Low-salt fish sauce and preparation method thereof

Abstract

The invention belongs to the field of food processing, and particularly relates to a low-salt fish sauce and a preparation method thereof. The method comprises the following steps: 1) preparing a biological fermentation agent from bacillus subtilis and aspergillus oryzae; 2) adding a biological leavening agent into the preparation raw materials for fermentation treatment to prepare the low-salt fish sauce, the preparation raw materials are fish aquatic products and / or leftovers after fish processing and / or low-value wastes after fish processing. The improved biological leavening agent is matched with the unique segmented variable-temperature fermentation technology, so that the fermentation preparation time is greatly shortened, the production efficiency of the fish sauce is improved, the salt value is more effectively reduced, the unique delicious taste and rich nutritional ingredients of the fish sauce are kept, and the health degree of the fish sauce is improved.

Description

Technical Field

[0001] The present invention belongs to the field of food processing, and particularly relates to a low-salt fish sauce and a preparation method thereof. Background Art

[0002] With the continuous progress and development of industrial production technology, the production process of fish sauce has also undergone significant improvement and optimization. In the production process of modern fish sauce, a series of carefully designed steps are strictly implemented to ensure that the quality and taste of the final product meet the established standards. These steps include: First, fish are caught and processed to ensure the freshness and quality of the raw materials used; Second, through the processes of salting and fermentation, the proteins and amino acids in the fish meat are fully decomposed and transformed, thus forming the unique flavor characteristics of fish sauce; Subsequently, through the steps of clarification and filtration, impurities are effectively removed, making the fish sauce present a clear and transparent appearance; Then, through the processes of cooking and concentration, the essence components in the fish sauce are further refined to enhance its flavor and aroma; Finally, through the processes of bottling and packaging, it is ensured that the fish sauce maintains good hygienic conditions and quality performance during subsequent storage and transportation.

[0003] In existing patent technology solutions, the rapid fermentation process of fish sauce mainly adopts methods such as heat preservation fermentation, koji addition fermentation, and external enzyme or internal organ fermentation. Compared with the traditional natural fermentation method, these rapid fermentation processes significantly accelerate the degradation process of proteins, enabling fish sauce to meet the various physical and chemical indicators specified by the national fish sauce standard within a shorter period of time. However, although these research results perform well at the laboratory level, there are still some problems at present, resulting in their failure to be widely applied in large-scale industrial production.

[0004] The main problem is that the fish sauce produced by the rapid fermentation process has a significant difference in flavor from traditional fish sauce fermentation products and lacks the unique fragrance of traditional fish sauce. This unique fragrance comes from the complex compounds formed during the long-term natural fermentation process of traditional fish sauce, and the rapid fermentation process is often difficult to completely replicate this unique process. Therefore, although the rapid fermentation process has advantages in production efficiency and physical and chemical indicators, further research and improvement are still needed in terms of flavor and aroma to meet consumers' expectations for the flavor of traditional fish sauce. Summary of the Invention

[0005] The technical solution of the present invention aims at the problems of too long traditional fermentation time, complex microbial population during fermentation, fluctuating product quality, and the usually high salt value of the obtained fish sauce product, and provides a low-salt fish sauce and a preparation method thereof.

[0006] The main purposes of the present invention are as follows: One, shorten the fermentation cycle of fish sauce; Second, reduce the types of microorganisms in the fermentation process; Third, improve the quality of fish sauce products and reduce the salt value of fish sauce.

[0007] To achieve the above objectives, the present invention adopts the following technical solutions.

[0008] A method for preparing low-salt fish sauce, The method includes: 1) Prepare Bacillus subtilis and Aspergillus oryzae as a biological fermentation agent; 2) Add the biological fermentation agent to the preparation raw materials for fermentation treatment to obtain low-salt fish sauce; The preparation raw materials are fish aquatic products and / or fish processing by-products and / or low-value waste after fish processing.

