Soybean paste and method for preparing the same

Abstract

The present application relates to the brewing technology field of fermentation products, in particular to a bean sauce and a preparation method thereof. The preparation method of the bean sauce comprises a step of modulating a half-finished product of sauce mash, and the modulating process comprises a step of adding soybean extract. The present application can solve the problem of gas swelling of the bean sauce during the shelf life.

Description

Technical Field

[0001] This invention relates to the field of fermentation technology, and particularly to soybean paste and its preparation method. Background Technology

[0002] Soybean paste is a type of condiment made primarily from steamed soybeans and wheat. It is produced by cultivating koji mold, followed by salt water fermentation, preparation, and cooking.

[0003] Soybean paste has problems with gas buildup and can swelling during its shelf life (transportation, sales, consumer storage, etc.). At the same time, the amino acid nitrogen content decreases, the product color darkens, the aroma weakens, and the flavor becomes less desirable, which reduces the commercial value of soybean paste.

[0004] Current methods for controlling shelf-life gas production and can swelling in fermented condiments mainly focus on inhibiting gas-producing microorganisms. For example, this can be achieved by mixing known antibacterial and antioxidant components in specific proportions to create an antibacterial solution. There are reports of inhibiting can swelling in pickled chili products by suppressing microorganisms; reports of regulating fresh yellow rice wine by inhibiting the growth of gas-producing bacteria; and reports of inhibiting can swelling in fermented bean curd by suppressing bacteria.

[0005] However, soybean paste systems have high salt content, low water activity, and a slightly acidic pH. They typically contain preservatives and undergo high-temperature sterilization, resulting in strong preservative capabilities. This means that soybean paste systems themselves have low microbial levels. Even without detected gas-producing bacteria, gas production can still occur during shelf life, indicating that traditional methods of inhibiting gas-producing microorganisms to address shelf-life gas production and can swelling are not suitable for mature soybean paste systems with strong preservatives. Summary of the Invention

[0006] Based on this, the present invention provides a method for preparing soybean paste that can solve the problem of soybean paste bloating during its shelf life.

[0007] The first aspect of this invention provides a method for preparing soybean paste. The technical solution is as follows:

[0008] A method for preparing soybean paste, characterized by including a step of conditioning a semi-finished paste mash, wherein the conditioning process includes adding soybean extract.

[0009] In some embodiments, the method for preparing the soybean extract includes the following steps:

[0010] Peel the soybeans and collect the peeled soybeans and soybean skins;

[0011] The soybean skins were added to water and subjected to ultrasonic extraction. The first extract was collected.

[0012] The peeled soybeans are added to the first extract for extraction, and the second extract is collected.

[0013] The second extract was concentrated to prepare a soybean extract.

[0014] In some embodiments, the ultrasonic extraction treatment satisfies one or more of the following conditions:

[0015] a1. The mass of the water is 3.5 to 4 times the mass of the soybean skin;

[0016] a2. The temperature of the ultrasonic extraction treatment is 50℃~60℃;

[0017] a3. The ultrasonic extraction treatment time is 20 min to 30 min;

[0018] a4. The ultrasonic frequency of the ultrasonic extraction treatment is 35kHz to 45kHz.

[0019] In some embodiments, the extraction treatment satisfies one or more of the following conditions:

[0020] b1. The mass of the first extract is 4.5 to 5 times the mass of the peeled soybeans;

[0021] b2. The extraction temperature is 30℃~40℃;

[0022] b3. The extraction treatment time is 2h to 4h.

[0023] In some embodiments, the method for preparing the soybean extract includes one or more of the following features:

[0024] c1. The peeling treatment method is dry peeling;

[0025] c2. Before the step of adding the soybean skin to water for ultrasonic extraction, the method further includes the steps of crushing and sieving the soybean skin; wherein the sieve used for sieving has a mesh size of 40 to 80 mesh, and the material passing through the sieve is taken for the next step of processing.

