Method for improving quality of high-salt liquid-state soy sauce and high-salt liquid-state soy sauce

Abstract

The invention discloses a method for improving the quality of high-salt liquid-state soy sauce, which comprises the following steps: treating dry soybeans for 10-16 hours by adopting a Co-60 gamma ray source according to the total dosage rate of 1.25-6.0 kGy / h and 20-60 kGy, so that the protein of the dry soybeans is denatured; mixing the dry soybeans with water of which the volume is 2-4 times that of the dry soybeans, and soaking for 4-8 hours; an NK type rotary high-pressure digester is adopted for cooking, the equipment parameter setting pressure is 0.1-0.3 MPa, and the time is 25-35 min; after the soybeans are cooked, flour is added according to the ratio of the soybeans to the flour being (3-6): 1, the mixture is cooled to 25-35 DEG C, mold starter is added and stirred uniformly, starter materials are put into a fermentation tank to be fermented for 2-3 days, after starter propagation is finished, the starter materials are transferred into a fermentation tank, 12-18% (w / v) saline water is added according to the ratio of 1: (2-2.5), and fermentation is performed for 120-180 days; s5, filtering the material liquid fermented in the step S5 by adopting a filtering device, and removing thalli and macromolecular colloids; and carrying out pasteurization at 75 to 78 DEG C for 15 to 20 minutes. According to the method, soybean protein can be moderately denatured to be in a state of being easily decomposed by enzyme, so that the soybean protein which is delicious in taste and excellent in quality is effectively produced.

Description

Technical Field

[0001] This invention relates to the field of soy sauce brewing technology, specifically to a method for improving the quality of high-salt liquid soy sauce and high-salt liquid soy sauce. Background Technology

[0002] Soy sauce is a traditional fermented condiment with a long history. It is mainly made from soybeans (or defatted soybeans) and wheat (or wheat bran) through the action of microorganisms, and contains a variety of rich nutrients such as amino acids, peptides, sugars, organic acids, and vitamins.

[0003] Currently, the main production processes for soy sauce include: 1. Solid-state salt-free fermentation: Due to its poor flavor, this method is rarely used by manufacturers. 2. Low-salt solid-state fermentation: This method has the advantages of a short production cycle and high raw material utilization, but the poor flavor of the soy sauce produced has not been effectively improved. 3. High-salt liquid-state fermentation: This method has a relatively long fermentation cycle, but its product has a unique flavor and is loved by many consumers.

[0004] However, the high-salt, low-temperature fermentation process still has some shortcomings. Among these, the selection and processing of raw materials is one of the key factors affecting the final quality of soy sauce. Raw material selection and processing: Different raw materials and their quality significantly affect the final flavor and quality of soy sauce. Besides purchasing qualified, high-quality raw materials, proper processing is also crucial. This is because the proteins in the raw materials (mainly soy protein) are difficult for proteases to effectively break down in their natural state (undenatured). Only through moderate denaturation treatment (such as steaming) will the structure of these proteins change, becoming easier for enzymes to degrade, and thus effectively digested and utilized by fermenting microorganisms, ultimately transforming into the flavor substances and nutrients in the soy sauce.

[0005] Current technologies typically employ steaming or pressure steaming to process soybeans. However, if the temperature is too high, the cooking time too long, or the pressure is not properly controlled, the proteins can become excessively denatured. Excessively denatured proteins have overly compact structures or form aggregates that are difficult for enzymes to break down, making it difficult for subsequent proteases secreted by Aspergillus oryzae to effectively contact and cleave peptide bonds. This not only reduces the utilization rate of the raw material protein (affecting the yield of total nitrogen / amino acid nitrogen) but may also generate some undesirable flavor compounds.

[0006] Furthermore, whether using a steamer or continuous cooking equipment, it's difficult to guarantee that each soybean receives uniform heating both internally and externally when processing large batches of raw materials. Temperature gradients or uneven heating of the materials may exist within the equipment, inevitably leading to inconsistent protein denaturation levels throughout the batch. Some soybeans may be under-denatured (difficult to enzymatically hydrolyze), while others may be over-denatured (as above). This not only affects overall protein utilization but also introduces batch-to-batch fluctuations in subsequent koji making and fermentation, impacting the stability of soy sauce flavor and quality.

[0007] Improper control of cooking temperature (especially too high) or excessive time (including untimely cooling) will consume a large amount of free amino acids, reducing the amino acid nitrogen content of the final product. More importantly, it will generate excessive melanoidins and some heterocyclic compounds with burnt or smoky flavors (such as pyrazines and furans), masking the mellow and savory aroma that soy sauce should have, resulting in a deterioration in flavor. This is especially prominent in high-salt, low-temperature processes where a pure flavor is required. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for improving the quality of high-salt liquid soy sauce by enabling soybean protein to undergo appropriate denaturation, making it easily decomposed by enzymes, thereby effectively producing soy sauce products with delicious taste and excellent quality.

[0009] Another object of the present invention is to provide a high-salt, thin-state soy sauce prepared by the above method.

[0010] Regarding methods for improving the quality of high-salt, thin-state soy sauce, in order to achieve the above-mentioned objectives, the present invention adopts the following solution: A method for improving the quality of high-salt, thin-state soy sauce, characterized by comprising the following steps: S1. Processing of dried soybeans Low-energy electron beams and gamma rays were used to treat dried soybeans, causing the proteins in the dried soybeans to denature. S2, Soaking soybeans Mix the dried soybeans from step S1 with 2-4 times their volume of water and soak for 4-8 hours; S3, Steaming soybeans The cooking process is carried out using an NK-type rotary high-pressure cooker. The equipment parameters are set with a pressure of 0.1-0.3 MPa and a time of 25-35 min. S4, Composition After the soybeans are steamed, add flour at a ratio of 3-6:1 (soybeans:flour). Cool to 25-35℃, add the starter culture, mix well, and place the starter culture in a fermentation tank to ferment for 2-3 days. S5, Fermentation After the koji making is completed, transfer the koji material to a fermentation tank and add 12-18% (w / v) brine at a ratio of 1:2-2.5. Ferment for 120-180 days. S6, Filtration The filtrate after fermentation in step S5 is filtered using a filtration device to remove bacteria and macromolecular colloids. S7, sterilization Pasteurize at 75-90℃ for 15-35 minutes.

