Brewing method of soybean paste

Abstract

The invention discloses a brewing method of soybean paste, and belongs to the technical field of fermented soybean products. According to the method, the fermentation process is controlled, the temperature and the fermentation stage are controlled, meanwhile, the mixed gas of oxygen and air is introduced in the fermentation process, self yeast can be proliferated on the basis of the fermentation characteristics of soy sauce mash and the growth characteristics of microbial flora, and meanwhile, the oxidation reaction rate and the Maillard reaction rate of the soybean paste are effectively regulated and controlled; therefore, the flavor substance content of the soybean paste is effectively increased, and the overall quality of the soybean paste is improved; the brewing method provided by the invention is simple to operate, simple in process and beneficial to large-scale production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fermented soy products, and particularly relates to a brewing method of soybean paste. BACKGROUND

[0002] The generation of sauce aroma and sauce flavor of soybean paste is mainly related to microbial fermentation and biochemical reactions. Yeast in microorganisms can produce alcohol, acid, ester, and heterocyclic flavor substances; the biochemical reactions mainly refer to Maillard reactions of hydroxyl compounds and reducing sugars generated in the fermentation process to generate aldehyde, heterocyclic sauce substances, and basic metabolites represented by ethanol to generate aldehyde, acid, ester, and other flavor substances through multi-step oxidation reactions.

[0003] Existing literatures or patents mainly focus on improving the flavor of soybean paste by adding exogenous microorganisms. For example, CN202410143041.X reports that the sauce aroma and thick flavor of the fermentation product are improved by inoculating Burton Pichia burtonii into the soy sauce fermentation broth, and patent CN202110275666.8 reports a strain of Saccharomyces cerevisiae which helps to significantly improve the sauce flavor when applied to soybean paste. Such methods have high requirements for the inoculation timing and fermentation microenvironment, and are prone to cause fluctuations in the quality of soybean paste. As for the patents for improving sauce aroma by improving the rate of Maillard reaction and oxidation reaction, patent 202311263236.X reports that the flavor of soybean paste is improved by changing the light and stage aeration fermentation, but the light is uncontrollable due to weather changes, which directly affects the quality stability of soybean paste; patent CN202310858055.5 significantly improves the aroma and taste of soy sauce by heating and oxygenating the soy sauce, but the fermentation process requires high-temperature heating of the soy sauce; considering the strict requirements of soybean paste on color, high temperature and excessive oxygenation will cause the color to be too dark, affecting the color sensation, and the fast Maillard reaction rate will generate bitter substances, greatly affecting the taste of soybean paste. SUMMARY

[0004] The present application aims to overcome the shortcomings of the prior art and provide a brewing method of soybean paste which can effectively improve the concentration of flavor substances, especially aldehyde substances, thereby improving the quality and flavor of soybean paste.

[0005] To achieve the above-mentioned purpose, in the first aspect of the present application, the present application provides a brewing method of soybean paste, which comprises the following steps: (1) mixing cooked soybeans with wheat flour after soaking and cooking, and then preparing koji to obtain finished koji; (2) mixing the finished koji with brine, and then sequentially performing first temperature-controlled fermentation and second temperature-controlled fermentation to obtain soybean paste; The temperature of the first temperature-controlled fermentation is 25-35℃, and the yeast number in the sauce mash obtained after the first temperature-controlled fermentation is 5×104 1x10 6 CFU / g; The temperature of the second temperature-controlled fermentation is 45-55℃. Ventilation is carried out during the first temperature-controlled fermentation and the second temperature-controlled fermentation, and the gas is a mixed gas of oxygen and air.

[0006] The present application can effectively improve the flavor substance content of the bean sauce and improve the overall quality of the bean sauce by controlling the fermentation process, including the control of the fermentation temperature and the ventilation process, such as limiting the mixed gas of oxygen and air in the fermentation process, based on the fermentation characteristics of the sauce and the growth characteristics of the microbial flora, proliferating the yeast itself, and effectively regulating the oxidation reaction and Maillard reaction rate of the bean sauce.