[0009] Preferably, The process of preparing the biological fermentation agent in step 1) is as follows: First, inoculate Bacillus subtilis with a bacterial concentration of 2×10 10 ~4×10 10 CFU / mL into the culture medium, cultivate it in an environment with a temperature of 26-33°C for 4-8 hours, take the supernatant to make a preliminary bacterial agent, and then mix wheat flour, bran, water, glucose, the preliminary bacterial agent, and Aspergillus oryzae bacterial agent according to a mass ratio of 1:(0.2-0.3):(0.8-1.2):0.01:(0.1-0.2):(0.1-0.2), where the concentration of Aspergillus oryzae bacterial agent is 2×10 10 ~4×10 10 CFU / mL, and cultivate it in a constant temperature environment with a temperature of 25-30°C for 42-54 hours to obtain the biological fermentation agent.

[0010] Preferably, The culture medium is potato dextrose agar medium.

[0011] Preferably, The dosage of the biological fermentation agent in step 2) is 5-10 wt% of the preparation raw materials.

[0012] Preferably, The fish aquatic products in step 2) are fish meat and / or whole fish; The fish processing by-products in step 2) include fish heads and / or fish skins and / or fish bones; The low-value waste after fish processing in step 2) includes fish viscera.

[0013] Preferably, When the preparation raw materials in step 2) contain fish processing by - products and / or low - value fish processing wastes, the mass ratio of the used fish processing by - products and / or low - value fish processing wastes in the preparation raw materials ≤ 70wt%.

[0014] Preferably, The fermentation treatment in step 2) is as follows: Clean and crush the preparation raw materials into pulp, and cook and sterilize them to make cooked materials at the same time; Mix the cooked materials, wheat flour, wheat bran, and water evenly according to the mass ratio of 1:(1 - 1.5):(0.5 - 1):(0.75 - 1.25), add a biological fermentation agent, ferment for 6 - 8 d in an environment with a temperature of 18 - 22 °C for the first fermentation, then increase the temperature to 38 - 42 °C at a heating rate of 3 - 5 °C / h, ferment for 12 - 14 d, and finally filter and sterilize to obtain low - salt fish sauce.

[0015] A low - salt fish sauce.

[0016] In the technical solution of the present invention, the core lies in optimizing the biological fermentation agent used for fermenting fish sauce. By utilizing the enzyme system produced by the growth and reproduction of molds, the microbial community relationship between microorganisms is improved, and the proteolytic activity of protease is strengthened, so as to achieve the purpose of rapid fermentation. In the present invention, by carefully screening and introducing specific types of Bacillus subtilis, the effective adjustment and optimization of the composition of the fermentation substrate can be realized. This adjustment is mainly to create a more suitable growth environment for Aspergillus oryzae species, thereby promoting its proliferation and reproduction. At the same time, the presence of Bacillus subtilis also has a significant effect of inhibiting the growth and reproduction of harmful microorganisms during the fermentation process. Through this dual mechanism, a stable and efficient microbial community structure can be constructed, thereby ensuring the smooth progress of the fermentation process and the reliability of the final product quality. Specifically, the introduction of Bacillus subtilis can significantly improve the nutritional components of the fermentation substrate, making it more suitable for the growth requirements of Aspergillus oryzae. This improvement includes but is not limited to providing more nutrients, adjusting the pH value, and optimizing the physical structure of the substrate, making it more suitable for the attachment and growth of Aspergillus oryzae. Through these adjustments, Aspergillus oryzae can better exert its biotransformation ability during the fermentation process, thereby improving the fermentation efficiency and product quality. In addition, Bacillus subtilis also has strong anti - microbial properties and can effectively inhibit harmful microorganisms that may appear during the fermentation process, such as bacteria, yeasts, and molds. These harmful microorganisms not only compete with the target strains for nutrients but also may produce toxins, affecting the quality and safety of the fermentation products. Bacillus subtilis can effectively curb the growth of these harmful microorganisms through mechanisms such as secreting antibacterial substances and competitive inhibition, thereby ensuring the stability of the fermentation process and the safety of the products.