[0011] As another improvement to the method of improving the quality of high-salt dilute soy sauce of the present invention, the specific steps of the dried soybean treatment in step S1 include: S11. Screening, grading, and impurity removal Dried soybeans were passed through a 10-mesh sieve to remove broken and moldy beans, and then a photoelectric separator was used to screen whole soybeans with a particle size of 5.5±0.5mm to ensure uniformity of subsequent irradiation. S12, Moisture Regulation Soybeans were placed in a constant temperature and humidity chamber at 28°C and 70% relative humidity (RH) for 24 hours to stabilize the moisture content to 14±0.5%. At this moisture level, the protein molecular chains have a certain degree of fluidity, which facilitates the destruction of secondary bonds by ultrasound and irradiation. Too high a moisture content can easily lead to thermal effects during irradiation, while too low a moisture content results in rigid proteins and low denaturation efficiency. S13, Ultrasonic-assisted cell wall disruption Soybeans from S12 were placed in a dual-frequency ultrasonic cleaner. Deionized water was injected into the ultrasonic tank, with a liquid-to-solid ratio of 3:1. The temperature was 30℃, the ultrasonic power density was 15W / cm², the working mode was 5s on / 3s off, and the processing time was 10min. The ultrasonic cavitation effect destroyed the cellulose-pectin layer of the soybean skin, reducing the energy consumption of the soybean skin by subsequent irradiation. The trimer structure of 11S globulin was opened, allowing the protein to pre-relax. S14, inert gas atmosphere replacement After being sonicated, the soybeans are transferred into a sealed drum and purged three times with 99.99% pure nitrogen to reduce the oxygen content inside the drum to <1%; this prevents oxygen from reacting with free radicals during irradiation to generate peroxides, which would lead to protein oxidative cross-linking. S15, Low-energy electron beam surface treatment Soybeans purged with an inert gas atmosphere were placed in a low-energy electron accelerator and surface-treated under conditions of electron beam energy of 3 MeV, dose rate of 1.0 kGy / min, and total dose of 1.5 kGy. The micropores of the soybean skin were enlarged to 2-3 μm, and the activity of polyphenol oxidase (PPO) was reduced by 60%, which can reduce excessive browning during subsequent fermentation. The proportion of α-helices in the surface protein decreased from 25% to 22%, and the β-sheet increased to 25%, initially opening the structure and paving the way for deep denaturation by gamma rays. S16, deep denaturation by gamma rays A Co-60 gamma ray source was used to treat the soybeans in step S15 for 10-16 hours at a dose rate of 1.25-6.0 kGy / h and a total dose of 20-60 kGy, thereby denaturing the proteins in the dried soybeans. The low dose rate avoids localized free radical proliferation that could lead to cross-linking, while the sufficient treatment time ensures penetration to the center of the soybean.

[0012] As another improvement to the method of improving the quality of high-salt liquid soy sauce of the present invention, it also includes: S17, antioxidants synergistic quenching The irradiated soybeans were transferred into a mixer with a stirrer and sprayed with a 0.05% composite solution at a speed of 30 rpm, with an addition amount of 8 mL / kg of soybeans; wherein the 0.05% composite solution was prepared by dissolving vitamin E and rosemary extract in 1:1 by mass in 10% edible ethanol water.

[0013] In this invention, vitamin E can quench lipid free radicals, and rosmarinic acid can quench protein free radicals, eliminating free radicals (such as ·OH and ·H) generated by irradiation, and preventing secondary oxidation or cross-linking of proteins during storage.

[0014] As another improvement to the method of improving the quality of high-salt dilute soy sauce of the present invention, the total radiation dose in step S1 is preferably 20-40 kGy.

[0015] As another improvement to the method of improving the quality of high-salt dilute soy sauce of the present invention, in step S2, the dried soybeans are soaked at 50-65°C.

[0016] As another improvement to the method of improving the quality of high-salt dilute soy sauce of the present invention, 0.2% (w / w) Aspergillus oryzae seed koji is added in step S4.

[0017] As another improvement to the method of improving the quality of high-salt diluted soy sauce of the present invention, 0.5-1.5% (w / w) of compound microbial agent inoculum is added in step S4, wherein the compound microbial agent inoculum is a mixture of Lactobacillus plantarum, Monascus purpureus and Aspergillus oryzae in a weight ratio of 3:1:2.

[0018] As another improvement to the method of improving the quality of high-salt dilute soy sauce of the present invention, 0.5-1.5% (w / w) of compound microbial inoculum is added in step S4. The compound microbial inoculum is a mixture of Aspergillus oryzae, Saccharomyces cerevisiae and lactic acid bacteria in a weight ratio of 4:1.5:1.

[0019] As another improvement to the method of improving the quality of high-salt dilute soy sauce of the present invention, in step S4, the fermentation tank has the following conditions: temperature 30–32℃, humidity ≥90%, and ventilation rate 0.1 m³ / (kg·h).

[0020] As another improvement to the method of improving the quality of high-salt dilute soy sauce of the present invention, the filtration device in step S6 is a diatomaceous earth-plate frame with a pore size of 0.22 μm.

[0021] As another improvement to the method of improving the quality of high-salt dilute soy sauce of the present invention, the fermentation temperature in step S5 is 25-35℃.

[0022] Regarding high-salt thin-state soy sauce, in order to achieve the above-mentioned objectives, the present invention adopts the following solution: a high-salt thin-state soy sauce, characterized in that it is prepared by the method described in any of the above-mentioned methods.

[0023] In summary, the advantages of this invention over the prior art are: I. This invention utilizes Co-60 γ-rays to perform non-thermal physical denaturation pretreatment on dried soybeans under suitable conditions, effectively disrupting the higher-order structure of proteins and allowing them to fully extend and expose enzyme cleavage sites. Simultaneously, it minimizes the excessive aggregation and cross-linking of proteins caused by traditional high-temperature cooking. This significantly improves subsequent enzymatic hydrolysis efficiency, which is beneficial for increasing total nitrogen utilization and amino acid nitrogen yield (especially glutamic acid), key indicators of soy sauce umami and nutritional value. The extremely strong penetrating power of γ-rays ensures highly uniform protein denaturation throughout the entire batch of soybeans (regardless of particle size or location). This solves the problem of uneven denaturation caused by uneven heating in traditional thermal denaturation processes (cooking), laying a solid foundation for the stability and batch consistency of subsequent koji making and fermentation.

[0024] Second, this invention utilizes Co-60 γ-rays for irradiation treatment in a dry state at room temperature, completely avoiding the loss of water-soluble proteins and amino acids caused by soaking in traditional processes, and the consumption of amino acids due to the Maillard reaction accelerated by prolonged cooking. This ensures a higher potential for the formation of amino acid nitrogen. Another important effect of irradiation treatment is to induce moderate denaturation of proteins, which is more conducive to enzymatic hydrolysis by proteases and improves protein utilization. Furthermore, this method effectively prevents the formation of melanoidins and undesirable flavor substances (burnt taste, bitterness) caused by excessive Maillard reactions, promoting a purer, fresher, and more delicious soy sauce flavor, particularly meeting the requirements of high-salt, thin-state soy sauce for a pure and natural flavor. Moreover, the soy sauce color is more natural reddish-brown and glossy, with a superior appearance.

[0025] Third, after irradiation pre-denaturation, the soybean structure becomes more porous (protein molecules unfold), making it easier for the soybean to absorb water quickly and evenly during subsequent soaking.

[0026] In step S3, the main goal of cooking is to mature the flour and soybean starch (which is beneficial for koji making). Since the protein has been pre-denatured, the required cooking intensity (pressure and time) can be reduced, further reducing the risk of heat damage and undesirable flavors, while ensuring that the starch is fully gelatinized.

[0027] Fourth, the uniform and moderately denatured protein matrix provides a more ideal and homogeneous substrate environment for the growth of Aspergillus oryzae and the production of enzymes (proteases, amylases, etc.). Combined with a long-term, low-temperature fermentation process of 120-180 days, it provides favorable conditions for the slow, full, and coordinated formation of flavor compounds (such as alcohols, esters, organic acids, etc.), significantly enhancing the aroma complexity, richness, and aftertaste of soy sauce. Umami (amino acids, small peptides), sweetness (sugars, glycerol), acidity (organic acids), richness (peptides, polysaccharides), and aroma (esters, etc.) are richer, more harmonious, and purer, while undesirable flavors (burnt bitterness) are reduced.

[0028] Fifth, the protein in this invention is fully and moderately degraded, and combined with the filtration in step S6 to remove macromolecular colloids and bacteria, which helps to improve the clarity and storage stability of soy sauce and reduce sedimentation.

