Aspergillus oryzae QHJ005, its application, and the preparation method of high-peptide, low-sodium soy sauce.

Abstract

This invention discloses an Aspergillus oryzae strain QHJ005, its application, and a method for preparing high-peptide, low-salt soy sauce. It relates to the field of microbial fermentation technology, solving the technical problems of low total peptide content and difficulty in balancing salt reduction and flavor quality in existing high-salt, dilute-state fermented soy sauces. This invention provides an Aspergillus oryzae strain QHJ005, which was deposited on March 27, 2026, at the China General Microbiological Culture Collection Center (CGMCC) under the accession name QHJ005 and accession number CGMCC No. 42543. The Aspergillus oryzae strain QHJ005 was obtained through mutagenesis and selection from Aspergillus oryzae strain Hu Niang 3.042. This Aspergillus oryzae strain QHJ005 is used for soy sauce fermentation, effectively increasing the total peptide content compared to conventional strains, and effectively reducing the salt content in soy sauce while maintaining a comparable total peptide content.

Description

Technical Field

[0001] This invention relates to the field of microbial fermentation technology, specifically to Aspergillus oryzae QHJ005, its application, and a method for preparing high-peptide, low-salt soy sauce. Background Technology

[0002] Soy sauce, a traditional Chinese fermented condiment, owes its flavor, quality, and nutritional value primarily to the degree of protein hydrolysis during the koji-making and fermentation processes. Traditional high-salt, liquid-state fermented soy sauce uses soybeans and wheat as raw materials. After koji-making with Aspergillus oryzae, a high-concentration brine is added for long-term fermentation. During this process, the proteases secreted by Aspergillus oryzae gradually hydrolyze the raw protein into free amino acids and peptides. These peptides not only contribute significantly to the umami and rich flavor of soy sauce but also possess antioxidant and ACE-inhibiting physiological activities.

[0003] However, existing soy sauce brewing technologies generally have the following problems:

[0004] (1) High salt fermentation inhibits peptide accumulation: Traditional high salt dilute state fermentation usually uses a high salt concentration of about 22% to inhibit contamination by miscellaneous bacteria. However, the high salt environment will significantly inhibit the activity of neutral protease and peptidase of Aspergillus oryzae, resulting in excessive degradation of protein into free amino acids, and the total peptide content is low, resulting in insufficient richness and smoothness of soy sauce.

[0005] (2) Difficulty in balancing salt reduction and flavor quality: With the increasing demand for low-salt foods, reducing the salt content of soy sauce has become an industry trend. However, while simply reducing the salt concentration can increase protease activity, it can easily lead to uncontrolled protein hydrolysis, an increase in the proportion of free amino acids and a decrease in peptide content. Furthermore, the low-salt environment increases the risk of contamination by miscellaneous bacteria, affecting the flavor stability of soy sauce.

[0006] (3) Existing strains have insufficient peptide secretion capacity: Currently, strains such as Aspergillus oryzae Hu Niang 3.042, which are widely used in the soy sauce industry, mainly produce free amino acids as their protease system. Their ability to retain and accumulate oligopeptides is limited, making it difficult to meet the flavor requirements of high-quality soy sauce for "high peptide, rich, and sweet".

[0007] Therefore, developing a fermentation method that can significantly increase the total peptide content of soy sauce while ensuring fermentation safety and achieving reasonable salt reduction is of significant industrial value for improving soy sauce quality and meeting the needs of healthy consumption. Summary of the Invention

[0008] The present invention aims to solve the technical problems in the prior art that the total peptide content in high-salt dilute-state fermented soy sauce is low and it is difficult to balance salt reduction and flavor quality. The purpose is to provide an Aspergillus oryzae QHJ005, its application, and a method for preparing high-peptide low-salt soy sauce. The soy sauce is fermented by using Aspergillus oryzae QHJ005 in combination with specific brine water activity and salt content, which greatly increases the total peptide content of the obtained soy sauce, significantly enhances the richness and roundness of the taste of the soy sauce. At the same time, under the condition of equivalent total peptide content, the salt content in the soy sauce can be effectively reduced, reducing sodium intake while meeting the flavor requirements, which conforms to the trend of low-salt healthy diet.

[0009] The present invention is realized through the following technical solutions.

[0010] The first object of the present invention is to provide an Aspergillus oryzae QHJ005. The Aspergillus oryzae QHJ005 was deposited with the China General Microbiological Culture Collection Center on March 27, 2026, and the deposit number is: CGMCC No. 42543. The Aspergillus oryzae QHJ005 described in the present invention is obtained by mutagenesis and breeding from Aspergillus oryzae Huniang 3.042.

[0011] The second object of the present invention is to provide an application of Aspergillus oryzae QHJ005 in koji-making fermentation of soy sauce.