[0007] Specifically, in the first aspect, the present application limits the temperature of the first temperature-controlled fermentation and the second temperature-controlled fermentation in the above range, wherein the first temperature-controlled fermentation can ensure the normal proliferation of microorganisms to produce various metabolic compounds, and the second temperature-controlled fermentation can utilize part of the compounds produced in the first temperature-controlled fermentation stage to carry out efficient Maillard reaction; the two cooperate with each other to effectively improve the flavor substance content of the bean sauce and improve the overall quality of the bean sauce. In the second aspect, the present application introduces a mixed gas of oxygen and air during the first temperature-controlled fermentation and the second temperature-controlled fermentation, which not only utilizes nitrogen in the air as a protective gas to prevent the problem of bean sauce oxidation and blackening caused by the introduction of pure oxygen alone, but also increases the proportion of oxygen in the mixed gas, thereby increasing the proliferation number of yeast, and further improving the overall quality of the bean sauce prepared subsequently.

[0008] It should be noted that the test method of the yeast number in the sauce is the first method of GB4789.15-2016.

[0009] As a preferred embodiment of the brewing method of the present application, the first stage ventilation is carried out in the first temperature-controlled fermentation for 0-40 days, and the second stage ventilation is carried out for 41-70 days. The volume ratio of oxygen to air in the gas of the first stage ventilation is 1:(6-10). The volume ratio of oxygen to air in the gas of the second stage ventilation is 1:(2-7).

[0010] The present application researches and finds that the staged ventilation in the first temperature-controlled fermentation and the selection of the appropriate volume ratio of oxygen to air in each stage can effectively regulate the oxidation reaction and Maillard reaction rate of the bean sauce, thereby effectively improving the flavor substance content, improving the overall flavor and quality of the bean sauce.

[0011] As a preferred embodiment of the brewing method, in the first stage aeration, aeration is performed once every 5-10 days, the single aeration time is 15-35 min, and the gas flow of aeration is 1.0-2.0 m 3 / min.

[0012] As a preferred embodiment of the brewing method, in the second stage aeration, aeration is performed once every 2-5 days, the single aeration time is 120-360 min, and the gas flow of aeration is 0.5-1.5 m 3 / min.

[0013] The present application found that the frequency, time and flow of aeration affect the temperature fluctuation of the fermentation system caused by the exchange of internal and external temperature, which indirectly affects the Maillard reaction rate, and when the frequency, time and flow of aeration are further selected within the above range, the comprehensive performance of the prepared bean sauce can be better improved.

[0014] As a preferred embodiment of the brewing method, in the second temperature-controlled fermentation, aeration is performed, and the volume ratio of oxygen to air in the aeration gas is 1: (1-5).

[0015] As a preferred embodiment of the brewing method, in the second temperature-controlled fermentation, aeration is performed once every 2-7 days, the single aeration time is 10-30 min, and the gas flow of aeration is 1.5-2.5 m 3 / min.

[0016] The present application found that controlling the gas and the frequency, time and flow of the gas in the second temperature-controlled fermentation can effectively improve the flavor substance content of the bean sauce and improve the comprehensive performance of the bean sauce.

[0017] It should be noted that the purity of the oxygen is ≥93%.

[0018] As a preferred embodiment of the brewing method, the amino acid nitrogen concentration in the bean sauce is 0.6-0.9 g / 100 g.

[0019] It should be noted that the test method of the amino acid nitrogen concentration in the bean sauce is GB5009.235-2016 detection method.

[0020] As a preferred embodiment of the brewing method, the mass ratio of koji to brine is 1: (0.8-1.5).

[0021] As a preferred embodiment of the brewing method, the salt content in the brine is 24-30 g / 100 L.

[0022] As a preferred embodiment of the brewing method of the present application, the temperature of the koji-making is 26-36℃, the humidity is 70-90%, the time is 40-60h, and the ventilation volume is 8000-15000m 3 / h.

[0023] As a preferred embodiment of the brewing method of the present application, the mass ratio of the soybeans and the wheat flour is 100: (40-60).

[0024] As a preferred embodiment of the brewing method of the present application, the koji-making further comprises a step of adding 0.05-0.1% of Aspergillus oryzae based on the total mass of the soybeans and the wheat flour.

[0025] As a preferred embodiment of the brewing method of the present application, the temperature of the soaking is 35-45℃, and the time is 4-10h.

[0026] As a preferred embodiment of the brewing method of the present application, the pressure of the steaming is 0.110-0.150MPa, and the time is 110-170s.

