Staphylococcus carnosus and application of staphylococcus carnosus in improving sour taste of soy sauce

Abstract

The invention discloses staphylococcus carnosus and application of the staphylococcus carnosus in improvement of sour taste of soy sauce. Belongs to the technical field of food fermentation. The staphylococcus carnosus CS1.21 is separated from soy sauce mash for the first time, and has the characteristics of salt resistance, strong acid production, ester production, bacteriostasis and the like. When the strain is used for fermenting the high-salt liquid-state soy sauce, lactic acid, acetic acid and succinic acid can be effectively produced and are respectively increased by 28.13%, 27.78% and 50.00% compared with fermented soy sauce without CS1.21, meanwhile, accumulation of ester substances is promoted, the content of the ester substances is increased by 86.23% compared with the fermented soy sauce without CS1.21, the content of ethyl lactate is increased by 70.11%, the content of ethyl acetate is increased by 85.76%, and the content of succinic acid is increased by 70.12%. The addition of the staphylococcus carnosus CS1.21 is beneficial for improving the sour taste of the soy sauce, the quality and flavor of the soy sauce are improved, and no preservative is needed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of food fermentation, and more particularly to a Staphylococcus carnosus and application thereof in improving the sour taste of soy sauce. BACKGROUND

[0002] Soy sauce is a traditional condiment originated in China and brewed by microorganisms from soybeans and wheat. During the fermentation of soy sauce, in addition to the main protein hydrolysis by Aspergillus oryzae, acid-producing bacteria such as Staphylococcus halophilus produce organic acids such as lactic acid and acetic acid through high-salt fermentation, which can improve the sour taste of soy sauce, thus being beneficial to the formation of sweet and mellow taste of soy sauce. The accumulation of organic acids can also promote the formation of organic acid esters, which can enhance the aroma of soy sauce. In addition, the accumulation of organic acids can also moderately reduce the pH of the mash, thereby achieving a certain antibacterial effect and enabling the preparation of soy sauce without the addition of preservatives.

[0003] Staphylococcus carnosus is a kind of acid-producing bacteria commonly found in fermented foods, which has the ability to produce acid, promote the accumulation of free amino acids, protect color and enhance aroma, and can improve the flavor and quality of fermented foods.

[0004] However, there are few reports on the research and application of Staphylococcus carnosus screened from soy sauce mash, and the performance of the strain and its effect on soy sauce fermentation will be beneficial to the improvement of soy sauce fermentation technology and quality.

[0005] Therefore, how to provide a Staphylococcus carnosus suitable for improving the sour taste and flavor of soy sauce during fermentation and develop a soy sauce fermentation process is a problem that needs to be solved by those skilled in the art. SUMMARY

[0006] Therefore, the present application provides a Staphylococcus carnosus and application thereof in improving the sour taste of soy sauce.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0008] A Staphylococcus carnosus, named CS1.21, is classified as Staphylococcus carnosus, and was preserved in the China General Microbiological Culture Collection Center on November 29, 2024, with the preservation number CGMCC No.32851 and the preservation address being No.3, Beichen West Road, Chaoyang District, Beijing.

[0009] Further, the Staphylococcus carnosus CS1.21 can tolerate a maximum of 16 g / 100 mL of NaCl.

[0010] The Staphylococcus carnosus described above is applied to improve the organic acid content in the production of soy sauce by high-salt dilute-state fermentation.

[0011] Further, the organic acid is lactic acid, acetic acid and succinic acid, compared with the un-added meat staphylococcus fermented raw soy sauce, the content of the above-mentioned organic acid in the added fermented raw soy sauce is increased.

[0012] The application of the above-mentioned meat staphylococcus in the fermentation production of soy sauce mainly includes the following steps:

[0013] S1, inoculating the meat staphylococcus CS1.21 into the fermentation mash;

[0014] S2, continuing to ferment the mash obtained by adding the meat staphylococcus CS1.21 in S1 for 90 days;

[0015] S3, squeezing, membrane filtering and sterilizing the fermented mash obtained in S2 to obtain the fermented soy sauce crude oil added with the meat staphylococcus CS1.21.

[0016] Further, the fermentation mash in the step S1 is high-salt dilute mash with a salt concentration of 16-18 g / 100 mL, and the fermentation time is 10-25 d.

