range; during the storage process, controlling the water content < 30% or > 60%, and the temperature < -7℃ or > 60℃, can delay the rice retrogradation, thereby maintaining the texture quality. 3) Adding anti-aging agents: mainly including enzyme preparations (α-amylase, β-amylase, maltogenic amylase, etc.), quality improvers (sugars, food gums, emulsifiers, plant extracts).

[0004] Current research on rice texture control is quite extensive: Patent CN201811620797.X discloses an acid solution with ≥0.1 mg / mL L-tyrosine obtained by fermenting rice water with Xanthobacter flavus, which is used to replace the rice soaking liquid to prevent rice from yellowing and instant softening. However, the Xanthobacter flavus in the patent is not included in the "List of Bacteria that can be used in food", and cannot be used in food.

[0005] Patent CN202411423377.8 uses cooking to remove a certain amount of starch, then steams the gelatinization, combines the magnetic field to delay the aging of rice, and maintains the texture quality, but in practical application, the requirement for equipment is high, and it is not universal.

[0006] (E,E)-2,4-decadienal, 1-octen-3-ol, and 3-hydroxy-2-butanone are aldehydes, alcohols, and ketones, respectively, which can be produced by lipid oxidation degradation and microbial metabolism. (E,E)-2,4-decadienal has the flavor characteristics of nut aroma, sweetness, and fat taste; 1-octen-3-ol has the flavor characteristics of mushroom and straw fragrance; 3-hydroxy-2-butanone has the flavor characteristics of sweet and creamy aroma. Among them, 1-octen-3-ol is a characteristic flavor substance of rice. The paper "Study on the influence of glutinous rice and bamboo leaves on the sensory quality of white rice dumplings" uses SDE method to extract the flavor of glutinous rice and analyzes it by flavor dilution method, indicating that (E,E)-2,4-decadienal has the highest dilution factor and is the key flavor substance in glutinous rice flavor. In the paper "Analysis of flavor substances of colored rice based on SDE-GC-MS technology", (E,E)-2,4-decadienal and 1-octen-3-ol are considered to be the main flavor substances of colored rice. In the paper "Study on the steaming and cooking aroma components of rice and glutinous rice", GC-MS and GC-O methods are used to indicate that 3-hydroxy-2-butanone is one of the important aroma substances commonly present in the cooking of rice and glutinous rice. In the paper "Effect of baking temperature on volatile flavor compounds of black rice", it is also pointed out that 3-hydroxy-2-butanone is one of the markers of black rice flavor. Therefore, (E,E)-2,4-decadienal, 1-octen-3-ol, and 3-hydroxy-2-butanone are important aroma markers for rice products. (E,E)-2,4-decadienal and 1-octen-3-ol are mainly synthesized by chemical methods. Patent CN202311105655.0 introduces lipoxygenase gene, hydroperoxide lyase gene, alcohol oxidoreductase gene, and triple promoter into Corynebacterium glutamicum to construct recombinant Corynebacterium glutamicum, realizing the biological production of 1-octen-3-ol, but this strain is not in the "List of Bacteria that can be used in food", and cannot be used in food industry. At present, the method of biological production of 3-hydroxy-2-butanone mainly uses Klebsiella, Enterobacter, and Serratia for fermentation, but some of them need genetic modification and have potential pathogenicity. Patent CN201510468138.9 improves the fermentation process of Bacillus amyloliquefaciens, thereby increasing the content of 3-hydroxy-2-butanone in the strong-flavor base liquor. Although Bacillus amyloliquefaciens is considered to be a safe and beneficial strain, it is also not in the "List of Bacteria that can be used in food", and cannot be used.

