Method for fermenting trachinotus ovatus byproduct by clostridium butyricum, high-value product and application

Abstract

The invention discloses a method for fermenting trachinotus ovatus by-products through clostridium butyricum, high-value products and application, and belongs to the technical field of microbial fermentation and resource utilization. According to the method, the trachinotus ovatus processing byproduct is directly used as a fermentation substrate, and the composition of a clostridium butyricum fermentation culture medium and fermentation conditions are systematically optimized through a response surface method, so that an efficient fermentation process is established. By adopting the technology, the trachinotus ovatus byproduct is converted into a high-added-value fermentation product. Experimental results show that compared with a control group, the biomass of clostridium butyricum in a fermentation product is increased by 13%, the content of butyric acid is increased by 102.5%, and the contents of n-valeric acid, isovaleric acid and hexanoic acid are all remarkably increased in a breakthrough manner; the total antioxidant capacity of a fermentation product is improved by 67%, and the activity of superoxide dismutase and the activity of catalase are improved by 105% and 83.9% respectively. According to the method, high-value utilization of aquatic byproducts is realized, and the obtained product can be applied to the fields of feeds, functional foods and the like.

Description

Technical Field

[0001] This invention relates to the field of microbial fermentation and resource utilization technology, and in particular to a method for fermenting oval pomfret by-products by Clostridium butyricum, as well as the high-value products and applications. Background Technology

[0002] The golden pomfret (Trachinotus ovatus), commonly known as the scad, is an important economically important marine fish. During its processing, byproducts such as the head, bones, fins, scales, and tail are generated, accounting for approximately 35% of the total fish weight. These byproducts are rich in protein. Discarding them indiscriminately not only causes severe environmental pollution but also wastes resources. Currently, research on the processing and utilization of these byproducts is limited, mainly focusing on processing them into fishmeal or further extracting crude enzymes, oils, collagen, or gelatin. However, no research has been reported on using these byproducts as substrates and employing systematic optimization techniques such as response surface methodology to utilize Clostridium butyricum fermentation to achieve high butyric acid production, synergistic generation of medium- and long-chain fatty acids such as valerate and hexanoic acid, while simultaneously significantly enhancing the antioxidant activity of the products.

[0003] Clostridium butyricum is an obligate anaerobic, Gram-positive spore-forming bacillus with significant probiotic properties, widely colonizing the digestive tracts of humans and various animals. Studies have found that in a hypoxic microenvironment, Clostridium butyricum metabolizes and produces short-chain fatty acids (SCFAs), primarily butyrate. These SCFAs significantly lower the intestinal pH, creating an acidic environment unfavorable to the colonization of opportunistic pathogens. Simultaneously, Clostridium butyricum exhibits a significant repair effect on intestinal mucosal tissue. Its metabolite, butyrate, serves as an important energy source for intestinal epithelial cell regeneration, accelerating the repair process of damaged tissues by promoting protein synthesis and maintaining cell structural integrity, thus playing a crucial role in maintaining intestinal health in animals.

[0004] However, according to current research, the main metabolites of Clostridium butyricum are butyric acid or shorter-chain acetic acid, propionic acid, and lactic acid. No research has been reported on the fermentation production of longer-chain valeric acid or hexanoic acid by Clostridium butyricum. Furthermore, medium- and short-chain fatty acids such as valeric acid and hexanoic acid have unique regulatory effects on the structure, function, and microbial composition of animal intestines in the aquaculture industry. Therefore, there is an urgent need to provide a method for utilizing Clostridium butyricum fermentation of oval pomfret byproducts to produce high-value products and achieve high-value utilization. Summary of the Invention

[0005] The purpose of this invention is to provide a method for fermenting oval pomfret by-products with Clostridium butyricum, as well as high-value products and applications, to solve the problems existing in the prior art. This invention successfully transforms low-value oval pomfret by-products into high-value microbial fermentation products, opening up a new path for the resource utilization of aquatic product processing by-products, which is in line with the circular economy and sustainable development strategy.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] This invention provides a method for fermenting oval pomfret by-products with Clostridium butyricum, comprising the following steps:

[0008] (1) Provide the processing by-products of oval pomfret, which are ground, sterilized, and dissolved to prepare an initial fermentation culture medium;

[0009] (2) Prepare a fermentation medium based on the initial fermentation medium;

[0010] (3) Using Clostridium butyricum as the fermentation strain, the composition of the fermentation medium and / or fermentation process conditions were optimized using response surface methodology to obtain the optimal fermentation parameters;

[0011] (4) The fermentation medium is subjected to anaerobic fermentation of Clostridium butyricum according to the optimal fermentation parameters to obtain the fermentation product.