[0017] Further, the inoculation amount of the meat staphylococcus CS1.21 in the step S1 is 10 8 ~ 10 10 CFU per L of fermentation mash.

[0018] Further, the fermentation temperature of the mash in the step S1 and the step S2 is 25-35℃.

[0019] The application of the above-mentioned meat staphylococcus in the fermentation production of soy sauce further increases the content of organic acid, amino acid nitrogen and volatile flavor components in the soy sauce.

[0020] The application of the above-mentioned meat staphylococcus in improving the sour taste of soy sauce.

[0021] According to the above-mentioned technical solution, compared with the prior art, the beneficial effects obtained by the application are:

[0022] The meat staphylococcus CS1.21 of the application is isolated from mash for the first time, has the characteristics of salt tolerance, strong acid production, ester production and bacteriostasis, and has good application value in the fermentation of soy sauce for improving sour taste and flavor. Fermenting high-salt dilute soy sauce with the strain can produce a certain concentration of organic acid and organic acid ester, realize the enhancement of the quality and flavor of soy sauce, and no preservative needs to be added. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced. Obviously, the accompanying drawings in the following description only represent some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on the provided drawings also belong to the protection scope of the present application.

[0024] Figure 1 Gram staining diagram of the strain CS1.21 in Embodiment 2 of the present application;

[0025] Figure 2 16S rDNA sequence fragment electrophoresis diagram of the strain CS1.21 in Embodiment 2 of the present application;

[0026] Figure 3 Phylogenetic tree of the strain CS1.21 in Embodiment 2 of the present application;

[0027] Figure 4 Organic acid chromatogram of Staphylococcus carnosus CS1.21 in Embodiment 4 of the present application;

[0028] Figure 5 Antibacterial characteristics of Staphylococcus carnosus CS1.21 in Embodiment 4 of the present application;

[0029] Figure 6 Hemolytic safety diagram of Staphylococcus carnosus CS1.21 in Embodiment 4 of the present application;

[0030] Figure 7 Metabolic characteristics of Staphylococcus carnosus CS1.21 in soy sauce fermentation in Embodiment 6 of the present application;

[0031] Figure 8 Sensory evaluation results of fermented soy sauce added with Staphylococcus carnosus CS1.21 in Embodiment 6 of the present application. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments only represent some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0033] Unless otherwise defined, all the professional terms used in the following description have the same meaning as commonly understood by those skilled in the art. The professional terms used in the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the protection scope of the present application.

[0034] Unless otherwise specifically indicated, all materials, reagents, solvents, and the like used in the present application are available from commercial sources or are prepared by conventional methods.

[0035] Example 1

[0036] Strain screening

[0037] The MRS medium (solid medium added with 18 g / 100 mL agar powder) containing 0.2 g / 100 mL bromocresol purple and 8 g / 100 mL NaCl was used to isolate and screen strains from high-salt dilute soy sauce. The soy sauce samples fermented for 15 and 45 days were selected, 10 g of the soy sauce was placed in a sterile flask with glass beads, 90 mL of sterile normal saline was added, and the sample was mixed and made uniform by oscillation at 100 r / min for 5 min. After gradient dilution, 100 μL of the bacterial suspension was spread on NaCl-bromocresol purple-MRS isolation plates, and incubated at 37°C for 2-5 days. The acid-producing strains with a large ratio of color change circle to colony diameter were screened, and after isolation and purification, they were subjected to re-screening.

[0038] The salt-tolerant acid-producing and well-growing strains after isolation and purification were inoculated into MRS liquid medium containing 80 g / L NaCl, and incubated at 37°C and 180 rpm for 48 h. 5 mL of the fermentation broth was centrifuged to obtain the supernatant, and the pH was determined. The strains with a fermentation broth pH <4.5 were screened.

[0039] 2 mL of the fermentation broth of the screened strain was filtered through a 0.22 μm water system membrane, and the lactic acid content was analyzed by liquid chromatography (liquid chromatography conditions: mobile phase 0.1% phosphoric acid-methanol (95:5), flow rate 0.6 mL / min, injection volume 10 μL, ultraviolet detection wavelength 210 nm, column temperature 30°C). The strain with the largest amount of lactic acid production was screened, and was named CS1.21.