[0007] Lactobacillus plantarum is one of the probiotics, which can be used in food. Its fermentation products are rich, and its metabolites such as antibacterial peptides, exopolysaccharides and other metabolites can improve food quality, increase nutritional value and prolong shelf life. In the paper "Antioxidant and antibacterial activity of lactic acid bacteria fermentation products of three kinds of rice", it is pointed out that the antioxidant capacity and antibacterial capacity of northeast rice and black rice are significantly enhanced (P<0.05) after fermentation by Lactobacillus plantarum, and the total polyphenol content is significantly increased (P<0.05), but the paper does not involve the influence of fermentation products on the texture quality and characteristic flavor of rice; In the paper "Exploring the physicochemical and microbiological properties of glutinous rice (Tapaipulut) fermented using Lactobacillus plantarum: A comprehensive characterization using 1H NMR", the cooked glutinous rice is fermented by Rhizopus oryzae and Lactobacillus plantarum. The conclusion shows that the combined fermentation of Lactobacillus plantarum shows significant inhibition effect on food-borne pathogenic bacteria, and the color, flavor, texture, taste and overall acceptability are good, but the paper only discusses the synergistic fermentation effect of Rhizopus oryzae and Lactobacillus plantarum, and does not discuss the effect of single strain fermentation on the texture quality of rice and the influence on the flavor. In addition, the storage conditions and shelf life of the application example are 30℃ and 48h, which are different from the storage conditions and shelf life of cold chain rice.

[0008] The patents and papers discussed above mainly adjust the cooking process and add anti-aging agents to achieve the purpose of adjusting the texture of rice. However, the magnetic field technology requires high equipment, and the influence of magnetic field on the health of employees cannot be accurately demonstrated. In addition, the selected strains cannot be used in food, which is difficult to realize, and the effect of the selected strains under specific storage conditions is also difficult to demonstrate. SUMMARY

[0009] The present application provides a Lactobacillus plantarum suitable for maintaining the texture quality and sensory quality of cold chain rice during the storage stage, increasing the content of flavor substances (E, E)-2,4-decadienal, 1-octen-3-ol and 3-hydroxy-2-butanone, and prolonging the shelf life of rice flavor, as well as the preparation and application of Lactobacillus plantarum INM3122.

[0010] The purpose of the application is achieved by the following scheme: a Lactobacillus plantarum strain, the strain is Lactobacillus plantarum (INM3122) Lactobacillus plantarum), the strain is preserved in Guangdong Microbial Culture Collection Center on November 4, 2024, the preservation number is: GDMCC No: 65411, and the preservation address is: No. 59, Building 5, 100, Xianlie Middle Road, Guangzhou, Guangdong.

[0011] A preparation method of lactobacillus plantarum, and the method comprises the following steps: isolating and screening lactic acid bacteria from yogurt samples, processing dairy products into slurry, adding sterile water, and diluting the concentration to 10 5 -10 6 The dairy products with different dilution concentrations are uniformly coated on solid MRS culture medium, and then placed in a culture box for 28 DEG C culture for 48 h, and then white colonies are selected on the solid MRS culture medium, and lactic acid bacteria meeting the morphology are screened. Lactic acid bacteria screening: the obtained lactic acid bacteria are cultured to the logarithmic growth phase, and then inoculated in an improved MRS solution at a 1% inoculation amount, and the strain final concentration is 1*10 6 cfu / mL, and then placed in 28 DEG C static culture for 3 days to obtain a fermentation liquor, and the required strain is screened according to pH, color and sensory indexes.

[0012] Application of lactobacillus plantarum in rice.

[0013] Further, according to the production process of rice products, the inoculation amount of the lactobacillus plantarum in the cooled rice is 10 4 -10 8 cfu / mL.

[0014] A fermentation agent prepared from lactobacillus plantarum.

[0015] Advantages of the present application: (1) the lactobacillus plantarum can effectively improve the texture quality of cold-chain rice and maintain good taste characteristics of rice during cold-chain storage.

[0016] (2) the lactobacillus plantarum can improve the content of characteristic flavor substances (E, E)-2,4-decadienal, 1-octen-3-ol and 3-hydroxy-2-butanone during application, and does not have adverse effects on the taste of rice.

[0017] (3) the lactobacillus plantarum can effectively prolong the shelf life of cold-chain rice and maintain the shelf life.

