Preparation method of soybean paste and soybean paste

Abstract

The invention provides a preparation method of soybean paste and the soybean paste, and the preparation method of the soybean paste comprises the following steps: cooking first soybeans to prepare first cooked whole soybeans; mixing the first cooked whole beans, wheat flour and aspergillus oryzae, and making koji to prepare finished koji; mixing the finished koji with saline water, and performing first fermentation to prepare first soy sauce mash; second soybeans are stir-fried, the stir-fried second soybeans are cooked, and second cooked whole soybeans are prepared; grinding and emulsifying a mixture containing the second cooked whole beans, saccharomyces rouxii and water to prepare a mixed milk material; under a salt-free condition, carrying out second fermentation on the mixed milk material to prepare second soy sauce mash; mixing the first soy sauce mash and the second soy sauce mash, and performing third fermentation to prepare third soy sauce mash. The natural aroma flavor and taste of the soybean paste prepared by the preparation method are remarkably improved.

Description

Technical Field

[0001] This application relates to the field of brewing technology, and in particular to a method for preparing soybean paste and soybean paste itself. Background Technology

[0002] Soybean paste, a representative of traditional Chinese fermented condiments, has long been an integral part of people's daily diet. With socio-economic development and the continuous improvement of residents' consumption levels, modern consumers' demands for food have gradually shifted from simply satisfying their appetites to pursuing a balance between nutrition, health, and food safety. Naturally fermented soybean paste products with zero added MSG and zero food additives are becoming new market favorites.

[0003] However, the soybean paste industry currently faces a significant product upgrade dilemma: on the one hand, market research shows that over 85% of consumers prioritize "additive-free" products when purchasing condiments; on the other hand, to cater to popular taste preferences, approximately 92% of commercially available soybean paste products still contain varying degrees of umami enhancers such as monosodium glutamate (MSG), yeast extract, and hydrolyzed animal and plant proteins (e.g., HVP / HAP). While this industrialized production model can quickly improve the flavor of products, it often comes at the cost of the loss of natural fermentation flavor and may result in unnecessary food additive residues.

[0004] Therefore, how to enhance the natural aroma, flavor, and taste of soybean paste is an urgent problem to be solved. Summary of the Invention

[0005] Based on this, this application provides a method for preparing soybean paste and soybean paste, so as to enhance the natural aroma, flavor and taste of soybean paste.

[0006] The first aspect of this application provides a method for preparing soybean paste, comprising the following steps:

[0007] The first batch of soybeans is steamed to prepare the first batch of cooked whole soybeans;

[0008] The first-cooked whole soybeans, wheat flour and Aspergillus oryzae are mixed and then used to make koji;

[0009] The koji and brine are mixed and then subjected to a first fermentation to prepare the first sauce mash.

[0010] The second soybean is stir-fried, and the stir-fried second soybean is then steamed to prepare the second cooked whole soybean.

[0011] A mixture containing second-ripened whole soybeans, yeast rhubarb, and water is milled and emulsified to prepare a mixed emulsion.

[0012] Under salt-free conditions, the mixed milk is subjected to a second fermentation to prepare a second sauce mash;

[0013] The first and second sauce mashes are mixed and then subjected to a third fermentation to prepare the third sauce mashe.

[0014] In some embodiments, the frying temperature is 160℃-240℃ and the time is 30min-60min.

[0015] In some embodiments, the moisture content of the second soybean after stir-frying is 2wt%-5wt%.

[0016] In some embodiments, the mass of the mixture is 2.2 to 3.5 times the mass of the second cooked whole beans.

[0017] In some embodiments, the content of *Saccharomyces rouxii* in the mixture is 10. ^ 6 CFU / g-10 ^ 9 CFU / g.

[0018] In some embodiments, the viscosity of the mixed emulsion is 10000 Cp-220000 Cp.

[0019] In some embodiments, the mass ratio of the first fermented sauce to the second fermented sauce is 1:(1.5-3).

[0020] In some embodiments, the temperature of the third fermentation is 40°C-55°C, and the time is 20-40 days.

[0021] In some embodiments, the temperature of the second fermentation is 25°C-35°C, and the time is 60-80 days.

[0022] In some embodiments, during the second fermentation process, from day 1 to day 20 of fermentation, aeration and stirring are performed every 1 to 3 days, with a single stirring time of 10 to 30 minutes and an aeration rate of 1.5 m³ / (m³×min) to 2.5 m³ / (m³×min); from day 21 to day 60 of fermentation, aeration and stirring are performed every 3 to 7 days, with a single stirring time of 5 to 10 minutes and an aeration rate of 0.5 m³ / (m³×min) to 1.0 m³ / (m³×min).

[0023] In some embodiments, the parameters for steaming the roasted second soybeans include: steaming pressure of 0.1MPa-0.2MPa and soybean pressure of 0.1kg-0.5kg.

[0024] In some embodiments, before steaming or boiling the second soybeans after frying, the second soybeans after frying are soaked in water, and the mass of the second soybeans after absorbing water is 2.0 to 2.6 times the mass of the second soybeans before frying.

[0025] In some embodiments, the mass of the wheat flour is 35%-50% of the mass of the first soybean.

[0026] In some embodiments, the mass of the Aspergillus oryzae is 0.02%-0.05% of the mass of the first soybean.

[0027] In some embodiments, the temperature for koji making is 30℃-35℃, the time is 20h-30h, and the wind frequency is 25Hz-50Hz.

[0028] In some embodiments, the mass of the brine is 1 to 1.5 times the mass of the first soybean.

[0029] In some embodiments, the salt content of the system obtained after mixing the koji and the brine is 10%-12%.

[0030] In some embodiments, the temperature of the first fermentation is 30°C-40°C, and the time is 30-50 days.

[0031] In some embodiments, the first soybeans are soaked in water before steaming or boiling.

[0032] In some embodiments, the mass of the water is 1 to 1.5 times the mass of the first soybean, and the soaking time is 2 to 3.5 hours.

[0033] The second aspect of this application provides a soybean paste, which is prepared using the soybean paste preparation method of the first aspect of this application.

[0034] The above-described method for preparing soybean paste involves steaming a portion of soybeans, then preparing koji (fermentation starter) using Aspergillus oryzae, followed by salt fermentation to obtain a mash rich in enzymatically hydrolyzed substrates. Another portion of soybeans is roasted, steamed, and then mixed with Saccharomyces roximate for salt-free fermentation, yielding a mash rich in reactants such as fatty acids, oxidized fatty acids, alcohols, and carboxylic acid esters. This mash provides aroma reactants for subsequent mixing and fermentation with the enzymatically hydrolyzed mash. The soybean paste prepared using this method exhibits a significant increase in the types and contents of flavor compounds for key aromas, a significant increase in the aroma activity value (OVA) related to ester and soy sauce aromas, and an increase in the proportion of L-glutamic acid, umami peptides (1-2 kD), and amino nitrogen content in the mash, resulting in a significantly enhanced umami sensory experience. Furthermore, this soybean paste preparation method does not involve the addition of monosodium glutamate (MSG) or umami enhancers, achieving additive-free processing. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application and to more completely understand this application and its beneficial effects, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 A flowchart of a method for preparing soybean paste according to one embodiment. Detailed Implementation

[0037] To facilitate understanding of this application, a more complete description of the application will be provided below with reference to relevant embodiments. Preferred embodiments of the application are given below. However, the application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0039] As used herein, the terms “and / or,” “or / and,” and “and / or” encompass any one of two or more of the relevant listed items, as well as any and all combinations of the relevant listed items, including any two of the relevant listed items, any more of the relevant listed items, or a combination of all the relevant listed items.

