Fermentation method of low-salt soy sauce

Abstract

The invention relates to the technical field of low-salt brewing fermentation, and particularly discloses a fermentation method of low-salt soy sauce, which is based on the problem that low-salt high-temperature fermentation is single in flavor and thin in taste, and by means of mixed culture of multiple strains (yeast rouxii and aspergillus oryzae), yeast materials or soy sauce mash can generate antibacterial substances, so that the low-salt soy sauce is obtained. Meanwhile, the level of microorganisms in soy sauce mash is controlled through yeast material stacking heating and staged water activity control, under the conditions of no salt, low salt and no other preservative additives, low-salt fermentation is achieved by regulating and controlling the yeast making or yellowing process and controlling the water content of the soy sauce mash, the taste and flavor of the soy sauce are improved, and the taste of the soy sauce is improved. The utilization rate of raw materials and the yield of products are improved, and the quality of crude oil is improved.

Description

Technical Field

[0001] The present application relates to the technical field of low-salt brewing and fermentation, and in particular to a fermentation method for low-salt soy sauce. Background Art

[0002] Salt is an important substance for producing soy sauce and fermented soybean food to prevent corruption and deterioration. Most soy sauces are fermented with 15-17% salt. High salt inhibits enzyme activity, resulting in a long fermentation cycle. Excessive salt intake is a predisposing factor for hypertension, heart disease, and kidney disease. Therefore, reduced-salt / salt-free soy sauce has emerged. However, low-salt fermentation has the problem of single taste and poor flavor of soy sauce. High-temperature fermentation conditions not only reduce the activity of some enzymes, but also inhibit the growth and reproduction of beneficial microorganisms. Currently, low-salt solid products on the market are all medium- and low-end products. With the continuous enrichment of food culture, in addition to meeting hygiene standards and physical and chemical indicators, soy sauce also requires a coordinated and unified aroma and taste. There are the following ways to improve the quality of low-salt solid fermentation: 1. Improve quality through blending; 2. Change the low-salt solid fermentation conditions, reduce the temperature by ensuring a certain amount of water and salt, and appropriately extend the fermentation time to give full play to the role of the enzyme; 3. Add microorganisms in appropriate amounts, add beneficial microorganisms such as high-temperature resistant aroma-producing yeast, so that they can adapt to the low-salt solid fermentation environment, grow and reproduce to produce metabolites, and improve the flavor of soy sauce.

[0003] In recent years, the industry has often added fermented soy sauce with antiseptic properties such as wine mash and Chinese medicine to achieve salt-free soy sauce fermentation. Patent Publication No. CN105614374A mixes wine mash into fermented soy mash when it turns yellow, and after 10-15 days of salt-free pre-fermentation, adds salt for dilute mash post-fermentation, and finally pours oil to prepare reduced-salt soy sauce. Patent Publication No. CN108968013A desalinates salt-fermented soy sauce by physical methods to obtain a physically desalted soy sauce. Patent Publication No. CN108991477A From making koji, piling warm koji, solid-state salt-free early fermentation, salt-free thick late fermentation, salt-free post-ripening to brewing salt-free soy sauce, the salt-free soy sauce finished product is brewed by accurate control of staged fermentation and temperature and oxygen content, during which nutrient activation liquid, red yeast, and Chinese medicinal materials are combined to comprehensively prevent the fermentation process from being corrupted and not breeding miscellaneous bacteria, and the fragrance of the obtained salt-free soy sauce can also be increased. In order to prevent the fermentation process, the sauce mash is contaminated by miscellaneous bacteria, and the industry is mainly based on adding preservatives. While adding wine mash or Chinese medicine to suppress other microorganisms, the enzyme system in the sauce mash is also suppressed to a certain extent, and its hydrolysis effect is affected, and the fermentation time is therefore extended; and the addition of preservatives in the fermented sauce mash will have production operation difficulties and low labor efficiency. However, there are few studies on the method for preparing low-salt soy sauce by koji regulation and water activity control. Summary of the invention

[0004] Based on the inhibition of enzyme activity in the soy sauce fermentation system and the negative impact on protein hydrolysis by high salt and high temperature in high-salt dilute and low-salt solid-state fermentation, the purpose of the present application is to overcome the shortcomings of the above-mentioned prior art and provide a fermentation method for low-salt soy sauce. The present application aims to achieve a flavor and quality similar to that of traditional soy sauce by optimizing fermentation conditions, utilizing the synergistic effect of microorganisms, and gradually adjusting the moisture through salt-free and low-salt combined fermentation, while reducing salt intake to meet the needs of a healthy diet.

[0005] To achieve the above purpose, the technical solution adopted by this application is:

[0006] The present application provides a fermentation method for low-salt soy sauce, comprising the following steps:

[0007] S1, mixing the cooked soybeans and fried wheat, inoculating Aspergillus oryzae for koji making, inoculating Saccharomyces rouxii during the koji making process or the yellowing process, and obtaining finished koji;

[0008] S2, stacking the koji to heat it, stirring it, heating it repeatedly to 35°C to 55°C, then adding water at a temperature of 30°C to 35°C, controlling the water activity of the koji to be less than 0.8, and then adding Saccharomyces cerevisiae;

[0009] S3, the fermented sauce mash processed by step S2 is stirred, and then salt-free solid-state fermentation is carried out, and the fermentation temperature is controlled to be 30°C-35°C, and then low-salt fermentation is carried out, and the fermentation temperature is controlled to be 35°C-40°C. The fermented sauce mash is stirred during the fermentation period, and is squeezed after the fermentation is completed to obtain low-salt soy sauce.