[0012] The third object of the present invention is to provide a method for preparing high-peptide low-salt soy sauce, which includes the following steps:

[0013] Mix the cooked soybeans and fried wheat flour evenly according to the mass ratio of (8 - 10):1, inoculate the spores of the Aspergillus oryzae QHJ005 described above, and the inoculation amount is 1×10 6 ~1×10 7 spores / g koji, and perform ventilation koji-making at 28 - 32 °C for 32 - 40 h. After the koji-making is completed, add brine so that the mass ratio of the raw materials to the brine is 1:(1.8 - 2.0), and ferment for 3 - 12 months to obtain crude soy sauce; wherein, the initial water activity of the brine is 0.83 - 0.85 and the salt content is 18 - 21%.

[0014] Furthermore, the mass ratio of the soybeans to the wheat flour is 9:1.

[0015] Furthermore, the salt content of the brine is 18%~20%.

[0016] Furthermore, the method for adjusting the initial water activity of the brine is: add crude soy sauce to the brine to adjust the water activity to 0.83 - 0.85.

[0017] The preparation method of the soy sauce crude oil added to the brine is as follows: Steamed soybeans and roasted wheat flour are mixed evenly at a mass ratio of 9:1, and then inoculated with Aspergillus oryzae QHJ005 spores at an inoculation amount of 1×10⁻⁶. 6 ~1×10 7 One spore / g of koji is added, and the koji is made in a ventilated environment at 28~32℃ for 32~40 hours. After the koji is made, brine is added so that the mass ratio of raw material to brine is 1:(1.8~2.0). Fermentation lasts for 6 months to obtain crude soy sauce.

[0018] Furthermore, the inoculum size of the Aspergillus oryzae QHJ005 spores is 1×10⁻⁶. 6 ~5×10 6 spores / g of koji.

[0019] Furthermore, the ratio of raw material mass to brine mass is 1:1.9.

[0020] Furthermore, the ventilation and fermentation conditions are 30°C for 36 hours.

[0021] Furthermore, the fermentation time is 6 to 10 months.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] 1. This invention uses Aspergillus oryzae QHJ005 combined with specific brine water activity and salt content to ferment and prepare soy sauce, which significantly increases the total peptide content of the soy sauce, greatly enhancing its richness and smoothness. At the same time, under the condition of comparable total peptide content, the salt content in the soy sauce can be effectively reduced, thus reducing sodium intake while meeting flavor requirements, which is in line with the trend of low-salt healthy diet.

[0024] 2. The Aspergillus oryzae QHJ005 of the present invention has unique protein hydrolysis characteristics. Under specific water activity conditions (0.83~0.85), it can balance the ratio of free amino acids to peptides, so that the umami flavor (amino acid nitrogen) and richness (peptides) of soy sauce can be better coordinated.

[0025] 3. This invention inhibits unwanted bacteria by controlling the brine activity rather than simply increasing the salt concentration, thus ensuring the microbial safety of the fermentation process while reducing the salt content. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0027] The embodiments of the present invention will be described in detail below. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art.

[0028] The "scope" disclosed in this invention is defined in the form of a lower limit and an upper limit. A given scope is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific scope. The scope defined in this way can include or exclude end values, and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a scope.

[0029] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0030] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.

[0031] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other substances not listed may also be included, or that only the listed substances may be included.

[0032] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0033] To address the technical problems of low total peptide content and difficulty in balancing salt reduction and flavor quality in existing high-salt, dilute-state fermented soy sauce, this invention provides an Aspergillus oryzae strain, QHJ005. This Aspergillus oryzae strain QHJ005 was deposited on March 27, 2026, at the China General Microbiological Culture Collection Center (CGMCC), with the accession name QHJ005 and accession number CGMCC NO.42543. Specifically, the Aspergillus oryzae strain QHJ005 of this invention was obtained through mutagenesis and selection of Aspergillus oryzae strain Hu Niang 3.042.

[0034] The present invention also provides an application of Aspergillus oryzae QHJ005 in soy sauce koji fermentation. Compared with conventional strains, the application of Aspergillus oryzae QHJ005 in soy sauce koji fermentation can effectively increase the total peptide content and, under the condition of comparable total peptide content, can effectively reduce the salt content in soy sauce.

[0035] This invention also provides a method for preparing high-peptide, low-sodium soy sauce, comprising the following steps:

[0036] Steamed soybeans and roasted wheat flour are mixed evenly at a mass ratio of (8~10):1, and then inoculated with Aspergillus oryzae QHJ005 spores at an inoculation amount of 1×10⁻⁶. 6 ~1×10 7 One spore / g of koji is added, and the koji is made in a ventilated environment at 28~32℃ for 32~40h. After the koji is made, brine is added so that the mass ratio of raw material to brine is 1:(1.8~2.0). Fermentation is carried out for 3~12 months to obtain crude soy sauce. The initial water activity of the brine is 0.83~0.85.

