Compound microbial fermentation agent and application thereof in improving flavor of fermented aquatic products

Abstract

The invention discloses a compound microbial fermentation agent and application thereof in improving the flavor of fermented aquatic products, and belongs to the technical field of food microbial fermentation. Specific lactic acid bacteria, saccharomycetes and staphylococcus are screened out through the characteristics of acid resistance (pH 4.5) and ethanol resistance (5%) and are compounded according to a specific proportion to obtain the compound microbial fermentation agent, the compound microbial fermentation agent is applied to aquatic product fermentation, stress resistance in the fermentation process can be ensured, infectious microbe pollution is avoided, and product stability is improved. The flavor diversity of the product is enhanced, the total amount of volatile flavor substances generated after fermentation is increased by 30%-50%, and the contents of esters (such as ethyl acetate) and alcohols (such as phenethyl alcohol) are remarkably increased.

Description

Technical Field

[0001] The present invention relates to the technical field of food microbial fermentation, and more particularly to a composite microbial fermentation agent and its application in improving the flavor of fermented aquatic products. Background Art

[0002] Aquatic product fermentation is an ancient and important food processing technology that not only significantly improves the efficiency of aquatic products but also imparts unique flavor and texture. Microorganisms play a key role in this transformation process. Through their interactions, they break down macromolecules in the raw materials into small, active molecules that are easily absorbed by the human body, thereby improving the texture, flavor, nutritional value, and aroma of the fermented products. Furthermore, some microbial metabolites have the potential to promote health and prevent disease.

[0003] Traditional aquatic product fermentation often relies on a single bacterial strain or spontaneous fermentation, resulting in long fermentation cycles, a single flavor profile, and poor environmental adaptability. Prior art uses lactic acid bacteria, yeast, and staphylococci separately, lacking synergistic screening methods and optimization of rapid fermentation systems for aquatic substrates. Furthermore, existing combined fermentation methods often lack specific strains. For example, CN102499386A, a method for producing low-value fish sausages through mixed bacterial strain combined fermentation, discloses the combined fermentation of lactic acid bacteria, staphylococci, and yeast, but lacks specific research on the specific strains and flavor compounds.

[0004] Therefore, screening strains with outstanding ability to produce flavor substances and constructing composite fermentation agents are of great significance to improving the flavor diversity of fermented aquatic products. Summary of the Invention

[0005] In response to the above problems, the present invention provides a composite microbial starter and its application in improving the flavor of fermented aquatic products.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A composite microbial fermentation agent is obtained by compounding Lactobacillus plantarum, Pichia fermentans and Staphylococcus saprophyticus.

[0008] Preferably, the total viable bacteria concentration of the composite microbial fermentation agent is 10 6 -10 8 CFU / mL.

[0009] Preferably, the total viable bacteria concentration of the composite microbial fermentation agent is 10 8 CFU / mL.

[0010] Preferably, the ratio of the number of live bacteria of Lactobacillus plantarum fermentation Pichia pastoris and Staphylococcus saprophyticus in the composite microbial starter is 1:1:1 to 1:2:2.

[0011] Preferably, the ratio of the number of live bacteria of Lactobacillus plantarum, Pichia fermentans and Staphylococcus saprophyticus in the composite microbial fermentation agent is 1:1:1.

[0012] Another object of the present invention is to provide the use of the composite microbial starter in improving the flavor of fermented aquatic products.

[0013] Another object of the present invention is to provide a method for enhancing the flavor of fermented aquatic products, wherein any of the composite microbial starter cultures is added to the aquatic product to be fermented at an inoculation rate of 1.0%-3.0% (v / w), and fermented at 25-30° C. for 24-72 hours.

[0014] Through the above technical solution, it can be seen that compared with the prior art, the present invention discloses a composite starter and its application in improving the flavor of fermented aquatic products. Specific lactic acid bacteria, yeasts and staphylococci are screened out through acid resistance (pH 4.5) and ethanol resistance (5%) to form a composite microbial starter for fermenting aquatic products, ensuring the stress resistance of the fermentation process, avoiding contamination by miscellaneous bacteria, and improving product stability. The flavor diversity of the product is enhanced, and the total amount of volatile flavor substances produced after fermentation is increased by 30%-50%, among which the content of esters (such as ethyl acetate) and alcohols (such as phenylethanol) is significantly increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 : Growth curves of the bacteria in Example 1, wherein (a): growth curves of three lactic acid bacteria, LP: Lactobacillus plantarum, PP: Pediococcus pentosaceus, LS: Lactobacillus sakei subsp. sakei;