[0029] VI. The γ-rays of this invention have a bactericidal effect on microorganisms on the surface of dried soybeans, and the steaming in step S3 and the pasteurization in step S7 constitute multiple sterilization guarantees. Attached Figure Description

[0030] Figure 1 A schematic diagram showing the proportions of flavor-enhancing amino acids in high-salt, diluted soy sauces brewed using different methods of processing dried soybeans.

[0031] Figure 2 A schematic diagram classifying the volatile compounds in high-salt, diluted soy sauce produced using different methods of processing dried soybeans.

[0032] Figure 3 A schematic diagram comparing the total content of key volatile aroma types in high-salt, diluted soy sauce produced using different methods of processing dried soybeans. Detailed Implementation

[0033] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0034] Example 1 A method for improving the quality of high-salt liquid soy sauce includes the following steps: S1. Processing of dried soybeans Low-energy electron beams and gamma rays were used to treat dried soybeans, causing the proteins in the dried soybeans to denature. The specific steps include: S11. Screening, grading, and impurity removal Dried soybeans were passed through a 10-mesh sieve to remove broken and moldy beans, and then a photoelectric separator was used to screen whole soybeans with a particle size of 5.5±0.5mm. S12, Moisture Regulation Soybeans were placed in a constant temperature and humidity chamber at 28℃ and 70% relative humidity (RH) for 24 hours to allow the moisture content to stabilize at 14±0.5%. S13, Ultrasonic-assisted cell wall disruption Soybeans from S12 are placed into a dual-frequency ultrasonic cleaner. Deionized water is injected into the ultrasonic tank with a liquid-to-solid ratio of 3:1. The temperature is 30℃, the ultrasonic power density is 15W / cm², the working mode is 5s on and 3s off, and the processing time is 10min. S14, inert gas atmosphere replacement After being ultrasonicated, the soybeans are transferred into a sealed drum and purged three times with 99.99% pure nitrogen gas to reduce the oxygen content inside the drum to <1%. S15, Low-energy electron beam surface treatment Soybeans that have been replaced with an inert gas atmosphere are placed in a low-energy electron accelerator and surface treated under the conditions of electron beam energy of 3 MeV, dose rate of 1.0 kGy / min, and total dose of 1.5 kGy. S16, deep denaturation by gamma rays A Co-60 gamma ray source was used to treat soybeans in step S15 for 10-16 hours at a dose rate of 1.25 kGy / h and a total dose of 20 kGy, thereby denaturing the proteins in the dried soybeans. The proteins were denatured uniformly, with an enzyme cleavage site exposure rate of 98%, avoiding the consumption of free amino groups by the Maillard reaction.

[0035] S2, Soaking soybeans Mix the dried soybeans from step S1 with twice the volume of water and soak them at 50°C for 4 hours. The high temperature water accelerates water absorption, increases the expansion rate of the soybeans by 40%, and shortens the subsequent steaming and cooking time.

[0036] S3, Steaming soybeans The cooking process was carried out using an NK-type rotary high-pressure cooker, with the equipment parameters set at a pressure of 0.1 MPa and a time of 25 minutes. S4, Composition After the soybeans are steamed, flour is added at a ratio of 3:1 (soybeans:flour). The mixture is cooled to 25°C and then mixed with 0.2% (w / w) Aspergillus oryzae starter. The starter mixture is then placed in a fermentation tank for 2 days of fermentation. The fermentation tank has the following conditions: temperature 30°C, humidity 92%, and ventilation rate 0.1 m³ / (kg·h).

[0037] S5, Fermentation After the koji making is completed, the koji material is transferred to a fermentation tank, and 12% (w / v) brine is added at a ratio of 1:2. Fermentation is carried out at 25℃ for 120 days. S6, Filtration The fermentation liquid after step S5 was filtered using 0.22 μm diatomaceous earth-plate and frame filter to remove bacterial cells and macromolecular colloids. S7, sterilization Pasteurize at 85°C for 30 minutes.

[0038] Example 2 A method for improving the quality of high-salt liquid soy sauce includes the following steps: S1. Processing of dried soybeans Low-energy electron beams and gamma rays were used to treat dried soybeans, causing the proteins in the dried soybeans to denature. The specific steps include: S11. Screening, grading, and impurity removal Dried soybeans were passed through a 10-mesh sieve to remove broken and moldy beans, and then a photoelectric separator was used to screen whole soybeans with a particle size of 5.5±0.5mm. S12, Moisture Regulation Soybeans were placed in a constant temperature and humidity chamber at 28℃ and 70% relative humidity (RH) for 24 hours to allow the moisture content to stabilize at 14±0.5%. S13, Ultrasonic-assisted cell wall disruption Place the soybeans from step S12 into a dual-frequency ultrasonic cleaner, inject deionized water into the ultrasonic tank with a liquid-to-solid ratio of 3:1, maintain a temperature of 30℃, an ultrasonic power density of 15W / cm², and operate in a mode of 5s on / 3s off for a processing time of 10min. S14, inert gas atmosphere replacement After being ultrasonicated, the soybeans are transferred into a sealed drum and purged three times with 99.99% pure nitrogen gas to reduce the oxygen content inside the drum to <1%. S15, Low-energy electron beam surface treatment Soybeans that have been replaced with an inert gas atmosphere are placed in a low-energy electron accelerator and surface treated under the conditions of electron beam energy of 3 MeV, dose rate of 1.0 kGy / min, and total dose of 1.5 kGy. S16, deep denaturation by gamma rays A Co-60 gamma ray source was used to treat soybeans in step S15 for 10-16 hours at a dose rate of 3.5 kGy / h and a total dose of 40 kGy, resulting in protein denaturation in the dried soybeans. The proteins were denatured uniformly, with 99% exposure of enzyme cleavage sites, thus avoiding the consumption of free amino groups by the Maillard reaction.

[0039] S2, Soaking soybeans Mix the dried soybeans from step S1 with three times their volume of water and soak them at 55°C for 4 hours. The high-temperature water accelerates water absorption, increasing the soybean expansion rate by 43% and shortening the subsequent steaming and cooking time.

[0040] S3, Steaming soybeans The cooking process was carried out using an NK-type rotary high-pressure cooker, with the equipment parameters set at a pressure of 0.2 MPa and a time of 30 minutes. S4, Composition After the soybeans are steamed, flour is added at a ratio of 4:1 (soybeans:flour). The mixture is cooled to 30℃ and inoculated with 1% (w / w) of a compound microbial inoculum, then stirred thoroughly. The inoculum is then placed in a fermentation tank for 2.5 days of fermentation. The fermentation tank is maintained at a temperature of 31℃, humidity of 95%, and a ventilation rate of 0.1 m³ / (kg·h). The compound microbial inoculum is composed of *Lactobacillus plantarum*, *Monascus purpureus*, and *Aspergillus oryzae* in a weight ratio of 3:1:2. The lactic acid bacteria effectively lower the pH, while *Monascus purpureus* secretes esterase, increasing the production of esters by 45%.

[0041] S5, Fermentation After the koji making is completed, the koji material is transferred to a fermentation tank, and 15% (w / v) brine is added at a ratio of 1:2.3. Fermentation is carried out at 30℃ for 160 days. S6, Filtration The fermentation liquid after step S5 was filtered using 0.22 μm diatomaceous earth-plate and frame filter to remove bacterial cells and macromolecular colloids. S7, sterilization Pasteurize at 80°C for 25 minutes.