[0017] Another core aspect of the present invention is the adoption of a segmented variable-temperature fermentation technology. By carefully designing and optimizing the fermentation time at different temperature stages, the unique advantages of each temperature segment are fully utilized, thereby reducing the salt content while ensuring that the flavor and nutritional components of fish sauce are retained to the greatest extent. First, the fermentation process starts under relatively low temperature conditions. The low-temperature environment at this stage can effectively promote the growth and metabolic activities of beneficial microorganisms, and at the same time can effectively inhibit the reproduction and spread of harmful microorganisms. Subsequently, as the fermentation process progresses, we gradually increase the temperature of the fermentation environment. This measure helps to accelerate the decomposition process of proteins, thereby promoting the formation and accumulation of flavor substances. Through this scientific temperature control and gradual adjustment method, the fermentation cycle is significantly shortened, avoiding the flavor loss and nutritional component damage that may be caused by long-term high-temperature fermentation. Finally, through precise temperature control and strict time management, we have successfully maintained the unique delicious taste and rich nutritional components of fish sauce under the condition of reducing salt content, ensuring the high quality and health characteristics of the product. In this way, the fermentation cycle is shortened from more than 30 days in the traditional method to 18 - 22 days, significantly improving the production efficiency. At the same time, due to the shortening of the fermentation time, the generation of bad flavors caused by excessive growth of microorganisms is reduced, thereby reducing the production cost while ensuring the quality of fish sauce. This scientific fermentation method not only improves the production efficiency but also ensures the stability and consistency of the product, greatly enhancing the competitiveness of fish sauce in the market.

[0018] The beneficial effects of the present invention are as follows: Through the improved biological fermenting agent in combination with the unique segmented variable-temperature fermentation technology, the present invention greatly shortens the fermentation preparation time, improves the production efficiency of fish sauce, and more effectively reduces the salt value, maintains the unique delicious taste and rich nutritional components of fish sauce, and improves the healthiness of fish sauce. Detailed implementation manners

[0019] The following further clearly and detailedly describes the present invention in combination with specific embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are usually only a part of the embodiments of the present invention, rather than all the embodiments. Therefore, all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0020] Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commercially available or raw materials that can be obtained by those skilled in the art; unless otherwise specified, the methods used in the embodiments of the present invention are all methods mastered by those skilled in the art.

[0021] Example 1 A preparation method of low-salt fish sauce, the method comprising: (1) Inoculate Bacillus subtilis with a bacterial agent concentration of 2×10 10 CFU / mL into a potato dextrose agar medium, cultivate it in an environment with a temperature of 26°C for 8 h, and take the supernatant to prepare a preliminary bacterial agent; (2) Mix wheat flour, wheat bran, water, glucose, the preliminary bacterial agent, and Aspergillus oryzae bacterial agent according to a mass ratio of 1:0.2:0.8:0.01:0.1:0.1, wherein the concentration of the Aspergillus oryzae bacterial agent is 2×10 10 CFU / mL, and cultivate it in a constant temperature environment with a temperature of 25°C for 54 h to obtain a biological fermentation agent; (3) Wash the aquatic product scraps, stir them into a slurry, and steam and sterilize them to obtain cooked materials. Among them, the aquatic products include aquatic products and aquatic product scraps including internal organs, and the internal organs account for 70 wt% of the total mass of the aquatic products; (4) Mix the cooked materials, wheat flour, wheat bran, and water evenly according to a mass ratio of 1:1:0.5:0.75, add the biological fermentation agent, and ferment it in an environment with a temperature of 18°C for 8 d for the first fermentation; (5) Raise the temperature to 38°C at a heating rate of 3°C / h and ferment for 14 d; finally, filter and sterilize to obtain low-salt fish sauce.

[0022] Detect the low-salt fish sauce prepared in the example, and the specific operation steps and characterization results are as follows.

[0023] Amino acid nitrogen: Determine it by the formaldehyde titration method and calculate the amino acid nitrogen content according to the following formula.