[0016] (b): Growth curves of three yeast strains, R: Saccharomyces rouxii, PF: Pichia fermentans, Ha: Hansenula anomala;

[0017] (c): Growth curves of three types of Staphylococci, SX: Staphylococcus xylosus, SS: Staphylococcus saprophyticus, SP: Staphylococcus carnosus;

[0018] Figure 2 : Acid resistance test results of three yeasts and three Staphylococci, R: Saccharomyces rouxii, PF: Pichia fermentans, Ha: Hansenula anomala, SX: Staphylococcus xylosus, SS: Staphylococcus saprophyticus, SP: Staphylococcus carnosus;

[0019] Figure 3:Ethanol resistance test results of three lactic acid bacteria and three Staphylococci, LP: Lactobacillus plantarum, PP: Pediococcus pentosaceus, LS: Lactobacillus sakei subsp. sakei, SX: Staphylococcus xylosus, SS: Staphylococcus saprophyticus, SP: Staphylococcus carnosus;

[0020] Figure 4 : Curves of changes in pH and total acid during the fermentation of fish meat with different bacterial strain combinations, AB: fermentation with Lactobacillus plantarum + Pichia pastoris, AC: fermentation with Lactobacillus plantarum + Staphylococcus saprophyticus, BC: fermentation with Pichia pastoris + Staphylococcus saprophyticus, ABC: fermentation with Lactobacillus plantarum + Pichia pastoris + Staphylococcus saprophyticus;

[0021] Figure 5 : Curve diagram of the reducing sugar content changes during the fermentation of fish meat with different bacterial strain combinations, AB: fermentation with Lactobacillus plantarum + Pichia pastoris, AC: fermentation with Lactobacillus plantarum + Staphylococcus saprophyticus, BC: fermentation with Pichia pastoris + Staphylococcus saprophyticus, ABC: fermentation with Lactobacillus plantarum + Pichia pastoris + Staphylococcus saprophyticus;

[0022] Figure 6 : Curves of changes in amino nitrogen content in fish meat fermented with different bacterial strain combinations, AB: fermentation with Lactobacillus plantarum + Pichia pastoris, AC: fermentation with Lactobacillus plantarum + Staphylococcus saprophyticus, BC: fermentation with Pichia pastoris + Staphylococcus saprophyticus, ABC: fermentation with Lactobacillus plantarum + Pichia pastoris + Staphylococcus saprophyticus;

[0023] Figure 7 : Statistical chart of the flavor composition and content of fish products fermented with different strains, AB: combined fermentation of Lactobacillus plantarum + Pichia pastoris, AC: combined fermentation of Lactobacillus plantarum + Staphylococcus saprophyticus, BC: combined fermentation of Pichia pastoris + Staphylococcus saprophyticus, ABC: combined fermentation of Lactobacillus plantarum + Pichia pastoris + Staphylococcus saprophyticus. DETAILED DESCRIPTION

[0024] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0025] The reagents involved in the embodiments of the present invention were all purchased from commercial channels, and the methods not mentioned are conventional experimental methods and will not be described in detail here.

[0026] The following reagents are illustrative:

[0027] MRS liquid medium, YPD liquid medium, and NB liquid medium were purchased from Qingdao Haibo Technology Biological Co., Ltd.

[0028] The strains involved in the examples can all be purchased from the corresponding depository institutions.

[0029] Example 1 Screening of strains

[0030] 1. Activation of strains

[0031] The three lactic acid bacteria in Table 1, Lactobacillus plantarum, Pediococcus pentosaceus, and Lactobacillus sakei subsp. sakei, were inoculated into MRS liquid medium and cultured at 30°C for 48 hours; the three yeasts, Pichia fermentans, Saccharomyces rouxii, and Hansenula anomala, were inoculated into YPD liquid medium and cultured at 30°C with shaking for 24 hours; the three grape strains, Staphylococcus xylosus, Staphylococcus saprophyticus, and Staphylococcus carnosus, were inoculated into NB liquid medium and cultured at 30°C with shaking for 24 hours. All strains were activated and cultured twice according to the above corresponding methods. After the activation, the cells were centrifuged at 10,000 r / min for 10 minutes at 4°C, the supernatant was discarded, and the cells were washed twice with an equal volume of sterile 0.9% saline, and then resuspended in sterile 0.9% saline. The final colony count of each activated bacterium was adjusted to 10 8 CFU / mL, set aside.