[0040] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0041] In this application, numerical ranges are involved. Unless otherwise specified, the numerical ranges mentioned above are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range.

[0042] This document only specifically discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0043] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows temperature fluctuations within the precision range controlled by the instrument, such as ±5°C, ±4°C, ±3°C, ±2°C, or ±1°C.

[0044] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0045] In this application, terms such as "further," "even further," and "particularly" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0046] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0047] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0048] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, but sequentially is preferred.

[0049] The soybean paste industry currently faces a significant product upgrade dilemma: on the one hand, market research shows that over 85% of consumers prioritize "additive-free" products when purchasing condiments; on the other hand, to cater to popular taste preferences, approximately 92% of commercially available soybean paste products still contain varying degrees of umami enhancers such as monosodium glutamate (MSG), yeast extract, and hydrolyzed animal and plant proteins (e.g., HVP / HAP). While this industrialized production model can quickly improve the flavor of products, it often comes at the cost of the loss of natural fermentation flavor and may result in unnecessary food additive residues.

[0050] Therefore, how to enhance the natural aroma, flavor, and taste of soybean paste is an urgent problem to be solved.

[0051] Studies have found that the aroma and flavor of soybean paste mainly come from polyols, esters, and aldehydes. Among the alcohols, isoamyl alcohol is the main contributor, followed by butanol, isobutanol, and propanol. Esters mainly consist of medium- and long-chain fatty acid esters such as ethyl palmitate, ethyl linoleate, and ethyl acetate, which contribute to the aroma. In addition, during the fermentation and maturation process, organic acids such as citric acid and succinic acid contained in the paste react with different higher alcohols to generate ester compounds, which can enhance the fermentation aroma level. Furthermore, in the fermentation process with excessive Maillard reactions, aldehydes, pyrazines, pyrroles, and other related aroma and flavor substances are produced, resulting in special aroma substances such as caramel and nutty aromas.

[0052] Based on the above problems, in the preparation of soybean paste in this application, some soybeans are steamed and then fermented with Aspergillus oryzae, followed by salt fermentation to obtain a mash rich in enzymatic hydrolysis substrates; some soybeans are stir-fried and then steamed, mixed with Saccharomyces roximatee for salt-free fermentation to produce a mash rich in reaction substrates such as fatty acids, oxidized fatty acids, alcohols and carboxylic acid esters; the two mashes are mixed and then subjected to high-temperature post-fermentation by controlling the pH value of the system to obtain special soy sauce aroma materials, giving the system a rich and special aroma and flavor.

[0053] One or more embodiments of this application provide a method for preparing soybean paste, comprising the following steps: steaming a first batch of soybeans to prepare a first batch of cooked whole soybeans; mixing the first batch of cooked whole soybeans, wheat flour, and Aspergillus oryzae to prepare koji; mixing the koji with brine and performing a first fermentation to prepare a first fermented paste mash; stir-frying a second batch of soybeans and steaming the stir-fried second batch of soybeans to prepare a second batch of cooked whole soybeans; grinding and emulsifying a mixture containing the second batch of cooked whole soybeans, Saccharomyces roximatee, and water to prepare a mixed emulsion; performing a second fermentation of the mixed emulsion under salt-free conditions to prepare a second fermented paste mash; and mixing the first fermented paste mash and the second fermented paste mash and performing a third fermentation to prepare a third fermented paste mash.

[0054] It should be noted that when preparing the second fermented soybean paste, the soybeans are stir-fried before steaming, which causes the protein in the soybeans to undergo special denaturation, producing a flavor-enhancing substrate for the later fermentation system.

[0055] When preparing the second fermented mash, introducing *Saccharomyces roximate* can decompose the fermentation substrate to produce alcohols and promote ester synthesis.

[0056] When preparing the second fermented mash, conducting the second fermentation under salt-free conditions helps to control the type and extent of the fermentation microbial reaction.

[0057] Understandably, the soybean paste preparation method of this application involves steaming a portion of soybeans, then preparing koji with Aspergillus oryzae, followed by salt fermentation to obtain a mash rich in enzymatically hydrolyzed substrates. Another portion of soybeans is roasted, then steamed, and mixed with Saccharomyces roximate for salt-free fermentation to obtain a mash rich in reaction substrates such as fatty acids, oxidized fatty acids, alcohols, and carboxylic acid esters. This provides aroma reaction substrates for subsequent mixing and fermentation with the mash rich in enzymatically hydrolyzed substrates. The soybean paste prepared using this method shows a significant increase in the types and contents of flavor compounds of key aroma species, a significant increase in the aroma activity value (OVA) related to ester aroma and soy sauce aroma, and an increase in the proportion of L-glutamic acid, umami peptides (1-2 kD), and amino nitrogen content in the mash, resulting in a significant improvement in umami sensory appeal. Furthermore, this soybean paste preparation method does not add monosodium glutamate or umami enhancers, achieving additive-free processing.

[0058] It should be noted that the terms "first soybean," "second soybean," "first cooked whole bean," "second cooked whole bean," "first fermentation," "second fermentation," "third fermentation," "first soy sauce mash," and "second soy sauce mash" mentioned in the context are for descriptive purposes only and should not be interpreted as indicating or implying relative importance or quantity, nor should they be interpreted as implicitly indicating the importance or quantity of the indicated technical features. Furthermore, "first," "second," and "third," etc., serve only a non-exhaustive enumeration purpose and should be understood as not constituting a closed limitation on quantity.

[0059] In some embodiments, when frying the second soybean, the frying temperature is 160℃-240℃; for example, it can be, but is not limited to, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃ or any range between two of the above temperatures.

[0060] As one possible implementation, when frying the second soybean, the frying time is 30-60 minutes; for example, it can be, but is not limited to, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes or any range between the above two times.

[0061] It should be noted that the frying temperature and time can be combined in any suitable way, and both can be selected from any of the frying temperatures and times described in this article.

[0062] When the second batch of soybeans is stir-fried, if the temperature and time are within the above-mentioned ranges, the proteins in the soybeans will undergo special denaturation, which will produce flavor-enhancing substrates for the later fermentation system.

[0063] In some embodiments, the moisture content of the second batch of roasted soybeans is 2wt%-5wt%; for example, it can be, but is not limited to, 2wt%, 2.2wt%, 2.4wt%, 2.6wt%, 2.8wt%, 3wt%, 3.2wt%, 3.4wt%, 3.6wt%, 3.8wt%, 4wt%, 4.2wt%, 4.4wt%, 4.6wt%, 4.8wt%, 5wt%, or any range between two of the above contents. This facilitates specific denaturation of the soybean proteins, providing a flavor-enhancing substrate for the subsequent fermentation system.