[0018] (4) the screening method has universality and can be widely applied to strain screening for improving the texture quality of cold-chain rice. DETAILED DESCRIPTION

[0019] Figure 1 It is a culture medium morphology diagram of lactobacillus plantarum.

[0020] Figure 2 It is a lactobacillus plantarum gram staining microscopic examination diagram.

[0021] Figure 3 is a standard curve graph of 3-hydroxy-2-butanone.

[0022] Figure 4 is a standard curve graph of 1-octen-3-ol.

[0023] Figure 5 is a standard curve graph of (E,E)-2,4-decadienal.

[0024] Figure 6 is a genetic stability test of Lactobacillus plantarum INM3122 of Example 2 Figure 1 .

[0025] Figure 7 is a genetic stability test of Lactobacillus plantarum INM3122 of Example 2 Figure 2 .

[0026] Figure 8 is a texture analysis of rice balls under different inoculation amounts of Lactobacillus plantarum of Example 3 Figure 1 .

[0027] Figure 9 is a texture analysis of rice balls under different inoculation amounts of Lactobacillus plantarum of Example 3 Figure 2 .

[0028] Figure 10 is a texture analysis of rice balls under different inoculation amounts of Lactobacillus plantarum of Example 3 Figure 1 .

[0029] Figure 11 is a texture analysis of rice balls under different inoculation amounts of Lactobacillus plantarum of Example 3 Figure 2 .

[0030] Figure 12 is a texture analysis of black rice of Example 4 Figure 1 .

[0031] Figure 13 is a texture analysis of black rice of Example 4 Figure 2 . DETAILED DESCRIPTION

[0032] The application will be further described below in conjunction with specific embodiments: The experimental methods used in the following implementation examples are conventional methods unless otherwise specified; the materials, reagents, etc. used are commercially available unless otherwise specified.

[0033] Example 1, refer to the attached Figures 1-13 A strain of Lactobacillus plantarum, the strain is Lactobacillus plantarum (INM3122) Lactobacillus plantarum), the strain is preserved in Guangdong Microbial Culture Collection Center on November 4, 2024, the preservation number is: GDMCC No: 65411, and the preservation address is: No. 59, Building 5, 100, Xianlie Middle Road, Guangzhou, Guangdong.

[0034] Application of lactobacillus plantarum in rice.

[0035] Application of lactobacillus plantarum in rice, according to the production process of rice products, the inoculation amount of lactobacillus plantarum in cooled rice is 10 4 -10 8 cfu / mL of lactobacillus plantarum.

[0036] A lactobacillus plantarum prepared fermenting agent.

[0037] The present application simulates twice chewing to carry out texture characteristic analysis of rice by using TPA full texture mode in a texture analyzer, so as to obtain hardness, elasticity, cohesiveness, gumminess, chewiness and resilience data, and the quality of the rice after cold storage is characterized.

[0038] The present application carries out sensory evaluation on the smell, appearance structure, palatability, taste and cold rice texture of rice balls according to GB / T 15682-2008.

[0039] The present application detects the shelf life of rice balls according to Q / ZYM instant rice balls.

[0040] The determination method of the present application: shelf life detection method: physical and chemical indexes are detected according to GB 5009.229, GB 5009.227, GB 5009.3 and GB 5009.12 respectively on acid value, peroxide value, moisture and lead; and microbial indexes are detected according to GB 4789.2, GB 4789.3, GB 4789.4 and GB 4789.10 on total number of colonies, coliform group, salmonella and staphylococcus aureus.

[0041] A preparation method of lactobacillus plantarum, 1, treatment of raw materials Take self-made yogurt, add sterile physiological saline and dilute to 10 -1 , 10 -2 , 10 -3 , 10 -4 , 10 -5 , 10 -6The concentration, the bacteria body diluent was made, 0.1 mL was taken from each concentration diluent and uniformly coated on MRS (containing 0.015% bromocresol purple) solid culture medium flat dish, 28°C culture for 48h, the medium-sized bacteria body, surface edge smooth, transparent, flat single colony was selected, the colony was streaked on MRS solid culture medium for secondary purification, 28°C culture for 48h, the single colony was picked and preserved in glycerol, and was named and coded as 2001~2009.