[0026] c3. Concentrate the second extract until its volume is reduced to 18% to 20% of its original volume, wherein the concentration method is vacuum evaporation concentration, the concentration temperature is 60℃ to 65℃, and the concentration vacuum degree is -0.08Mpa to -0.06Mpa.

[0027] In some embodiments, the preparation method of the fermented sauce semi-finished product includes the following steps:

[0028] Soybeans are steamed or boiled to prepare cooked soybeans;

[0029] The cooked soybeans and wheat flour are mixed, inoculated with koji (fermented starter), and cultivated to obtain koji.

[0030] Mix koji (a type of starter culture) and brine, and ferment to prepare semi-finished sauce mash.

[0031] In some embodiments, the method for preparing the semi-finished fermented sauce includes one or more of the following features:

[0032] d1. The wheat flour accounts for 20% to 45% of the mass of the cooked soybeans;

[0033] d2. The mass of the koji (fermented rice) accounts for 0.01% to 0.2% of the sum of the masses of the cooked soybeans and wheat flour;

[0034] d3. The incubation time is 30h to 60h;

[0035] d4. The mass of the brine is 1 to 3 times the mass of the Daqu (a type of starter culture);

[0036] d5. The fermentation time is 50 to 100 days.

[0037] In some embodiments, the modulation process satisfies one or more of the following conditions:

[0038] e1. The soybean extract is added at a temperature of 90℃~95℃;

[0039] e2. Prior to the step of adding the soybean extract, a step of adding a flavoring agent is also included;

[0040] e3. The mass ratio of the semi-finished soy sauce to the soybean extract is (12-18):1.

[0041] In some embodiments, the flavoring agent is selected from one or more of white sugar, monosodium glutamate, brewed vinegar, xanthan gum, and potassium sorbate.

[0042] In some embodiments, after the step of conditioning the semi-finished sauce, a cooking step is also included.

[0043] In some embodiments, the steam pressure of the boiling process is 0.2 MPa to 0.4 MPa, and the boiling time is 10 min to 40 min.

[0044] A second aspect of the present invention provides a soybean paste, which is prepared by the above-described preparation method.

[0045] Compared with traditional solutions, the present invention has the following advantages:

[0046] The inventors of this invention discovered through research that gas production and swelling of soybean paste during its shelf life are mainly related to the Maillard reaction. The intermediate product of the second stage of the Maillard reaction, a dicarbonyl compound, reacts with amino acids and undergoes Streck degradation to produce CO2, causing gas production and swelling of the soybean paste during its shelf life. This invention incorporates soybean extract during the soybean paste preparation stage, which not only solves the problem of gas production and swelling during the shelf life of soybean paste but also slows down the rate of decrease in amino acid nitrogen and the rate of increase in total acid, resulting in minimal sensory changes during the shelf life of the produced soybean paste. Simultaneously, the soybean paste has a rich red color, a strong aroma, and an excellent taste and flavor. Detailed Implementation

[0047] The present invention will be further described in detail below with reference to specific embodiments. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0048] 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 invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0049] The first aspect of the present invention provides a method for preparing soybean paste, the method comprising a step of conditioning a semi-finished paste mash, the conditioning process comprising adding a soybean extract.

[0050] By adding soybean extract during the processing of soybean paste, the problem of gas buildup and can swelling during shelf life can be solved. Furthermore, the rate of decrease in amino acid nitrogen and the rate of increase in total acidity during shelf life are slowed, resulting in minimal sensory changes in the produced soybean paste. Simultaneously, the soybean paste exhibits a rich red color, a strong aroma, and excellent taste. The possible mechanism is that soybean extract contains specific components such as chelates, sulfides, and antioxidants. These components are related to inhibiting the formation of dicarbonyl compounds in the second stage of the Maillard reaction and the Streck degradation reaction, thereby reducing CO2 generation.

[0051] Optionally, the preparation method of the soybean extract includes the following steps:

[0052] Peel the soybeans and collect the peeled soybeans and soybean skins;

[0053] The soybean skins were added to water and subjected to ultrasonic extraction. The first extract was collected.