[0064] In some embodiments, the mass of the mixture is 2.2 to 3.5 times the mass of the second-ripened whole beans; for example, it can be, but is not limited to, 2.2 times, 2.4 times, 2.6 times, 2.8 times, 3 times, 3.2 times, 3.4 times, 3.5 times, or any range between two of the above values. This is beneficial for achieving optimal moisture content during the koji-making process.

[0065] As one possible implementation, the mixture contains 10g of *Saccharomyces rouxii*. ^ 6 CFU / g-10 ^ 9 CFU / g; for example, it can be, but is not limited to, 10. ^ 6 CFU / g, 5×10 ^ 6 CFU / g, 10 ^ 7 CFU / g, 5 × 10 ^ 7 CFU / g, 10 ^ 8 CFU / g, 5×10 ^ 8 CFU / g, 10 ^ 9 CFU / g or any two of the above concentrations. When the *Saccharomyces rouxii* concentration in the mixture is within the above range, it is beneficial for regulating the reaction type and extent of the fermenting microorganisms.

[0066] In some embodiments, the viscosity of the mixed emulsion is 10,000 Cp to 220,000 Cp; for example, it can be, but is not limited to, 10,000 Cp, 20,000 Cp, 40,000 Cp, 60,000 Cp, 80,000 Cp, 100,000 Cp, 120,000 Cp, 140,000 Cp, 160,000 Cp, 180,000 Cp, 200,000 Cp, 220,000 Cp, or any range between two of the above viscosity values. When the viscosity of the mixed emulsion is within the above range, it is beneficial to control the reaction type and degree of the fermenting microorganisms.

[0067] It should be noted that the viscosity of the mixed emulsion can be determined by referring to section 4, the rotation method, of GB / T 10247-2008 Viscosity Measurement Method.

[0068] In some embodiments, the mass ratio of the first fermented mash to the second fermented mash is 1:(1.5-3); for example, it can be, but is not limited to, 1:1.5, 1:1.6, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, 1:3, or any range between two of the above mass ratios. When the mass ratio of the first fermented mash to the second fermented mash is within the above range, it is beneficial to produce substances with optimal aroma.

[0069] In some alternative embodiments, the temperature of the third fermentation is 40°C-55°C; for example, it can be, but is not limited to, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 55°C, or any range between two of the above temperatures.

[0070] As one possible implementation method, the third fermentation time is 20-40 days; for example, it can be, but is not limited to, 20 days, 22 days, 24 days, 26 days, 28 days, 30 days, 32 days, 34 days, 36 days, 38 days, 40 days, or any range between two of the above times.

[0071] It should be noted that the temperature and time of the third fermentation can be combined in any suitable way, and both can be selected from any of the third fermentation temperatures and times described in this article.

[0072] In some embodiments, the temperature of the second fermentation is 25°C-35°C; for example, it can be, but is not limited to, 25°C, 26°C, 28°C, 30°C, 32°C, 34°C, 35°C, or any two of the above temperatures.

[0073] As one possible implementation, the second fermentation time is 60-80 days; for example, it can be, but is not limited to, 60 days, 62 days, 64 days, 66 days, 68 days, 70 days, 72 days, 74 days, 76 days, 78 days, 80 days, or any range between any two of the above times.

[0074] It should be noted that the temperature and time of the second fermentation can be combined in any suitable way, and both can be selected from any of the second fermentation temperatures and times described in this article.

[0075] In some optional embodiments, during the second fermentation process, from day 1 to day 20 of fermentation, aeration and stirring are performed every 1 to 3 days, with each stirring session lasting 10 to 30 minutes and an aeration rate of 1.5 m³ / (m³×min) to 2.5 m³ / (m³×min); from day 21 to day 60 of fermentation, aeration and stirring are performed every 3 to 7 days, with each stirring session lasting 5 to 10 minutes and an aeration rate of 0.5 m³ / (m³×min) to 1.0 m³ / (m³×min). This helps to ensure the oxygen concentration of the fermentation substrate, meeting the optimal fermentation effect of microorganisms in the fermented mash.

[0076] As a non-limiting example, during the first to 20 days of the second fermentation, the stirring time for a single aeration and stirring can be, but is not limited to, 10 min, 15 min, 20 min, 25 min, 30 min, or any range between any two of the above times. The aeration rate for a single aeration and stirring can be, but is not limited to, 1.5 m³ / (m³×min), 1.6 m³ / (m³×min), 1.8 m³ / (m³×min), 2.0 m³ / (m³×min), 2.2 m³ / (m³×min), 2.4 m³ / (m³×min), 2.6 m³ / (m³×min), or any range between any two of the above aeration rates.

[0077] During the second fermentation period from day 21 to day 60, the stirring time for a single aeration and stirring can be, but is not limited to, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, or any range between two of the above times. The aeration rate for a single aeration and stirring can be, but is not limited to, 0.5 m³ / (m³×min), 0.6 m³ / (m³×min), 0.7 m³ / (m³×min), 0.8 m³ / (m³×min), 0.9 m³ / (m³×min), 1.0 m³ / (m³×min), 2.6 m³ / (m³×min), or any range between two of the above times.

[0078] As one possible implementation method, the parameters for steaming the roasted second soybeans include: steaming pressure of 0.1MPa-0.2MPa and soybean pressure of 0.1kg-0.5kg.

[0079] The steaming pressure for the second batch of roasted soybeans can be, but is not limited to, 0.1 MPa, 0.12 MPa, 0.14 MPa, 0.16 MPa, 0.18 MPa, 0.2 MPa, or any two of the above pressures.

[0080] When steaming the second batch of roasted soybeans, the pressure on the soybeans can be, but is not limited to, 0.1 kg, 0.2 kg, 0.3 kg, 0.4 kg, 0.5 kg, or any two of the above pressures. When the soybean pressure is between 0.1 kg and 0.5 kg, the protein denaturation and decomposition of key substances in the cooked soybeans are at a better level, meeting the requirements for subsequent koji making and fermentation.

[0081] It should be noted that the test method for bean pressure is as follows: select 50 cooked soybeans evenly, flatten them on a weighing tray, record the maximum weight of each bean during the pressing, and take the average value of the 50 beans as the bean pressure.

[0082] In some embodiments, before steaming or boiling the roasted soybeans, the roasted soybeans are soaked in water, and the mass of the soaked soybeans is 2.0 to 2.6 times the mass of the soybeans before roasting; for example, it can be, but is not limited to, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6 times, or any range between two of the above values. This is beneficial for achieving optimal moisture content during the koji-making process.

[0083] In some optional embodiments, when soaking the roasted soybeans in water, the mass of the water is 3 to 3.5 times the mass of the soybeans; for example, it can be, but is not limited to, 3.1, 3.2, 3.3, 3.4, 3.5 times, or any range between any two of the above values. The soaking time is 4 hours to 16 hours; for example, it can be, but is not limited to, 4 hours, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, or any range between any two of the above times.

[0084] In some embodiments, the mass of wheat flour is 35%-50% of the mass of the first soybean; for example, it can be, but is not limited to, 35%, 40%, 45%, 50% or any range between the above two values.