[0032]

[0033] CICC is the China Industrial Microbiology Culture Collection Center; ATCC is the American Cell Culture Collection

[0034] 2. Plotting the growth curve of each strain

[0035] Using a 1% (v / v) inoculum, the activated Lactobacillus plantarum, Pediococcus pentosaceus, and Lactobacillus sakei subsp. sakei were inoculated into MRS liquid culture medium; Pichia fermentans, Saccharomyces rouxii, and Hansenula anomala were inoculated into YPD liquid culture medium; Staphylococcus xylosus, Staphylococcus saprophyticus, and Staphylococcus carnosus were inoculated into NB liquid culture medium. All cultures were placed in a constant temperature incubator at 30°C for 24 hours. The OD600 of each bacterial solution was measured every 4 hours, and a growth curve was plotted with the incubation time as the x-axis. The results are shown in Figure 1. Figure 1 .

[0036] Depend on Figure 1 From the growth curves of the three lactic acid bacteria shown in (a), it can be seen that the concentration of Lactobacillus plantarum changes little from 0h to 8h, and the bacteria are all in the hysteresis period. Starting from 8h, Lactobacillus plantarum enters the logarithmic growth phase first; while Pediococcus pentosaceus and Lactobacillus sakei subsp. sakei enter the logarithmic growth phase from 14h.

[0037] Depend on Figure 1 From the growth curves of the three yeasts shown in (b), it can be seen that S. rouxii is in the hysteresis phase from 0 h to 4 h and enters the logarithmic growth phase from 4 h; while Pichia fermentans and Hansenula anomala enter the logarithmic growth phase from 10 h.

[0038] Depend on Figure 1 From the growth curves of the three Staphylococci shown in (c), it can be seen that Staphylococcus xylosus and Staphylococcus carnosus are in the hysteresis phase from 0h to 6h, and enter the logarithmic growth phase from 6h; while Staphylococcus saprophyticus enters the logarithmic growth phase from 10h. The growth rates of all three strains slow down at 20h and enter the stable phase.

[0039] When the strain is in the logarithmic growth phase, the growth and metabolic rate is the fastest and the activity is the best. Therefore, samples of all three strains were taken 24 hours after activation for subsequent experiments.

[0040] 3. Determination of acid resistance of each strain

[0041] Lactic acid bacteria ferment and produce acid, which will lower the pH of the system. This is because lactic acid bacteria are suitable for growing in an acidic environment. The present invention uses three bacteria for co-fermentation, so only the above three yeasts and three Staphylococci are tested for acid resistance. The specific operation is: lactic acid is added to YPD and NB liquid culture media respectively, and the pH is adjusted to 4.5 and then sterilized at 121°C. Using an inoculation amount of 1% (v / v), fermented Pichia pastoris, Rupke yeast and Hansenula abnormalis were inoculated into YPD liquid culture medium with a pH of 4.5, respectively. Staphylococcus xylosus, Staphylococcus saprophyticus and Staphylococcus carnosus were inoculated into NB liquid culture medium with a pH of 4.5, respectively, and recorded as sample groups. Each bacteria was inoculated into the corresponding culture without lactic acid addition (pH 6.5) at an inoculation amount of 1% (v / v) as the control group. After culturing at 30°C for 24 hours, the OD600 ratio of the sample group and the control group of the same strain was calculated, which is the growth rate of each strain when grown under acidic conditions for 24 hours. The results are shown in FIG. Figure 2 .

[0042] Depend on Figure 2 Yeasts all have a certain tolerance to acidic environments. In a culture medium at pH 4.5, Pichia pastoris exhibited the best acid tolerance, achieving the highest growth rate of 91.7% (compared to the original culture medium pH 6.5), while Saccharomyces rouxii had the lowest growth rate of 86.5%. Staphylococci, on the other hand, exhibited poor acid tolerance overall. At pH 4.5, the highest growth rate was achieved by Staphylococcus saprophyticus, reaching 50%, while the lowest was achieved by Staphylococcus xylosus, at only 25.5%.