[0010] The present application provides a solid-state fermentation method combining salt-free and low-salt fermentation. By optimizing the fermentation conditions, more stringent fermentation condition control is adopted, including temperature, humidity, and oxygen supply (the whole fermentation process is sealed with a film to control the oxygen content to a certain extent), etc., Saccharomyces rouxii is added in the koji-making process or the yellowing process, so that it is fermented together with Aspergillus oryzae, and a unique mixed fermentation aroma is generated while producing alcohol. In addition, the water and oxygen supply of the fermentation system are controlled to be relatively low in the early stage of fermentation, so as to form a salt-free solid state with low water activity and low oxygen, which plays a role in inhibiting the growth of other miscellaneous bacteria. In the middle and late stages of fermentation, the salt content and water activity of the system are gradually increased. At the same time, under the conditions of salt-free and low-salt fermentation, the enzyme activity is fully exerted, the protein hydrolysis efficiency is accelerated, the growth and reproduction of multiple strains are synergistically fermented, and the metabolites of the soy sauce fermentation system are increased, thereby obtaining a low-salt soy sauce with high physical and chemical indicators and rich flavor.

[0011] As a preferred embodiment of the fermentation method of low-salt soy sauce described in the present application, in the step S1, 100 parts by weight of soybeans are added to 160 to 240 parts by weight of water for soaking at a soaking temperature of 20°C to 40°C for 5h to 8h, and then the water of the soaked soybeans is filtered out, and the soybeans are steamed at a temperature of 110°C to 130°C for 10 to 30 minutes, and cooled to obtain the steamed soybeans.

[0012] Preferably, in step S1, the steamed soybeans and fried wheat are mixed to form koji material, and after the koji material is cooled to a temperature of 35°C to 40°C, Aspergillus oryzae is inoculated to make koji at 30°C to 36°C.

[0013] Preferably, in step S1, when the koji making time is 30 to 36 hours and the temperature of the koji material is controlled at 28° C. to 32° C., Saccharomyces rouxii is inoculated.

[0014] As a preferred embodiment of the fermentation method of low-salt soy sauce described in the present application, in the step S2, the wheat is roasted at a roasting temperature of 180°C to 260°C and a roasting time of 3min to 10min, and then the roasted wheat is crushed to obtain fried wheat.

[0015] As a preferred embodiment of the fermentation method of low-salt soy sauce described in the present application, in the step S1, Saccharomyces rouxii with a weight ratio of 0.5‰ to 1‰ to the koji material is introduced by spraying Saccharomyces rouxii liquid.

[0016] The present application introduces Saccharomyces rouxii into the process of making soy sauce koji or yellowing, and ferments with Aspergillus oryzae to produce alcohol to inhibit the growth of miscellaneous bacteria, while improving the flavor of soy sauce, balancing the umami and richness, and making the aroma richer.

[0017] As a preferred embodiment of the fermentation method of low-salt soy sauce described in the present application, in the step S2, the finished koji is piled up for heating, and the temperature of the finished koji is raised to 35°C-55°C and stirred. After stirring, the temperature of the koji is reduced to 30-35°C, and the heating and stirring operations are repeated. The temperature of the finished koji is evenly raised to 35°C-55°C, and the entire stacking and heating time is 3h-4h.

[0018] The present application adopts the above-mentioned conditions for stacking and heating to reduce the problem of bacteria growth in fermented mash under low-temperature fermentation conditions; and the finished koji is evenly heated to 35°C to 55°C, which can reduce the microbial level of the koji. The microbial level of the finished koji is reduced by 2 to 3 orders of magnitude before and after the koji is stacked and heated.

[0019] As a preferred embodiment of the fermentation method of low-salt soy sauce described in the present application, in the step S2, the amount of water added is 0.4 to 0.8 times the weight of the finished koji.

[0020] The present application adds warm water in the above amount at a temperature of 30-35° C. to control the water activity of the fermentation system.

[0021] Preferably, in step S2, after adding water at a temperature of 30°C to 35°C, the mixture is immediately stirred, with special attention paid to the water accumulation at the bottom of the fermentation tank, and the koji material is required to be evenly moistened with water after stirring; after stirring, the fermented sauce and mash are compacted layer by layer.

[0022] As a preferred embodiment of the fermentation method of low-salt soy sauce described in the present application, in the step S3, the fermented mash treated in the step S2 is stirred during the fermentation process, the bottom mash and the upper mash are swapped, and then 0.15 to 0.2 times the weight of the fermented mash is added with water to make up to 1.05 to 1.20 times the weight.

[0023] In some specific embodiments, the stirring step includes:

[0024] The fermented mash treated in step S2 is stirred on the day of fermentation, the 2nd, 3rd, 5th, 7th, 10th and 14th day, the bottom mash and the upper mash are swapped, and then 0.15 to 0.2 times the weight of the fermented mash is added with water on the 7th, 10th and 14th day of fermentation to make up the water to 1.05 to 1.20 times.

[0025] The fermentation process uses special food-grade materials to cover the mouth of the fermentation tank to isolate oxygen, and the mouth of the tank is sealed immediately after the operation is completed.

[0026] As a preferred embodiment of the fermentation method of low-salt soy sauce described in the present application, in step S3, the low-salt fermentation step includes:

[0027] During the fermentation process, the fermented mash is stirred and additional salt water is sprayed on the surface of the fermented mash to control the final crude salt content to 4% to 6%.

[0028] In some specific embodiments, the low-salt fermentation step comprises:

[0029] On the 16th, 21st, 28th and 35th days of fermentation, the fermented mash was turned over and stirred, and additional salt water was sprayed on the surface of the fermented mash to control the final crude salt content to 4% to 6%.

[0030] The above-mentioned low-salt fermentation process uses special food-grade materials to cover the mouth of the fermentation tank to isolate oxygen, and the mouth of the tank is sealed immediately after the operation is completed; after the fermented sauce and mash has been fermented for 35 days, it is stirred every other week until the fermentation expires.

[0031] In the technical solution of the present application, salt-free and low-salt fermentation is adopted, and no other preservatives are required, and the sauce mash can still be kept from spoiling, and the enzyme activity can be fully exerted to improve the product quality.