[0027] Compared with the prior art, the present application has the following beneficial effects: By controlling the fermentation process, including the control of the temperature and the fermentation stage, and by passing the mixed gas of oxygen and air during the fermentation process, the present application can be based on the characteristics of the soy sauce fermentation and the growth characteristics of the microbial flora, proliferate the yeast itself, and effectively regulate the oxidation reaction and the Maillard reaction rate of the soy sauce; thereby effectively improving the flavor substance content of the soy sauce. Specifically, compared with the conventional process (Comparative Example 9), the content of the key soy sauce flavoring aldehyde substance is increased by more than 10.9 times, the content of the phenolic substance is increased by more than 4.2 times, and the content of the heterocyclic substance is increased by more than 1.9 times; and the overall quality of the soy sauce can be effectively improved. Specifically, the application effect of the soy sauce prepared by the brewing method of the present application is significantly better than that of the soy sauce of the same period, in which the aroma is increased by 2.3 points, the taste is increased by more than 2.0 points, the soy sauce flavor is more sufficient, and the color is better. In addition, the oxidation coloration and aroma of the soy sauce can be ensured, and the nitrogen in the air can be used as a protective gas to prevent the soy sauce from being excessively oxidized and having a dark color. At the same time, the brewing method provided by the present application is simple to operate and has a simple process, which is beneficial to large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The brewing method flow chart of the soy sauce in Example 1. DETAILED DESCRIPTION

[0029] For the purpose of better illustrating the present application, technical solutions and advantages, the present application will be further described in conjunction with specific examples.

[0030] The reagents, methods and devices used in the present application are conventional reagents, methods and devices in the art unless otherwise specified; and the raw materials used in parallel experiments are the same batch of raw materials unless otherwise specified.

[0031] Example 1 The brewing method of the soybean paste provided by the embodiment of the present application has a flow chart as shown in Figure 1 The brewing method of the soybean paste provided by the embodiment of the present application has a flow chart as shown in (1) Soaking and cooking: non-transgenic soybeans are selected and impurities are removed by a color sorter (impurity rate <0.3%), then the soybeans are soaked in water at 40℃ for 8h, and then high-pressure cooking is performed, with a cooking pressure of 0.120Mpa and a cooking time of 140s, to obtain cooked beans; (2) Mixing: after the cooked beans are cooled by a spiral cooler, wheat flour is added at a proportion of 50% of the mass of the non-transgenic soybeans, and then Aspergillus oryzae spores are added at a proportion of 0.07% of the total mass of the non-transgenic soybeans and the wheat flour, and then the mixture is sent to a disc koji-making machine for ventilation culture; (3) Koji-making: the koji-making temperature is controlled at 32℃, the ventilation volume is controlled at 12000m 3 / h, and the humidity is controlled at 80%, and the koji is obtained after 50h of koji-making culture; (4) First temperature-controlled fermentation: the koji is mixed with salt water at a mass ratio of 1.0:1.2, and then fermentation is performed, wherein the salt content of the salt water is 27.0g / 100L, and the temperature of the mixture is 31℃; during the first temperature-controlled fermentation, the first-stage aeration (a mixture of oxygen and air, with a volume ratio of oxygen to air being 1:8) is performed from the 0th day to the 40th day, specifically, aeration is performed once every 7 days, with a single aeration time of 25min and an aeration flow rate of 1.5m 3 / min; the second-stage aeration (a mixture of oxygen and air, with a volume ratio of oxygen to air being 1:5) is performed from the 41st day to the 70th day, specifically, aeration is performed once every 3 days, with an aeration time of 240min and an aeration flow rate of 1.0m 3 / min, and the yeast number in the material is monitored and controlled at 8×10 5 CFU / g, to obtain soybean mash; (5) Second temperature-controlled fermentation: the heat exchange process is adopted to increase the temperature of the soybean mash to 50℃ for heat preservation fermentation; during the second temperature-controlled fermentation (from the 71st day to the 90th day of fermentation), aeration (a mixture of oxygen and air, with a volume ratio of oxygen to air being 1:3) is performed, specifically, aeration is performed once every 4 days, with an aeration time controlled at 20min and an aeration flow rate of 2.0m 3 / min, and the soybean paste is matured on the 90th day of fermentation, with an amino acid nitrogen content of 0.78g / 100g in the soybean paste.