[0040] Example 2

[0041] Strain identification

[0042] 1. Morphological characteristics

[0043] (1) The fermentation broth of the strain CS1.21 was gradient diluted and spread on MRS plates, and incubated at 37°C for 48 h. The colony morphology was observed. The plate bacterial phase results showed that the strain CS1.21 was a milky white round shape with smooth surface, opaque, central uplift, and regular edge.

[0044] (2) The strain CS1.21 was subjected to Gram staining, and the strain morphology characteristics were observed under an oil lens (100x). It was found that the strain was single cell, arranged in pairs or short chains, and part of the strains could be seen irregularly aggregated, and was a Gram-positive bacteria. Figure 1 ).

[0045] 2. Molecular biology characteristics

[0046] Genomic DNA of the strain CS1.21 was extracted by bacterial kit of Shengwo Bioengineering (Wuhan) Co., Ltd. PCR amplification of 16S rDNA was performed by using bacterial universal primers 27F and 1492R.

[0047] Primer design: Forward primer: 5'-AGAGTTTGATCCTGGCTCAG-3', SEQ ID No. 1; Reverse primer: 5'-AAGGAGGTGATCCAGCCGCA-3', SEQ ID No. 2.

[0048] PCR reaction system (50 μL): 2 μL template DNA, 2 μL upstream primer (10 μmol / mL), 2 μL downstream primer (10 μmol / mL), 5 μL 10×PCR Buffer, 3 μL Mg 2+ (25 mol / mL), 4 μL dNTP (2.5 mol / mL), 1 μL Taq DNA polymerase (5 U / μL), 31 μL double distilled water.

[0049] PCR reaction conditions: 95 °C template DNA pre-denaturation for 5 min; 95 °C denaturation for 30 s, 55 °C annealing for 30 s, 72 °C extension for 1 min, 30 cycles; 72 °C extension for 10 min, 4 °C storage.

[0050] The PCR product was detected by agarose electrophoresis. The results are shown in Figure 2 .

[0051] The PCR product was sent to Changsha Branch of Shengwo Bioengineering (Shanghai) Co., Ltd. for sequencing, and the sequencing results are shown in SEQ ID No. 3. The 16S rDNA results obtained by sequencing were compared in the Genbank database of NCBI (National Center for Biotechnology Information). The results were identified as Staphylococcus carnosus Figure 3 .

[0052]

[0053]

[0054] Example 3

[0055] Preservation of strains

[0056] Staphylococcus carnosus CS1.21, which is classified as Staphylococcus carnosus, was preserved in the China General Microbiological Culture Collection Center on November 29, 2024, with a preservation number of CGMCC No. 32851 and a preservation address of No. 3, Beichen West Road, Chaoyang District, Beijing.

[0057] Example 4

[0058] Staphylococcus carnosus CS1.21 strain performance determination

[0059] 1. Salt tolerance:

[0060] Staphylococcus carnosus CS1.21 cultured to 10 7 CFU / mL was inoculated on MRS plates containing 8, 10, 12, 14, 16, 18, and 20 g / 100 mL NaCl, respectively, and incubated in a 37°C incubator until visible colonies were formed. The salt tolerance of the strain was determined according to its growth on the salt plates.

[0061] Table 1 Staphylococcus carnosus CS1.21 salt tolerance results

[0062]

[0063] Note: “+++” indicates good growth, “++” indicates better growth, “+” indicates general growth, and “-” indicates no growth.

[0064] As shown in the salt tolerance results in Table 1, Staphylococcus carnosus CS1.21 can grow in MRS medium containing 8-16 g / 100 mL NaCl, with a maximum tolerance of 16 g / 100 mL NaCl, indicating good tolerance to high concentrations of salt.

[0065] 2. Acid production performance:

[0066] Staphylococcus carnosus CS1.21 cultured to 10 7 CFU / mL was inoculated into MRS liquid medium containing 16 g / 100 mL NaCl and fermented at 37°C for 48 h. 2 mL of the fermentation broth was mixed with 5 mL of zinc sulfate solution (3 g / 100 mL) and 5 mL of potassium ferrocyanide solution (10.6 g / 100 mL), and then diluted to 100 mL. After standing for 30 min, the supernatant was centrifuged, filtered with a 0.22 μm water system membrane, and the filtrate was analyzed for organic acid content by liquid chromatography.