[0042] 2, Strain preliminary screening The 9 strains were inoculated into MRS liquid medium at 1% inoculation amount, and cultured at 28°C for 24h. Then, the 9 strains were inoculated into modified MRS medium at 1% inoculation amount, and cultured at 28°C for 24h, and the final concentration of bacteria body reached 10 6 CFU / mL. The formula of modified MRS medium was as follows: 10g proteose peptone, 8g beef infusion powder, 4g yeast infusion powder, 10g cellulose, 2g potassium phosphate dibasic, 2g ammonium citrate dibasic, 5g sodium acetate, 0.2g magnesium sulfate, 0.04g manganese sulfate, 1g Tween 80 were weighed and dissolved in 1000 mL distilled water, and sterilized at 0.1 MPa and 121°C for 15 min. At 24h of fermentation, the sample was taken from each tube, centrifuged at 10 000 r / min for 10 min to obtain the supernatant, and the basic indexes of fermentation product and the contents of (E, E)-2,4-decadienal, 1-octen-3-ol and 3-hydroxy-2-butanone were detected, and the absolute content was quantified by external standard method. The flavor determination method was as follows: GC-MS conditions: initial temperature of chromatographic column was 40°C, maintained for 3 min, increased to 200°C at a speed of 4°C / min, and then increased to 230°C at a speed of 10°C / min, maintained for 3 min. The carrier gas (He) flow rate was 1.0 mL / min, and the unsplit mode was selected.

[0043] EI energy source; electronic energy 70 eV, mass scan range 35~450 m / z, ion source temperature 220°C, transmission line temperature 250°C.

[0044] Qualitative and quantitative method: qualitative according to retention time.

[0045] The standard curve regression equation was obtained by drawing the standard curve with the standard substance concentration as abscissa and peak area as ordinate, and the quantitative analysis was carried out by external standard method.

[0046] The obtained standard curve is shown in the accompanying Figures 3-5 The results are shown in Table 1.

[0047] Table 1 Analysis of three flavor substances fermented

[0048] It can be known that the content of (E, E)-2, 4-decadienal, 1-octen-3-ol and 3-hydroxy-2-butanone in the fermentation broth of strains 2001, 2002 and 2006 is higher, and there is difference in score with other strains. The pH value of the fermentation broth is weakly acidic, close to neutral, and the activity of the strain is better. Therefore, the three strains are re-screened.

[0049] 3. Strain rescreening The strains of lactic acid bacteria 2001, 2002 and 2006 selected by preliminary screening are reactivated and cultured, and the fermentation product with a bacterial concentration of 10 6 The fermentation product with a bacterial concentration of 10

[0050] Table 2. Content of target flavor substances in rice balls treated by strains of preliminary screening and results of sensory evaluation

[0051] Note: 6 people with high sensory sensitivity are selected to participate in the evaluation, and the score is the average score. The higher the score, the better the result.

[0052] Table 3. Texture analysis of rice balls treated by strains of rescreening

[0053] From the results of Tables 2 and 3, it can be seen that the contents of (E, E)-2,4-decadienal, 1-octen-3-ol and 3-hydroxy-2-butanone in the rice made by inoculating the fermentation liquor are significantly increased, and the content of flavor substances of the 2001 strain is the highest. The rice with good sensory evaluation should have the characteristics of moderate hardness, high elasticity, smoothness, stickiness but not sticky teeth, and the sensory evaluation of the treated groups is significantly improved, and the 2001 strain has the optimal sensory evaluation. In the texture index, hardness refers to the resistance of rice when subjected to chewing action. Elasticity refers to the degree of recovery of rice after chewing. Chewiness is a comprehensive index for evaluating the energy and feeling required when food is repeatedly chewed in the mouth. Resilience refers to the ability of rice to restore its original shape or state after being subjected to external force (such as compression, stretching, etc.), which is an important index for evaluating the “chewing strength” and “rebound force” of rice. Gumminess is the property of rice to resist further deformation after being compressed. Cohesiveness refers to the ability of rice to maintain its original shape after being subjected to external force. Analysis of the texture results shows that the 2001 strain treatment group reduces the hardness of rice at the end of storage, while improving the elasticity, chewiness, resilience and gumminess of rice, and the results of the 2001 strain are the best, corresponding to the optimal palatability results in the sensory evaluation, so the 2001 strain can be used as a target strain for re-screening. The morphological observation of the 2001 strain on the solid MRS plate culture medium is shown in Figure 1 The results of observation under a microscope after Gram staining are shown in Figure 2 .