[0032] Example 2 The brewing method of the soybean paste provided by the embodiment of the present application has a flow chart as shown in (1) Soaking and cooking: Selected non-GMO soybeans were cleaned by color sorter (impurity rate <0.3%), soaked in water at 35℃ for 10h, and then steamed under high pressure at a pressure of 0.150Mpa for 170s to obtain cooked soybeans; (2) Mixing: After the cooked soybeans are cooled by a spiral cooler, wheat flour is added at a ratio of 40% of the mass of non-GMO soybeans. After mixing evenly, 0.05% of the total mass of non-GMO soybeans and wheat flour is added to Aspergillus oryzae. Then the mixture is transported to a disc koji maker for aeration and cultivation. (3) Koji making: The koji making temperature is controlled at 26℃ and the ventilation volume is controlled at 15000m³. 3 / h, humidity controlled at 90%, koji cultured for 60h to obtain koji; (4) First temperature-controlled fermentation: Fermentation is carried out after mixing the koji and brine at a mass ratio of 1.0:0.8. The brine has a salt content of 24.0 g / 100 L, and the temperature of the mixed material is 32 °C. During the first temperature-controlled fermentation, the first stage of aeration (a mixture of oxygen and air with a volume ratio of 1:6) is carried out from day 0 to day 40. Specifically, aeration is carried out once every 5 days, with a single aeration duration of 35 min and an aeration flow rate of 2.0 m³ / s. 3 / min; During fermentation days 41-70, the second stage of aeration (a mixture of oxygen and air, with an oxygen to air volume ratio of 1:2) is carried out, specifically ventilating once every 2 days, for a duration of 360 minutes, at a flow rate of 1.5 m³ / min. 3 / min, monitor the yeast count in the material and control it to 1×10 6 CFU / g yields fermented soybean paste; (5) Second temperature-controlled fermentation: The temperature of the fermented mash is raised to 55℃ using a heat exchange process for heat preservation fermentation; during the second temperature-controlled fermentation (days 71-85 of fermentation), aeration (a mixture of oxygen and air, with a volume ratio of oxygen to air of 1:1) is carried out, specifically once every 2 days, with a ventilation duration of 30 minutes and a ventilation flow rate of 2.5 m³ / min. 3 The fermentation process takes 85 days to mature into soybean paste, with an amino acid nitrogen content of 0.80g / 100g.

[0033] Example 3 This invention provides a method for brewing soybean paste, the brewing method comprising the following steps: (1) Soaking and cooking: Selected non-GMO soybeans were cleaned by color sorter (impurity rate <0.3%), soaked in water at 45℃ for 4 hours, and then steamed under high pressure at a pressure of 0.110 MPa for 170 seconds to obtain cooked soybeans. (2) Mixing: After the cooked soybeans are cooled by a spiral cooler, wheat flour is added at a ratio of 60% of the mass of non-GMO soybeans. After mixing evenly, 0.1% of Aspergillus oryzae inoculum is added to the total mass of non-GMO soybeans and wheat flour. Then the mixture is transported to a disc koji maker for aeration and cultivation. (3) Koji making: The koji making temperature is controlled at 36℃ and the ventilation volume is controlled at 15000m³. 3 / h, humidity controlled at 70%, koji cultured for 40h to obtain koji; (4) First temperature-controlled fermentation: Fermentation is carried out after mixing the koji and brine at a mass ratio of 1.0:1.5, with the brine having a salt content of 30.0 g / 100 L. The temperature of the mixed material is 35 °C. During the first temperature-controlled fermentation, the first stage of aeration (a mixture of oxygen and air with a volume ratio of 1:10) is carried out from day 0 to day 40. Specifically, aeration is carried out once every 10 days, with a single aeration duration of 15 min and an aeration flow rate of 1.0 m³ / s. 3 / min; the second stage of aeration (a mixture of oxygen and air, with a volume ratio of oxygen to air of 1:7) is carried out from day 41 to day 70 of fermentation, specifically once every 5 days, for a duration of 120 minutes and a flow rate of 0.5 m³ / min. 3 / min, monitor the yeast count in the material and control it to 5×10 4 CFU / g yields fermented soybean paste; (5) Second temperature-controlled fermentation: The temperature of the fermented mash is raised to 55℃ using a heat exchange process and kept warm during fermentation; during the second temperature-controlled fermentation (days 71-80 of fermentation), aeration (a mixture of oxygen and air, with a volume ratio of oxygen to air of 1:5) is carried out, specifically once every 7 days, with a ventilation time of 10 minutes and a ventilation flow rate of 1.5 m³ / min. 3 The fermentation process takes 80 days to mature into soybean paste, which contains 0.82 g of amino acid nitrogen per 100 g.