[0032] As a preferred embodiment of the fermentation method of low-salt soy sauce described in the present application, the mass concentration of the brine is 16% to 18%, and the amount of brine sprayed is 0.1 to 0.2 times the weight of the fermented soy sauce.

[0033] The present application gradually increases the system salt content of the fermented mash in the later stage by spraying salt water on the surface of the fermented mash.

[0034] Preferably, the complete fermentation cycle of the fermentation method is 40 to 70 days.

[0035] Preferably, in step S3, the pressing process takes less than 24 hours to avoid whitening of the mash; after pressing, the crude oil is salted according to product requirements, and after pasteurization, it is heated and cooked to obtain low-salt soy sauce.

[0036] The present application also provides low-salt soy sauce prepared by the fermentation method of the low-salt soy sauce.

[0037] After extensive research and experiments, the inventors of the present application discovered that by introducing Saccharomyces rouxii into the soy sauce koji-making process or the yellowing process and introducing the koji-piling heating process for brewing, and at the same time controlling the water activity of the mash in stages, the problem of the growth of miscellaneous bacteria under low-temperature fermentation conditions can be overcome. Under salt-free / low-salt conditions, there is no need to add other preservatives, the mash can still be kept from spoiling, and the enzyme activity can be fully exerted to improve product quality, thereby achieving a balanced improvement in raw material utilization and product yield.

[0038] In addition, the fermentation system that combines the koji stacking process and the salt-free and low-salt processes can, on the one hand, reduce the koji microbial level and inhibit the growth of miscellaneous bacteria by high-temperature stacking and low-water-activity solid-state fermentation. On the other hand, the absence of salt in the early stage and the low fermentation temperature control (30-35°C) can maintain more microorganisms participating in the fermentation process compared to traditional low-salt and high-temperature fermentation. In the later stage, the salt content of the system can be gradually increased, the fermentation cycle can be appropriately extended, and the taste and flavor of the soy sauce can be improved.

[0039] Compared with the prior art, this application has the following beneficial effects:

[0040] The present application provides a fermentation method for low-salt soy sauce. Based on the problem that low-salt and high-temperature fermentation has a single flavor and a thin taste, the present application adopts a mixed culture method of multiple strains (Saccharomyces rouxii and Aspergillus oryzae) to make the koji or the mash itself produce antibacterial substances. At the same time, the microbial level in the mash is controlled by heating the koji accumulation and controlling the water activity in stages. Under salt-free and low-salt conditions and without other preservative additives, low-salt fermentation is achieved by regulating the koji making or yellowing process and controlling the water content of the mash, thereby improving the taste and flavor of the soy sauce, improving the utilization rate of the raw materials and the yield rate of the product, and improving the quality of the crude oil. DETAILED DESCRIPTION

[0041] In order to better illustrate the purpose, technical solutions and advantages of the present application, the present application will be further described below in conjunction with specific embodiments.

[0042] In the following examples and comparative examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified, and the components and raw materials used in each parallel experiment are of the same type.

[0043] Embodiment 1, a kind of fermentation method of low-salt soy sauce

[0044] This embodiment provides a fermentation method for low-salt soy sauce, comprising the following steps:

[0045] 1. Place soybeans in a container and soak them in 30℃ water for 6.5h; place the soaked soybeans in a steamer and steam them at 125℃ for 25min; take wheat with full grains and impurities removed, place it in a wheat roasting machine for roasting, set the roasting temperature to 210℃, the roasting time to 7min, then place the roasted wheat in a grinder for crushing to obtain roasted wheat for later use;

[0046] 2. Cool the steamed soybeans to 35°C, mix with the roasted wheat, add 1% koji of soy sauce (Aspergillus oryzae), and culture at 35°C;

[0047] 3. During the 34 hours of koji making, inoculate Saccharomyces rouxii with a weight ratio of 0.6‰ to the raw materials by spraying Saccharomyces rouxii liquid, and culture for 48 hours to make finished koji;

[0048] 4. The above-mentioned koji is piled up and heated to 45°C. At this time, the koji material is turned over and stirred. The temperature of the koji material is required to drop to 30°C after stirring. The heating and stirring operations are repeated 3-4 times to make the whole koji material uniformly heated to 45°C. The whole stacking heating process lasts for 3 hours.

[0049] 5. After the stacking and heating is completed, add 0.6 times the weight of the finished koji with water, and control the water temperature at 30°C. Stir the upper and lower layers of the koji evenly, and there is no obvious water accumulation at the bottom; at the same time, spray the Roux yeast liquid, and add Roux yeast with a weight ratio of 0.6‰ to the finished koji, and control the water activity of the sauce mash to about 0.8;

[0050] 6. After stirring, pat the sauce layer by layer tightly;

[0051] 7. On the day of fermentation, and on the 2nd, 3rd, 5th, 7th, 14th, 21st, 28th, and 35th days, the fermented mash should be turned over and stirred. When turning over and stirring, the bottom mash and the upper mash should be swapped to achieve uniform water exchange.

[0052] 8. Use special food-grade sealing materials during the fermentation process to cover the mouth of the fermentation tank to isolate oxygen; seal the mouth of the tank immediately after the stirring operation is completed;

[0053] 9. Control the temperature at 30-35℃ for 15 days before fermentation, and control the temperature at 35-40℃ after 15 days of fermentation; stir the fermented mash on the 16th, 21st, 28th and 35th days, and add 18% salt water to spray on the surface of the fermented mash. The amount of each spray is controlled at 0.25 times, and slowly dissolved in the fermented mash from top to bottom. The total ratio is controlled at 1.6 times ((water + salt water) weight: koji input amount), and the final crude oil salt content is controlled at 10%. During the fermentation process, special food-grade materials are used to cover the mouth of the fermentation tank to isolate oxygen, and the mouth of the tank is sealed immediately after the operation is completed; after 35 days of fermentation, stir once every week until the fermentation expires. The entire fermentation cycle is 55 days;

[0054] 10. After the fermentation is over, stir and squeeze evenly. The whole squeezing process should be less than 24 hours to avoid the sauce mash from turning white.