[0054] The 2001 strain obtained by the above screening was subjected to 16S rDNA sequencing identification, and through comparative analysis, the 16S region sequence of the strain of the present application reached 99.86% similarity with Lactobacillus plantarum Lactobacillus plantarum ), and it can be determined that the strain is a Lactobacillus plantarum, which can be applied to the food fermentation industry, and is named Lactobacillus plantarum INM3122. The strain was preserved in the Guangdong Microbial Culture Collection Center on November 4, 2024, and the preservation number is GDMCC No: 65411, so INM3122 and 2001 in this application refer to the same strain. The 2001 strain of the present application is genetically identified, and its gene sequence is as follows: Example 2: Detection of the genetic stability of Lactobacillus plantarum INM3122 The *Lactobacillus plantarum* INM3122 from Example 1 was passaged 10 times on modified MRS liquid medium. The 1st, 5th, and 10th generation samples were centrifuged at 10,000 rpm for 10 min, and the supernatant was used as the sample. This supernatant was then inoculated into rice balls. The contents of (E,E)-2,4-decadienal, 1-octen-3-ol, and 3-hydroxy-2-butanone were measured. Simultaneously, texture analysis and sensory evaluation were performed to determine its passage stability. Specific data can be found in […]. Figure 6 , Figure 7 And Table 4.

[0055] Table 4. Analysis of Passage Stability Test

[0056] Note: Six individuals with high sensory sensitivity were selected to participate in the evaluation. The score is the average score, and the higher the score, the better the result.

[0057] Combination Figure 6 , Figure 7 As shown in Table 4, the fermentation performance of Lactobacillus plantarum INM3122 strains of different generations was normal. The contents of (E,E)-2,4-decadienal, 1-octen-3-ol, and 3-hydroxy-2-butanone varied within 10%. Significance analysis of the texture indicators of the rice balls showed no significant differences, and the sensory evaluation results were similar, indicating that the strain has good genetic stability and meets the requirements for production and use.

[0058] Example 3: Shelf life test of cold chain rice balls treated with Lactobacillus plantarum INM3122 To verify the optimal concentration of Lactobacillus plantarum INM3122 and its effect on the shelf life of cold-chain japonica rice balls, Lactobacillus plantarum INM3122 was inoculated into rice balls cooled to 28°C. The inoculation concentration of the fermentation bacteria was 10... 5 -10 8 At CFU / mL, fermented cold-chain rice balls were prepared separately, with a control group treated with the same strain but without added fermentation strain. After 78 hours of storage, the contents of (E,E)-2,4-decadienal, 1-octen-3-ol, and 3-hydroxy-2-butanone were measured, and the sensory evaluation results are shown in Table 5. The texture test results are as follows: Figure 8 , Figure 9 As shown.

[0059] The optimal concentration of fermentation bacteria was selected for shelf life testing. The fermented cold chain rice balls were stored for 7 days, and tests were conducted at 0, 1, 3, 5 and 7 days. The results are shown in Table 6.

[0060] Table 5. The content of target flavor substances and sensory evaluation results of different concentrations of fermentation strains

[0061] Note: 6 people with high sensory sensitivity were selected to participate in the evaluation, and the score was the average score. The higher the score, the better the result.