[0067] Using common organic acids in soy sauce as standard control substances, the organic acids produced by Staphylococcus carnosus CS1.2 were qualitatively analyzed using high-performance liquid chromatography. The organic acid chromatogram is shown in Figure 4The standard curve of organic acid is shown in Table 2, the results of fermentation of Staphylococcus carnosus CS1.21 to generate organic acid are shown in Table 3, the total content of the six organic acids is 1.43 g / 100 mL, wherein the content of lactic acid and acetic acid accounts for more than 75% of the total content of the six organic acids, wherein the content of acetic acid is 0.91 g / 100 mL, the content of lactic acid is 0.19 g / 100 mL, and the content of citric acid is 0.30 g / 100 mL, which are the main organic acids.

[0068] Table 2 Standard curve of organic acid

[0069]

[0070]

[0071] Note: x is the concentration of organic acid; y is the peak area.

[0072] Table 3 Content of organic acid metabolized by Staphylococcus carnosus CS1.21

[0073]

[0074] Note: * represents the unit of fumaric acid, which is "mg / 100 mL".

[0075] 3. Bacteriostatic performance:

[0076] Staphylococcus carnosus CS1.21 strain is inoculated on the lower layer of MRS plate with crosswise streak, and is cultured at 37°C for 24 h, and then 10 5 CFU / mL Bacillus megatherium BB15 (isolated and preserved by Hunan Seasoning Fermentation Engineering Center from deteriorated soy sauce) beef extract peptone medium is poured on the upper layer of MRS plate, and the culture is continued for 8-24 h to observe the results. The transparent circle formed around the crosswise streak area indicates that the strain can inhibit the growth of Bacillus megatherium, and vice versa.

[0077] The results of the bacteriostatic test of Staphylococcus carnosus CS1.21 on Bacillus megatherium BB15 are shown in Figure 5 Staphylococcus carnosus CS1.21 forms a transparent bacteriostatic circle obviously larger than the crosswise streak area on the plate with Bacillus megatherium, which indicates that the strain can obviously inhibit the growth of Bacillus megatherium which causes deterioration of soy sauce.

[0078] 4. Hemolytic safety performance:

[0079] Staphylococcus carnosus CS1.21 was inoculated on defibrinated sheep blood plate, and Staphylococcus aureus ATCC 6538 was inoculated as a positive control, and Escherichia coli DH-5α was inoculated as a negative control. The culture conditions of Staphylococcus carnosus CS1.21, the positive and negative control bacteria were 37°C, 24h. If there was a hemolytic ring, it was recorded as "positive", and if there was no hemolytic ring, it was recorded as "negative".

[0080] Defibrinated sheep blood medium: 7% sheep blood agar base 33g, 1000ml water, 121°C sterilization for 20min; after sterilization, add 5% sterile defibrinated sheep blood when cooled to 50°C, shake well and pour into sterile plate and cool for standby.

[0081] Compared with the positive and negative controls, the hemolysis test results of CS1.21 showed no hemolysis Figure 6 According to the search, Staphylococcus carnosus is a strain included in the "List of Microbial Strains for Traditional Fermented Foods in China", which is a completely safe food-grade strain in the Staphylococcus genus. Therefore, Staphylococcus carnosus CS1.21 can be used as a safe food fermentation bacteria.

[0082] Example 5

[0083] Application of Staphylococcus carnosus CS1.21 in the fermentation of soy sauce

[0084] The following steps are adopted:

[0085] (1) Staphylococcus carnosus CS1.21 was inoculated into high-salt thin-state soy sauce with a salt concentration of 16-18g / 100ml and fermented for 15d, and the inoculation amount was 1x10 9 CFU per L of fermented soy sauce;

[0086] (2) The soy sauce inoculated with Staphylococcus carnosus CS1.21 was continuously fermented to 90 days, and the temperature was controlled at 30°C throughout the process;

[0087] (3) The soy sauce fermented for 90d in the above step was squeezed, membrane filtered and sterilized to obtain Staphylococcus carnosus CS1.21 fermented soy sauce.

[0088] Example 6

[0089] Quality indicators of Staphylococcus carnosus CS1.21 fermented soy sauce

[0090] Staphylococcus carnosus CS1.21 fermented soy sauce was prepared by the method of Example 5, and Staphylococcus carnosus CS1.21 was not added as a control group.