[0034] Example 4 This invention provides a method for brewing soybean paste, the brewing method comprising the following steps: (1) Soaking and cooking: Selected non-GMO soybeans were cleaned by color sorter (impurity rate <0.3%), soaked in 40℃ water for 8 hours, and then steamed under high pressure at a pressure of 0.120 MPa for 140 seconds to obtain cooked soybeans; (2) Mixing: After the cooked soybeans are cooled by a spiral cooler, wheat flour is added at a ratio of 50% of the mass of non-GMO soybeans. After mixing evenly, 0.07% of the total mass of non-GMO soybeans and wheat flour is added with Aspergillus oryzae. Then the mixture is sent to a disc koji maker for aeration and cultivation. (3) Koji making: The koji making temperature is controlled at 32℃ and the ventilation volume is controlled at 12000m³. 3 / h, humidity controlled at 80%, koji cultured for 50h to obtain koji; (4) First temperature-controlled fermentation: Fermentation is carried out after mixing the koji and brine at a mass ratio of 1.0:1.2. The brine has a salt content of 27.0 g / 100 L, and the temperature of the mixed material is 32 °C. During the first temperature-controlled fermentation, the first stage of aeration (a mixture of oxygen and air with a volume ratio of 1:8) is carried out from day 0 to day 40. Specifically, aeration is carried out once every 5 days, with a single aeration duration of 25 min and an aeration flow rate of 1.5 m³ / h. 3 / min; During fermentation days 41-70, the second stage of aeration (a mixture of oxygen and air, with an oxygen to air volume ratio of 1:5) is carried out, specifically ventilating once every 2 days, with a ventilation duration of 240 min and a ventilation flow rate of 1.0 m³ / min. 3 / min, yeast count was measured on day 50 of fermentation; yeast count <6×10 4 When CFU / g is [value missing], adjust the ventilation duration to 360 min and the ventilation rate to 1.5 m [value missing]. 3 / min, yeast number>9×10 5 When CFU / g is [value missing], adjust the ventilation duration to 120 min and the ventilation rate to 0.5 m³ / g. 3 / min; finally, monitor the yeast count in the material and control it to 9×10 5 CFU / g yields fermented soybean paste; (5) Second temperature-controlled fermentation: The temperature of the fermented mash is raised to 50℃ using a heat exchange process for heat preservation fermentation; during the second temperature-controlled fermentation (days 71-90 of fermentation), aeration (a mixture of oxygen and air, with a volume ratio of oxygen to air of 1:3) is carried out, specifically once every 4 days, with a ventilation duration of 20 minutes and a ventilation flow rate of 2.0 m³ / min. 3 The fermentation process takes 90 days to mature into soybean paste, with an amino acid nitrogen content of 0.85g / 100g.