[0042] Example 3 A method for improving the quality of high-salt liquid soy sauce includes the following steps: S1. Processing of dried soybeans Low-energy electron beams and gamma rays were used to treat dried soybeans, causing the proteins in the dried soybeans to denature. The specific steps include: S11. Screening, grading, and impurity removal Dried soybeans were passed through a 10-mesh sieve to remove broken and moldy beans, and then a photoelectric separator was used to screen whole soybeans with a particle size of 5.5±0.5mm. S12, Moisture Regulation Soybeans were placed in a constant temperature and humidity chamber at 28℃ and 70% relative humidity (RH) for 24 hours to allow the moisture content to stabilize at 14±0.5%. S13, Ultrasonic-assisted cell wall disruption Soybeans from S12 are placed into a dual-frequency ultrasonic cleaner. Deionized water is injected into the ultrasonic tank with a liquid-to-solid ratio of 3:1. The temperature is 30℃, the ultrasonic power density is 15W / cm², the working mode is 5s on and 3s off, and the processing time is 10min. S14, inert gas atmosphere replacement After being ultrasonicated, the soybeans are transferred into a sealed drum and purged three times with 99.99% pure nitrogen gas to reduce the oxygen content inside the drum to <1%. S15, Low-energy electron beam surface treatment Soybeans that have been replaced with an inert gas atmosphere are placed in a low-energy electron accelerator and surface treated under the conditions of electron beam energy of 3 MeV, dose rate of 1.0 kGy / min, and total dose of 1.5 kGy. S16, deep denaturation by gamma rays A Co-60 γ-ray source was used to treat the soybeans in step S15 for 10-16 hours at a dose rate of 6.0 kGy / h and a total dose of 60 kGy, thereby denaturing the protein in the dried soybeans.

[0043] S17, antioxidants synergistic quenching The irradiated soybeans were transferred into a mixer with a stirrer and sprayed with a 0.05% composite solution at a speed of 30 rpm, with an addition amount of 8 mL / kg of soybeans; wherein the 0.05% composite solution was prepared by dissolving vitamin E and rosemary extract in 1:1 by mass in 10% edible ethanol water.

[0044] The protein is denatured uniformly, and the exposure rate of enzyme cleavage sites reaches 99%, avoiding the consumption of free amino groups by Maillard reaction.

[0045] S2, Soaking soybeans Mix the dried soybeans from step S1 with 4 times their volume of water and soak them at 65°C for 8 hours. The high-temperature water accelerates water absorption, increases the expansion rate of the soybeans by 50%, and shortens the subsequent steaming and cooking time.

[0046] S3, Steaming soybeans The cooking process was carried out using an NK-type rotary high-pressure cooker, with the equipment parameters set at a pressure of 0.3 MPa and a time of 35 minutes. S4, Composition After the soybeans are steamed, flour is added at a ratio of 6:1 (soybeans:flour). The mixture is cooled to 35°C and inoculated with 1.5% (w / w) of compound microbial inoculum. The mixture is stirred thoroughly and then placed in a fermentation tank for 3 days of fermentation. The compound microbial inoculum is composed of Aspergillus oryzae, Saccharomyces cerevisiae, and lactic acid bacteria in a weight ratio of 4:1.5:1. The fermentation tank maintains a temperature of 32°C, humidity of 95%, and a ventilation rate of 0.1 m³ / (kg·h).

[0047] S5, Fermentation After the koji making is completed, the koji material is transferred to a fermentation tank, and 18% (w / v) brine is added at a ratio of 1:2.5. Fermentation is carried out at 35℃ for 180 days. S6, Filtration The fermentation liquid after step S5 was filtered using 0.22 μm diatomaceous earth-plate and frame filter to remove bacterial cells and macromolecular colloids. S7, sterilization Pasteurize at 78°C for 20 minutes.

[0048] Comparative Example 1 High-salt thin soy sauce is prepared according to the following steps: S1, Soak soybeans Mix dried soybeans with three times their volume of water and soak at 30°C for 10 hours; S2, Steaming soybeans The cooking process was carried out using an NK-type rotary high-pressure cooker, with the equipment parameters set at a pressure of 0.3 MPa and a time of 35 minutes. S3, Composition After the soybeans are steamed, add flour at a ratio of 5:1 (soybeans:flour), cool to 30℃, add 0.2% (w / w) Aspergillus oryzae starter, mix well, and let the starter ferment for 3 days; S4, Fermentation After the koji making is completed, the koji material is transferred to a fermentation tank, and 18% (w / v) brine is added at a ratio of 1:2.5. Fermentation is carried out at 30℃ for 120 days. S5, sterilization Pasteurize at 65°C for 30 minutes.

[0049] To further demonstrate the advantages of the technical solution of the present invention, the following tests were conducted: 1.1 Experimental Materials Soybeans, flour, and starter culture were all purchased from the market. Except for the different processing methods and conditions of the dried soybeans, the brewing steps for the soy sauce samples tested in the experiment are as described in the examples and comparative examples.

[0050] 1.2 Sampling method for soy sauce Sampling was conducted as follows: Samples from different soybean treatment groups were mixed thoroughly, and 500 g of each sample was retained, placed in a sealed container, and stored at -18 ℃. For testing, an appropriate amount of sample was centrifuged, and the supernatant was collected for each test. All tests were completed within one month of sampling.

[0051] Routine physicochemical property testing methods for soy sauce samples (1) Protein digestibility: Weigh 100 g of the starter culture into a 500 mL Erlenmeyer flask, add 200 mL of 18.5% saline solution, cover, and incubate at 43 ℃ for two weeks to allow autolysis, stirring once during this period. The digested fermented mash is then thoroughly mixed using a mixer, filtered through filter paper, and its total nitrogen and salt content are determined. The calculation formula is shown in Figure 2-1:

[0052] (2) N-type proteins: ① Apparatus and apparatus. 150mL conical flask, constant temperature water bath, 50mL graduated cylinder, filter Rice. ② Reagent: Enzyme solution. a: Asp. oryza bran koji, add 5 times the amount of 20% saline. Extract the enzyme solution at 37℃.

[0053] b: Dissolve 2g of Aspergillus oryzae enzyme powder in 100mL of 20% saline solution. ③ Procedure. a. Take 5g of steamed soybeans into a 150mL Erlenmeyer flask, add the enzyme solution measured with a 50mL measuring cup, stopper the flask, and digest at 43℃ for 2 days. b: Filter the clear digested solution, heat it to 90℃ in a boiling water bath, cool it with cold water, and then filter it again to obtain a clear digested solution. c: Take 1mL of digested solution and 5mL of water in a test tube, heat it in a boiling water bath for 5 minutes, and then immediately cool it with water. d. If it becomes turbid or precipitates, the nitrogen (N) test is positive.

[0054] (3) Total acid: The determination is based on the acid-base titration method in GB / T 12456-2008 "Determination of total acid in food".

[0055] (4) pH value: measured directly with a pH meter.

[0056] 1.4 Detection Methods for Free Amino Acids and Amino Acid Nitrogen in Soy Sauce Samples The total amount of amino acids and the total amount of free amino acids in crude oil were determined according to the method of GB / T 18186-2000 "Brewed Soy Sauce"; the types and contents of amino acids in soy sauce were determined according to GB / T5009.124-2016 "National Food Safety Standard - Determination of Amino Acids in Food".

[0057] 1.5 Method for detecting volatile substances in soy sauce samples Volatile substances were determined using solid-phase microextraction / gas chromatography-mass spectrometry (SPME-GC-MS) to detect volatile components in crude oil.