[0043] 4. Determination of ethanol tolerance of each strain

[0044] Yeast produces ethanol as a metabolic product during fermentation, so yeast growth requires an ethanol-tolerant environment. However, lower concentrations of ethanol can inhibit microbial cell division, reducing cell volume and specific growth rate. Higher concentrations of ethanol can inhibit amino acid absorption, disrupt cell structure, and cause cell sap loss, slowing microbial growth and metabolism, and even leading to death. Therefore, exogenously added lactic acid bacteria and Staphylococci need to have a certain tolerance to ethanol. The specific procedure is to add ethanol to MRS and NB liquid culture media, adjust the ethanol concentration to 5%, and then sterilize at 121°C. Using an inoculum size of 1% (v / v), three lactic acid bacteria, Lactobacillus plantarum, Pediococcus pentosaceus, and Lactobacillus sakei subsp. sakei, were inoculated into MRS liquid medium containing 5% ethanol, and Staphylococcus xylosus, Staphylococcus saprophyticus, and Staphylococcus carnosus were inoculated into NB liquid medium containing 5% ethanol, respectively, as sample groups. Each bacterium was inoculated into the corresponding medium without ethanol addition at an inoculum size of 1% (v / v) as a control group. After culturing at 30°C for 24 h, the OD600 ratio of the sample group and the control group of the same strain was calculated, which is the growth rate of each strain when grown under ethanol conditions for 24 h. The results are shown in FIG. Figure 3 .

[0045] Depend on Figure 3 As can be seen, at an ethanol concentration of 5%, the ethanol tolerance of Lactobacillus plantarum among the lactic acid bacteria was significantly higher than that of the other two strains, reaching 87.6%, while the lowest was Pediococcus pentosaceus, which had a rate of only 64%. Staphylococci, on the other hand, showed better ethanol tolerance. There was no significant difference in the growth rates of Staphylococcus xylosus and Staphylococcus saprophyticus, both around 100%, while the overall growth rate of Staphylococcus carnosus was lower than that of the other two strains, at 91.7%.

[0046] In summary, Lactobacillus plantarum among lactic acid bacteria showed good ethanol resistance, Staphylococcus saprophyticus among Staphylococci showed excellent tolerance in both acid resistance and ethanol resistance, and Pichia fermentative yeast had the best acid resistance. Therefore, these three strains were selected for subsequent experiments.

[0047] Example 2 Composite screening of strains

[0048] The three single strains of Lactobacillus plantarum, Pichia fermentans and Staphylococcus saprophyticus screened out in Implementation 1 were mixed and fermented according to the three types of bacteria, namely lactic acid bacteria, yeast and Staphylococcus, and compounded to form four combinations (AB group: lactic acid bacteria + yeast; AC group: lactic acid bacteria + Staphylococcus; BC group: yeast + Staphylococcus; ABC group: lactic acid bacteria + yeast + Staphylococcus).

[0049] Specifically, lactic acid bacteria were inoculated into MRS liquid medium and cultured at 30°C for 48 hours. Yeast was inoculated into YPD liquid medium and cultured at 30°C with shaking for 24 hours. Staphylococcus was inoculated into NB liquid medium and cultured at 30°C with shaking for 24 hours. All strains were activated and cultured twice according to the above corresponding methods, and then centrifuged at 10,000 r / min for 10 minutes at 4°C. The supernatant was discarded and washed twice with an equal volume of sterile 0.9% saline, and then resuspended in sterile 0.9% saline to prepare a single bacterial solution. The concentration of live bacteria in each bacterial solution was adjusted to 10 8 CFU / mL, set aside.

[0050] The total inoculum volume was 3% (v / w), the inoculation ratio between the strains was 1:1 when two strains were compounded, and the inoculation ratio between the strains was 1:1:1 when three strains were compounded. They were added to small pieces of raw fish meat of equal mass. After mixing, 2% glucose was added. The mixture was kept warm and fermented at 30°C for 3 days. Samples were taken at regular intervals every day from the start of fermentation (3 parallel samples were taken for each group). The microbial growth, pH and total acid, reducing sugar content, and amino nitrogen content during the fermentation process were tested.

[0051] 1. From the beginning of fermentation, the growth of microorganisms during the fermentation process was monitored and recorded daily. The results are shown in Table 2.

[0052]

[0053] From the perspective of different fermentation days within the same group, the growth trends of microorganisms in each group in Table 2 are generally similar, with rapid reproduction on the first and second days and stabilization or even a decrease in number on the third day.