[0035] Example 5 This invention provides a method for brewing soybean paste, the brewing method comprising the following steps: (1) Soaking and cooking: Selected non-GMO soybeans were cleaned by color sorter (impurity rate <0.3%), soaked in water at 35℃ for 10h, and then steamed under high pressure at a pressure of 0.150Mpa for 110s to obtain cooked soybeans; (2) Mixing: After the cooked soybeans are cooled by a spiral cooler, wheat flour is added at a ratio of 40% of the mass of non-GMO soybeans. After mixing evenly, 0.1% of the total mass of non-GMO soybeans and wheat flour is added to Aspergillus oryzae. Then the mixture is sent to a disc koji maker for aeration and cultivation. (3) Koji making: The koji making temperature is controlled at 32℃ and the ventilation volume is controlled at 12000m³. 3 / h, humidity controlled at 80%, koji cultured for 50h to obtain koji; (4) First temperature-controlled fermentation: Fermentation is carried out after mixing the koji and brine at a mass ratio of 1.0:1.2. The brine has a salt content of 27.0 g / 100 L, and the temperature of the mixed material is 31 °C. The first stage of aeration is carried out from day 0 to day 40 of the first temperature-controlled fermentation (the oxygen to air volume ratio is 1:8 for the first 20 days of fermentation, and the yeast count is detected on day 20 of fermentation. When the yeast count is <1.0 × 10 4 When CFU / g, the oxygen to air volume ratio is adjusted to 1:6, and the yeast count is >1.0×10⁻⁶. 5 When CFU / g, the oxygen to air volume ratio is adjusted to 1:10, specifically, ventilation is performed once every 7 days, with a single ventilation duration of 25 minutes and a ventilation flow rate of 1.5 m³ / g. 3 / min; Second-stage aeration is carried out from day 41 to day 70 of fermentation (for the first 10 days of fermentation, the oxygen to air volume ratio is 1:5; the yeast count is measured on day 50 of fermentation, and when the yeast count is <6.0×10 4 When CFU / g, the oxygen to air volume ratio is adjusted to 1:3, and the yeast count is >9.0×10⁻⁶. 5 When CFU / g, the oxygen to air volume ratio is adjusted to 1:7, specifically, ventilation is performed once every 2 days, with a ventilation duration of 240 min and a ventilation flow rate of 1.0 m³ / g. 3 / min, monitor the yeast count in the material, and control it to 7.5×10 5 CFU / g yields fermented soybean paste; (5) Second temperature-controlled fermentation: The temperature of the fermented mash is raised to 50℃ using a heat exchange process for heat preservation fermentation; during the second temperature-controlled fermentation (days 71-90 of fermentation), aeration (a mixture of oxygen and air, with a volume ratio of oxygen to air of 1:3) is carried out, specifically once every 4 days, with a ventilation duration of 20 minutes and a ventilation flow rate of 2.0 m³ / min. 3 The fermentation process takes 90 days to mature into soybean paste, with an amino acid nitrogen content of 0.83g / 100g.

[0036] Comparative Example 1 The present invention provides a comparative method for brewing soybean paste. The difference between the brewing method and Example 5 is that the temperature of the material after mixing in step (4) is 20°C, and in step (5) a heat exchange process is adopted to raise the temperature of the mash to 40°C for heat preservation and fermentation.

[0037] Comparative Example 2 The present invention provides a comparative method for brewing soybean paste. The difference between the brewing method and Example 5 is that the temperature of the material after mixing in step (4) is 40°C, and in step (5) a heat exchange process is adopted to raise the temperature of the mash to 60°C for heat preservation and fermentation.

[0038] Comparative Example 3 This invention provides a comparative method for brewing soybean paste, the difference between this method and Example 5 being that step (4) does not involve aeration; the resulting mash contains 3.5 × 10⁻⁶ yeast cells. 3 CFU / g.

[0039] Comparative Example 4 The present invention provides a comparative method for brewing soybean paste, the difference between the brewing method and Example 5 is that there is no aeration operation in step (5).

[0040] Comparative Example 5 This invention provides a comparative method for brewing soybean paste, the difference between which is that the gas introduced in steps (4) and (5) is oxygen, and the yeast count in the mash obtained in step (4) is 3.0 × 10⁻⁶. 7 CFU / g.

[0041] Comparative Example 6 This invention provides a comparative method for brewing soybean paste, the difference between which is that the gas introduced in steps (4) and (5) is air, and the yeast count in the mash obtained in step (4) is 1.9 × 10⁻⁶. 3 CFU / g.

[0042] Comparative Example 7 The present invention provides a comparative method for brewing soybean paste, the difference between the brewing method and Example 5 is that the temperature of the material after mixing in step (4) is 50°C.

[0043] Comparative Example 8 The present invention provides a comparative method for brewing soybean paste, the difference between the brewing method and Example 5 is that step (5) adopts a heat exchange process to keep the temperature of the mash at 31°C for heat preservation and fermentation.

[0044] Comparative Example 9 The present invention provides a comparative method for brewing soybean paste. The difference between the brewing method and Example 5 is that the gas introduced in steps (4) and (5) is air, and step (5) does not involve raising the temperature of the mash to 50°C for heat preservation and fermentation.

[0045] Example of effect The effects of this invention are explored in the examples and comparative examples, examining the properties of the soybean paste prepared by these embodiments and the following: 1. Sensory analysis and testing The sensory evaluation team consisted of 10 people. Each person gave a sensory score, and the average of the sensory scores was taken as the final sensory score.

[0046] 1) The scoring criteria for the aroma of fermented soybean paste are as follows: Significant aroma defect: 1 point; Strong mellow / sour / fermented flavor and other off-flavors, no soy sauce flavor: 2 points; The aroma is slightly weak / has a slight musty smell / has a slightly sour smell, and the aroma is not pure: 3 points; Slight to strong soy sauce aroma, no off-odors: 4 points; Rich in soy sauce aroma, with strong ester and mellow flavors: 5 points.