[0062] From Table 5, Figure 8 , Figure 9 The results show that with the increase of inoculation concentration, the content of (E, E)-2,4-decadienal, 1-octene-3-ol and 3-hydroxy-2-butanone shows a trend of first increasing and then flattening, and the sensory evaluation shows a trend of first rising and then falling. The content of 1.0 x 10 7 CFU / mL is similar to that of 1.0 x 10 8 CFU / mL, but the sensory score of 1.0 x 10 7 CFU / mL is the best. The overall texture shows a decrease in hardness, gumminess and chewiness, but the texture of the rice ball with an inoculation concentration of 1.0 x 10 8 CFU / mL is similar to that of 1.0 x 10 7 CFU / mL, and the difference between the five groups of rice in resilience, elasticity and cohesiveness is small. Therefore, the most suitable inoculation concentration is 1.0 x 10 7 CFU / mL, at which the content of the three flavor substances is relatively high, and the texture of the cold chain rice ball is well maintained, so that the taste of the rice at the end of the storage period still maintains good hardness, gumminess and chewiness, and the sensory evaluation has the best smell, appearance structure, palatability, taste and cold rice texture.

[0063] According to the most suitable inoculation concentration, the rice ball inoculated with Lactobacillus plantarum INM3122 at a concentration of 1.0 x 10 7 CFU / mL was tested for shelf life. Since some literature suggests that Lactobacillus plantarum has antibacterial activity and can significantly inhibit some foodborne pathogens, the shelf life test time of cold chain rice was extended to 7 days. The normal treatment of cold chain rice ball was used as the control group, and the shelf life test results are shown in Table 6. At the same time, texture analysis was carried out, and the results are shown in Figure 10 , Figure 11

[0064] Table 6. Shelf life analysis of rice balls

[0065] ​As shown in Table 6, the control group rice balls failed the test on day 5 of their shelf life, with coliform bacteria reaching 560 CFU / g, exceeding the standard by more than 10 CFU / g. The rice balls treated with the inoculum strain still showed results within the standard range on day 7, indicating that inoculation with *Lactobacillus plantarum* INM3122 has antibacterial activity and can effectively extend the shelf life of cold-chain japonica rice balls to 7 days. Figure 10 , Figure 11 The results show that as the storage period is extended, the control group and 10 7 The group showed an increasing trend in hardness, adhesiveness, and chewiness, but the increase in the control group was much greater than 10%. 7 The most significant indicator was hardness; the hardness increase in the control group was 330.78 G, 10 7 The group with a concentration of only 102.95 G showed that the elasticity, cohesion, and resilience of the inoculated treatment at the end of storage were higher than those of the control group, and were closer to the values ​​at the beginning of storage. These results indicate that inoculation for 10... 7 Concentrated concentrations of Lactobacillus plantarum INM3122 can extend the shelf life of glutinous rice balls to 7 days, while maintaining the textural properties of the rice during storage.

[0066] Example 4: Preparation of cold-chain black rice balls using Lactobacillus plantarum INM3122 Take the final concentration as 10 7 Black rice balls were inoculated with *Lactobacillus plantarum* INM3122 at a dose of CFU / mL, with the untreated group serving as the control. The rice was stored at a cold chain temperature of 2-6°C for 7 days. Shelf life, content of (E,E)-2,4-decadienal, 1-octen-3-ol, and 3-hydroxy-2-butanone, sensory evaluation, and texture were measured at 0, 3, and 7 days, using the same methods as in Example 1. The results are shown in Tables 7 and 8, respectively. Figure 12 , Figure 13 As shown.

[0067] Table 7 Shelf life test of black rice balls

[0068] Table 8. Target flavor content and sensory evaluation results of black rice balls

[0069] Note: Six individuals with high sensory sensitivity were selected to participate in the evaluation. The score is the average score, and the higher the score, the better the result.