[0054] The peeled soybeans are added to the first extract for extraction, and the second extract is collected.

[0055] The second extract was concentrated to prepare a soybean extract.

[0056] Alternatively, the peeling process can be performed using a dry peeling method. Understandably, dry peeling can be carried out in a peeling machine.

[0057] Optionally, before the step of adding the soybean hulls to water for ultrasonic extraction, the method further includes a step of crushing and sieving the soybean hulls. Preferably, the sieve used for sieving has a mesh size of 40 to 80 mesh, and the material passing through the sieve is used for the next step.

[0058] Alternatively, during ultrasonic extraction, the mass of the water is 3.5 to 4 times the mass of the soybean skin.

[0059] Further optionally, the temperature of the ultrasonic extraction treatment is 50°C to 60°C.

[0060] Further optionally, the ultrasonic extraction treatment time is 20 min to 30 min.

[0061] Further optionally, the ultrasonic frequency of the ultrasonic extraction treatment is 35kHz to 45kHz.

[0062] Further optionally, during the extraction process, the mass of the first extract is 4.5-5 times the mass of the peeled soybeans;

[0063] Further optionally, the extraction treatment temperature is 30°C to 40°C;

[0064] Alternatively, the extraction process may be carried out for 2 to 4 hours.

[0065] Further optionally, the second extract is concentrated until its volume is reduced to 18% to 20% of its original volume. Preferably, the concentration method is vacuum evaporation. More preferably, the concentration temperature is 60°C to 65°C, and the concentration vacuum degree is -0.08 MPa to -0.06 MPa.

[0066] The soybean extract prepared by the above method can improve the problem of gas buildup in containers caused by chemical reactions such as the Maillard reaction during shelf life. The soybean extract includes soybean hull extract (i.e., the first extract), which fully utilizes the soybean hull and improves the utilization rate of raw materials.

[0067] Optionally, during the preparation process, the soybean extract is added at a temperature of 90°C to 95°C.

[0068] Optionally, during the conditioning process, a step of adding a flavoring agent is included before the step of adding the soybean extract.

[0069] In some embodiments, the modulation process includes the following steps:

[0070] The soybean extract is added to the mixture of the semi-finished sauce mash and seasoning at a temperature of 90℃~95℃.

[0071] Optionally, the mass ratio of the semi-finished fermented soybean paste to the soybean extract is (12-18):1.

[0072] Optionally, the flavoring agent is selected from one or more of white sugar, monosodium glutamate, brewed vinegar, xanthan gum, and potassium sorbate.

[0073] Optionally, after the step of conditioning the semi-finished sauce mash, a cooking step is also included.

[0074] Further optionally, the steam pressure of the boiling treatment is 0.2 MPa to 0.4 MPa, and the boiling time is 10 min to 40 min.

[0075] Understandably, after cooking, the finished soybean paste can be obtained.

[0076] In this invention, the preparation method of the semi-finished fermented soybean paste may include the following steps:

[0077] Soybeans are steamed or boiled to prepare cooked soybeans;

[0078] The cooked soybeans and wheat flour are mixed, inoculated with koji (fermented starter), and cultivated to obtain koji.

[0079] Mix koji (a type of starter culture) and brine, and ferment to prepare semi-finished sauce mash.

[0080] Further optionally, the wheat flour accounts for 20% to 45% of the mass of the cooked soybeans; further optionally, the koji seed accounts for 0.01% to 0.2% of the sum of the masses of the cooked soybeans and wheat flour.

[0081] Alternatively, the culture time is 30h to 60h.

[0082] Further optionally, the mass of the brine is 1 to 3 times the mass of the soybeans.

[0083] Alternatively, the fermentation time is 50 to 100 days.

[0084] A second aspect of the present invention provides a soybean paste, which is prepared by the above-described preparation method.

[0085] The following description, in conjunction with specific embodiments and comparative examples, will provide further details. Unless otherwise specified, all raw materials and instruments used in the following specific embodiments are commercially available. Unless otherwise specified, all processes involved are conventionally selected by those skilled in the art.