[0047] 2) The color scoring criteria for soybean paste are as follows: Light yellow: 1 point; Yellow: 2 points; Light brown: 3 points; Reddish-brown: 4 points; Reddish-brown color: 5 points; Dark red with a slight black tinge: 6 points; Dark color, too dark: 7-8 points.

[0048] 3) The scoring criteria for the taste of soybean paste are as follows: The taste is sour, salty, or bitter, with a noticeable sensory disharmony: 1 point; Taste is slightly sour or salty, with a slightly bitter, yeasty flavor: 2 points; Slightly savory sauce flavor, but the overall taste is slightly unbalanced: 3 / 5; The sauce flavor is quite strong, the taste lingers in the mouth for a while, and there are no off-flavors: 4 points; The flavor is lingering and rich, with a strong and lasting sauce taste: 5 points.

[0049] Among the sensory ratings, 5 points is the best, and scores below or above 5 points indicate varying degrees of defects.

[0050] 2. Flavor compound content analysis and detection: The types and contents of flavor compounds in the fermented soybean paste were determined using solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). Specifically: Solid-phase microextraction (SPME) conditions and methods: Soybean paste was centrifuged at 5000 rpm for 5 min. 5 mL of the supernatant was collected and transferred to an extraction flask, which was then heated in a water bath (55℃, stirring for 30 min). The extraction head was then inserted and allowed to adsorb for 30 min before being removed. Gas chromatography-mass spectrometry (GC-MS) conditions: GC employed a programmed temperature ramp, starting at 40℃ and holding for 10 min, then ramping to 150℃ at a rate of 4℃ / min, followed by ramping to 250℃ at a rate of 8℃ / min. 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℃, the ion source temperature was controlled at 230℃, EI was used, ionization was 70 eV, and the scan range was 33-450 amu. 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.

[0051] The results are shown in Tables 1-3. Table 1 Table 2 Table 3 As can be seen from Tables 1-3, when the technical solution provided by this invention is adopted, flavored soybean paste rich in aldehydes can be obtained; the concentration of aldehydes in soybean paste can be significantly increased, thereby enhancing the flavor of the soybean paste. For example, furfural, an aldehyde, has an almond aroma and can increase the roasted and caramelized aroma of the soybean paste, enriching its flavor profile. Simultaneously, the peak areas of other heterocyclic compounds, esters, and other flavor substances in this invention are also larger. These flavor compounds and aldehydes together contribute to the rich taste and strong aroma of the soybean paste obtained by this invention. Specifically, the total peak area of ​​volatile substances in the obtained product is 4.74 × 10⁻⁶. 8 The peak area of ​​esters is above 4.10 × 10⁴. 7 The peak area of ​​alcohols is above 9.80 × 10⁻⁶. 7 The peak area of ​​aldehydes is above 1.70 × 10⁴. 8 The peak area of ​​phenols is above 9.90 × 10⁻⁶. 6 The peak area of ​​acids is above 8.50 × 10⁴. 7 The peak area of ​​ketones is above 2.10 × 10⁻⁶. 7 The peak area of ​​heterocyclic compounds is above 2.12 × 10⁴. 7 The peak area of ​​alkanes is above 4.90 × 10⁻⁶. 6 The peak area of ​​sulfur-containing compounds is above 8.10 × 10⁴. 6 The scores for the color of the soybean paste are between 4.4 and 4.8, the score for the aroma of the soybean paste is between 4.6 and 4.8, and the score for the taste of the soybean paste is between 4.5 and 4.9. When the temperatures of the first and second temperature-controlled fermentations in Comparative Examples 1 and 2 are not within the range given in this invention, the total peak area of ​​volatile substances in the obtained product decreases significantly, as do the peak areas of esters, alcohols, aldehydes, ketones, and heterocyclic compounds. The resulting soy sauce color, aroma, and taste scores deviate significantly from the optimal value of 5 points. When aeration was not carried out in either the first or second temperature-controlled fermentation in Comparative Examples 3-4, the total peak area of ​​volatile substances in the obtained product decreased significantly, as did the peak areas of aldehydes, ketones, and heterocyclic compounds. Furthermore, the color, aroma, and taste scores of the obtained soybean paste also decreased significantly. When oxygen was introduced into Comparative Example 5, the color of the resulting product was poor, and the aroma and taste scores also decreased to some extent; in addition, the total peak area of ​​volatile substances in the resulting product also decreased significantly. When air was introduced into Comparative Example 6, the resulting product was significantly lighter in color, and its aroma and taste were significantly reduced; the total peak area of ​​volatile substances in the resulting product was significantly reduced. When the temperatures of the first and second temperature-controlled fermentations were changed in Comparative Examples 7 and 8, the product obtained in Comparative Example 7 had an abnormally dark color, a burnt and bitter taste, and a significant decrease in aroma and taste scores; the product obtained in Comparative Example 8 had an abnormally light color, and a significant decrease in aroma and taste scores; and the total peak area of ​​volatile substances in the products obtained in both examples decreased to some extent.