[0055] 11. After pressing, the crude oil is pasteurized, heated and cooked, and then blended to obtain the finished soy sauce (low-salt soy sauce).

[0056] Embodiment 2, a kind of fermentation method of low-salt soy sauce

[0057] This embodiment provides a fermentation method for low-salt soy sauce, comprising the following steps:

[0058] 1. Place soybeans in a container and soak them in 30℃ water for 6.5h; place the soaked soybeans in a steamer and steam them at 125℃ for 25min; take wheat with full grains and impurities removed, place it in a wheat roasting machine for roasting, set the roasting temperature to 210℃, the roasting time to 7min, then place the roasted wheat in a grinder for crushing to obtain roasted wheat for later use;

[0059] 2. Cool the steamed soybeans to 35°C, mix with the roasted wheat, add 1% koji of soy sauce (Aspergillus oryzae), and culture at 35°C;

[0060] 3. During the 34 hours of koji making, inoculate 0.6‰ of Saccharomyces cerevisiae by weight ratio to the raw materials by spraying Saccharomyces cerevisiae liquid, and cultivate for 48 hours to obtain the koji;

[0061] 4. The above-mentioned koji is piled up and heated to 45°C. At this time, the koji material is turned over and stirred. The temperature of the koji material is required to drop to 30-35°C after stirring. The heating and stirring operations are repeated 3-4 times to make the whole koji material uniformly heated to 45°C. The whole stacking heating process lasts for 3 hours.

[0062] 5. After the stacking and heating is completed, add 0.6 times the weight of the finished koji with water, and control the water temperature at 30-35℃. Stir the upper and lower layers of the koji evenly, and there should be no obvious water accumulation at the bottom. At the same time, spray the Roux yeast liquid, and add Roux yeast with a weight ratio of 0.6‰ to the finished koji, and control the water activity of the sauce and mash to about 0.8.

[0063] 6. After stirring, pat the sauce layer by layer tightly;

[0064] 7. On the day of fermentation, and on the 2nd, 3rd, 5th, 7th, and 14th days, the fermented mash should be turned over and stirred. When turning over and stirring, the bottom mash and the upper mash should be swapped to achieve uniform water exchange.

[0065] 8. Use special food-grade sealing materials during the fermentation process to cover the mouth of the fermentation tank to isolate oxygen; seal the mouth of the tank immediately after the stirring operation is completed;

[0066] 9. The temperature is controlled at 30-35° C. for 15 days before fermentation. After 15 days of fermentation, low-salt fermentation is carried out by spraying salt water on the surface of the mash, and the temperature is controlled at 35-40° C. On the 16th, 21st, 28th and 35th days of fermentation, the mash is turned over and evenly sprayed with 0.25 times the weight of the raw material salt water (salt content is 8%), and the total ratio is controlled at 1.6 times ((water + salt water) weight: raw material weight). After 35 days of fermentation, the mash is turned over once every week until the fermentation expires. The entire fermentation cycle is 55 days, and the final crude oil salt content is controlled at 4%;

[0067] 10. After the fermentation period is over, stir the mash evenly and squeeze it. The whole squeezing process should take less than 24 hours to avoid the mash from turning white.

[0068] 11. After pressing, the crude oil is pasteurized, heated and cooked, and then blended to obtain the finished soy sauce (low-salt soy sauce).

[0069] Embodiment 3, a kind of fermentation method of low-salt soy sauce

[0070] This embodiment provides a fermentation method for low-salt soy sauce, comprising the following steps:

[0071] 1. Place soybeans in a container and soak them in 30℃ water for 6.5h; place the soaked soybeans in a steamer and steam them at 125℃ for 25min; take wheat with full grains and impurities removed, place it in a wheat roasting machine for roasting, set the roasting temperature to 210℃, the roasting time to 7min, then place the roasted wheat in a grinder for crushing to obtain roasted wheat for later use;

[0072] 2. Cool the steamed soybeans to 30-40°C, mix with the roasted wheat, add 1% koji of soy sauce (Aspergillus oryzae), and culture at 30-40°C;

[0073] 3. During the 34 hours of koji making, inoculate the koji with 0.6‰ of the weight ratio of the raw material koji by spraying the koji yeast liquid, and cultivate it for 48 hours to obtain the koji;

[0074] 4. Pile the above koji and heat it to 45℃, stir it 3-5 times continuously, and the whole process lasts for 3 hours to make the koji material evenly heated;

[0075] 5. After the stacking and heating is completed, add 0.6 times the weight of the finished koji with water, and add 0.6‰ of the weight ratio of the raw material to the Roux yeast. The temperature is controlled at 30-35°C. The upper and lower layers of the koji are evenly stirred, and there is no obvious water accumulation at the bottom. At the same time, spray the Roux yeast liquid, add 0.6‰ of the weight ratio of the finished koji to the Roux yeast, and control the water activity of the sauce mash to about 0.8;

[0076] 6. After stirring, pat the sauce layer by layer tightly;

[0077] 7. On the day of fermentation, and on the 2nd, 3rd, 5th, 7th, and 14th days, the fermented mash should be turned over and stirred. When turning over and stirring, the bottom mash and the upper mash should be swapped to achieve uniform water exchange.

[0078] 8. On the 5th, 7th and 14th days of fermentation, add 0.20 times the weight of the fermented mash water while stirring, and add water to 1.20 times. During the fermentation process, use special food-grade materials to cover the mouth of the fermentation tank to isolate oxygen, and seal the mouth of the tank immediately after the operation is completed;

[0079] 9. The temperature is controlled at 30-35° C. for 15 days before fermentation. After 15 days of fermentation, low-salt fermentation is carried out by spraying salt water on the surface of the mash, and the temperature is controlled at 35-40° C. On the 16th, 21st, 28th and 35th days of fermentation, the mash is stirred and evenly sprayed with salt water (salt content is 14%) at 0.1 times the weight of the koji material, and the total ratio is controlled at 1.6 times ((water + salt water) weight: raw material weight). After 35 days of fermentation, the mash is stirred once every week until the fermentation expires. The entire fermentation cycle is 55 days, and the final crude oil salt content is controlled at 4%;

[0080] 10. After the fermentation period is over, stir the mash evenly and squeeze it. The whole squeezing process should take less than 24 hours to avoid the mash from turning white.