[0054] Looking at inter-group differences, the same microorganism exhibited different growth rates in different groups. This is because when Lactobacillus plantarum, Pichia fermentans, and Staphylococcus saprophyticus are mixed and fermented in fish meat, they produce complex interactions, which can be competitive or mutually beneficial. In a mixed fermentation environment, the interactions between different microorganisms can significantly affect the fermentation process and the characteristics of the final product.

[0055] In general, in the ABC group of mixed fermentation of three bacteria, all three bacteria showed good growth. Although the number was slightly lower than that of other groups with two bacteria, the difference was not large, indicating that the three bacteria can coexist in fish meat and exert their fermentation characteristics.

[0056] 2. Changes in pH and total acidity of each group during fermentation Figure 4As shown in the figure, the pH value of the system before fermentation was 6.77, and the total acid content was 0.252 g / 100 mL. Lactobacillus plantarum is a lactic acid bacteria. Compared with the other two strains, it has the strongest acid production ability and the fastest pH drop. It dominates the pH change in mixed fermentation. Therefore, the pH drop of the BC group without Lactobacillus plantarum was significantly slower than that of the other groups. The pH values on the three days were: 5.53, 4.59, and 4.38, respectively. The pH change trends of the AB, AC, and ABC groups were very similar, with values of 4.52, 4.51, and 4.44 on the first day, 4.24, 4.24, and 4.17 on the second day, and 4.19, 4.12, and 4.11 on the third day. There was no significant difference in pH between the AB and AC groups in the first two days, and the pH of the ABC group was slightly lower than that of the AB and AC groups. Since the pH value is already around 4, although the pH is slightly lower, it also means that most of the weakly acidic organic acids are more than those in the AB and AC groups. This can also be seen from the changes in total acid content in the figure. On the second day, the total acid content of the ABC group reached 0.932g / 100mL, which was significantly higher than the 0.743g / 100mL of the AB group and the 0.761g / 100mL of the AC group. This shows that due to the rich metabolic pathways of the three bacteria in the ABC group, more organic acids were produced. It also proves that the fermentation of the three bacteria has a mutually beneficial effect at the level of metabolites, which has a positive effect on the production of flavor substances.

[0057] 3. In the production of fermented foods, the consumption of reducing sugars is directly related to the growth of microorganisms and the formation of metabolites, and is one of the key indicators for evaluating the dynamics of the fermentation process. The changes in the reducing sugar content of each group during the fermentation process are as follows: Figure 5 As shown by Figure 5 It can be seen that the AB group consumed reducing sugar from 20.5 mg / mL to 7.07 mg / mL on the first day, and continued to decrease to 5.94 mg / mL on the second day. There was no significant difference on the third day. This is because Lactobacillus plantarum and Pichia fermentans consume very large amounts of sugar in the early stages of growth, while the opposite is true for Staphylococcus saprophyticus. This also explains why the sugar consumption curves of the BC and ABC groups containing Staphylococcus saprophyticus are relatively flat. The AC group consumed very little sugar on the first and second days. There may be two reasons: first, Staphylococcus has poor acid resistance, and its growth is affected by the organic acids metabolized by lactic acid bacteria; second, under certain conditions, lactic acid bacteria may preferentially use non-sugar substances for metabolism.

[0058] 4. Amino nitrogen is an important indicator for determining amino acid metabolism in food. The higher the amino nitrogen content, the better the flavor of the product. The changes in amino nitrogen (AAN) content in each group during the fermentation process are as follows: Figure 6 As shown by Figure 6As can be seen, the AAN content in each group showed a gradual downward trend with prolonged fermentation time, indicating that the further metabolism of amino acids during the fish fermentation process was faster than the decomposition of residual peptides. Inter-group analysis showed that there was no significant difference between groups, ranging from 0.258 g / mL on day 0 to around 0.24 g / mL on day 1. Starting on day 2, the AAN content in the BC group dropped to 0.217 g / mL, significantly lower than in all other groups, reaching 0.197 g / mL on day 3. This suggests that Staphylococcus saprophyticus possesses a richer variety of amino acid metabolizing enzymes than Lactobacillus plantarum and Pichia fermentans.