[0052] When only a single gas—air—was introduced into the first and second temperature-controlled fermentation stages of Comparative Example 9, and no heat exchange process was adopted in the second temperature-controlled stage to meet the fermentation temperature, the decrease in esters, aldehydes, and heterocyclic compounds in the comparative example was particularly prominent; the resulting product had the lightest color, and its aroma and taste were significantly reduced.

[0053] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of the present invention and not to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for brewing soybean paste, characterized in that, The brewing method includes the following steps: (1) Soak and steam soybeans, then mix them with wheat flour, and then make koji to obtain koji; (2) After mixing the koji with the brine, the first temperature-controlled fermentation and the second temperature-controlled fermentation are carried out in sequence to obtain soybean paste; The temperature for the first temperature-controlled fermentation is 25-35℃. After the first temperature-controlled fermentation is completed, a fermented sauce mash is obtained, and the yeast count in the mash is 5×10⁻⁶. 4 ~1×10 6 CFU / g; The temperature for the second temperature-controlled fermentation is 45-55℃; During the first and second temperature-controlled fermentation processes, aeration is carried out, and the gas is a mixture of oxygen and air.

2. The brewing method according to claim 1, characterized in that, The first stage of aeration was carried out from day 0 to day 40 in the first temperature-controlled fermentation, and the second stage of aeration was carried out from day 41 to day 70. The volume ratio of oxygen to air in the first stage of ventilation is 1:(6~10). The volume ratio of oxygen to air in the second stage of ventilation is 1:(2~7).

3. The brewing method according to claim 2, characterized in that, During the first stage of ventilation, ventilation is performed once every 5 to 10 days, with each ventilation session lasting 15 to 35 minutes and a gas flow rate of 1.0 to 2.0 m³ / min. 3 / min; And / or, during the second stage of ventilation, ventilation is performed once every 2 to 5 days, with a single ventilation duration of 120 to 360 minutes and a gas flow rate of 0.5 to 1.5 m³ / min. 3 / min.

4. The brewing method according to claim 1, characterized in that, In the second temperature-controlled fermentation, aeration is carried out, and the volume ratio of oxygen to air in the aerated gas is 1:(1~5).

5. The brewing method according to claim 4, characterized in that, In the second temperature-controlled fermentation, aeration is performed once every 2-7 days, with each aeration lasting 10-30 minutes and a gas flow rate of 1.5-2.5 m³ / h. 3 / min.

6. The brewing method according to claim 4, characterized in that, The concentration of amino acid nitrogen in the soybean paste is 0.6~0.9g / 100g.

7. The brewing method according to claim 1, characterized in that, The mass ratio of the fermented starter culture to the brine is 1:(0.8~1.5). And / or, the salt content in the brine is 24~30g / 100L.

8. The brewing method according to claim 1, characterized in that, The fermentation process is carried out at a temperature of 26-36℃, a humidity of 70-90%, for a time of 40-60 hours, and with a ventilation volume of 8000-15000 m³ / h. 3 / h.

9. The brewing method according to claim 1, characterized in that, The mass ratio of soybeans to wheat flour is 100:(40~60). And / or, the step of adding 0.05-0.1% of Aspergillus oryzae by weight of the total mass of soybeans and wheat flour before koji making is further included.

10. The brewing method according to claim 1, characterized in that, The soaking temperature is 35~45℃, and the soaking time is 4~10h; And / or, the cooking pressure is 0.110~0.150MPa, and the time is 110~170s.

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