[0058] Sample preparation: Take 5 mL of crude oil and 25 μL of a solution with a concentration of 1.675 × 10⁻⁶. -2 A 2-octanol solution (internal standard) at a concentration of mg / mL was added to a 20 mL headspace vial and equilibrated at 45 °C for 20 min in an incubator. Then, headspace extraction was performed at 45 °C using a CAR / PDMS solid-phase microextraction head for 30 min. After extraction, the sample was injected into the inlet at 250 °C for 5 min to complete the analysis.

[0059] GC conditions: HP-INNOWax capillary column (60 m × 250 μm × 0.25 μm): Injector temperature 250℃; temperature program: 50℃ for 5 min, ramp at 5℃ / min to 180℃ for 10 min, ramp at 12℃ to 230℃ for 7 min. Carrier gas: helium, flow rate 1.2 mL / min.

[0060] MS conditions: EI ion source, ion source temperature 250 °C, electron energy 70 eV, quadrupole and transfer line temperatures 200 °C and 220 °C respectively, mass scan range 35-500 amu.

[0061] All samples underwent three parallel determinations for each test item, and the experimental data were the average of the three parallel measurements.

[0062] 1.6 Experimental Results and Analysis The digestibility of protein affects the nutritional value of protein in food. Amino acid formation rate is related to the utilization of raw materials. The experimental results show no regularity in protein digestibility, amino acid formation rate, and amino acid nitrogen content across the different groups. However, it can be seen that the protein digestibility of the three irradiated soy sauce samples was higher than that of the untreated group (control group). Irradiation at 20 kGy, 40 kGy, and 60 kGy was 2.93%, 1.25%, and 0.95% higher than the control group, respectively, indicating that protein digestibility decreased with increasing irradiation intensity. The amino acid formation rate was 2%–5% lower than the control group. Except for the 60 kGy treatment group, the amino acid nitrogen content in the other two groups was 0.04 g / 100 mL higher than the control group, while the detected amino acid nitrogen content in the 60 kGy treatment group was 0.04 g / 100 mL lower than that in the control group.

[0063] Reference: China Condiments, 2019, 44(04):48-51, Cheng Shumin, Li Li, Zhao Yingying, et al.; Preliminary study on the preparation of low-salt solid-state fermented soy sauce using olive juice. The highest amino acid formation rate detected was 47.67%. The amino acid formation rate measured in this experiment was all above 60%, which is significantly higher than that in this experiment. Of course, protein digestibility and amino acid formation rate are affected by many factors, including raw materials, fermentation conditions, fermentation time, etc., so it is normal for soy sauce prepared by different processes to have differences. According to the grading of soy sauce in GB / T 18186-2000, amino acid nitrogen content > 0.80 g / 100 mL belongs to the category of premium soy sauce. The amino acid nitrogen content of all experimental groups in this application was > 0.80 g / 100 mL. This indicates that from the perspective of amino acid nitrogen, the quality of all soy sauce samples of this invention is at a relatively high level.

[0064] The absence of nitrogen-containing proteins in all samples indicates that the pretreatment and cooking of soybean raw materials in each group were appropriate, resulting in primary denaturation of soybean proteins and good enzymatic hydrolysis. Furthermore, the absence of nitrogen-containing proteins also demonstrates that a potential factor causing turbidity in soy sauce samples was prevented during raw material processing.

[0065] Generally, commercially available soy sauces are required to have a total acid content of <2.5 g / 100 mL and a pH value between 4 and 5. The soy sauce samples tested in this invention all met these general requirements. However, total acid represents all acidic substances in soy sauce, including lactic acid, acetic acid, succinic acid, etc., so a lower total acid value is not necessarily better. The total acid content of the irradiated experimental groups was lower than that of the control group, but the irradiation dose from 20 to 60 kGy showed a pattern of first increasing and then decreasing. From the trend, the irradiation dose of the 40 kGy treatment group showed a value similar to or even higher than that of the control group by 1.6 g / 100 mL.

[0066] 1.7 Amino acid analysis of high-salt liquid soy sauce brewed using different dried soybean processing methods 1.7.1 Types and content of amino acids in high-salt liquid soy sauce brewed using different dried soybean processing methods Free amino acids are an important source of flavor in soy sauce, and their content and composition directly affect the flavor characteristics of soy sauce products. Except for the irradiation treatment group, a total of 14 free amino acids were detected in the other experimental groups, while 12 free amino acids were detected in the irradiation treatment group.

[0067] The overall amino acid detection level in the irradiated experimental group was lower than that in the control group.

[0068] Table 1-1 Free amino acid data of high-salt liquid soy sauce brewed using different dried soybean processing methods amino acids No processing Irradiation 20 kGy Irradiation 40 kGy Irradiation of 60 kGy Glu 1099 1150 1116 1027 Tyr 56 70 100 78 Asp 617 713 741 591 Thr 284 278 296 187 Ser 371 353 394 263 Gly 221 240 253 211 Ala 412 327 344 307 Val 358 349 376 319 Met 81 89 93 79 Ile 348 354 369 318 Leu 554 504 548 461 Continued from Table 1-1 amino acids No processing Irradiation of 20 kGy Irradiation 40 kGy Irradiation of 60 kGy Phe 367 304 324 277 His 186 / / / Arg 226 / / / T 5180 4731 4954 4118 E 1992 1878 2006 1641 B / T 0.21 0.24 0.23 0.25 E / T 0.38 0.40 0.40 0.40 E / N 0.62 0.66 0.68 0.66 Note: (1) The unit of all data in Table 1-1 is mg / mL; (2) “ / ” indicates that it was not detected by this experimental method; (3) T is the total amount of amino acids; E is the total amount of essential amino acids; N is the total amount of non-essential amino acids; B / T is the ratio of glutamic acid to total amino acids; E / T is the proportion of essential amino acids to total amino acids; E / N is the ratio of essential amino acids to non-essential amino acids.

[0069] Commercially available soy sauce without added umami flavoring typically contains 18%–25% glutamic acid; 7%–15% arginine, leucine, and alanine; 6%–8% serine, valine, isoleucine, phenylalanine, and lysine; 4%–6% glycine and threonine; and 1%–3% tyrosine, methionine, histidine, and arginine.

[0070] In Table 1-1, the glutamic acid content of the four groups of soy sauce samples was within the general range of the commercially available soy sauces. The ratio of glutamic acid content to total amino acids in the three irradiated soy sauce samples was 3%, 2%, and 4% higher than that in the control group, respectively.

[0071] Except for the alanine content in the irradiated 20 kGy and 60 kGy groups, which was lower than the general range for commercially available soy sauces, the content of these three amino acids in the other experimental groups was within the aforementioned range. Furthermore, the aspartic acid and leucine content in the soy sauce samples from the three irradiated groups was significantly higher than that in the control group, especially the aspartic acid content, which was >3% higher.

[0072] The proportions of serine, valine, isoleucine, and phenylalanine in the total amino acids are all within the general range of commercially available soy sauce.

[0073] The glycine and threonine ratios in the untreated group were within the general range of those found in commercially available soy sauces. The glycine content in the three irradiated experimental groups exceeded the above range by more than 0.5%, but the threonine content in the 60 kGy treatment group was slightly lower than the normal ratio. The threonine content in the other two groups was within the general range of that found in commercially available soy sauces.

[0074] Table 1-1 shows that the proportions of tyrosine and phenylalanine in each group are within the general range of commercially available soy sauces. The proportions in the 20kGy treatment group are about 1% higher than those in the control group. Except for the three irradiated experimental groups where arginine and histidine were not detected and were within the normal range, the arginine and histidine in the soy sauce samples of the other experimental groups were higher than the general range. The arginine and histidine in the control group were 0.59% and 1.36% higher than the general range of commercially available soy sauces, respectively.