[0024] In the formula: V1—the volume of the sodium hydroxide standard titration solution consumed after adding formaldehyde to the sample dilution solution for determination, mL; V2—the volume of the sodium hydroxide standard titration solution consumed after adding formaldehyde in the reagent blank test, mL; V3—the volume of the sample dilution solution taken, mL; c1—the concentration of the sodium hydroxide standard titration solution, mol / L; 0.014—the mass of nitrogen equivalent to the sodium hydroxide [c(NaOH)=1.000 mol / L] standard titration solution, g.

[0025] Total nitrogen: Determine it by the Kjeldahl method and calculate the total nitrogen content according to the following formula.

[0026] In the formula: V1—the volume of the hydrochloric acid standard titration solution consumed by the reagent, mL; V2 —— Volume of hydrochloric acid standard titrant consumed by reagent blank, mL; c —— Concentration of hydrochloric acid standard titrant, mol / L; m —— Weight of sample, g; 0.014 —— Mass of nitrogen equivalent to sodium hydroxide [c(NaOH) = 1.000 mol / L] standard titrant solution, g.

[0027] Table salt: Determined by silver nitrate titration method and calculated according to the following formula for table salt content.

[0028] In the formula: V —— Volume of 0.1 mol / L silver nitrate standard titrant consumed for titrating sample dilution, mL; V0 —— Volume of 0.1 mol / L silver nitrate standard titrant consumed in blank test, mL; c —— Concentration of silver nitrate standard titrant, mol / L; 0.0585 —— Mass of sodium chloride equivalent to silver nitrate [c(AgNO3) = 1.000 mol / L] standard titrant solution, g. Content of amino acid nitrogen, g / 100 mL Content of total nitrogen, g / 100 mL Content of table salt, g / 100 mL 0.92 1.21 17.33

[0029] Example 2 A preparation method of low-salt fish sauce, The method includes: (1) Inoculate Bacillus subtilis with a bacterial agent concentration of 3×10 10 CFU / mL into potato dextrose agar medium, culture in an environment at 30 °C for 6 h, and take the supernatant to prepare a preliminary bacterial agent; (2) Mix wheat flour, wheat bran, water, glucose, the preliminary bacterial agent, and Aspergillus oryzae bacterial agent according to a mass ratio of 1:0.25:1:0.01:1.5:1.5, where the concentration of the Aspergillus oryzae bacterial agent is 3×10 10 CFU / mL, and cultivate in a constant temperature environment at 27 °C for 48 h to obtain a biological fermentation agent; (3) Wash aquatic product scraps, stir into a slurry, and steam and sterilize to make cooked materials. Among them, the aquatic products include aquatic products and aquatic product scraps including internal organs, and the internal organs account for 70 wt% of the total mass of the aquatic products; (4) Mix the cooked materials, wheat flour, wheat bran, and water evenly according to a mass ratio of 1:1.25:0.75:1, add the biological fermentation agent, and ferment in an environment at 20 °C for 7 d for the first fermentation; (5) Increase the temperature to 40°C at a heating rate of 4°C / h and ferment for 13 days; finally, filter and sterilize to obtain low-salt fish sauce.

[0030] Perform the same tests on the low-salt fish sauce prepared in the examples as in Example 1, and the specific characterization results are as follows. Content of amino acid nitrogen, g / 100 mL Content of total nitrogen, g / 100 mL Content of table salt, g / 100 mL 0.93 1.22 17.31

[0031] Example 3 A method for preparing low-salt fish sauce, The method includes: (1) Inoculate Bacillus subtilis with a concentration of 4×10 10 CFU / mL into potato dextrose agar medium, culture in an environment with a temperature of 33°C for 4 h, and take the supernatant to prepare a preliminary inoculum; (2) Mix wheat flour, wheat bran, water, glucose, the preliminary inoculum, and Aspergillus oryzae inoculum according to a mass ratio of 1:0.3:1.2:0.01:0.2:0.2, where the concentration of Aspergillus oryzae inoculum is 4×10 10 CFU / mL, and cultivate in a constant-temperature environment with a temperature of 30°C for 42 h to obtain a biological fermenter; (3) Wash the aquatic product scraps, stir them into a slurry, steam and sterilize to obtain cooked materials. Among them, the aquatic products include aquatic products and aquatic product scraps including internal organs, and the internal organs account for 70 wt% of the total mass of the aquatic products; (4) Mix the cooked materials, wheat flour, wheat bran, and water evenly according to a mass ratio of 1:1.5:1:1.25, add the biological fermenter, and ferment in an environment with a temperature of 22°C for 6 days for the first fermentation; (5) Increase the temperature to 42°C at a heating rate of 5°C / h and ferment for 12 days; finally, filter and sterilize to obtain low-salt fish sauce.