[0091] 1. Physicochemical indicators of Staphylococcus carnosus CS1.21 fermented soy sauce:

[0092] The physicochemical properties of the Staphylococcus carnosus CS1.21 fermented soy sauce were analyzed, the reducing sugar content determination method referred to the national standard of the People's Republic of China GB / T 5009.7-2016, the total acid content determination method referred to the national standard of the People's Republic of China GB / T 12456-2021, and the amino acid nitrogen determination method referred to the national standard of the People's Republic of China GB / T 5009.39-2003.

[0093] The role of Staphylococcus carnosus CS1.21 in soy sauce fermentation was investigated, and the physicochemical indexes of the soy sauce fermented for 90 days were determined with the soy sauce without Staphylococcus carnosus CS1.21 as the control group. As shown in Table 4, the reducing sugar content decreased by 4.40 compared with the control group, the total acid and amino acid nitrogen contents were higher than those of the control group, the total acid content was 1.76 g / 100 mL, which was increased by 15.79% compared with the control group; the amino acid nitrogen content was 0.96 g / 100 mL, which was increased by 4.35% compared with the control group, exceeding 20% of the special grade soy sauce (amino acid nitrogen of special grade soy sauce ≥0.80 g / 100 mL), and the total acid index met the national standard (total acid ≤2.5 g / 100 mL). The addition of the fermented soy sauce improved the total acid content and the acid taste, and did not cause the total acid content to be unqualified. It can be seen that the addition of Staphylococcus carnosus CS1.21 helps to increase the total acid and amino acid nitrogen contents of the soy sauce, and improve the acid taste and umami taste of the soy sauce. Overall, compared with the control group, the addition of Staphylococcus carnosus CS1.21 can accelerate the utilization of reducing sugar, promote the accumulation of total acid and amino acid nitrogen, and thus improve the quality of the soy sauce.

[0094] Table 4 Physicochemical indexes of Staphylococcus carnosus CS1.21 fermented soy sauce

[0095]

[0096] 2. Organic acid composition and content of Staphylococcus carnosus CS1.21 fermented soy sauce:

[0097] The contents of six organic acids (L-malic acid, lactic acid, acetic acid, citric acid, succinic acid and fumaric acid) in the Staphylococcus carnosus CS1.21 fermented soy sauce were determined by the organic acid analysis method of Reference Example 4, and the results are shown in Table 5.

[0098] Table 5 Contents of organic acids in Staphylococcus carnosus CS1.21 fermented soy sauce

[0099]

[0100] Note: * represents the unit of fumaric acid as "mg / 100 mL".

[0101] The results are shown in Table 5, the total content of 6 kinds of organic acids in the fermented soy sauce added with Staphylococcus carnosus CS1.21 is 1.24 g / 100 mL, which is increased by 24.00% compared with the control group. The addition of Staphylococcus carnosus CS1.21 fermentation mainly affects the content of lactic acid, acetic acid and succinic acid in the 6 kinds of organic acids, which are 0.41, 0.46 and 0.18 g / 100 mL, respectively, which are increased by 28.13%, 27.78% and 50.00% respectively compared with the control group.

[0102] Figure 7 In the fermentation of Staphylococcus carnosus CS1.21, the net increase in the number of moles of lactic acid, acetic acid and succinic acid in the fermented soy sauce is in the up-regulated state; the net increase in the number of moles of L-malic acid, citric acid and fumaric acid in the fermented soy sauce is in the down-regulated state, and the accumulation of lactic acid and acetic acid is most significantly up-regulated, which is beneficial to the formation of important lactic acid esters and acetic acid esters in soy sauce. Lactic acid and acetic acid are important organic acids for the formation of sour taste in soy sauce, and succinic acid has a typical meaty flavor. The up-regulation of these three organic acids has a great effect on the formation of palatable sour taste and the improvement of umami flavor in soy sauce.

[0103] 3. Volatile flavor substances and contents in the fermented soy sauce by Staphylococcus carnosus CS1.21

[0104] Take 2 mL of the soy sauce sample fermented by Staphylococcus carnosus CS1.21 for 90 days and place it in a 20 mL gas chromatography-mass spectrometry special sample bottle, and add 2 μL of 2-methyl-3-heptanone solution (0.816 μg / μL) as an internal standard. The SPME conditions are: oscillator heating temperature 50°C, heating and oscillation time 20 min, extraction time 20 min; the GC conditions are: injection port temperature 250°C, analysis time 5 min, programmed temperature conditions are 40°C for 1 min, increased to 120°C at 5°C / min, maintained for 2 min, increased to 250°C at 10°C / min, maintained for 5 min, carrier gas is high-purity helium, carrier gas flow rate is 1.0 mL / min, injection is not split; the MS conditions are: EI ion source, electron energy is 70 eV, emission current is 200 μA, transmission line and ion source temperature is 250°C, ion fragment mass scan range is 40-500 m / z.