[0085] As one possible implementation, the mass of Aspergillus oryzae is 0.02%-0.05% of the mass of the first soybean; for example, it can be, but is not limited to, 0.02%, 0.03%, 0.04%, 0.05%, or any range between two of the above values. This is beneficial for Aspergillus oryzae to be in an optimal growth state.

[0086] In some alternative implementations, the temperature for koji making is 30°C-35°C; for example, it can be, but is not limited to, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, or any range between two of the above temperatures.

[0087] In some exemplary embodiments, the koji-making time is 20h-30h; for example, it can be, but is not limited to, 20h, 22h, 24h, 26h, 28h, 30h or any range between the above two times.

[0088] In some of these implementations, the wind frequency for melody production is 25Hz-50Hz; for example, it can be, but is not limited to, 25Hz, 30Hz, 35Hz, 40Hz, 45Hz, 50Hz, or any range between any two of the above wind frequencies.

[0089] It should be noted that the temperature, time, and wind frequency of music production can be combined in any suitable way, and each of the three can be selected from any music production temperature, time, and wind frequency described in this article.

[0090] In some embodiments, the mass of the brine is 1 to 1.5 times the mass of the first soybean; for example, it can be, but is not limited to, 1.1 times, 1.2 times, 1.3 times, 1.4 times, 1.5 times, or any range between two of the above values.

[0091] In some alternative embodiments, the salt content of the system obtained after mixing the koji and brine is 10%-12%; for example, it can be, but is not limited to, 10%, 11%, 12% or any range between the above two values.

[0092] In one possible implementation, the temperature of the first fermentation is 30°C-40°C; for example, it can be, but is not limited to, 30°C, 32°C, 34°C, 36°C, 38°C, 40°C, or any range between two of the above temperatures.

[0093] In some alternative implementations, the first fermentation time is 30 to 50 days; for example, it can be, but is not limited to, 30 days, 35 days, 40 days, 45 days, 50 days or any range between the above two times.

[0094] It should be noted that the temperature and time of the first fermentation can be combined in any suitable way, and both can be selected from any of the first fermentation temperatures and times described in this article.

[0095] In some embodiments, the first soybeans are soaked in water before being steamed or boiled.

[0096] In some alternative implementations, the mass of water is 1 to 1.5 times the mass of the first soybean, and the soaking time is 2 to 3.5 hours.

[0097] As a non-limiting example, the mass of water is 1 to 1.5 times the mass of the first batch of soybeans; for example, it can be, but is not limited to, 1.1, 1.2, 1.3, 1.4, 1.5 times, or any range between any two of the above values. The soaking time can be, but is not limited to, 2 hours, 2.5 hours, 3 hours, 3.5 hours, or any range between any two of the above times.

[0098] In some embodiments, the method for preparing soybean paste further includes mixing a third mash with a seasoning agent.

[0099] In some alternative implementations, the flavoring agents include white sugar and garlic.

[0100] like Figure 1 As shown, in some embodiments, the preparation method of soybean paste includes the following steps:

[0101] S1. Preparation of the first fermented sauce:

[0102] S11. Steaming and cooking treatment: Select non-GMO soybeans, remove impurities, stones, and color sort as the first soybeans. Soak the soybeans in a soaking tank, add water with 1 to 1.5 times the weight of the first soybeans, and soak for 2 to 3.5 hours. Steam the soaked first soybeans until they are cooked, not undercooked, not peeled, not clumped together, and have the right softness and firmness. Cool to 40°C to obtain the first cooked whole soybeans.

[0103] S12. Koji-making process: Wheat flour is added to the first batch of whole soybeans, with the amount of wheat flour added being 50% of the weight of the first batch of soybeans. After being evenly mixed by an auger, 0.05% of Aspergillus oryzae by weight of the first batch of soybeans is added. Then, the mixture is conveyed to the koji-making room via a conveyor belt for koji-making. The koji-making process is carried out in a ventilated environment. The temperature of the koji-making material is controlled at 30℃-35℃, the air frequency is controlled at 25Hz-50Hz, and the cultivation time is 20h-30h to obtain the finished koji.

[0104] S13. Fermentation process 1: Mix the starter culture and brine. The amount of brine added is 1 to 1.5 times the weight of the first soybeans. The salt content of the system is controlled at 10% to 12%. The temperature is controlled at 30℃ to 40℃. After 30 to 50 days of first fermentation, the first sauce mash is obtained.

[0105] S2. Preparation of the second fermented sauce:

[0106] S21. Roasting process: Select non-GMO soybeans, which are then cleaned of impurities, stones, and color-sorted to serve as the second soybeans. Put the second soybeans into a rotating roasting pan and use hot air circulation to ensure uniform roasting. The roasting temperature is controlled within the range of 160℃-240℃, and the roasting time is controlled within the range of 30min-60min. After roasting, the moisture content of the second soybeans should be controlled within the range of 2%-5%.

[0107] S22. Steaming and Cooking Process: After roasting, the second batch of soybeans is washed and placed in a soaking tank with 3-3.5 times their weight in water. Soak for 4-16 hours, ensuring the soybeans absorb water and increase in weight to 2.0-2.6 times their original weight before roasting. Then, steam at a pressure of 0.10-0.20 MPa, controlling the pressure on the soybeans at approximately 0.1-0.5 kg. Cool to 40°C to obtain the second batch of whole roasted soybeans.

[0108] S23. Mixing and milling: Mix the second-ripened whole soybeans with the yeast extract and water, then mill and emulsify. The total weight of the mixed material is controlled within the range of 2.2 to 3.5 times the weight of the second-ripened whole soybeans. The number of yeast cells in the mixed system is controlled within the range of 10^6 CFU / g to 10^9 CFU / g. The viscosity after emulsification is controlled within the range of 10000 Cp to 220000 Cp.

[0109] S24. Fermentation Process 2: The temperature of the mixed materials is controlled within the range of 25℃-35℃ for salt-free fermentation, i.e., the second fermentation. During the first 1-20 days of fermentation, aeration and stirring are carried out every 1-3 days, with each stirring time controlled at 10-30 minutes and the aeration rate controlled at 1.5m³ / (m³×min)-2.5m³ / (m³×min); during the second 21-60 days of fermentation, aeration and stirring are carried out every 3-7 days, with each stirring time controlled at 5-10 minutes and the aeration rate controlled at 0.5m³ / (m³×min)-1.0m³ / (m³×min); the total fermentation takes 60-80 days to mature, yielding the second fermented sauce mash.

[0110] S3. Preparation of the third type of fermented sauce:

[0111] After mixing the first and second fermented soybean pastes at a mass ratio of 1:1.5 to 1:3 and stirring evenly, the third fermentation is carried out. The fermentation temperature is controlled within the range of 40℃-55℃. Finally, the fermented soybean paste is fermented for 20 to 40 days and then matures into the third fermented soybean paste.

[0112] S4. Cooking the finished product: After adding various seasonings to the third sauce mash, the soybean paste is obtained. The soybean paste is boiled for 10-40 minutes, cooled to 80℃, and bottled while hot.

[0113] One or more embodiments of this application provide a soybean paste prepared using the soybean paste preparation method described above.