[0059] Example 3 Verification of the Effect of Three-bacteria Composite Fermentation on the Improvement of Aquatic Product Flavor Substances

[0060] After the fermentation of each group in Example 2 was completed, GC-MS combined with headspace solid phase microextraction was used to detect the content and type distribution of volatile flavor substances in each group of products. The results are shown in FIG. Figure 7 .from Figure 7 As can be seen, there are significant differences in the content of volatile odor substances among the fermented fish samples. The total amount of volatile substances in the four fermented groups AB, AC, BC, and ABC were 56416.36μg / L, 70311.05μg / L, 56381.49μg / L, and 112102.46μg / L, respectively. It can be seen that the addition of three microorganisms, Lactobacillus plantarum, Pichia fermentans, and Staphylococcus saprophyticus, causes the fish to produce a large amount of volatile metabolites. In particular, the ABC group, which is a combination of three bacteria, shows an excellent synergistic effect in the metabolism of volatile flavor substances. The total amount of volatile flavor substances produced after fermentation is 30%-50% higher than that of the three groups AB, AC, and BC, which are a combination of two strains. Among them, the content of esters (such as ethyl acetate) and alcohols (such as phenylethanol) is significantly increased.

[0061] The odor of food is related not only to the content of volatile odorants but also to their odor activity value (OAV). The OAV of an odorant is calculated by dividing the concentration of the odorant in a sample by its threshold value in water. Table 3 shows the substances with an OAV greater than 1 in the fermented fish samples from different groups.

[0062]

[0063]

[0064] ROC (Relative Odor Contribution) can more intuitively reflect the contribution of each flavor substance to the overall flavor. It is the ratio of the OAV (>1) of each flavor substance to the total OAV (>1) of all flavor substances. Analysis of the ROC percentages of various flavor substances in Table 3 shows that esters and aldehydes (total contribution exceeds 90%) are dominant.

[0065] Esters are typically produced by the esterification reaction of alcohols and carboxylic acids. Esters derived from short-chain acids typically contribute fruity aromas, while those derived from long-chain acids impart a fatty flavor. These two compounds play a decisive role in regulating the flavor profile of fermented foods. In this study, the BC group had the highest proportion of esters, reaching 85.85%, followed by the AB group at 80.31%, and the ABC group at a slightly lower 63.74%. Although the ABC group contained a lower proportion of ester compounds than the BC and AB groups, its overall flavor content was higher. Analysis of the odor activity value (OAV, Table 3) showed that the flavor profile of the ABC group was comparable to that of the other two groups. This phenomenon suggests that the proportion of ester compounds alone does not fully determine the richness and layering of flavor; instead, the OAV more comprehensively reflects the contribution of flavor compounds.

[0066] Ethyl acetate and isoamyl acetate, ester compounds with distinct fruity aromas, exhibited significant OAV values in each group, particularly in the ABC group, where the OAV value was significantly higher than in the other groups. Specifically, ethyl acetate has a distinct apple aroma, with OAV values of 1756.84, 989.50, 1599.44, and 4098.04 in the AB, AC, BC, and ABC groups, respectively. Isoamyl acetate has a banana aroma, with OAV values of 5927.59, 1316.48, 9028.20, and 9432.32 in the four groups, respectively. This suggests that fermenting fish with Lactobacillus plantarum, Pichia pastoris, and Staphylococcus saprophyticus has a significant synergistic effect in improving the flavor of aquatic products.

[0067] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0068] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A composite microbial fermentation agent, characterized in that: The composite microbial fermentation agent is obtained by compounding Lactobacillus plantarum, Pichia fermentans and Staphylococcus saprophyticus.

2. The composite microbial fermentation agent according to claim 1, characterized in that The total live bacteria concentration of the composite microbial fermentation agent is 10 6 -10 8 CFU / mL.

3. The composite microbial fermentation agent according to claim 1, characterized in that The ratio of the number of live bacteria of Lactobacillus plantarum, Pichia fermentans and Staphylococcus saprophyticus in the composite microbial fermentation agent is 1:1:1 to 1:2:

2.

4. Use of the composite microbial fermentation agent according to any one of claims 1 to 3 in improving the flavor of fermented aquatic products.

5. A method for enhancing the flavor of a fermented aquatic product, characterized in that: The composite microbial fermentation agent according to any one of claims 1 to 3 is added to the aquatic product to be fermented at an inoculation rate of 1.0% to 3.0% (v / w), and fermented at 25-30° C. for 24-72 hours.

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