[0105] Table 6 Volatile flavor substances in the fermented soy sauce by Staphylococcus carnosus CS1.21

[0106]

[0107] The results of the types and contents of volatile substances in the Staphylococcus carnosus CS1.21 fermented soy sauce for 90 days are shown in Table 6. The types of volatile flavor substances in the Staphylococcus carnosus CS1.21 fermented soy sauce were 54, which was 9 more than the control group. The total content of volatile flavor substances in the Staphylococcus carnosus CS1.21 fermented soy sauce was 5424.52 μg / L, which was 50.04% higher than the control group. In addition, ethyl acetate and ethyl lactate were ester substances related to the metabolism of organic acids by Staphylococcus carnosus CS1.21, and their contents were significantly higher than those of the control group. The content of ethyl acetate, which has a fruity aroma, increased by 85.76% compared to the control group, and the content of ethyl lactate, which has a creamy aroma, increased by 70.11% compared to the control group. Therefore, the addition of Staphylococcus carnosus CS1.21 for fermentation is beneficial to increasing the content and richness of volatile flavor substances in soy sauce.

[0108] In summary, the addition of Staphylococcus carnosus CS1.21 for fermentation of soy sauce significantly improves the content of amino acid nitrogen, total acid, important organic acid, and volatile flavor substances compared to the fermentation of soy sauce without the addition of CS1.21. The addition of Staphylococcus carnosus CS1.21 is beneficial to improving the quality and flavor of soy sauce.

[0109] Example 7

[0110] Acid taste and overall sensory evaluation of Staphylococcus carnosus CS1.21 fermented soy sauce

[0111] 1. Acid taste characteristics of Staphylococcus carnosus CS1.21 fermented soy sauce

[0112] According to the lactic acid content of different brands of soy sauce, it was found that the lactic acid content in special-grade soy sauce was generally low. In order to determine the effect of lactic acid content on the taste of soy sauce, the acid taste characteristics of Staphylococcus carnosus CS1.21 fermented soy sauce were evaluated according to the sensory evaluation method in the reference (Wu, M. C. Food analysis and sensory evaluation [M]. Beijing: China Agriculture Press; 2002.) and the basic principles of soy sauce sensory evaluation (GB18186-2025). Before evaluation, the RANDBETWEEN function in Excel 2023 was used to select pseudo-random numbers between 100 and 999 to randomly number the soy sauce samples with different lactic acid content gradients. The numbering personnel did not participate in the evaluation. Eleven people from different age groups and different regions (5 men and 6 women) were invited to evaluate the taste of soy sauce. Lactic acid was used as the main organic acid affecting the taste of soy sauce. The taste of soy sauce with different lactic acid contents was evaluated on a scale of 10. The evaluation rules were as follows: according to the acidity, saltiness, bitterness, and other factors, the score was deducted according to the degree of over-acidity, over-salinity, or bitterness. The score range was 0-5. The acid taste was general, the acid and salt were basically coordinated, and there was a fresh taste. The score range was 5-8. The acid and salt were moderate, and the taste was delicious. The score range was 8-10. The average score of the total score of each evaluator was the final score. The sensory evaluation data were statistically analyzed using SPSS 18.0 data analysis software.

[0113] A certain soy sauce enterprise a level brewing process special brewing soy sauce as the basis of soy sauce, the determination of its lactic acid content is 0.30±0.00g / 100mL, to this as the basis of the deployment of different lactic acid concentration of soy sauce, concentration gradient set to 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.70g / 100mL; The evaluation method above for the evaluation results of different lactic acid concentration of soy sauce acid sense and taste as shown in table 7. From table 7, it can be seen that the lactic acid content of 0.4-0.5g / 100mL, the sensory score of sample is 9.14-9.56, indicating that the lactic acid content range of acid sense and taste coordination is best. The lactic acid content of meat staphylococcus CS1.21 fermented soy sauce is 0.41g / 100mL (table 5), for example, the lactic acid of meat staphylococcus CS1.21 fermented soy sauce can be seen that the acid sense and taste coordination is in good range.