[0081] 11. After pressing, the crude oil is pasteurized, heated and cooked, and then blended to obtain the finished soy sauce (low-salt soy sauce).

[0082] Embodiment 4, a kind of fermentation method of low-salt soy sauce

[0083] This embodiment provides a fermentation method for low-salt soy sauce, comprising the following steps:

[0084] 1. Place soybeans in a container and soak them in 25°C water for 5 hours; place the soaked soybeans in a steamer and steam them at 110°C for 10 minutes; take wheat with full grains and impurities removed, place it in a wheat roasting machine for roasting, set the roasting temperature to 180°C, the roasting time to 3 minutes, then place the roasted wheat in a grinder for crushing to obtain roasted wheat for later use;

[0085] 2. Cool the steamed soybeans to 30°C, mix with the roasted wheat, add 1% koji of soy sauce (Aspergillus oryzae), and culture at 30°C;

[0086] 3. Within 30 hours of koji making, inoculate 0.5‰ of the koji material with saccharomyces rouxii by spraying the saccharomyces rouxii liquid, and culture for 38 hours to obtain the koji;

[0087] 4. Pile the above koji and heat it to 35℃, stir it 3-5 times continuously, and the whole process lasts for 3 hours to make the koji material heat evenly;

[0088] 5. After the stacking and heating is completed, add 0.4 times the weight of the finished koji with water, and add 0.5‰ of the weight ratio of the raw material to the Roux yeast. The temperature is controlled at 30°C. The upper and lower layers of the koji are evenly stirred, and there is no obvious water accumulation at the bottom. At the same time, spray the Roux yeast liquid, add 0.5‰ of the weight ratio of the finished koji to the Roux yeast, and control the water activity of the sauce mash to about 0.8;

[0089] 6. After stirring, pat the sauce layer by layer tightly;

[0090] 7. On the day of fermentation, and on the 2nd, 3rd, 5th, 7th, and 14th days, the fermented mash should be turned over and stirred. When turning over and stirring, the bottom mash and the upper mash should be swapped to achieve uniform water exchange.

[0091] 8. On the 5th, 7th and 14th days of fermentation, add 0.15 times the weight of the fermented sauce and mash water while stirring, and add water to 1.05 times. During the fermentation process, use special food-grade materials to cover the mouth of the fermentation tank to isolate oxygen, and seal the mouth of the tank immediately after the operation is completed;

[0092] 9. The temperature is controlled at 30° C. for 15 days before fermentation. After 15 days of fermentation, low-salt fermentation is carried out by spraying salt water on the surface of the mash, and the temperature is controlled at 35° C. On the 16th, 21st, 28th and 35th days of fermentation, the mash is turned over and evenly sprayed with salt water (salt content is 15%) at a weight of 0.15 times the weight of the koji material. After 35 days of fermentation, the mash is turned over once every week until the fermentation expires. The entire fermentation cycle is 40 days, and the final crude oil salt content is controlled at 4%;

[0093] 10. After the fermentation period is over, stir the mash evenly and squeeze it. The whole squeezing process should take less than 24 hours to avoid the mash from turning white.

[0094] 11. After pressing, the crude oil is pasteurized, heated and cooked, and then blended to obtain the finished soy sauce (low-salt soy sauce).

[0095] Example 5: A fermentation method for low-salt soy sauce

[0096] This embodiment provides a fermentation method for low-salt soy sauce, comprising the following steps:

[0097] 1. Place soybeans in a container and soak them in 40℃ water for 8h; place the soaked soybeans in a steamer and steam them at 130℃ for 30min; take wheat with full grains and impurities removed, place it in a wheat roasting machine for roasting, set the roasting temperature to 260℃, the roasting time to 10min, then place the roasted wheat in a grinder for crushing to obtain roasted wheat for later use;

[0098] 2. Cool the steamed soybeans to 40°C, mix with the roasted wheat, add 1% koji of soy sauce (Aspergillus oryzae), and culture at 40°C;

[0099] 3. During the 36 hours of koji making, inoculate the koji with 1‰ of koji material by weight of koji yeast by spraying the koji yeast liquid, and culture for 55 hours to obtain the koji;

[0100] 4. Pile the above koji and heat it to 55℃, stir it 5 times continuously, and the whole process lasts for 4 hours to make the koji material heat evenly;

[0101] 5. After the stacking and heating is completed, add 0.8 times the weight of the finished koji with water, and add 1‰ of the weight ratio of the raw material to the Roux yeast. The temperature is controlled at 35°C. The upper and lower layers of the koji are evenly stirred, and there is no obvious water accumulation at the bottom. At the same time, spray the Roux yeast liquid, add 1‰ of the weight ratio of the finished koji to the Roux yeast, and control the water activity of the sauce mash to about 0.8;

[0102] 6. After stirring, pat the sauce layer by layer tightly;

[0103] 7. On the day of fermentation, and on the 2nd, 3rd, 5th, 7th, and 14th days, the fermented mash should be turned over and stirred. When turning over and stirring, the bottom mash and the upper mash should be swapped to achieve uniform water exchange.