[0012] Furthermore, in step (3), the response value optimized by the response surface methodology includes the cell biomass of Clostridium butyricum and / or the total antioxidant capacity of the fermentation system.

[0013] Further, in step (3), the optimization of the composition of the fermentation medium includes: supplementing it with a carbon source, a nitrogen source and a deoxidizer, wherein the carbon source includes maltose and the nitrogen source includes beef meal.

[0014] Further, in step (3), the optimization of the composition of the fermentation medium includes: adding a deoxygenating agent thereto, wherein the added deoxygenating agent is L-cysteine ​​hydrochloride.

[0015] Furthermore, the concentration of the supplementary carbon source is 15-22 g / L, the concentration of the supplementary nitrogen source is 16-20 g / L, and the concentration of the supplementary deoxidizer is 0.7-1.1 g / L.

[0016] Furthermore, the anaerobic fermentation conditions are: a temperature of 35-38℃ and a time of 72 h.

[0017] The present invention also provides a fermentation broth obtained according to the above method.

[0018] The present invention also provides an application of the above-mentioned fermentation broth in the preparation of functional foods that help with antioxidation.

[0019] The present invention also provides the application of the above-mentioned fermentation broth in the preparation of antioxidant drugs.

[0020] The present invention also provides an application of the above-mentioned fermentation broth in the preparation of animal feed.

[0021] The present invention discloses the following technical effects:

[0022] 1. Significantly improved fermentation efficiency: Through systematic optimization of the fermentation process, the biomass of Clostridium butyricum on the by-product substrate was ultimately increased by 13%, while the butyric acid content in the fermentation product achieved a leap increase of 102%.

[0023] 2. Significantly enhanced antioxidant activity: The fermentation product exhibits excellent antioxidant properties, with SOD and CAT activities increasing by 105% and 83.9% respectively, and total antioxidant capacity (T-AOC) increasing by 67%. This indicates that it has great potential as a functional food, medicine or feed additive in anti-stress and improving human health.

[0024] 3. Short-chain fatty acid profile optimization: After fermentation, the content of key short-chain fatty acids such as valeric acid, isovaleric acid and hexanoic acid increased significantly (P<0.05), which greatly enhanced the nutritional and functional value of the fermentation product.

[0025] 4. Turning waste into treasure, green and environmentally friendly: This invention successfully transforms low-value oval pomfret by-products into high-value microbial fermentation products, opening up a new path for the resource utilization of aquatic product processing by-products, which is in line with the circular economy and sustainable development strategy. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 Growth curves of Clostridium butyricum determined by different methods;

[0028] Figure 2 Figure 1 shows the experimental results of the effects of different carbon sources and initial maltose concentration on the cell mass of Clostridium butyricum.

[0029] Figure 3 The figure shows the experimental results of the effects of different nitrogen sources and initial concentrations of beef meal on the bacterial mass of Clostridium butyricum.

[0030] Figure 4Figure 1 shows the experimental results of the effects of different oxygen scavengers and initial concentrations of L-cysteine ​​hydrochloride on the bacterial mass of Clostridium butyricum.

[0031] Figure 5 Figure showing the experimental results of the effect of different culture temperatures on the bacterial mass of Clostridium butyricum;

[0032] Figure 6 The experimental results show the effect of different inoculum amounts on the bacterial mass of Clostridium butyricum.

[0033] Figure 7 The total ion current spectra of short-chain fatty acids in experimental group (a), control group 1 (b), control group 2 (c) and control group 3 (d) in Example 2 are shown.

[0034] Figure 8 This is a graph showing the peak area ratios of characteristic SCFAs ions in the experimental group, control group 1, control group 2, and control group 3 in Example 2.