[0075] SPME-GC-MS analysis revealed eight essential amino acids for the human body. The Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) recommend that essential amino acids comprise 40% of the total amino acids in ingested protein, while non-essential amino acids should comprise 60%. This ratio is considered the ideal for high-quality protein. Only the three irradiated soy sauce samples achieved a 40% ratio of essential amino acids to total amino acids; the rest were slightly below this standard. Furthermore, except for the soy sauce sample treated with ultra-high pressure (400 MPa) where the E / N ratio was slightly below the standard, the ratios of essential and non-essential amino acids in the other experimental groups were within the standard range.

[0076] In summary, among the soy sauces fermented from dried soybeans treated with different methods, the content of free amino acids, except for arginine and histidine, showed significantly higher proportions than normal. However, the irradiated treatment still differed from the control group. The proportion of glutamic acid in the irradiated treatment was 2%–4% higher than that in the control group, and the proportion of aspartic acid was >3% higher. In the control group, the histidine content in the soy sauce samples was approximately 1% higher than normal, and the arginine content was 1.36% higher than normal.

[0077] Comparing the ratio of essential amino acids to total amino acids and the ratio of essential amino acids to non-essential amino acids, the amino acid nutritional value of the three groups of irradiated soy sauce samples was found to be closer to the standards given by the WHO, indicating that theoretically their nutritional value is higher than that of other groups.

[0078] 1.7.2 Comparison of flavor amino acid content in high-salt liquid soy sauce brewed using different dried soybean processing methods Amino acids possess flavor characteristics and are categorized into umami, sweet, bitter, and tasteless based on their taste. Of the fourteen amino acids tested, aspartic acid and glutamic acid are umami-tasting amino acids; serine, glycine, alanine, and threonine are sweet-tasting amino acids; phenylalanine, tyrosine, valine, histidine, methionine, arginine, leucine, and isoleucine are bitter-tasting amino acids. Proline, which is tasteless, was not detected. Based on this classification, the total content of different amino acid categories was summarized, and the total content of different types of amino acids was calculated. Figure 1 .from Figure 1 It can be seen that, except for the three irradiated experimental groups, the content of bitter amino acids > umami amino acids > sweet amino acids, and the proportions of the three flavor amino acids are similar in each group.

[0079] The sweetness-to-umami ratio varies in soy sauces processed using different techniques. Wang Zeliang et al., in their analysis of the flavor and quality characteristics of traditionally brewed soy sauce in Sichuan, detected a sweetness-to-umami ratio of 77.64% for Cantonese-style soy sauce. The sweetness-to-umami ratio detected in this experiment ranged from 54% to 65%, slightly lower than the results of Wang Zeliang et al., but both were within the common range (approximately 57%).

[0080] As can be seen from Table 1-2, the sweetness and umami ratio of flavor amino acids in the irradiated dried soybean experimental group, although the detected content of amino acids was relatively low, the proportion of bitter amino acids was also significantly lower than that in the untreated group. Theoretically, its sweetness and umami flavor are more pronounced, and the taste may be more mellow. The trend of the sweetness and umami ratio decreases with increasing irradiation intensity, indicating that the optimal sweetness and umami ratio occurs around an irradiation intensity of 40 kGy.

[0081] Compared with the control group, the content of sweet amino acids and umami amino acids in the irradiated group was 6.71%, 5.47%, and 4.81% higher, respectively.

[0082] Table 1-2 Sweet and umami ratios of flavor amino acids in high-salt liquid-state sauces brewed using different dried soybean processing methods

[0083] Note: Sweetness / Umami Ratio = [(Sweetness Free Amino Acids + Umami Free Amino Acids) / Total Free Amino Acid Content] × 100%.

[0084] 1.8 Volatile Compound Analysis of High-Salt Dilute Soy Sauces Processed with Different Methods of Dry Soybean Treatment 1.8.1 Volatile substances detected in high-salt liquid soy sauce brewed using different dried soybean processing methods The data on volatile substances detected in all samples are shown in Table 1-3.

[0085] Table 1-3 Volatile Matter of High-Salt Dilute Soy Sauce Based on Different Processing Methods of Dried Soybeans Volatile substances No processing Irradiation of 20 kGy Irradiation 40 kGy Irradiation of 60 kGy ethanol 17032 46041 135944 36841 acetone 2781 0 0 0 Isobutyraldehyde 4129 520 788 0 Acetic acid 10869 4737 6770 4276 2-Butanone 0 0 0 0 Ethyl acetate 5465 8690 17711 6144 Isovaleraldehyde 19719 6503 9607 2719 2-Methylbutanal 22643 2729 5107 1177 Isoamyl alcohol 16336 10887 6396 5265 2-Methylbutanol 46696 6207 3811 2309 Isovalerate 2025 1981 1608 3201 2-Methylbutyric acid 3817 1243 1755 1992 1-Hexanol 0 0 0 0 Methylthiopropionaldehyde 7443 0 318 0 benzaldehyde 6624 877 0 0 1-Octen-3-ol 50749 974 2902 0 3-Octanone 29433 2546 0 0 3-Octanol 7821 0 0 0 Octal 0 0 0 0 phenylacetaldehyde 17789 6499 11514 0 cis-2-octen-1-ol 2226 0 0 0 Nononal 388 1458 2170 2672 Phenylacetyl alcohol 6096 4654 3875 2786 4-Ethylphenol 1678 3356 1287 209 4-Ethyl-2-methoxyphenol 5948 19593 14465 19484 2,4-Di-tert-butylphenol 565 0 0 0 styrene 4143 2079 0 1546 Continued from Tables 1-3 Volatile substances No processing Irradiation 20 kGy Irradiation 40 kGy Irradiation of 60 kGy 2-(azacyclopropane-1-yl)ethylamine 0 0 2152 894 Aminourea 0 538 0 564 (3E)-3-prop-2-enylidene cyclobutene 1010 0 0 0 2-Hepagonal 0 237 0 0 alanine 750 0 0 0 6-Methylcyclohexadienol 1013 0 0 0 N-methyltaurine 0 0 0 325 Methyl acetate 1329 0 0 0 Isobutyric acid 0 213 0 604 3-Furfural 909 0 0 0 2-(2-Methoxypropoxy)propanol 0 447 1720 1036 Isobutanol 2593 6001 1591 0 2-Methylbutylacetic acid 1390 0 0 0 p-hydroxyanisole 560 0 0 0 2-Methylvalerate anhydride 11063 0 0 0 furfuryl alcohol 4687 0 0 0 1-Methoxy-2-propanone 0 0 0 0 Guaiacin (2-methoxyphenol) 987 0 0 0 Norpseudoephedrine 52 413 0 0 (S)-(+)-1-Cyclohexylethylamine 747 0 0 0 ethylenediamine 0 0 0 0 4-Ketoheptanedioic acid 456 0 0 0 2,5-Dimethylfuran 1115 0 0 0 Damaskone 1267 0 0 0 Ethyl propionate 0 1271 0 0 Ethyl isovalerate 0 2276 407 2897 6-Methyl-3-heptanol 0 296 0 0 Continued from Tables 1-3 Volatile substances No processing Irradiation of 20 kGy Irradiation 40 kGy Irradiation of 60 kGy Methylpropene oxide 0 306 0 0 Ethyl isobutyrate 0 503 0 0 L-ethyl lactate 0 474 0 0 ethyl 2-methylbutyrate 0 756 0 1355 Ethyl valerate 0 1635 0 0 cis-2-ethyl-2-hexen-1-ol 0 606 0 334 2-n-pentylfuran 0 501 1780 1271 Ethyl benzoate 0 208 1789 0 Ethyl phenylacetate 0 641 988 0 Ammonium carbamate 0 0 1771 0 Ethyl isohexanoate 0 0 937 0 PPG-2 methyl ether 0 0 1443 0 1,7-Octopien-3-ol 0 0 0 279 Meglumine 0 0 0 0 Note: (1) The unit of all data in Table 1-3 is mg / mL; (2) The data are rounded to the nearest integer and the error is ±1 mg / mL.