[0104] 8. On the 5th, 7th and 14th days of fermentation, add 0.20 times the weight of the fermented mash water while stirring, and add water to 1.20 times. During the fermentation process, use special food-grade materials to cover the mouth of the fermentation tank to isolate oxygen, and seal the mouth of the tank immediately after the operation is completed;

[0105] 9. The temperature is controlled at 35° C. for 15 days before fermentation. After 15 days of fermentation, low-salt fermentation is carried out by spraying salt water on the surface of the mash, and the temperature is controlled at 40° C. On the 16th, 21st, 28th and 35th days of fermentation, the mash is turned over and evenly sprayed with salt water (salt content is 19%) at a weight of 0.25 times the weight of the koji material. After 35 days of fermentation, the mash is turned over every other week until the fermentation expires. The entire fermentation cycle is 70 days, and the final crude oil salt content is controlled at 8%;

[0106] 10. After the fermentation period is over, stir the mash evenly and squeeze it. The whole squeezing process should take less than 24 hours to avoid the mash from turning white.

[0107] 11. After pressing, the crude oil is pasteurized, heated and cooked, and then blended to obtain the finished soy sauce (low-salt soy sauce).

[0108] Comparative Example 1

[0109] 1. Place soybeans in a container and soak them in 30℃ water for 6.5h; place the soaked soybeans in a steamer and steam them at 125℃ for 25min; take wheat with full grains and impurities removed, place it in a wheat roasting machine for roasting, set the roasting temperature to 210℃, the roasting time to 7min, then place the roasted wheat in a grinder for crushing to obtain roasted wheat for later use;

[0110] 2. Cool the steamed soybeans to 35°C, mix with the roasted wheat, add 1% koji of soy sauce koji (Aspergillus oryzae), and culture at 35°C for 48h to obtain koji;

[0111] 3. Add 0.6 times the weight of raw material mash, control the temperature at 30-35℃, stir the upper and lower layers of the koji evenly, and there should be no obvious accumulation of liquid at the bottom;

[0112] 5. After stirring evenly, pat the sauce layer by layer;

[0113] 6. On the day of fermentation and on the 2nd, 3rd, 5th, 7th, 14th, 21st, 28th and 35th day, the fermented mash should be turned over and stirred. When turning over and stirring, the bottom mash and the upper mash should be swapped to achieve uniform solid-liquid exchange.

[0114] 7. During the fermentation process, special food-grade materials are used to cover the mouth of the fermentation tank to isolate oxygen, and the mouth of the tank is sealed immediately after the operation is completed;

[0115] 8. Control the temperature at 30-35℃ for 15 days before fermentation, and control the temperature at 35-40℃ after 15 days of fermentation; after 35 days of fermentation, stir once every week until the fermentation is due. The whole fermentation cycle is 40-70 days;

[0116] 9. After the fermentation is completed, add sterile water about 0.9-1.1 times the weight of the finished koji, stir evenly and squeeze;

[0117] 10. After pressing, the crude oil is pasteurized, heated and cooked, and then blended to obtain the finished soy sauce.

[0118] Comparative Example 2

[0119] 1. Place soybeans in a container and soak them in 30℃ water for 6.5h; place the soaked soybeans in a steamer and steam them at 125℃ for 25min; take wheat with full grains and impurities removed, place it in a wheat roasting machine for roasting, set the roasting temperature to 210℃, the roasting time to 7min, then place the roasted wheat in a grinder for crushing to obtain roasted wheat for later use;

[0120] 2. Cool the steamed soybeans to 30-40°C, mix with the roasted wheat, add 1% of the soy sauce koji (Aspergillus oryzae), and culture at 30-40°C for 48 hours to obtain koji;

[0121] 3. Add 12%-19% salt water with a salt content of 1.5-1.9 times the weight of the raw materials, control the temperature at 40-55°C, stir the upper and lower layers of the koji material evenly, and there should be no obvious water accumulation at the bottom;

[0122] 4. Fermentation is resumed on the 2nd, 4th, 6th and 8th days, and the fermentation cycle is 10-35 days;

[0123] 5. After the fermentation is completed, the mixture is stirred and squeezed evenly, and the crude oil is blended to obtain the finished soy sauce.

[0124] Comparative Example 3

[0125] This comparative example provides a fermentation method for low-salt soy sauce, comprising the following steps:

[0126] 1. Place soybeans in a container and soak them in 30℃ water for 6.5h; place the soaked soybeans in a steamer and steam them at 125℃ for 25min; take wheat with full grains and impurities removed, place it in a wheat roasting machine for roasting, set the roasting temperature to 210℃, the roasting time to 7min, then place the roasted wheat in a grinder for crushing to obtain roasted wheat for later use;

[0127] 2. Cool the steamed soybeans to 35°C, mix with the roasted wheat, add 1% of the soy sauce koji (Aspergillus oryzae), and culture at 35°C for 48 hours to obtain the finished koji.

[0128] 3. The above-mentioned koji is piled up and heated to 45°C. At this time, the koji material is turned over and stirred. The temperature of the koji material is required to drop to 30°C after stirring. The heating and stirring operations are repeated 3-4 times to make the whole koji material evenly heated to 45°C. The whole stacking heating process lasts for 3 hours.

[0129] 4. After the stacking and heating is completed, add 0.6 times the weight of the koji with water, and control the water temperature at 30°C. Stir the upper and lower layers of the koji evenly, and there should be no obvious water accumulation at the bottom; control the water activity of the sauce and mash to about 0.8;

[0130] 5. After stirring, pat the sauce layer by layer;

[0131] 6. On the day of fermentation, and on the 2nd, 3rd, 5th, 7th, 14th, 21st, 28th, and 35th days, the fermented mash should be turned over and stirred. When turning over and stirring, the bottom mash and the upper mash should be swapped to achieve uniform water exchange.

[0132] 7. Use special food-grade sealing materials during the fermentation process to cover the mouth of the fermentation tank to isolate oxygen; seal the mouth of the tank immediately after the stirring operation is completed;

[0133] 8. Control the temperature at 30-35℃ for 15 days before fermentation, and control the temperature at 35-40℃ after 15 days of fermentation; stir the fermented mash on the 16th, 21st, 28th and 35th days, and add 18% salt water to spray on the surface of the fermented mash. The amount of each spray is controlled at 0.25 times, and slowly dissolved in the fermented mash from top to bottom. The total ratio is controlled at 1.6 times ((water + salt water) weight: koji input amount), and the final crude oil salt content is controlled at 10%. During the fermentation process, special food-grade materials are used to cover the mouth of the fermentation tank to isolate oxygen, and the mouth of the tank is sealed immediately after the operation is completed; after 35 days of fermentation, stir once every week until the fermentation expires. The entire fermentation cycle is 55 days;

[0134] 9. After the fermentation is over, stir and squeeze evenly. The whole squeezing process should be less than 24 hours to avoid the sauce mash from turning white.