[0035] Figure 9 The graph shows the detection results of CAT and SOD activities in experimental groups 1-3 and control groups 1-3 in Example 3. Detailed Implementation

[0036] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0037] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0038] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0039] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This specification and embodiments are merely exemplary.

[0040] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0041] The Clostridium butyricum strain of this invention was purchased from the Guangdong Provincial Center for Microbial Culture Collection, with accession number GDMCC 1.2756.

[0042] Unless otherwise specified, all percentages in the embodiments of this invention are volume fractions.

[0043] Example 1

[0044] To develop a high-efficiency fermentation medium based on pomfret byproducts, it is first necessary to determine the types and optimal ratios of key nutrients (carbon and nitrogen sources) to be added to the initial medium prepared from the byproducts. To this end, single-factor and response surface methodology experiments were designed to screen for the optimal supplementary components and fermentation conditions.

[0045] The byproducts of oval pomfret were washed and ground to obtain a dense substance with a particle size of less than 3 mm, which was used as the initial fermentation culture medium.

[0046] 1. Fermentation medium design

[0047] To facilitate efficient screening, a well-defined synthetic fermentation medium was prepared to simulate and screen key components that require exogenous addition in subsequent byproduct fermentation systems. This fermentation medium contained: 10.0 g peptone, 3.0 g yeast extract, 5.0 g glucose, 10.0 g beef meal, 1.0 g soluble starch, 0.5 g L-cysteine ​​hydrochloride, 5.0 g sodium chloride, 3.0 g sodium acetate, and 100 g of byproduct, dissolved in 1000 mL of deionized water and autoclaved at 121°C for 20 min. 2% agar was added to the solid medium.

[0048] The carbon source, nitrogen source, deoxygenating agent, culture temperature, and inoculum size for Clostridium butyricum fermentation were optimized using both single-factor and response surface methodology. The results are as follows:

[0049] 2. Growth curve

[0050] Clostridium butyricum was inoculated into the above fermentation medium and fermented. The bacterial count and OD were determined by plate count and spectrophotometry, respectively. 600 value.

[0051] Result: As Figure 1 As shown, plate counting and spectrophotometry revealed that *Clostridium butyricum* entered the logarithmic growth phase after 4 hours of culture, grew rapidly from 4 to 12 hours, and reached the stationary phase after 20 hours. At this point, the highest bacterial count was 7.7 × 10⁻⁶. 8 CFU / mL, OD 600 The value is 1.46.

[0052] 3. Carbon source optimization

[0053] The carbon source in the fermentation medium was replaced with soluble starch, glucose, lactose, maltose, and sucrose, respectively. Clostridium butyricum was inoculated, fermented, and the bacterial count was measured. Maltose concentrations of 5 g / L, 8 g / L, 11 g / L, 14 g / L, and 17 g / L were set, and fermentation was carried out, with bacterial count measured.

[0054] Result: As Figure 2 As shown, maltose was the optimal carbon source, with a cell count of 7.6 × 10⁻⁶. 8 CFU / mL. Further optimization of maltose concentration revealed that the bacterial count increased with increasing concentration within the range of 5-11 g / L, reaching a maximum of 9.52 × 10⁻⁶ CFU / mL at 11 g / L. 8 CFU / mL; further increases in concentration result in a decrease in bacterial count.

[0055] 4. Nitrogen source optimization results

[0056] The nitrogen sources (peptone, yeast extract, and beef meal) in the fermentation medium were replaced with peptone, yeast extract, beef meal, urea, and ammonium chloride, respectively. Clostridium butyricum was inoculated, fermented, and the bacterial count was measured. Beef meal concentrations of 10 g / L, 12 g / L, 14 g / L, 16 g / L, and 18 g / L were set, and fermentation was carried out, with bacterial count measured.

[0057] Result: As Figure 3 As shown, beef meal was the best nitrogen source, with a bacterial count of 8.8 × 10⁻⁶. 8 CFU / mL. Further concentration optimization showed that the concentration increased with increasing beef meal concentration within the range of 10-14 g / L, reaching a maximum of 9.1 × 10⁻⁶ CFU / mL at 14 g / L. 8 CFU / mL; excessively high concentrations will inhibit growth.