[0114] The types and contents of flavor compounds of key aroma species in this soy sauce are significantly improved, and the aroma activity value (OVA) related to ester aroma and soy sauce aroma is significantly improved; in addition, the proportion of L-glutamic acid, umami peptides (1-2kD) in the soy sauce and the content of amino nitrogen in the soy sauce mash are all increased, and the umami sensory experience is significantly improved.

[0115] The technical solutions of this application will be described in detail below with reference to specific embodiments. It should be understood that these embodiments are only for illustrating this application and are not intended to limit the scope of this application. For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this application first, or follow experimental manuals or conventional conditions in the field, or follow the conditions recommended by the manufacturer, or refer to experimental methods known in the field.

[0116] In the specific embodiments described below, the measurement parameters involving raw material components may have slight deviations within the weighing accuracy range unless otherwise specified. Temperature and time parameters are subject to acceptable deviations due to instrument testing accuracy or operational precision.

[0117] It should be noted that,

[0118] The concentration of *Saccharomyces rouxii* culture used in the following examples and comparative examples is 6 × 10⁻⁶. 8 CFU / mL.

[0119] The flavoring agents used in the following examples and comparative examples are 5 wt% white sugar and 2 wt% garlic.

[0120] I. Preparation of Soybean Paste

[0121] Example 1

[0122] S1. Preparation of the first fermented sauce:

[0123] S11. Steaming and cooking treatment: 100 kg of non-GMO soybeans were selected and treated as the first batch of soybeans after impurity removal, stone removal and color sorting. The soybeans were soaked in a soaking tank with 120 kg of water for 2.8 hours. The soaked soybeans were then steamed until they were cooked without being undercooked, peeling, clumping, or too soft. They were then cooled to 40°C to obtain the first batch of cooked whole soybeans.

[0124] S12. Koji-making process: Wheat flour is added to the first batch of whole soybeans, with the amount of wheat flour added being 50% of the first batch of soybeans, i.e., 50 kg; after being evenly mixed by the auger, 0.05 kg of Aspergillus oryzae is added, and then the mixture is conveyed to the koji-making room via a conveyor belt for koji-making. The koji-making process is carried out with ventilation, and the temperature of the koji-making material is controlled at 32℃, the air frequency is controlled at 28Hz, and the cultivation time is 26 hours to obtain the finished koji.

[0125] S13. Fermentation process 1: Mix 100kg of koji with brine, add 120kg of brine, control the salt content of the system at 11%, and control the temperature at 35℃ for the first fermentation for 42 days to obtain the first sauce mash.

[0126] S2. Preparation of the second fermented sauce:

[0127] S21. Roasting process: Select 200kg of non-GMO soybeans, which are then cleaned of impurities, stones, and color-sorted as the second batch of soybeans. Put the second batch of soybeans into a rotating roasting pan and use hot air circulation to ensure uniform roasting. The roasting temperature is controlled at 180℃ and the roasting time is controlled at 45min. The moisture content of the second batch of soybeans after roasting should be controlled at 3%.

[0128] S22. Steaming and cooking process: After frying, the second batch of soybeans is washed and placed in a soaking tank with 600 kg of water. It is soaked for 5 hours to ensure that the weight of the second batch of soybeans increases to 400 kg after absorbing water. Then, it is steamed at a pressure of 0.11 MPa with the pressure of the soybeans controlled at 0.3 kg. After cooling to 40°C, the second batch of whole soybeans is obtained.

[0129] S23. Mixing and milling: Mix 150kg of second-ripened whole soybeans with 200kg of Rhus oryzae liquid, then mill and emulsify. After mixing, the number of yeast cells in the system is controlled at 3.43×10^8 CFU / g, and the viscosity after emulsification is controlled at 12000Cp.

[0130] S24. Fermentation Process 2: The temperature of the mixed materials is controlled at 28℃ for salt-free fermentation, i.e., the second fermentation. During fermentation 1-20 days, aeration and stirring are performed every 2 days, with each stirring time controlled at 15 minutes and the aeration rate controlled at 1.8 m³ / (m³×min); during fermentation 21-60 days, aeration and stirring are performed every 5 days, with each stirring time controlled at 8 minutes and the aeration rate controlled at 0.8 m³ / (m³×min); the total fermentation takes 66 days to mature, yielding the second fermented sauce mash.

[0131] S3. Preparation of the third type of fermented sauce:

[0132] The first and second fermented soybean pastes are mixed at a mass ratio of 1:1.8 and stirred evenly before undergoing a third fermentation. The fermentation temperature is controlled at 48℃. Finally, the soybean paste is fermented for 28 days and matures into the third fermented soybean paste.

[0133] S4. Cooking the finished product: After adding various seasonings to the third sauce mash, the soybean paste is obtained. The soybean paste is boiled for 40 minutes, cooled to 80℃, and bottled while hot.

[0134] Example 2

[0135] S1. Preparation of the first fermented sauce:

[0136] S11. Steaming and cooking treatment: 100 kg of non-GMO soybeans were selected and treated as the first batch of soybeans after impurity removal, stone removal and color sorting. The soybeans were soaked in a soaking tank with 150 kg of water for 3.0 h. The soaked soybeans were then steamed until they were cooked without being undercooked, peeling, clumping, or too soft. They were then cooled to 40°C to obtain the first batch of cooked whole soybeans.

[0137] S12. Koji-making process: Wheat flour is added to the first batch of whole soybeans, with the amount of wheat flour added being 50% of the first batch of soybeans, i.e., 50 kg; after being evenly mixed by the auger, 0.05 kg of Aspergillus oryzae is added, and then the mixture is conveyed to the koji-making room via a conveyor belt for koji-making. The koji-making process is carried out with ventilation, and the temperature of the koji-making material is controlled at 35℃, the air frequency is controlled at 50 Hz, and the cultivation time is 30 h to obtain the finished koji.

[0138] S13. Fermentation process 1: Mix 100kg of starter culture with brine, add 150kg of brine, control the salt content of the system at 12%, and control the temperature at 40℃ for the first fermentation for 50 days to obtain the first sauce mash.

[0139] S2. Preparation of the second fermented sauce:

[0140] S21. Roasting process: Select 200kg of non-GMO soybeans, which are then cleaned of impurities, stones, and color-sorted as the second soybeans. Put the second soybeans into a rotating roasting pan and use hot air circulation to ensure uniform roasting. The roasting temperature is controlled at 220℃ and the roasting time is controlled at 60min. The moisture content of the second soybeans after roasting should be controlled at 2%.

[0141] S22. Steaming and cooking process: After frying, the second batch of soybeans is washed and placed in a soaking tank with 700 kg of water. It is soaked for 4.5 hours to ensure that the weight of the second batch of soybeans increases to 500 kg after absorbing water. Then, it is steamed at a pressure of 0.115 MPa with the pressure of the soybeans controlled at 0.2 kg. After cooling to 40°C, the second batch of whole soybeans is obtained.

[0142] S23. Mixing and milling: Mix 150kg of second-ripened whole soybeans with 200kg of Rhus oryzae liquid, then mill and emulsify. After mixing, the number of yeast cells in the system is controlled at 3.43×10^8 CFU / g, and the viscosity after emulsification is controlled at 11000Cp.