[0070] As shown in Table 7, only the control group's black rice balls had an E. coli count greater than 10 CFU / g on day 7, resulting in product non-compliance. This indicates that the inoculation treatment group effectively extended the shelf life of the cold-chain black rice balls to 7 days. (Based on Table 8 and...) Figure 12 , Figure 13 The results show that after 10 doses... 7The content of (E, E)-2, 4-decadienal, 1-octen-3-ol and 3-hydroxy-2-butanone in the black rice rice ball of Lactobacillus plantarum INM3122 was significantly increased compared with the control group, and gradually increased with the extension of the storage period. The sensory evaluation results showed that the inoculation treatment effectively inhibited the deterioration of the taste of black rice during the storage period, and the sensory score was close to that at the beginning of storage. The texture change rule of black rice during storage was similar to that of japonica rice. With the extension of the storage period, the hardness, gumminess and chewiness increased, and the elasticity, cohesiveness and resilience decreased. The inoculation of 10 7 The black rice rice ball inoculated with 10

[0071] Example 5, Lactobacillus plantarum INM3122 for making cold chain mixed rice ball Pearl japonica rice, long glutinous rice and black rice were mixed and cooked at a ratio of 3:1:1. Lactobacillus plantarum INM3122 was inoculated at a final concentration of 10 7 CFU / mL to make mixed rice ball. The rest of the treatment was referred to Example 4, and the untreated group was used as the control group. The detection indexes were the same as Example 4. The texture results were obtained by separating different types of rice in the mixed rice. The results are shown in Tables 9, 10 and 11.

[0072] Table 9: Shelf life test of mixed rice ball

[0073] Table 10: Texture analysis of mixed rice

[0074] Table 11: 3-hydroxy-2-butanone content and sensory evaluation results of mixed rice ball

[0075] Note: 6 people with high sensory sensitivity were selected for evaluation. The score is the average score. The higher the score, the better the result.

[0076] From the results in Table 9, only the control group of mixed rice ball had a total number of colonies greater than 10,000 CFU / g and E. coli greater than 10 CFU / g on the 7th day, and the product was unqualified, indicating that the inoculation treatment effectively extended the shelf life of the cold chain mixed rice ball to 7 days. According to the results in Table 10, the inoculation of 10 7The Lactobacillus plantarum INM3122 treatment of 10 7 The content of (E, E)-2,4-decadienal, 1-octen-3-ol and 3-hydroxy-2-butanone in the mixed rice ball treated with 10

[0077] The above-described embodiments only express several embodiments of the present application, which are described in a more specific and detailed manner, but should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, which belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A strain of *Lactobacillus plantarum*, characterized by: The strain is Lactobacillus plantarum ( Lactobacillus plantarum This strain was deposited on November 4, 2024, at the Guangdong Provincial Center for Microbial Culture Collection, with accession number GDMCC No:65411, located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, Guangdong Province.

2. A method for preparing *Lactobacillus plantarum* as described in claim 1, characterized in that: Isolation of lactic acid bacteria: Lactic acid bacteria were isolated and screened from yogurt samples. The dairy products were processed into a paste and added to sterile water to dilute to a concentration of 10⁵-10⁶. The dairy products of different dilution concentrations were evenly spread on solid MRS medium and incubated at 28°C for 48 hours. White colonies and lactic acid bacteria with the correct morphology were selected from the solid MRS medium for screening. Lactic acid bacteria screening: The obtained lactic acid bacteria were cultured to the logarithmic growth phase, and then inoculated at a 1% rate, with a final strain concentration of 1×10⁻⁶. 6 The cfu / mL was inoculated into a modified MRS solution and incubated at 28°C for 3 days to obtain the fermentation broth. The desired strains were screened based on pH and color sensory indicators.

3. The application of Lactobacillus plantarum as described in claim 1 in rice.

4. The application of *Lactobacillus plantarum* in rice as described in claim 3: According to the rice product manufacturing process, the inoculation amount in cooled rice is 10... 4 -10 8 Lactobacillus plantarum cfu / mL.

5. A starter culture prepared from Lactobacillus plantarum as described in claim 1.

Images