[0058] 5. Results of deoxidizer optimization

[0059] The deoxygenating agents in the fermentation medium were replaced with L-cysteine ​​hydrochloride, ascorbic acid, sodium sulfite, and sodium thioglycolate, respectively. Clostridium butyricum was inoculated, fermented, and the bacterial count was measured. L-cysteine ​​hydrochloride concentrations of 0.3 g / L, 0.5 g / L, 0.7 g / L, 0.9 g / L, and 1.1 g / L were also set for fermentation, and the bacterial count was measured.

[0060] Result: As Figure 4 As shown, L-cysteine ​​hydrochloride was the most effective deoxygenating agent, achieving a bacterial count of 9.2 × 10⁻⁶. 8 CFU / mL. Further concentration optimization resulted in a maximum bacterial count of 9.8 × 10⁻⁶ cells / mL at a deoxygenating agent concentration of 0.7 g / L. 8 CFU / mL.

[0061] 6. Results of Optimization of Culture Temperature

[0062] The culture temperatures were set to 28℃, 31℃, 34℃, 37℃ and 40℃, and the fermentation culture was carried out to detect the cell count.

[0063] Result: As Figure 5 As shown, Clostridium butyricum can grow at a culture temperature of 31-40℃, with 37℃ being the optimal temperature, resulting in the highest bacterial count of 10.2 × 10⁻⁶. 8 CFU / mL.

[0064] 7. Results of Optimized Inoculation Volume

[0065] The inoculum amounts were set to 1%, 3%, 5%, 7%, and 9%, and fermentation culture was carried out to detect the bacterial cell count.

[0066] Result: As Figure 6 As shown, among inoculum amounts of 1-9%, 5% is optimal, achieving a bacterial count of 10.6 × 10⁻⁶. 8 CFU / mL.

[0067] 8 Response Surface Optimization Results

[0068] Results: Plackett-Burman and ramp-up experiments identified three key factors (maltose, beef meal, and inoculum size). Response surface methodology determined the optimal conditions to be: maltose 19.02 g / L, beef meal 18.63 g / L, and inoculum size 1%, at which point the bacterial cell count reached 13.67 × 10⁻⁶. 8 The CFU / mL and T-AOC of 13.56 U / mL were consistent with the model prediction.

[0069] Table 1. Results of the Placket-Burman Experiment

[0070] Standard sequence Run sequence Maltose (g / L) Beef powder (g / L) Cysteine ​​hydrochloride (g / L) Inoculation volume (%) Incubation temperature (°C) <![CDATA[Cell mass (×10 8 cells / mL)]]> 12 1 8 12 0.5 3 34 6.6 10 2 8 16 0.9 7 34 7.6 1 3 14 16 0.5 7 40 8.3 2 4 8 16 0.9 3 40 8.6 9 5 14 16 0.9 3 34 11.3 8 6 14 16 0.5 3 34 10.8 7 7 14 12 0.5 3 40 9 6 8 8 12 0.5 7 34 4.3 3 9 14 12 0.9 7 34 6.6 4 10 8 16 0.5 7 40 5.8 5 11 8 12 0.9 3 40 5.5 11 12 14 12 0.9 7 40 8.2

[0071] Table 2. Levels and results of various factors in the steepest climb test

[0072] gradient Maltose (g / L) Beef powder (g / L) Inoculation volume (%) <![CDATA[Cell mass (×10 8 cells / mL)]]> 1 11 13.5 5.5 10.5 2 14 15 4 11.5 3 17 16.5 2.5 12.3 4 20 18 1 9.3