[0114] Table 7 different lactic acid content in the taste of brewing soy sauce sensory evaluation

[0115]

[0116] Note: the letters a, b, c, d in the sensory score column represent the significant difference (p<0.05) of the sensory score of each sample.

[0117] 2. Analysis of total acid and lactic acid content of different brands of special soy sauce

[0118] In order to determine the lactic acid and total acid content of the soy sauce on the market, in order to determine the influence of lactic acid content on acid sense in soy sauce, 10 different brands of special soy sauce (amino acid nitrogen content≥0.8g / 100mL) sold on the market were selected to determine their lactic acid and total acid content, and the results are shown in table 8. From table 8, it can be found that the highest lactic acid content in special soy sauce is only 0.33g / 100mL, and there are 7 special soy sauce whose lactic acid content is less than 0.30g / 100mL, which is still far from the best content corresponding to the acid sense score of lactic acid production in table 7. Therefore, the use of endogenous meat staphylococcus CS1.21 screened in soy sauce fermentation to produce lactic acid and other organic acids is an important and safe way to improve the acid sense of soy sauce without the need for external addition of food acidulant to improve the acid sense.

[0119] Table 8 lactic acid and total acid content of each special soy sauce

[0120]

[0121]

[0122] 3. Overall sensory evaluation of meat staphylococcus CS1.21 fermented soy sauce

[0123] The sensory evaluation of soy sauce was performed using a 100-point system for color, taste, aroma, and body (Table 9). The average of the total scores of all the panelists for each individual index was used as the final score for the individual index. The sensory evaluation panel consisted of 11 healthy and professionally trained panelists (5 males and 6 females, aged 20-45 years).

[0124] Table 9. Sensory evaluation criteria for soy sauce

[0125]

[0126] The sensory differences between the soy sauce fermented with CS1.21 and the control group were analyzed by sensory evaluation. As shown in Table 10, the total sensory score of the CS1.21 group was 86.0, which was higher than the total sensory score of the control group (73.6). The taste of the soy sauce fermented with CS1.21 was significantly improved compared to the control group, and the taste score was increased by 20.69%. The taste was fresh and palatable. These results indicated that S. equorum CS1.21 had a significant effect on the aroma, taste, and overall flavor of soy sauce, and had good potential for soy sauce brewing. Figure 8

[0127] The embodiments described in the specification are progressive, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be mutually referred to.

[0128] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.​

Claims

1. A strain of Staphylococcus aureus, characterized in that, Named CS1.21, and classified as Staphylococcus carnosus, it was deposited on November 29, 2024, at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 32851, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing.

2. The Staphylococcus aureus as described in claim 1, characterized in that, It can tolerate 16g / 100mL of NaCl.

3. The application of Staphylococcus aureus as described in claim 1 in increasing the organic acid content in the production of soy sauce through high-salt dilute fermentation.

4. The application as described in claim 3, characterized in that, The organic acids are lactic acid, acetic acid, and succinic acid.

5. The application of Staphylococcus aureus as described in claim 1 in the fermentation production of soy sauce, characterized in that, Includes the following steps: S1. Inoculate the fermented sauce mash with Staphylococcus aureus CS1.21 as described in claim 1; S2. Continue fermenting the mash obtained in S1 for 90 days; S3. Press, membrane filter, and sterilize the fermented soy sauce mash obtained in S2 to obtain crude soy sauce.

6. As described in claim 5, characterized in that, In step S1, the fermented sauce mash is a high-salt, dilute sauce mash with a salt concentration of 16–18 g / mL, and the fermentation period is 10–25 days.

7. As described in claim 5, characterized in that, In step S1, the inoculation amount of Staphylococcus aureus CS1.21 is 10 mg / L of fermented mash. 8 ~10 10 CFU.

8. As described in claim 5, characterized in that, The fermentation temperature of the sauce mash in step S1 is 25-35℃.

9. The application as described in claim 5, characterized in that, It is used to increase the content of organic acids, amino acid nitrogen, and volatile flavor components in soy sauce.

10. The use of Staphylococcus carbofurans as described in claim 1 in enhancing the acidity of soy sauce.

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