[0086] Example 1

[0087] This embodiment provides a soybean paste and its preparation method, the steps of which are as follows:

[0088] (1) Making koji: Steam soybeans to prepare cooked soybeans. After the cooked soybeans are cooled to room temperature, add wheat flour accounting for 30% of the weight of the cooked soybeans and mix evenly. Then, inoculate 0.08% of koji seed accounting for the sum of the weight of the cooked soybeans and wheat flour to cultivate koji for 45 hours.

[0089] (2) Fermentation: After the Daqu (a type of starter culture) has been cultured, it is mixed with brine and pumped into a fermentation tank or fermentation pool. The brine mass is twice the mass of the Daqu. The starter culture is fermented for 70 days to obtain the semi-finished sauce mash.

[0090] (3) Preparation of soybean extract:

[0091] ① Take soybeans separately, remove impurities and stones, and then dry peel them using a peeling machine to obtain peeled soybeans and soybean skins;

[0092] ② The soybean skins are ground by a pulverizer and then sieved through an 80-mesh sieve. The sieve material is collected to obtain soybean skin powder.

[0093] ③Put the soybean skin powder into the soaking tank, add water with a weight of 4 times that of the soybean skin powder, and then transfer it into the ultrasonic extractor for extraction. The extraction temperature is 55℃, the extraction time is 30min, and the ultrasonic frequency is 35KHz.

[0094] ④ After ultrasonic extraction, filter and collect the first extract, add peeled soybeans to the first extract, and perform extraction. The mass of the first extract is 5 times the mass of the peeled soybeans, the extraction temperature is 40℃, and the extraction time is 3.5h.

[0095] ⑤ After the extraction process is completed, the second extract is collected by filtration through a 120-mesh filter. The second extract is then concentrated by vacuum evaporation at a concentration temperature of 65℃ and a vacuum degree of -0.08Mpa until the volume of the second extract is 18% of the original volume, thus obtaining soybean extract.

[0096] (4) Preparation and cooking of soybean paste

[0097] ① Prepare the raw materials according to the following weight proportions:

[0098] The semi-finished soy sauce mash consists of 65 parts, soybean extract 3.6 parts, white sugar 19 parts, monosodium glutamate 10 parts, brewed vinegar 1.4 parts, xanthan gum 0.8 parts, and potassium sorbate 0.2 parts. Among them, white sugar, monosodium glutamate, brewed vinegar, and xanthan gum are designated as the first ingredient, and soybean extract is designated as the second ingredient. The first and second ingredients are added to prepare the semi-finished soy sauce mash.

[0099] ② Mix the obtained semi-finished sauce mash with the first material, heat the temperature to 95℃, add the second material, steam pressure 0.4MPa, boil for 20 minutes, cool to 80℃ and fill while hot.

[0100] Example 2

[0101] This embodiment provides a soybean paste and its preparation method, the steps of which are as follows:

[0102] (1) Making koji: Steam soybeans to prepare cooked soybeans. After the cooked soybeans are cooled to room temperature, add wheat flour accounting for 20% of the weight of the cooked soybeans and mix evenly. Then, inoculate 0.01% of koji seed accounting for the sum of the weight of the cooked soybeans and wheat flour to cultivate koji. The cultivation time is controlled to be 60h.

[0103] (2) Fermentation: After the Daqu (a type of starter culture) has been cultivated, it is mixed with brine and pumped into a fermentation tank or fermentation pool. The brine mass is 1 times the mass of the Daqu. The starter culture is fermented for 50 days to obtain the semi-finished sauce mash.

[0104] (3) Preparation of soybean extract:

[0105] ① Take soybeans separately, remove impurities and stones, and then dry peel them using a peeling machine to obtain peeled soybeans and soybean skins;

[0106] ② The soybean skins are ground by a pulverizer and then sieved through a 60-mesh sieve. The sieve material is collected to obtain soybean skin powder.