[0073] Table 3 Response Surface Experimental Design and Results

[0074] Standard sequence Run sequence Maltose (g / L) Beef powder (g / L) Inoculation volume (%) <![CDATA[Cell mass (×10 8 cells / mL)]]> T-AOC (U / mL) 9 4 17 15 1 11.5 6.54 5 16 14 16.5 1 10.7 8.76 6 9 20 16.5 1 10.6 5.92 10 17 17 18 1 11.8 10.62 1 3 14 15 2.5 9 7.65 2 5 20 15 2.5 10.1 11.72 16 6 17 16.5 2.5 12.3 7.03 17 10 17 16.5 2.5 12.1 9.32 14 11 17 16.5 2.5 12.5 9.99 15 13 17 16.5 2.5 12.7 12.36 13 14 17 16.5 2.5 12.3 12.32 3 1 14 18 2.5 9.9 7.28 4 12 20 18 2.5 9.9 12.55 11 2 17 15 4 11.2 12.1 7 7 14 16.5 4 10.2 10.14 8 15 20 16.5 4 10.6 10.88 12 8 17 18 4 11.6 10.36

[0075] 9. Optimized culture medium for Clostridium butyricum

[0076] Optimized culture medium for Clostridium butyricum: maltose 19.02 g / L, beef meal 18.63 g / L, L-cysteine ​​hydrochloride 0.9 g / L, sodium chloride 5.0 g / L, sodium acetate 3.0 g / L, byproduct 100 g, culture temperature 37℃, inoculum size 1%. 2% agar was added to the solid culture medium.

[0077] Example 2

[0078] 1. Preparation of by-products and fermentation medium from oval pomfret

[0079] The byproducts of oval pomfret were washed and ground to obtain a dense material with a particle size of less than 3 mm, which was used as the fermentation substrate. The material was sterilized by high-temperature steam at 121℃ for 20 min and dissolved in sterile water at a mass concentration of 100 g / L to prepare the initial fermentation medium.

[0080] 2. Clostridium butyricum fermentation

[0081] Clostridium butyricum was inoculated at a rate of 1% into an optimized culture medium (19.02 g / L maltose, 18.63 g / L beef meal, 0.9 g / L L-cysteine ​​hydrochloride, 5.0 g / L sodium chloride, 3.0 g / L sodium acetate, and 100 g of byproducts), and cultured anaerobicly at 37°C. The Clostridium butyricum culture was then collected.

[0082] Experimental group: The optimal supplement formulation (maltose 19.02 g / L, beef powder 18.63 g / L, L-cysteine ​​hydrochloride 0.9 g / L, sodium chloride 5.0 g / L, sodium acetate 3.0 g / L, by-product 100 g) and process parameters (inoculum 1%, temperature 37℃) obtained by response surface methodology in Example 1 were added to the initial fermentation medium and fermented for 72 hours.

[0083] Control group 1: Clostridium butyricum bacterial culture was inoculated into optimized culture medium without supplementation of by-products at an inoculation rate of 1%, and anaerobic fermented at 37°C for 72 h.

[0084] Control group 2: Take the optimized culture medium and add it to the initial fermentation medium at a volume fraction of 1%, and anaerobic ferment at 37℃ for 72 h.

[0085] Control group 3: Sterile water was added to the initial fermentation medium at a volume fraction of 1%, and anaerobic fermentation was carried out at 37°C for 72 hours.

[0086] 3. Detection and Analysis

[0087] After fermentation, the fermentation broth of the experimental group, the liquid of control group 1, and the fermentation broth of control group 2 and control group 3 were analyzed by gas chromatography-mass spectrometry (GC-MS).

[0088] The chromatographic column was a TraceGOLD TG-WaxMS GC column (30 m × 0.32 mm, 0.25 μm); the carrier gas was helium (purity 99.999%), the flow rate was 1.0 mL / min, the injection was in splitless mode, the injection port temperature was 250℃, and the transfer line temperature was 280℃; the temperature program was as follows: initial temperature 60℃ held for 2 min, increased to 200℃ at 10℃ / min, held for 5 min, then increased to 250℃ at 10℃ / min, held for 2 min.

[0089] The mass spectrometry conditions were: EI source, ion source temperature 230℃, transfer line temperature 250℃, and full scan mode (m / z=30-300).