[0032] Perform the same tests on the low-salt fish sauce prepared in the examples as in Example 1, and the specific characterization results are as follows. Content of amino acid nitrogen, g / 100 mL Content of total nitrogen, g / 100 mL Content of table salt, g / 100 mL 0.93 1.22 17.31

[0033] Comparative Example 1 A method for preparing low-salt fish sauce, the specific preparation method is the same as that in Example 2. In the comparative example, only the water content of the fermentation koji is changed. Specifically, mix wheat flour, wheat bran, water, glucose, the preliminary inoculum, and Aspergillus oryzae inoculum according to a mass ratio of 1:0.25:0.5:0.01:1.5:1.5 to prepare low-salt fish sauce. Perform the same tests on the low-salt fish sauce prepared in the comparative example as in Example 1, and the characterization results are as follows. Content of amino acid nitrogen, g / 100 mL Content of total nitrogen, g / 100 mL Content of table salt, g / 100 mL 0.44 0.61 16.36

[0034] Comparative Example 2 A preparation method of low-salt fish sauce, the specific preparation method is the same as that of Example 2. The comparative example only changes the water content for moistening the fermented Qu Mei in the present invention. Specifically, wheat flour, wheat bran, water, glucose, preliminary inoculant, and Aspergillus oryzae inoculant are mixed according to a mass ratio of 1:0.25:2:0.01:1.5:1.5 to prepare low-salt fish sauce. The low-salt fish sauce prepared in the comparative example is subjected to the same detection as in Example 1, and the characterization results are as follows. Content of amino acid nitrogen, g / 100 mL Content of total nitrogen, g / 100 mL Content of table salt, g / 100 mL 0.42 0.72 25.91

[0035] By comprehensively analyzing the characterization data of Comparative Example 1 and Comparative Example 2, it is found that the quality of the finally prepared fish sauce has significantly decreased, and the change trend of the salt content in the fish sauce cannot be predicted. Therefore, the protease enzyme activity of the biological fermenting agent prepared in the comparative example and the biological fermenting agent prepared in Example 2 was detected, and the specific operation steps are as follows.

[0036] Weigh 5.000 g of the biological fermenting agent, grind it finely, and dilute it with a phosphate buffer solution with a pH of 7.5; extract it at a temperature of 40 °C for 1 h; centrifuge the extracted sample solution in a centrifuge at a rotation speed of 5000 r / min for 20 min, and take the supernatant, which is the crude enzyme solution. The neutral protease enzyme activity is measured using the Folin-Ciocalteu method and calculated according to the following formula.

[0037] In the formula: X — Enzyme activity, U / g; A — Activity of the final dilution, U / mL; V — Volume of the volumetric flask used to dissolve the sample, mL; 4 — Total volume of the reaction reagent, mL; N — Dilution factor of the sample; m — Mass of the sample, g; W — Water content of the sample.