[0037] Preferably, the mass ratio of soybeans to wheat flour is 9:1.

[0038] Preferably, the salt content of the brine is 18% to 20%.

[0039] As a preferred method, the initial water activity of the brine is adjusted by adding soy sauce to the brine to adjust the water activity to 0.83~0.85.

[0040] Preferably, the inoculum size of Aspergillus oryzae QHJ005 spores is 1×10⁻⁶. 6 ~5×10 6 spores / g of koji.

[0041] As a preferred option, the ratio of raw material mass to brine mass is 1:1.9.

[0042] Preferably, the ventilation and fermentation conditions are 30°C for 36 hours.

[0043] Preferably, the fermentation time is 6 to 10 months, and more preferably, the fermentation time is 6 months.

[0044] The technical solution of the present invention will be further described in detail below with reference to the embodiments.

[0045] It should be noted that the water activity determination method in this invention is in accordance with GB 5009.238, the total peptide content determination method is in accordance with GB / T 22492, and the ammonia nitrogen and total nitrogen detection methods are in accordance with GB / T 18186. Unless otherwise specified, the experimental methods used in the examples are conventional methods. Unless otherwise specified, all materials, reagents, methods, and instruments used are conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0046] Example 1

[0047] A method for preparing a high-peptide, low-sodium soy sauce includes the following steps:

[0048] After thoroughly mixing steamed soybeans and roasted wheat flour (soybeans to wheat in a 9:1 mass ratio), inoculate with Aspergillus oryzae QHJ005 or Hu Niang 3.042 spores at an inoculation rate of 1×10⁻⁶. 7 The inoculation rate was 1 spore / g koji, with the same amount of both strains. After inoculation, the koji was ventilated at 30℃ for 36 hours. After the koji was made, brine with a salt content of 22% was added at a mass ratio of raw material mass to brine mass of 1:1.9. After 6 months of fermentation, the crude soy sauce was obtained. The parameters of the soy sauce were measured, and the results are shown in Table 1.

[0049] Table 1. Comparison of parameters for preparing soy sauce using different Aspergillus oryzae strains

[0050] QHJ005 44.7 2.64 16.2 Shanghai Brewing 3.042 55.6 1.88 16.4

[0051] Example 2

[0052] A method for preparing a high-peptide, low-sodium soy sauce includes the following steps:

[0053] After thoroughly mixing steamed soybeans and roasted wheat flour (soybeans to wheat in a 9:1 mass ratio), inoculate with Aspergillus oryzae QHJ005 at a rate of 10. 7 One spore / g of koji. After inoculation, the koji is ventilated at 30℃ for 36 hours. After the koji is made, brine with a salt content of 20% is added at a mass ratio of raw material mass to brine mass of 1:1.9. After fermentation for 6 months, the crude soy sauce is obtained, and the parameters of the soy sauce are measured.

[0054] Example 3

[0055] A method for preparing a high-peptide, low-sodium soy sauce includes the following steps:

[0056] After thoroughly mixing steamed soybeans and roasted wheat flour (soybeans to wheat in a 9:1 mass ratio), inoculate with Aspergillus oryzae QHJ005 spores at a rate of 10. 7One spore / g of koji. After inoculation, the koji is ventilated at 30℃ for 36 hours. After the koji is made, brine is added at a mass ratio of raw material mass to brine mass = 1:1.9. Soy sauce crude oil is added to the brine to adjust the water activity of the brine to 0.85 and the salt content to 20%. Soy sauce crude oil is obtained after 6 months of fermentation. The parameters of soy sauce are measured.

[0057] The preparation method of soy sauce crude oil added to the initial brine is as follows: Steamed soybeans and roasted wheat flour are mixed evenly at a mass ratio of 9:1, and inoculated with Aspergillus oryzae QHJ005 spores at an inoculation amount of 10... 7 One spore / g of koji is added, and the koji is made in a ventilated environment at 30℃ for 36 hours. After the koji is made, brine is added to make the ratio of raw material mass to brine mass 1:1.9. Fermentation is carried out for 6 months to obtain crude soy sauce.

[0058] Example 4

[0059] A method for preparing a high-peptide, low-sodium soy sauce includes the following steps:

[0060] After thoroughly mixing steamed soybeans and roasted wheat flour (soybeans to wheat in a 9:1 mass ratio), inoculate with Aspergillus oryzae QHJ005 spores at a rate of 10. 7 One spore / g of koji. After inoculation, the koji is ventilated at 30℃ for 36 hours. After the koji is made, brine is added at a mass ratio of raw material mass to brine mass = 1:1.9. Soy sauce crude oil is added to the brine to adjust the water activity of the brine to 0.83 and the salt content to 20%. Soy sauce crude oil is obtained after 6 months of fermentation. The parameters of soy sauce are measured.