[0090] 4. Experimental Results

[0091] The total ion current spectra of short-chain fatty acids in the experimental group, control group 1, control group 2, and control group 3 are as follows: Figure 7 Figures a, b, c, and d show the peak area ratios of characteristic ions of SCFAs in the experimental group, control group 1, control group 2, and control group 3. Figure 8 As shown in the figure. Compared with control group 1, under the optimal culture conditions of Clostridium butyricum, the experimental group fermented with oval pomfret by-products as substrates, and the butyric acid content in the fermentation broth increased by 102.5%, while the contents of valeric acid, isovaleric acid, and hexanoic acid also showed significant increases. The contents of butyric acid, valeric acid, isovaleric acid, and hexanoic acid in the fermentation broth of the experimental group were 9.19 g / L, 2.84 g / L, 4.48 g / L, and 3.50 g / L, respectively.

[0092] The above results indicate that using oval pomfret byproducts as a substrate and inoculating Clostridium butyricum can produce high yields of butyric acid, valeric acid, isovaleric acid, and hexanoic acid. The yields are significantly higher than the sum of the fermentation yields of Clostridium butyricum in the optimized medium without supplemented byproducts (control group 1), the fermentation yields of oval pomfret byproducts in the optimized medium (control group 2), and the fermentation yields of oval pomfret byproducts in the initial fermentation medium (control group 3).

[0093] Example 3

[0094] The fermentation method of the experimental group in Example 2 was repeated three times, and three fermentation broths were collected and named experimental group 1, experimental group 2 and experimental group 3, respectively. The fermentation method of control group 1 in Example 2 was repeated three times, and three fermentation broths were collected and named control group 1, control group 2 and control group 3, respectively.

[0095] The above 6 groups of fermentation broth were taken and treated with catalase (CAT) and superoxide dismutase (SOD). The activities of CAT and SOD in experimental groups 1-3 and control groups 1-control groups 3 were detected using catalase (CAT) activity assay kit (Nanjing Jiancheng Bioengineering Institute, A007-1-1) and superoxide dismutase (SOD) activity assay kit (Nanjing Jiancheng Bioengineering Institute, A001-1-1), respectively.

[0096] The results are as follows Figure 9 As shown, the CAT and SOD activities of experimental groups 1-3 were significantly higher than those of control groups 1-3, indicating that the fermentation broth obtained by fermenting Clostridium butyricum with oval pomfret by-products as substrate has stronger antioxidant capacity; the average CAT and SOD activities of the experimental groups were 16.22 and 22.21 U / mL, respectively.

[0097] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing high-value-added fermented products from oval pomfret by-products, characterized in that, Includes the following steps: (1) Provide the processing by-products of oval pomfret, which are ground, sterilized, and dissolved to prepare an initial fermentation culture medium; (2) Prepare a fermentation medium based on the initial fermentation medium; (3) Using Clostridium butyricum as the fermentation strain, the composition of the fermentation medium and / or fermentation process conditions were optimized using response surface methodology to obtain the optimal fermentation parameters; (4) The fermentation medium is subjected to anaerobic fermentation of Clostridium butyricum according to the optimal fermentation parameters to obtain the fermentation product.

2. The method as described in claim 1, characterized in that, In step (3), the response value optimized by the response surface methodology includes the cell biomass of Clostridium butyricum and / or the total antioxidant capacity of the fermentation system.

3. The method as described in claim 1, characterized in that, In step (3), the optimization of the composition of the fermentation medium includes: supplementing it with carbon source, nitrogen source and deoxidizer; the optimal fermentation parameters include: the concentration of supplemented carbon source is 15-22 g / L, the concentration of supplemented nitrogen source is 16-20 g / L, and the concentration of supplemented deoxidizer is 0.7-1.1 g / L.

4. The method as described in claim 3, characterized in that, The supplementary carbon source is maltose, the supplementary nitrogen source is beef meal, and the supplementary deoxidizer is L-cysteine ​​hydrochloride.

5. The method as described in claim 1, characterized in that, In step (4), the anaerobic fermentation conditions are: temperature 35-38℃ and time 72 h.

6. A fermentation broth obtained by the method according to any one of claims 1-5.

7. The use of the fermentation broth according to claim 6 in the preparation of functional foods that contribute to antioxidant activity.

8. The use of the fermentation broth according to claim 6 in the preparation of an antioxidant drug.

9. The use of the fermentation broth according to claim 6 in the preparation of animal feed.

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