[0135] 10. After pressing, the crude oil is pasteurized, heated and cooked, and then blended to obtain the finished soy sauce (low-salt soy sauce).

[0136] Compared with Example 1, in Comparative Example 1, no Saccharomyces rouxii liquid was added in the later stage of koji making.

[0137] Comparative Example 4

[0138] Compared with Example 1, Comparative Example 4 does not contain step 4 (heat generation by accumulation).

[0139] This comparative example provides a fermentation method for low-salt soy sauce, comprising the following steps:

[0140] 1. Place soybeans in a container and soak them in 30℃ water for 6.5h; place the soaked soybeans in a steamer and steam them at 125℃ for 25min; take wheat with full grains and impurities removed, place it in a wheat roasting machine for roasting, set the roasting temperature to 210℃, the roasting time to 7min, then place the roasted wheat in a grinder for crushing to obtain roasted wheat for later use;

[0141] 2. Cool the steamed soybeans to 35°C, mix with the roasted wheat, add 1% of the soy sauce koji (Aspergillus oryzae), and culture at 35°C for 48 hours to obtain the finished koji.

[0142] 3. Add 0.6 times the weight of the koji with water, and control the water temperature at 30℃. Stir the koji evenly, and there should be no obvious water accumulation at the bottom. Control the water content of the sauce and mash to about 0.8.

[0143] 4. After stirring, pat the sauce layer by layer;

[0144] 5. On the day of fermentation, and on the 2nd, 3rd, 5th, 7th, 14th, 21st, 28th, and 35th days, the fermented mash should be turned over and stirred. When turning over and stirring, the bottom mash and the upper mash should be swapped to achieve uniform water exchange.

[0145] 6. Use special food-grade sealing materials during the fermentation process to cover the mouth of the fermentation tank to isolate oxygen; seal the mouth of the tank immediately after the stirring operation is completed;

[0146] 7. Control the temperature at 30-35°C for 15 days before fermentation, and control the temperature at 35-40°C after 15 days of fermentation; on the 16th, 21st, 28th and 35th days of fermentation, stir and add 18% salt water to spray on the surface of the fermented mash. The spraying amount is controlled at 0.25 times each time, and slowly dissolved in the fermented mash from top to bottom. The total ratio is controlled at 1.6 times ((water + salt water) weight: koji input amount), and the final crude oil salt content is controlled at 10%. During the fermentation process, special food-grade materials are used to cover the mouth of the fermentation tank to isolate oxygen, and the mouth of the tank is sealed immediately after the operation is completed; after 35 days of fermentation, stir once every week until the fermentation expires. The entire fermentation cycle is 55 days;

[0147] 8. After the fermentation is over, stir and squeeze evenly. The whole squeezing process should be less than 24 hours to avoid the sauce mash from turning white.

[0148] 9. After pressing, the crude oil is pasteurized, heated and cooked, and then blended to obtain the finished soy sauce (low-salt soy sauce).

[0149] Comparative Example 5

[0150] Compared with Example 1, in step 7 of Comparative Example 5, no salt water was added, but pure water was added (salt-free fermentation throughout the process).

[0151] This comparative example provides a fermentation method for low-salt soy sauce, comprising the following steps:

[0152] 1. Place soybeans in a container and soak them in 30℃ water for 6.5h; place the soaked soybeans in a steamer and steam them at 125℃ for 25min; take wheat with full grains and impurities removed, place it in a wheat roasting machine for roasting, set the roasting temperature to 210℃, the roasting time to 7min, then place the roasted wheat in a grinder for crushing to obtain roasted wheat for later use;

[0153] 2. Cool the steamed soybeans to 35°C, mix with the roasted wheat, inoculate with soy sauce koji (Aspergillus oryzae), and culture at 35°C for 48 hours to obtain finished koji;

[0154] 3. Add 0.6 times the weight of the koji with water, and control the water temperature at 30℃. Stir the koji evenly, and there should be no obvious water accumulation at the bottom. Control the water content of the sauce and mash to about 0.8.

[0155] 4. After stirring, pat the sauce layer by layer;

[0156] 5. On the day of fermentation, and on the 2nd, 3rd, 5th, 7th, 14th, 21st, 28th, and 35th days, the fermented mash should be turned over and stirred. When turning over and stirring, the bottom mash and the upper mash should be swapped to achieve uniform water exchange.

[0157] 6. Use special food-grade sealing materials during the fermentation process to cover the mouth of the fermentation tank to isolate oxygen; seal the mouth of the tank immediately after the stirring operation is completed;

[0158] 7. Control the temperature at 30-35℃ for 15 days before fermentation, and control the temperature at 35-40℃ after 15 days of fermentation; on the 16th, 21st, 28th and 35th days of fermentation, stir and add water to the surface of the fermented mash, and control the amount of each spray to 0.25 times, slowly penetrate into the fermented mash from top to bottom, and control the total ratio to 1.6 times (water weight: koji input amount). During the fermentation process, use special food-grade materials to cover the mouth of the fermentation tank to isolate oxygen, and seal the mouth of the tank immediately after the operation is completed; after 35 days of fermentation, stir once every week until the fermentation expires. The entire fermentation cycle is 55 days;

[0159] 8. After the fermentation is over, stir and squeeze evenly. The whole squeezing process should be less than 24 hours to avoid the sauce mash from turning white.