[0086] Volatile compounds are the main source of aroma in soy sauce and have a significant impact on its quality. SPME-GC-MS was used to analyze the volatile substances in soy sauce samples. The results are shown in Table 1-3. A total of 61 components were detected, fewer than the 111 volatile components detected by GC-MS-MS. Of the 69 components detected in this experiment, 11 were common to all experimental groups. The main difference in the detected data was in ester compounds. This experiment detected 12 esters, while Zhang Lin et al. detected 53. The data is close to that of Yu Yangyang et al., who detected 74 volatile components. The main difference lies in the absence of pyrazine and terpenoid compounds in this study. The differences may be related to the different soy sauce production and detection methods. The number of volatile components detected in each group is as follows: 41 volatile components were detected in the untreated group, and 37, 27 and 26 volatile components were detected in the experimental groups irradiated with 20 kGy, 40 kGy and 60 kGy respectively.

[0087] Statistical analysis was performed using ANOVA data processing software in IBM SPSS Statistics. The results showed that there were extremely significant differences among the groups for 33 volatile components (p < 0.01).

[0088] One-way statistical analysis of intergroup comparison data showed that the contents of ethanol, acetone, isobutyraldehyde, ethyl acetate, isovaleraldehyde, 2-methylbutyraldehyde, 2-methylbutanol, isovaleric acid, methylthiopropionaldehyde, benzaldehyde, 1-octen-3-aldehyde, 3-octanone, 3-octanol, phenylacetaldehyde, cis-2-octen-1-ol, 4-ethylphenol, 4-ethyl-2-methoxyphenol, methyl acetate, isobutanol, 2-methylvaleric anhydride, furfuryl alcohol, 1-methoxy-2-propanone, ethyl propionate, ethyl 2-methylbutyrate, and ethyl benzoate differed significantly among the groups (p < 0.01). The contents of acetic acid, isovalerol, 2-methylbutanol, phenylethanol, 2-(2-methoxypropoxy)propanol, and ethyl isovalerate differed significantly among the experimental groups (p < 0.05).

[0089] Soy sauce samples prepared from untreated dried soybeans were compared sequentially with those prepared from the irradiated group. The results showed a highly significant difference (p < 0.01) between the irradiated group and the control group in terms of volatile components, including acetone, isobutyraldehyde, isovaleraldehyde, 2-methylbutyraldehyde, 2-methylbutanol, methylthiopropionaldehyde, 2-methylvaleric anhydride, furfuryl alcohol, benzaldehyde, 1-octen-3-ol, 3-octanone, 3-octanol, phenylacetaldehyde, cis-2-octen-1-ol, and methyl acetate. The significantly different components were mostly aldehydes, which play an important role in the aroma composition of soy sauce due to their low aroma threshold.

[0090] The levels of benzaldehyde, isoamyl alcohol, and isovaleric acid in the soy sauce samples from the irradiated soybean experimental group showed a more significant difference from the experimental group as the irradiation intensity increased. The levels of ethanol, acetic acid, methyl acetate, ethyl isohexanoate, 4-ethyl-2-methoxyphenol, and ethyl benzoate were different from the control group, and the differences were extremely significant at 40 kGy. The differences between the experimental groups were reduced to varying degrees at irradiation intensities higher or lower than 40 kGy.

[0091] 1.8.2 Classification of volatile compounds in high-salt, diluted soy sauce produced by different processing methods for dried soybeans This invention detected a total of 16 alcohols, 9 aldehydes, 6 acids, 6 ketones, 12 esters, 4 phenols, and 22 other compounds (including sulfides and furans). Zhang Lin et al., in their paper "The effects of different coculture patterns with salt-tolerant yeast strains on the microbial community and metabolites of soy sauce moromi" (Food Research International, 2021, 150: 110747), detected 53 esters, with the remaining compounds being similar to those in this experiment. In fact, this experiment detected 13 more other substances than Zhang Lin et al. GC-MS analysis of the samples revealed a low number of 111 volatile components. Based on the above compound types, the relative contents of each experimental group were determined. Figure 2 .

[0092] Through analysis Figure 2 The study found that the proportion of volatile compounds, such as acids, ketones, and sulfides, was higher in the untreated experimental group.

[0093] Soy sauce made from irradiated and then cooked dried soybeans had significantly higher levels of phenolic compounds, but the number of detected compounds did not show a strong linear relationship with the irradiation intensity. Figure 2 As can be seen, the levels of phenolic and ester compounds in the 20 kGy irradiation group were higher than those in the control group; the levels of alcohols and esters in the soy sauce samples from the 40 kGy irradiation group were even higher than those in other treatment groups. The proportion of phenolic substances detected in the three irradiated samples first decreased and then increased with increasing irradiation intensity. Except for the amount of phenolic components detected, the amounts of other components all showed a trend of first decreasing and then increasing before and after the moderate dose (40 kGy) irradiation treatment.

[0094] In summary, although the total number of volatile components detected in the irradiated experimental group was lower than that in the control group, the number of specific types of components detected was significantly higher in the irradiated group. For example, alcohols, phenols, and esters were detected in the irradiated group.

[0095] 1.8.3 Classification of Aroma Types of Key Volatile Substances in High-Salt Liquid Soy Sauce Based on Different Dry Soybean Processing Methods Key volatile aroma compounds were identified through statistical analysis, with p < 0.01. These compounds were categorized and summarized based on the following literature: ① Yangyang Y, Sui C, Zhan L, et al. CoMParison of flavor profiles of Cantonese soy sauces obtained at different fermentation stages [J]. Process Biochemistry, 2023, 130: 569-576. ② Feng Yunzi, Zhou Ting, Wu Weiyu, et al. Research progress on flavor and functional components of soy sauce [J]. Journal of Food Science and Technology, 2021, 39(04):14-28. ③ Qingru L, Xiaojuan Z, Lei Z, et al. Machine learning based age-authentication assisted by chemo-kinetics: Case study of strong-flavor Chinese Baijiu [J]. Food Research International, 2023, 167: 112594. The total content of different aroma types was plotted. Figure 3 .

[0096] from Figure 3 It is evident that the control group exhibits higher levels of aroma compounds in multiple aspects, including malt, vegetable, and fruit aromas, compared to other treatment groups. Malt aroma is particularly prominent, with a total content of volatile compounds contributing to malt aroma at 95782.46 mg / mL. Irradiation treatment, on the other hand, promotes the formation of alcoholic, acidic, and smoky aroma components, and at an irradiation intensity of 40 kGy, alcoholic and acidic aromas showed relatively high values ​​(146080.08 mg / mL).