[0107] ③Put the soybean skin powder into the soaking tank, add water at 3.5 times the weight of the soybean skin powder, and then transfer it into the ultrasonic extractor for extraction. The extraction temperature is 60℃, the extraction time is 25min, and the ultrasonic frequency is 40KHz.

[0108] ④ After ultrasonic extraction, filter and collect the first extract, add peeled soybeans to the first extract, and perform extraction. The mass of the first extract is 4.5 times the mass of the peeled soybeans, the extraction temperature is 35℃, and the extraction time is 3h.

[0109] ⑤ After the extraction process is completed, the second extract is collected by filtration through a 100-mesh filter. The second extract is then concentrated by vacuum evaporation at a concentration temperature of 60℃ and a vacuum degree of -0.06Mpa until the volume of the second extract is 19% of the original volume, thus obtaining soybean extract.

[0110] (4) Preparation and cooking of soybean paste

[0111] ① Prepare the raw materials according to the following weight proportions:

[0112] The ingredients are: 70 parts of fermented soybean paste semi-finished product, 4.5 parts of soybean extract, 16 parts of white sugar, 7.5 parts of monosodium glutamate, 1.2 parts of brewed vinegar, 0.6 parts of xanthan gum, and 0.2 parts of potassium sorbate. Among them, white sugar, monosodium glutamate, brewed vinegar, and xanthan gum are designated as the first ingredient, and soybean extract is designated as the second ingredient. The first and second ingredients are added to prepare the fermented soybean paste semi-finished product.

[0113] ② Mix the obtained semi-finished sauce mash with the first material, heat the temperature to 94°C, add the second material, steam pressure 0.4MPa, boil for 25 minutes, cool to 75°C and fill while hot.

[0114] Example 3

[0115] This embodiment provides a soybean paste and its preparation method, the steps of which are as follows:

[0116] (1) Making koji: Steam soybeans to prepare cooked soybeans. After the cooked soybeans are cooled to room temperature, add 45% wheat flour (by weight of cooked soybeans) and mix evenly. Then, inoculate 0.2% koji starter (by weight of cooked soybeans and wheat flour) for koji cultivation. The cultivation time is controlled to be 30 hours.

[0117] (2) Fermentation: After the Daqu (a type of starter culture) has been cultivated, it is mixed with brine and pumped into a fermentation tank or fermentation pool. The brine is 3 times the mass of the Daqu. The starter culture is fermented for 100 days to obtain the semi-finished sauce mash.

[0118] (3) Preparation of soybean extract:

[0119] ① Take soybeans separately, remove impurities and stones, and then dry peel them using a peeling machine to obtain peeled soybeans and soybean skins;

[0120] ② The soybean skins are ground by a pulverizer and then sieved through a 40-mesh sieve. The sieve material is collected to obtain soybean skin powder.

[0121] ③Put the soybean skin powder into the soaking tank, add water at 3.5 times the weight of the soybean skin powder, and then transfer it into the ultrasonic extractor for extraction. The extraction temperature is 50℃, the extraction time is 20min, and the ultrasonic frequency is 45KHz.

[0122] ④ After ultrasonic extraction, filter and collect the first extract, add peeled soybeans to the first extract, and perform extraction. The mass of the first extract is 5 times the mass of the peeled soybeans, the extraction temperature is 30℃, and the extraction time is 4h.

[0123] ⑤ After the extraction process is completed, the second extract is collected by filtration through a 120-mesh filter. The second extract is then concentrated by vacuum evaporation at a concentration temperature of 62℃ and a vacuum degree of -0.07Mpa until the volume of the second extract is 20% of the original volume, thus obtaining soybean extract.

[0124] (4) Preparation and cooking of soybean paste

[0125] ① Prepare the raw materials according to the following weight proportions:

[0126] The semi-finished soy sauce mash consists of 75 parts, soybean extract 6.25 parts, white sugar 12 parts, monosodium glutamate 5 parts, brewed vinegar 1.05 parts, xanthan gum 0.5 parts, and potassium sorbate 0.2 parts. Among them, white sugar, monosodium glutamate, brewed vinegar, and xanthan gum are designated as the first ingredient, and soybean extract is designated as the second ingredient. The first and second ingredients are added to prepare the semi-finished soy sauce mash.