[0143] S24. Fermentation Process 2: The temperature of the mixed materials is controlled at 30℃ for salt-free fermentation, i.e., the second fermentation. During fermentation 1-20 days, aeration and stirring are performed every 3 days, with each stirring time controlled at 25 minutes and the aeration rate controlled at 1.9 m³ / (m³×min); during fermentation 21-60 days, aeration and stirring are performed every 5 days, with each stirring time controlled at 8 minutes and the aeration rate controlled at 0.9 m³ / (m³×min); the total fermentation takes 72 days to mature, yielding the second fermented sauce mash.

[0144] S3. Preparation of the third type of fermented sauce:

[0145] The first and second fermented soybean pastes are mixed at a mass ratio of 1:2 and stirred evenly before undergoing a third fermentation. The fermentation temperature is controlled at 48℃. Finally, the soybean paste is fermented for 32 days and matures into the third fermented soybean paste.

[0146] S4. Cooking the finished product: After adding various seasonings to the third sauce mash, the soybean paste is obtained. The soybean paste is boiled for 10 minutes, cooled to 80℃, and bottled while hot.

[0147] Example 3

[0148] S1. Preparation of the first fermented sauce:

[0149] S11. Steaming and cooking treatment: 100 kg of non-GMO soybeans were selected and treated as the first batch of soybeans after impurity removal, stone removal, and color sorting. The soybeans were soaked in a soaking tank with 100 kg of water for 2.2 hours. The soaked soybeans were then steamed until they were cooked without being undercooked, peeling, clumping, or having the right texture. The mixture was then cooled to 40°C to obtain the first batch of cooked whole soybeans.

[0150] S12. Koji-making process: Wheat flour is added to the first batch of whole soybeans, with the amount of wheat flour added being 50% of the first batch of soybeans, i.e., 50 kg; after being evenly mixed by the auger, 0.05 kg of Aspergillus oryzae is added, and then the mixture is conveyed to the koji-making room via a conveyor belt for koji-making. The koji-making process is carried out with ventilation, and the temperature of the koji-making material is controlled at 31℃, the air frequency is controlled at 25Hz, and the cultivation time is 22 hours to obtain the finished koji.

[0151] S13. Fermentation process 1: Mix 100kg of starter culture with brine, add 100kg of brine, control the salt content of the system at 10.5%, and control the temperature at 32℃ for the first fermentation for 35 days to obtain the first sauce mash.

[0152] S2. Preparation of the second fermented sauce:

[0153] S21. Roasting process: Select 200kg of non-GMO soybeans, remove impurities, stones and color sort them as second soybeans. Put the second soybeans into a rotating roasting pan and use hot air circulation to ensure uniform roasting. The roasting temperature is controlled at 170℃ and the roasting time is controlled at 35min. The moisture content of the second soybeans after roasting is controlled at 4.5%.

[0154] S22. Steaming and cooking process: After frying, the second batch of soybeans is washed and placed in a soaking tank with 650 kg of water. It is soaked for 12 hours to ensure that the weight of the second batch of soybeans increases to 450 kg after absorbing water. Then, it is steamed at a pressure of 0.180 MPa with the pressure of the soybeans controlled at 0.1 kg. After cooling to 40°C, the second batch of whole soybeans is obtained.

[0155] S23. Mixing and milling: Mix 150kg of second-ripened whole soybeans with 270kg of Rhus oryzae liquid, then mill and emulsify. After mixing, the number of yeast cells in the system is controlled at 3.86×10^8 CFU / g, and the viscosity after emulsification is controlled at 18000 Cp.

[0156] S24. Fermentation Process 2: The temperature of the mixed materials is controlled at 28℃ for salt-free fermentation, i.e., the second fermentation. During fermentation 1-20 days, aeration and stirring are performed every 3 days, with each stirring time controlled at 12 minutes and the aeration rate controlled at 2.2 m³ / (m³×min); during fermentation 21-60 days, aeration and stirring are performed every 5 days, with each stirring time controlled at 6 minutes and the aeration rate controlled at 0.9 m³ / (m³×min); the total fermentation takes 62 days to mature, yielding the second fermented sauce mash.

[0157] S3. Preparation of the third type of fermented sauce:

[0158] The first and second fermented soybean pastes are mixed at a mass ratio of 1:2.2 and stirred evenly before undergoing a third fermentation. The fermentation temperature is controlled at 48℃. After 22 days of fermentation, the soybean paste is matured into the third fermented soybean paste.

[0159] S4. Cooking the finished product: After adding various seasonings to the third sauce mash, the soybean paste is obtained. The soybean paste is boiled for 20 minutes, cooled to 80℃, and bottled while hot.

[0160] Comparative Example 1

[0161] In Comparative Example 1, the second soybeans were not stir-fried; they were directly steamed. The specific preparation method for Comparative Example 1 is as follows:

[0162] S1. Preparation of the first fermented sauce:

[0163] S11. Steaming and cooking treatment: 100 kg of non-GMO soybeans were selected and treated as the first batch of soybeans after impurity removal, stone removal and color sorting. The soybeans were soaked in a soaking tank with 150 kg of water for 3.0 h. The soaked soybeans were then steamed until they were cooked without being undercooked, peeling, clumping, or too soft. They were then cooled to 40°C to obtain the first batch of cooked whole soybeans.

[0164] S12. Koji-making process: Wheat flour is added to the first batch of whole soybeans, with the amount of wheat flour added being 50% of the first batch of soybeans, i.e., 50 kg; after being evenly mixed by the auger, 0.05 kg of Aspergillus oryzae is added, and then the mixture is conveyed to the koji-making room via a conveyor belt for koji-making. The koji-making process is carried out with ventilation, and the temperature of the koji-making material is controlled at 35℃, the air frequency is controlled at 50 Hz, and the cultivation time is 30 h to obtain the finished koji.

[0165] S13. Fermentation process 1: Mix 100kg of starter culture with brine, add 150kg of brine, control the salt content of the system at 12%, and control the temperature at 40℃ for the first fermentation for 50 days to obtain the first sauce mash.

[0166] S2. Preparation of the second fermented sauce:

[0167] S21. Cooking Process: 200 kg of non-GMO soybeans were selected and, after impurity removal, stone removal, and color sorting, were used as the second batch of soybeans. The second batch of soybeans were washed and placed in a soaking tank with 620 kg of water for 12 hours, ensuring the weight of the second batch of soybeans increased to 450 kg after water absorption. They were then cooked at a pressure of 0.180 MPa, with the pressure on the soybeans controlled at 0.1 kg. The mixture was cooled to 40°C to obtain the second batch of cooked whole soybeans.

[0168] S22. Mixing and milling: Mix 150kg of second-ripened whole soybeans with 270kg of Rhus oryzae liquid, then mill and emulsify. After mixing, the number of yeast cells in the system is controlled at 3.86×10^8 CFU / g, and the viscosity after emulsification is controlled at 18000 Cp.