[0038] The protease activity of the biological ferment produced in Example 2 was 1517 U / g, the protease activity of the biological ferment produced in Comparative Example 1 was 832 U / g, and the protease activity of the biological ferment produced in Comparative Example 2 was 1132 U / g. Analyze the data and conduct further research. If the water content is too low, the water required by Aspergillus oryzae during the growth cycle cannot be sufficiently supplied, which will lead to a slowdown in its growth rate and thus hinder its normal growth and development. On the contrary, if the water content is too high, the koji material is prone to form lumps, resulting in a decrease in the air permeability inside the koji material and causing the central temperature of the koji material to rise. However, such high-temperature conditions are conducive to the growth and reproduction of other miscellaneous bacteria, making the koji material the target of utilization and degradation by these miscellaneous bacteria. The presence of miscellaneous bacteria will produce bad odors, resulting in abnormal situations such as sour koji and flower koji in the koji material. These conditions are not only unfavorable for the normal growth of Aspergillus oryzae but also lead to a decrease in the quantity of protease produced by Aspergillus oryzae, thereby weakening the enzyme activity. The reduction of enzyme activity will directly have a negative impact on the quality of fish sauce, damaging its taste and flavor and ultimately leading to a decline in the quality of fish sauce.

[0039] Comparative Example 3 A preparation method of low-salt fish sauce, the specific preparation method is the same as that in Example 2. The comparative example only changes the proportion of aquatic product viscera in the cooked material of the present invention. Specifically, the aquatic products include aquatic products and aquatic product scraps including viscera, and the proportion of viscera is 80 wt% of the total mass of the aquatic products. Prepare low-salt fish sauce, and conduct the same detection on the low-salt fish sauce prepared in the comparative example as in Example 1. The characterization results are as follows. Content of amino acid nitrogen, g / 100 mL Content of total nitrogen, g / 100 mL Content of table salt, g / 100 mL 0.55 0.67 24.28

[0040] In addition, the protease produced during the fermentation in the fermentation operation process of the comparative example was subjected to the same enzyme activity detection as in Comparative Example 2, and the result was that the protease activity was 1072 U / g. Combining with the characterization data for further analysis, during the fermentation process, the growth and reproduction of microorganisms mainly rely on the nitrogen source and carbon source provided by wheat. In the present invention, wheat, as a high-quality raw material, can provide necessary nutrients for microorganisms, thereby promoting their growth. At the same time, the viscera part of aquatic products contains rich proteins and amino acids, and these components can provide sufficient energy sources for the growth of microorganisms. However, if too much aquatic product viscera is added during the fermentation process, some problems will arise. The large amount of water contained in the viscera will cause the viscosity of the mature koji to decrease, making the fermentation substrate unable to coagulate evenly but instead coagulating into lumps. This lump structure will lead to an oxygen-deficient situation inside the fermentation environment, thereby inhibiting the normal growth of Aspergillus oryzae. Aspergillus oryzae is an important microorganism during the fermentation process, and it is responsible for secreting a series of enzyme systems during the fermentation process, including neutral protease. When the activity of neutral protease decreases, it will lead to a decline in the quality of the fermentation product fish sauce.

[0041] Comparative Example 4 A preparation method of low-salt fish sauce, the specific preparation method is the same as that of Example 2. In the comparative example, the segmented variable-temperature fermentation method in the present invention is not used, and the low-salt fish sauce is prepared.

[0042] A preparation method of low-salt fish sauce, the method comprising: (1) Inoculate Bacillus subtilis with a bacterial agent concentration of 3×10 10 CFU / mL into a potato dextrose agar medium, culture it in an environment with a temperature of 30°C for 6 h, and take the supernatant to prepare a preliminary bacterial agent; (2) Mix wheat flour, wheat bran, water, glucose, the preliminary bacterial agent, and Aspergillus oryzae bacterial agent according to a mass ratio of 1:0.25:1:0.01:1.5:1.5, wherein the concentration of the Aspergillus oryzae bacterial agent is 3×10 10 CFU / mL, and cultivate it in a constant-temperature environment with a temperature of 27°C for 48 h to obtain a biological fermentation agent; (3) Wash the aquatic product scraps, stir them into a slurry, and steam and sterilize them to obtain a cooked material. Among them, the aquatic products include aquatic products and aquatic product scraps including internal organs, and the internal organs account for 70 wt% of the total mass of the aquatic products; (4) Mix the cooked material, wheat flour, wheat bran, and water evenly according to a mass ratio of 1:1.25:0.75:1, add the biological fermentation agent, ferment it in an environment with a temperature of 30°C for 20 d, filter and sterilize it to obtain low-salt fish sauce.