[0127] ② Mix the obtained semi-finished sauce mash with the first material, heat the temperature to 95℃, add the second material, steam pressure 0.4MPa, boil for 10 minutes, cool to 78℃ and fill while hot.

[0128] Comparative Example

[0129] This comparative example provides a soybean paste and its preparation method, the steps of which are as follows:

[0130] (1) Making koji: Steam soybeans to prepare cooked soybeans. After the cooked soybeans are cooled to room temperature, add 45% wheat flour (by weight of cooked soybeans) and mix evenly. Then, inoculate 0.2% koji starter (by weight of cooked soybeans and wheat flour) for koji cultivation. The cultivation time is controlled to be 30 hours.

[0131] (2) Fermentation: After the Daqu (a type of starter culture) has been cultivated, it is mixed with brine and pumped into a fermentation tank or fermentation pool. The brine is 3 times the mass of the Daqu. The starter culture is fermented for 100 days to obtain the semi-finished sauce mash.

[0132] (3) Preparation and cooking of soybean paste

[0133] ① Prepare the raw materials according to the following weight proportions:

[0134] The semi-finished sauce mash consists of 75 parts water, 6 parts white sugar, 12 parts monosodium glutamate, 5 parts monosodium glutamate, 1.3 parts brewed vinegar, 0.5 parts xanthan gum, and 0.2 parts potassium sorbate. Among these, white sugar, monosodium glutamate, brewed vinegar, xanthan gum, and water are designated as the first ingredient. The first ingredient is added to prepare the semi-finished sauce mash.

[0135] ② Mix the obtained semi-finished sauce mash with the first material, boil for 10 minutes, steam pressure 0.4 MPa, cool to 78℃ and fill while hot.

[0136] According to ASLT's accelerated food shelf-life test, the changes in soybean paste products after 30 days at 38°C can simulate the changes during the actual storage period of 1 year, and the changes after 60 days at 38°C can simulate the changes during the actual storage period of 2 years.

[0137] The performance of Examples 1-3 and the Comparative Examples was tested in the initial state, after being placed at 38°C for 30 days, and after being placed at 38°C for 60 days. The results are shown in Table 1.

[0138] Table 1

[0139]

[0140]

[0141] The testing and rating methods for each performance aspect are as follows:

[0142] ① Gas production:

[0143] The volume of the entire bag sample was collected by water displacement method based on the gas production volume under ASLT food storage period accelerated test at 38°C for 450g stand-up pouches.

[0144] ② Browning Index:

[0145] The absorbance of the sample at 420 nm is used to reflect the color and Maillard reaction degree of the sample; it is measured after dilution, pulping, α-amylase hydrolysis, and filtration through filter paper.

[0146] ③ Criteria for judging the color of soybean paste:

[0147] Dark brown: 1 point; darker than brownish-red, leaning towards black: 2 points; darker than brownish-red: 3 points; reddish-brown to red: 4 points; brownish-brown, glossy: 5 points.

[0148] ④ Criteria for judging the aroma of soybean paste:

[0149] Rich in soy sauce aroma: 1 point; Sour to savory: 2 points; Slightly weak savory aroma with sweet potato notes: 3 points; Slightly weak savory aroma: 4 points; Rich and pure savory aroma: 5 points.

[0150] ⑤ Criteria for judging the taste of soybean paste:

[0151] Sour and bitter: 1 point; no soy sauce flavor, overall weak taste: 2 points; unbalanced taste, slightly weak soy sauce flavor: 3 points; slightly unbalanced taste, strong soy sauce flavor: 4 points; balanced taste, fresh, savory and salty, strong soy sauce flavor: 5 points.