[0169] S23. Fermentation Process 2: The temperature of the mixed materials is controlled at 28℃ for salt-free fermentation, i.e., the second fermentation. During fermentation 1-20 days, aeration and stirring are performed every 3 days, with each stirring time controlled at 12 minutes and the aeration rate controlled at 2.2 m³ / (m³×min); during fermentation 21-60 days, aeration and stirring are performed every 4 days, with each stirring time controlled at 6 minutes and the aeration rate controlled at 0.9 m³ / (m³×min); the total fermentation takes 62 days to mature, yielding the second fermented sauce mash.

[0170] S3. Preparation of the third type of fermented sauce:

[0171] The first and second fermented soybean pastes are mixed at a mass ratio of 1:2.2 and stirred evenly before undergoing a third fermentation. The fermentation temperature is controlled at 48℃. After 22 days of fermentation, the soybean paste is matured into the third fermented soybean paste.

[0172] S4. Cooking the finished product: After adding various seasonings to the third sauce mash, the soybean paste is obtained. The soybean paste is boiled for 20 minutes, cooled to 80℃, and bottled while hot.

[0173] Comparative Example 2

[0174] In Comparative Example 2, no yeast extract was added during the preparation of the second fermented soybean mash. Instead, the second-ripened whole soybeans were mixed with water and then milled and emulsified. The specific preparation method for Comparative Example 2 is as follows:

[0175] S1. Preparation of the first fermented sauce:

[0176] S11. Steaming and cooking treatment: 100 kg of non-GMO soybeans were selected and treated as the first batch of soybeans after impurity removal, stone removal, and color sorting. The soybeans were soaked in a soaking tank with 100 kg of water for 2.1 hours. The soaked soybeans were then steamed until they were cooked without being undercooked, peeling, clumping, or having the right texture. The mixture was then cooled to 40°C to obtain the first batch of cooked whole soybeans.

[0177] S12. Koji-making process: Wheat flour is added to the first batch of whole soybeans, with the amount of wheat flour added being 50% of the first batch of soybeans, i.e., 50 kg; after being evenly mixed by the auger, 0.05 kg of Aspergillus oryzae is added, and then the mixture is conveyed to the koji-making room via a conveyor belt for koji-making. The koji-making process is carried out with ventilation, and the temperature of the koji-making material is controlled at 31℃, the air frequency is controlled at 28Hz, and the cultivation time is 30 hours to obtain the finished koji.

[0178] S13. Fermentation process 1: Mix 100kg of starter culture with brine, add 110kg of brine, control the salt content of the system at 10.8%, and control the temperature at 32℃ for the first fermentation for 35 days to obtain the first sauce mash.

[0179] S2. Preparation of the second fermented sauce:

[0180] S21. Roasting process: Select 200kg of non-GMO soybeans, which are then cleaned of impurities, stones, and color-sorted as the second batch of soybeans. Put the second batch of soybeans into a rotating roasting pan and use hot air circulation to ensure uniform roasting. The roasting temperature is controlled at 180℃ and the roasting time is controlled at 35min. The moisture content of the second batch of soybeans after roasting should be controlled at 4.2%.

[0181] S22. Steaming and cooking process: After frying, the second batch of soybeans is washed and placed in a soaking tank with 650 kg of water. It is soaked for 12 hours to ensure that the weight of the second batch of soybeans increases to 450 kg after absorbing water. Then, it is steamed at a pressure of 0.180 MPa with the pressure of the soybeans controlled at 0.1 kg. After cooling to 40°C, the second batch of whole soybeans is obtained.

[0182] S23. Mixing and grinding: Mix 150kg of second-ripened whole beans with 270kg of water and grind and emulsify them. The viscosity after emulsification is controlled at 19000Cp.

[0183] S24. Fermentation Process 2: The temperature of the mixed materials is controlled at 28℃ for salt-free fermentation, i.e., the second fermentation. During fermentation 1-20 days, aeration and stirring are performed every 3 days, with each stirring time controlled at 12 minutes and the aeration rate controlled at 2.2 m³ / (m³×min); during fermentation 21-60 days, aeration and stirring are performed every 4 days, with each stirring time controlled at 6 minutes and the aeration rate controlled at 0.9 m³ / (m³×min); the total fermentation takes 62 days to mature, yielding the second fermented sauce mash.

[0184] S3. Preparation of the third type of fermented sauce:

[0185] The first and second fermented soybean pastes are mixed at a mass ratio of 1:2 and stirred evenly before undergoing a third fermentation. The fermentation temperature is controlled at 48℃. Finally, the soybean paste is fermented for 32 days and matures into the third fermented soybean paste.

[0186] S4. Cooking the finished product: After adding various seasonings to the third sauce mash, the soybean paste is obtained. The soybean paste is boiled for 10 minutes, cooled to 80℃, and bottled while hot.

[0187] Comparative Example 3

[0188] The preparation method of Comparative Example 3 is similar to that of Example 1, except that when preparing the second mash in Comparative Example 3, *Saccharomyces cerevisiae* was used instead of *Saccharomyces rouxii* liquid, while all other aspects were the same.

[0189] Comparative Example 4

[0190] The preparation method of Comparative Example 4 is similar to that of Example 1, except that in Comparative Example 4, all soybeans were treated in step S1 to prepare the first fermented soybean paste, but step S2 was not performed. All other steps were the same. The specific preparation method of Comparative Example 4 is as follows:

[0191] S1. Preparation of the first fermented sauce:

[0192] S11. Steaming and cooking treatment: Select 300 kg of non-GMO soybeans, remove impurities, stones, and color sort as the first batch of soybeans. Soak the soybeans in a soaking tank with 360 kg of water for 2.8 hours. Then steam the soaked soybeans until they are cooked without being undercooked, peeling, clumping, or too soft. Cool them to 40°C to obtain the first batch of cooked whole soybeans.

[0193] S12. Koji-making process: Wheat flour is added to the first batch of whole soybeans, with the amount of wheat flour added being 50% of the first batch of soybeans, i.e., 150 kg; after being evenly mixed by the auger, 0.15 kg of Aspergillus oryzae is added, and then the mixture is conveyed to the koji-making room via a conveyor belt for koji-making. The koji-making process is carried out with ventilation, and the temperature of the koji-making material is controlled at 32℃, the air frequency is controlled at 28Hz, and the cultivation time is 26 hours to obtain the finished koji.

[0194] S13. Fermentation process 1: Mix 300kg of koji and brine, add 360kg of brine, control the salt content of the system at 11%, and control the temperature at 35℃ for the first fermentation for 42 days to obtain the first sauce mash.

[0195] S2. Preparation of the third type of fermented sauce:

[0196] The first batch of fermented soybean paste undergoes a third fermentation, with the fermentation temperature controlled at 48℃. After 28 days of fermentation, the soybean paste matures into the third batch of fermented soybean paste.

[0197] S3. Cooking the finished product: After adding various seasonings to the third sauce mash, the soybean paste is obtained. The soybean paste is boiled for 40 minutes, cooled to 80℃, and bottled while hot.

[0198] II. Physicochemical and Sensory Analysis and Testing

[0199] 1. Total acid / amino acid nitrogen content detection: determined according to standard Q / HT-JF-00-033.

[0200] 2. L-glutamic acid content detection: determined according to standard Q / HT-JF-03-028.