[0160] 9. After pressing, the crude oil is pasteurized, heated and cooked, and then blended to obtain the finished soy sauce (low-salt soy sauce).

[0161] The finished soy sauces obtained in Examples 1 to 5 and Comparative Examples 1 to 5 were tested, and the results are shown in Table 1.

[0162] Table 1

[0163]

[0164]

[0165]

[0166] Conclusion As shown in Table 1, Examples 1 to 5 can maintain no growth of spoilage bacteria during the fermentation period, have sufficient thickness and freshness, and have good sensory flavor. Among them, Example 3 has a stronger thickness and freshness than Examples 1 to 2 in terms of flavor; the total acidity of the crude oil in the late fermentation and expired stage of Example 1 is relatively high.

[0167] The soy sauce prepared in Comparative Example 1 has a weak umami taste, rich wine aroma and ester aroma, and the soy sauce flavor is not as good as Examples 1 to 5;

[0168] The soy sauce prepared in Comparative Example 2 has a weak taste and a thin mouthfeel, and its flavor is inferior to that of Examples 1 to 5;

[0169] The soy sauce prepared in Comparative Example 3 was weak in freshness, high in total acidity, thin in taste, and lighter in flavor than that in Example 1;

[0170] The soy sauce prepared in Comparative Example 4 was weak in freshness, high in total acidity, poor in thickness, and inferior in flavor to that of Examples 1 to 5;

[0171] The soy sauce prepared in Comparative Example 5 has high total acidity, a sour taste, and weak umami taste.

[0172] The embodiments of the present application introduce Saccharomyces rouxii into the soy sauce koji-making process or the yellowing process, and introduce the koji-piling heating process of wine making, while controlling the water activity of the mash in stages to overcome the problem of bacteria growth under low-temperature fermentation conditions. Under salt-free / low-salt conditions, there is no need to add other preservatives, the mash can still be kept from spoiling, and the enzyme activity can be fully exerted to improve product quality, and the raw material utilization rate and product yield rate are balanced.

[0173] In addition, the fermentation system that combines the koji stacking process and the salt-free and low-salt processes can, on the one hand, reduce the koji microbial level and inhibit the growth of miscellaneous bacteria by high-temperature stacking and low-water-activity solid-state fermentation. On the other hand, the absence of salt in the early stage and the low fermentation temperature control (30-35°C) can maintain more microorganisms participating in the fermentation process compared to traditional low-salt and high-temperature fermentation. In the later stage, the salt content of the system can be gradually increased, the fermentation cycle can be appropriately extended, and the taste and flavor of the soy sauce can be improved.

[0174] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application rather than to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that the technical solution of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present application.

Claims

1. A fermentation method for low-salt soy sauce, characterized in that: The following steps are involved: S1, mixing the cooked soybeans and fried wheat, inoculating Aspergillus oryzae for koji making, inoculating Saccharomyces rouxii during the koji making process or the yellowing process, and obtaining finished koji; S2, stacking the koji to heat it, stirring it, heating it repeatedly to 35°C to 55°C, then adding water at a temperature of 30°C to 35°C, controlling the water activity of the koji to be less than 0.8, and then adding Saccharomyces cerevisiae; S3, the fermented sauce mash processed by step S2 is stirred, and then salt-free solid-state fermentation is carried out, and the fermentation temperature is controlled to be 30°C-35°C, and then low-salt fermentation is carried out, and the fermentation temperature is controlled to be 35°C-40°C. The fermented sauce mash is stirred during the fermentation period, and is squeezed after the fermentation is completed to obtain low-salt soy sauce.

2. The fermentation method of low-salt soy sauce according to claim 1, characterized in that: In the step S1, 100 parts by weight of soybeans are added to 160 to 240 parts by weight of water for soaking at a temperature of 20° C. to 40° C. for 5 to 8 hours, and then the soaked soybeans are filtered to remove water, and the soybeans are steamed at a temperature of 110° C. to 130° C. for 10 to 30 minutes, and cooled to obtain the steamed soybeans.

3. The fermentation method of low-salt soy sauce according to claim 1, characterized in that: In the step S2, the wheat is roasted at a roasting temperature of 180°C to 260°C and a roasting time of 3min to 10min, and then the roasted wheat is crushed to obtain roasted wheat.

4. The fermentation method of low-salt soy sauce according to claim 1, characterized in that: In the step S1, Saccharomyces rouxii is added in a weight ratio of 0.5‰ to 1‰ to the koji material by spraying Saccharomyces rouxii liquid.

5. The fermentation method of low-salt soy sauce according to claim 1, characterized in that: In the step S2, the finished koji is piled up for heating, and the temperature of the finished koji is raised to 35°C-55°C for stirring. After stirring, the temperature of the koji material is reduced to 30-35°C, and the heating and stirring operations are repeated until the temperature of the finished koji is evenly raised to 35°C-55°C. The entire stacking and heating time is 3h-4h.

6. The fermentation method of low-salt soy sauce according to claim 1, characterized in that: In step S2, the amount of water added is 0.4 to 0.8 times the weight of the finished koji.

7. The fermentation method of low-salt soy sauce according to claim 1, characterized in that: In step S3, the stirring step includes: The fermented mash treated in step S2 is stirred during the fermentation process, the bottom mash and the upper mash are swapped, and then 0.15 to 0.2 times the weight of the fermented mash is added with water until the weight is 1.05 to 1.20 times.

8. The fermentation method of low-salt soy sauce according to claim 1, characterized in that: In step S3, the low-salt fermentation step comprises: During the fermentation process, the fermented mash is stirred and additional salt water is sprayed on the surface of the fermented mash to control the final crude salt content to 4% to 6%.

9. The fermentation method of low-salt soy sauce according to claim 8, characterized in that: The mass concentration of the brine is 10% to 18%, and the amount of the brine sprayed is 0.1 to 0.2 times the weight of the fermented mash.

10. Low-salt soy sauce prepared by the fermentation method of low-salt soy sauce according to any one of claims 1 to 9.

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