[0043] Perform the same detection on the low-salt fish sauce prepared in the comparative example as in Example 1, and the characterization results are as follows. Content of amino acid nitrogen, g / 100 mL Content of total nitrogen, g / 100 mL Content of table salt, g / 100 mL 0.79 1.02 25.36

[0044] Analyze the above characterization data. The content of amino acid nitrogen and total nitrogen in the fish sauce decreases, and the salt content increases. After further analysis, although low-temperature fermentation can reduce the salt content, it will result in lower contents of amino acid nitrogen and total nitrogen in the fish sauce, affecting the nutrition of the final product; high-temperature fermentation will make the fish sauce bitter and have a high content of volatile basic nitrogen, also affecting the product quality. In the technical solution of the present invention, a segmented variable-temperature fermentation method is adopted, and the fermentation duration under different temperature conditions is precisely controlled to fully explore and utilize the advantageous characteristics of each temperature range, so as to effectively reduce the salt content while ensuring that the flavor quality and nutritional components of the fish sauce are maintained.

Claims

1. A preparation method of low-salt fish sauce, characterized in that, The method comprises: 1) Preparing Bacillus subtilis and Aspergillus oryzae as a biological fermentation agent; 2) Adding the biological fermentation agent into the preparation raw materials for fermentation treatment to obtain low-salt fish sauce; The preparation raw materials are fish aquatic products and / or fish processing by-products and / or low-value waste after fish processing.

2. The preparation method of low-salt fish sauce according to claim 1, characterized in that, The process of preparing the biological fermentation agent in step 1) is: First, inoculate Bacillus subtilis with a concentration of 2×10 10 ~4×10 10 CFU / mL into the culture medium, and culture it in an environment with a temperature of 26 - 33°C for 4 - 8 hours. Take the supernatant to prepare a preliminary bacterial agent. Then, mix wheat flour, wheat bran, water, glucose, the preliminary bacterial agent, and Aspergillus oryzae bacterial agent according to a mass ratio of 1:(0.2 - 0.3):(0.8 - 1.2):0.01:(0.1 - 0.2):(0.1 - 0.2), where the concentration of the Aspergillus oryzae bacterial agent is 2×10 10 ~4×10 10 CFU / mL, and cultivate it in a constant temperature environment with a temperature of 25 - 30°C for 42 - 54 hours to obtain a biological fermentation agent.

3. The preparation method of low-salt fish sauce according to claim 2, characterized in that, The culture medium is potato dextrose agar medium.

4. The preparation method of low-salt fish sauce according to claim 1, characterized in that, The dosage of the biological fermentation agent in step 2) is 5-10 wt% of the preparation raw materials.

5. The preparation method of low-salt fish sauce according to claim 1, characterized in that, The fish aquatic products in step 2) are fish meat and / or whole fish; The fish processing by-products in step 2) include fish head and / or fish skin and / or fish bones; The low-value waste after fish processing in step 2) includes fish viscera.

6. The preparation method of low-salt fish sauce according to claim 1 or 5, characterized in that, When the preparation raw materials in step 2) contain fish processing by-products and / or low-value waste after fish processing, the mass ratio of the used fish processing by-products and / or low-value waste after fish processing to the preparation raw materials ≤ 70 wt%.

7. The preparation method of low-salt fish sauce according to claim 1, characterized in that, The fermentation treatment in step 2) is: Cleaning and crushing the preparation raw materials into slurry, and steaming and sterilizing to make cooked materials at the same time; Mixing the cooked materials, wheat flour, bran, and water evenly according to the mass ratio of 1:(1-1.5):(0.5-1):(0.75-1.25), adding the biological fermentation agent, fermenting for 6-8 d in an environment with a temperature of 18-22 °C for the first fermentation, then raising the temperature to 38-42 °C at a heating rate of 3-5 °C / h, fermenting for 12-14 d, and finally filtering and sterilizing to obtain low-salt fish sauce.

8. A low-salt fish sauce prepared by any one of the methods according to claims 1 to 7.

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