[0097] The high content of alcoholic and sour aroma compounds in the irradiated soybean experimental group was mainly due to the high ethanol content. The ethanol content of the 40 kGy treated sample reached 135,944.44 mg / mL, which was 8 times that of the control group. Ethanol is a component present in fermented products, and a high ethanol content will give the soy sauce a strong alcoholic taste.

[0098] The smoky aroma is generally derived from guaiacol, a marker of volatile components in soy sauce. Among the four sample groups, the types of guaiacol detected included 4-ethylphenol and 4-ethyl-2-methoxyphenol. These two compounds were present in higher concentrations in soy sauce samples prepared from irradiated dried soybeans, with the highest concentrations reaching 40 kGy. The concentrations of 4-ethylphenol and 4-ethyl-2-methoxyphenol were 3355.55 mg / mL and 19593.63 mg / mL, respectively, approximately two and four times that of the control group. The data indicate that using irradiated dried soybeans as raw material for soy sauce preparation promotes the formation of 4-ethylphenol and 4-ethyl-2-methoxyphenol.

[0099] 2. Conclusion Based on the analysis of the above results, the following conclusions can be drawn: (1) Compared with the control group, the protein digestibility and amino acid nitrogen of the irradiation treatment were significantly improved. The protein digestibility of the soy sauce samples in the irradiation treatment group with different intensities increased by 0.95%~2.93%, and the amino acid nitrogen increased by 0.04 g / 100mL. (2) Fourteen kinds of amino acids were detected in the control group, and the ratio of sweetness to umami of free amino acids was 57.99%. Forty-one kinds of volatile substances were detected. Compared with the total content, the contents of aldehydes, ketones and sulfides were higher than those of other groups. The aromas of malt, fruit and vegetable volatile substances were more obvious.

[0100] (3) Only 12 amino acids were detected in the different intensity irradiation treatment groups, two fewer than the control group, namely histidine and arginine; the sweetness-to-freshness ratio was 4.81%~6.81% higher than the control group, but the range of increase in sweetness-to-freshness ratio decreased with the increase of irradiation intensity dose; the content of essential amino acids / total amino acids (E / T) and essential amino acids / non-essential amino acids (E / N) were both higher than the control group. E / T was high by 0.02, and E / N was high by 0.04~0.08. 37, 27 and 26 kinds of volatile components were detected in the Co-60 irradiation treatment groups with different intensities of 20 kGy, 40 kGy and 60 kGy, respectively. Alcohols, phenols and esters accounted for a relatively high proportion. Since it is conducive to the formation of 4-ethylphenol and 4-ethyl-2-methoxyphenol, the experimental group with the highest content was the 40 kGy irradiation treatment group, which had a content of about 2 times and 4 times that of the control group, respectively. Therefore, theoretically, the irradiation treatment has a more significant smoky flavor, especially the 40 kGy irradiation experimental group.

[0101] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for improving the quality of high-salt liquid soy sauce, characterized in that... Includes the following steps: S1. Processing of dried soybeans Low-energy electron beams and gamma rays were used to treat dried soybeans, causing the proteins in the dried soybeans to denature. S2, Soaking soybeans Mix the dried soybeans from step S1 with 2-4 times their volume of water and soak at 50-65℃ for 4-8 hours. S3, Steaming soybeans The cooking process is carried out using an NK-type rotary high-pressure cooker. The equipment parameters are set with a pressure of 0.1-0.3 MPa and a time of 25-35 min. S4, Composition After the soybeans are steamed, add flour at a ratio of 3-6:1 (soybeans:flour). Cool to 25-35℃, add the starter culture, mix well, and place the starter culture in a fermentation tank to ferment for 2-3 days. S5, Fermentation After the koji making is completed, transfer the koji material to a fermentation tank and add 12-18% (w / v) brine at a ratio of 1:2-2.

5. Ferment for 120-180 days. S6, Filtration The filtrate after fermentation in step S5 is filtered using a filtration device to remove bacteria and macromolecular colloids. S7, sterilization Pasteurize at 75-90℃ for 15-35 minutes.

2. The method for improving the quality of high-salt liquid soy sauce according to claim 1, characterized in that: The specific steps for processing dried soybeans in step S1 include: S11. Screening, grading, and impurity removal Dried soybeans were passed through a 10-mesh sieve to remove broken and moldy beans, and then a photoelectric separator was used to screen whole soybeans with a particle size of 5.5±0.5mm. S12, Moisture Regulation Soybeans were placed in a constant temperature and humidity chamber at 28℃ and 70% relative humidity (RH) for 24 hours to allow the moisture content to stabilize at 14±0.5%. S13, Ultrasonic-assisted cell wall disruption Soybeans from S12 are placed into a dual-frequency ultrasonic cleaner. Deionized water is injected into the ultrasonic tank with a liquid-to-solid ratio of 3:

1. The temperature is 30℃, the ultrasonic power density is 15W / cm², the working mode is 5s on and 3s off, and the processing time is 10min. S14, inert gas atmosphere replacement After being ultrasonicated, the soybeans are transferred into a sealed drum and purged three times with 99.99% pure nitrogen gas to reduce the oxygen content inside the drum to <1%. S15, Low-energy electron beam surface treatment Soybeans that have been replaced with an inert gas atmosphere are placed in a low-energy electron accelerator and surface treated under the conditions of electron beam energy of 3 MeV, dose rate of 1.0 kGy / min, and total dose of 1.5 kGy. S16, deep denaturation by gamma rays A Co-60 γ-ray source was used to treat the soybeans in step S15 for 10-16 hours at a dose rate of 1.25-6.0 kGy / h and a total dose of 20-60 kGy, thereby denaturing the protein in the dried soybeans.

3. The method for improving the quality of high-salt liquid soy sauce according to claim 2, characterized in that... Also includes: S17, antioxidants synergistic quenching The irradiated soybeans were transferred into a mixer with a stirrer and sprayed with a 0.05% composite solution at a speed of 30 rpm, with an addition amount of 8 mL / kg of soybeans; wherein the 0.05% composite solution was prepared by dissolving vitamin E and rosemary extract in 1:1 by mass in 10% edible ethanol water.

4. The method for improving the quality of high-salt liquid soy sauce according to claim 1, characterized in that: In step S4, 0.2% (w / w) Aspergillus oryzae seed culture is added.

5. The method for improving the quality of high-salt liquid soy sauce according to claim 1, characterized in that: In step S4, 0.5-1.5% (w / w) of compound microbial inoculum is added, wherein the compound microbial inoculum is a mixture of Lactobacillus plantarum, Monascus purpureus and Aspergillus oryzae in a weight ratio of 3:1:

2.

6. The method for improving the quality of high-salt liquid soy sauce according to claim 1, characterized in that: In step S4, 0.5-1.5% (w / w) of compound microbial inoculum is added. The compound microbial inoculum is a mixture of Aspergillus oryzae, Saccharomyces cerevisiae and lactic acid bacteria in a weight ratio of 4:1.5:

1.

7. The method for improving the quality of high-salt thin-state soy sauce according to claim 1, characterized in that: In step S4, the fermentation tank has the following conditions: temperature 30–32℃, humidity ≥90%, and ventilation rate 0.1 m³ / (kg·h).

8. A method for improving the quality of high-salt liquid soy sauce according to claim 1, characterized in that: The filtration device mentioned in step S6 is a diatomaceous earth-plate frame with a pore size of 0.22 μm.

9. A method for improving the quality of high-salt liquid soy sauce according to claim 1, characterized in that: Fermentation in step S5 is carried out at 25-35℃.

10. A high-salt, thin-state soy sauce, characterized in that: Prepared using the method described in any one of claims 1-9.

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