[0152] Table 1 shows that, in the comparative example, no soybean extract was added during the preparation of the fermented soybean paste. After being stored at 38℃ for 30 days and 60 days, the resulting soybean paste exhibited significantly increased gas production, decreased amino acid nitrogen content, and increased total acid content. Furthermore, the color, aroma, and taste scores of the soybean paste were significantly reduced. This indicates that traditional soybean paste suffers from significant gas production and swelling issues during its shelf life, with key shelf-life indicators and sensory properties deteriorating.

[0153] Examples 1-3 all involved adding soybean extract during the preparation of the fermented soybean paste semi-finished product. After being stored at 38°C for 30 days and 60 days, the resulting soybean paste exhibited lower gas production, a slower rate of decrease in amino acid nitrogen, a slower rate of increase in total acidity, and relatively stable scores for color, aroma, and taste. This indicates that the soybean paste produced using the method of this invention can improve the problem of gas production and can swelling caused by chemical reactions such as the Maillard reaction during shelf life, with minimal changes in key shelf-life indicators and sensory characteristics.

[0154] 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.

[0155] The embodiments described above are merely illustrative of several implementations of the present invention, 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 the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing soybean paste, characterized in that, The steps are as follows: Prepare the semi-finished fermented soybean paste; then cook it. The preparation process is as follows: first add the flavoring agent, then add the soybean extract, which is added at a temperature of 90℃~95℃, and the mass ratio of the fermented sauce semi-finished product to the soybean extract is (12~18):1; the flavoring agent is selected from one or more of white sugar, monosodium glutamate, brewed vinegar, xanthan gum and potassium sorbate. The steps of the preparation method of the soybean extract are as follows: Soybeans are dehulled, and the dehulled soybeans and soybean skins are collected. The dehulling method is dry dehulling. The soybean skins are pulverized and sieved; wherein the sieve used for sieving has a mesh size of 40-80 mesh, the sieved material is collected, and ultrasonic extraction is performed on the sieved material in water. The first extract is collected, and the mass of the water is 3.5-4 times the mass of the sieved material. The ultrasonic extraction meets the following conditions: a1. The temperature of the ultrasonic extraction is 50℃-60℃; a2. The time of the ultrasonic extraction is 20min-30min; a3. The ultrasonic frequency of the ultrasonic extraction is 35kHz-45kHz. The peeled soybeans are added to the first extract for extraction, and a second extract is collected. The extraction process meets the following conditions: b1. The mass of the first extract is 4.5-5 times the mass of the peeled soybeans; b2. The extraction temperature is 30℃~40℃; b3. The extraction time is 2h~4h. Concentrate the second extract to prepare a soybean extract; The steam pressure for the boiling process is 0.2 MPa to 0.4 MPa, and the boiling time is 10 min to 40 min. The second extract is concentrated until its volume is reduced to 18% to 20% of its original volume; wherein the concentration method is vacuum evaporation concentration, the concentration temperature is 60℃ to 65℃, and the concentration vacuum degree is -0.08Mpa to -0.06Mpa.

2. The method for preparing soybean paste according to claim 1, characterized in that, The preparation method of the semi-finished sauce mash includes the following steps: Soybeans are steamed or boiled to prepare cooked soybeans; The cooked soybeans and wheat flour are mixed, inoculated with koji (fermented starter), and cultivated to obtain koji. Mix koji (a type of starter culture) and brine, and ferment to prepare semi-finished sauce mash.

3. The method for preparing soybean paste according to claim 2, characterized in that, The wheat flour accounts for 20% to 45% of the mass of the cooked soybeans.

4. The method for preparing soybean paste according to claim 2, characterized in that, The mass of the koji variety accounts for 0.01% to 0.2% of the sum of the masses of the cooked soybeans and wheat flour.

5. The method for preparing soybean paste according to claim 2, characterized in that, The culture time is 30h~60h.

6. The method for preparing soybean paste according to claim 2, characterized in that, The mass of the brine is 1 to 3 times the mass of the Daqu (a type of Chinese liquor).

7. The method for preparing soybean paste according to claim 2, characterized in that, The fermentation time is 50 to 100 days.

8. A soybean paste prepared by the preparation method according to any one of claims 1 to 7.

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