[0201] 3. Total nitrogen content detection method: Determined according to standard GB 4789.2-2010.

[0202] 4. Peptide Detection Methods

[0203] Peptide distribution was tested according to Appendix A of GB / T 22492-2008, using GPC / UV. Based on the peptide distribution test results, the mass percentage of peptides with specific molecular weights in the total peptides was calculated and denoted as "peptide / total peptide percentage".

[0204] 5. Criteria for judging the aroma of soybean paste

[0205] Based on the classification of special aroma substances in soybean paste (divided into ester aroma, soy sauce aroma, etc.): 1 point; strong sourness / strong koji aroma and other off-flavors: 2 points; slightly weak aroma / slight koji aroma / slight sourness: 3 points; slightly soy sauce aroma (ester aroma) to strong soy sauce aroma (ester aroma), no off-flavors: 4 points; strong soy sauce aroma (ester aroma), rich aroma: 5 points.

[0206] 6. Criteria for Judging the Taste of Soybean Paste

[0207] Very weak umami: 1 point; weak umami: 2 points; medium umami: 3 points; strong umami: 4 points; high umami: 5 points.

[0208] Strange taste: 1 point; Unharmonious: 2 points; Harmonious: 3 points; Good harmony: 4 points; Very harmonious: 5 points.

[0209] The test results of the above embodiments and comparative examples are shown in Table 1.

[0210] Table 1

[0211]

[0212] III. Qualitative and Quantitative Determination of Aroma Compounds

[0213] The types and contents of flavor compounds in fermented soybean paste were determined by solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS).

[0214] Solid-phase microextraction (SPME) conditions and methods: Centrifuge the fermented soybean paste sample at 5000 rpm for 5 min, take 5 ml of the supernatant and aspirate it into the extraction flask, then heat and stir in a water bath (55℃, stirring for 30 min). Subsequently, insert the extraction head for adsorption for 30 min, and then remove it.

[0215] Gas chromatography-mass spectrometry (GC-MS) conditions: GC employed a programmed temperature ramp, starting at 40 °C, holding for 10 min, then ramping at 4 °C / min to 150 °C, followed by ramping at 8 °C / min to 250 °C. Nitrogen was used as the carrier gas, with a column flow rate of 1 ml / min and a total flow rate of 9 ml / min. The mass spectrometry interface temperature was 220 °C, the ion source temperature was controlled at 230 °C, EI was used, ionization was 70 eV, and the scan range was 33-450 amu.

[0216] By comparing the mass spectra recorded by the mass spectrometer with standard mass spectra, compounds were identified and their relative contents were determined by area normalization for quantification.

[0217] The aroma activity values ​​(OVA) of the key aroma compounds in the above embodiments and comparative examples are shown in Table 2; the types and proportions of aroma components are shown in Table 3.

[0218] Table 2

[0219]

[0220] Table 3

[0221]

[0222] As shown in Tables 1-3, the soybean paste prepared by the method of this application exhibits a significant increase in the types and contents of flavor compounds for each key aroma component, a significant increase in the aroma activity value (OVA) related to ester aroma and soy sauce aroma, and an increase in the proportion of L-glutamic acid, umami peptides (1-2 kD), and amino nitrogen content in the soy sauce mash, resulting in a significant improvement in umami sensory flavor. Furthermore, this soybean paste preparation method does not involve the addition of monosodium glutamate or umami enhancers, achieving additive-free preparation.

[0223] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0224] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing soybean paste, characterized in that, Includes the following steps: The first batch of soybeans is steamed to prepare the first batch of cooked whole soybeans; The first-cooked whole soybeans, wheat flour and Aspergillus oryzae are mixed and then used to make koji. The koji and brine are mixed and then subjected to a first fermentation to prepare the first sauce mash. The second soybean is stir-fried, and the stir-fried second soybean is then steamed to prepare the second cooked whole soybean. A mixture containing second-ripened whole soybeans, yeast rhubarb, and water is milled and emulsified to prepare a mixed emulsion. Under salt-free conditions, the mixed milk is subjected to a second fermentation to prepare a second soy sauce mash; The first and second sauce mashes are mixed and then subjected to a third fermentation to prepare the third sauce mashe.

2. The method for preparing soybean paste as described in claim 1, characterized in that, The frying temperature is 160℃-240℃, and the time is 30min-60min; and / or, The moisture content of the second soybean after stir-frying is 2wt%-5wt%.

3. The method for preparing soybean paste as described in claim 1, characterized in that, The mass of the mixture is 2.2 to 3.5 times the mass of the second cooked whole beans; and / or, The content of *Saccharomyces rouxii* in the mixture is 10. ^ 6 CFU / g-10 ^ 9 CFU / g; and / or, The viscosity of the mixed emulsion is 10000Cp-220000Cp.

4. The method for preparing soybean paste as described in claim 1, characterized in that, The mass ratio of the first fermented soybean paste to the second fermented soybean paste is 1:(1.5-3); and / or, The third fermentation is carried out at a temperature of 40℃-55℃ for 20-40 days.

5. The method for preparing soybean paste as described in claim 1, characterized in that, The second fermentation is carried out at a temperature of 25℃-35℃ for 60-80 days; and / or, During the second fermentation process, from day 1 to day 20 of fermentation, aeration and stirring are carried out every 1 to 3 days, with a single stirring time of 10 to 30 minutes and an aeration rate of 1.5 m³ / (m³×min) to 2.5 m³ / (m³×min); from day 21 to day 60 of fermentation, aeration and stirring are carried out every 3 to 7 days, with a single stirring time of 5 to 10 minutes and an aeration rate of 0.5 m³ / (m³×min) to 1.0 m³ / (m³×min).

6. The method for preparing soybean paste as described in claim 1, characterized in that, The parameters for steaming the second batch of roasted soybeans include: steaming pressure of 0.1 MPa-0.2 MPa, and soybean pressure of 0.1 kg-0.5 kg; and / or, Before steaming or boiling the second soybeans after roasting, soak the roasted second soybeans in water. The weight of the second soybeans after absorbing water is 2.0 to 2.6 times that of the second soybeans before roasting.

7. The method for preparing soybean paste as described in claim 1, characterized in that, The mass of the wheat flour is 35%-50% of the mass of the first soybean; and / or, The mass of the Aspergillus oryzae is 0.02%-0.05% of the mass of the first soybean; and / or, The temperature for koji making is 30℃-35℃, the time is 20h-30h, and the wind frequency is 25Hz-50Hz.

8. The method for preparing soybean paste as described in claim 1, characterized in that, The mass of the brine is 1 to 1.5 times the mass of the first soybeans; and / or, The salt content of the system obtained after mixing the fermented rice and the brine is 10%-12%; and / or, The temperature for the first fermentation is 30℃-40℃, and the time is 30-50 days.

9. The method for preparing soybean paste according to any one of claims 1 to 8, characterized in that, Before steaming or boiling the first soybeans, the first soybeans are soaked in water. Optionally, the mass of the water is 1 to 1.5 times the mass of the first soybean, and the soaking time is 2 to 3.5 hours.

10. A type of soybean paste, characterized in that, It is prepared by the method for preparing soybean paste as described in any one of claims 1 to 9.

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