[0061] The preparation method of soy sauce crude oil added to the initial brine is as follows: Steamed soybeans and roasted wheat flour are mixed evenly at a mass ratio of 9:1, and inoculated with Aspergillus oryzae QHJ005 spores at an inoculation amount of 10... 7 One spore / g of koji is added, and the koji is made in a ventilated environment at 30℃ for 36 hours. After the koji is made, brine is added to make the ratio of raw material mass to brine mass 1:1.9. Fermentation is carried out for 6 months to obtain crude soy sauce.

[0062] Example 5

[0063] A method for preparing a high-peptide, low-sodium soy sauce includes the following steps:

[0064] After thoroughly mixing steamed soybeans and roasted wheat flour (soybeans to wheat in a mass ratio of 8:1), inoculate with Aspergillus oryzae QHJ005 spores at a quantity of 10. 7One spore / g of koji. After inoculation, the koji is ventilated at 28℃ for 32 hours. After the koji is made, brine is added at a mass ratio of raw material mass to brine mass = 1:1.8. Soy sauce crude oil is added to the brine to adjust the water activity of the brine to 0.83 and the salt content to 20%. Soy sauce crude oil is obtained after 6 months of fermentation. The parameters of soy sauce are measured.

[0065] The preparation method of soy sauce crude oil added to the initial brine is as follows: Steamed soybeans and roasted wheat flour are mixed evenly at a mass ratio of 9:1, and inoculated with Aspergillus oryzae QHJ005 spores at an inoculation amount of 10... 7 One spore / g of koji is added, and the koji is made in a ventilated environment at 30℃ for 36 hours. After the koji is made, brine is added to make the ratio of raw material mass to brine mass 1:1.9. Fermentation is carried out for 6 months to obtain crude soy sauce.

[0066] Example 6

[0067] A method for preparing a high-peptide, low-sodium soy sauce includes the following steps:

[0068] After thoroughly mixing steamed soybeans and roasted wheat flour (soybeans to wheat in a 10:1 mass ratio), inoculate with Aspergillus oryzae QHJ005 spores at a rate of 10. 7 One spore / g of koji. After inoculation, the koji is ventilated at 32℃ for 40 hours. After the koji is made, brine is added at a mass ratio of raw material mass to brine mass = 1:2.0. Soy sauce crude oil is added to the brine to adjust the water activity of the brine to 0.83 and the salt content to 20%. Soy sauce crude oil is obtained after 6 months of fermentation. The parameters of soy sauce are measured.

[0069] The preparation method of soy sauce crude oil added to the initial brine is as follows: Steamed soybeans and roasted wheat flour are mixed evenly at a mass ratio of 9:1, and inoculated with Aspergillus oryzae QHJ005 spores at an inoculation amount of 10... 7 One spore / g of koji is added, and the koji is made in a ventilated environment at 30℃ for 36 hours. After the koji is made, brine is added to make the ratio of raw material mass to brine mass 1:1.9. Fermentation is carried out for 6 months to obtain crude soy sauce.

[0070] Comparative Example 1

[0071] The only difference between this comparative example and Example 2 is that the koji was inoculated with Aspergillus oryzae 3.042 spores.

[0072] A method for preparing soy sauce includes the following steps:

[0073] After thoroughly mixing steamed soybeans and roasted wheat flour (soybeans to wheat in a 9:1 mass ratio), inoculate with Aspergillus oryzae spores (3.042 spores) at a rate of 10. 7One spore / g of koji. After inoculation, the koji is ventilated at 30℃ for 36 hours. After the koji is made, brine with a salt content of 20% is added at a mass ratio of raw material mass to brine mass of 1:1.9. After fermentation for 6 months, the crude soy sauce is obtained, and the parameters of the soy sauce are measured.

[0074] Comparative Example 2

[0075] The only difference between this comparative example and Example 3 is that the koji was inoculated with Aspergillus oryzae 3.042 spores.

[0076] A method for preparing soy sauce includes the following steps:

[0077] After thoroughly mixing steamed soybeans and roasted wheat flour (soybeans to wheat in a 9:1 mass ratio), inoculate with Aspergillus oryzae spores (3.042 spores) at a rate of 10. 7 One spore / g of koji. After inoculation, the koji is ventilated at 30℃ for 36 hours. After the koji is made, brine is added at a mass ratio of raw material mass to brine mass = 1:1.9. Soy sauce crude oil is added to the brine to adjust the water activity of the brine to 0.85 and the salt content to 20%. Soy sauce crude oil is obtained after 6 months of fermentation. The parameters of soy sauce are measured.

[0078] The preparation method of soy sauce crude oil added to the initial brine is as follows: Steamed soybeans and roasted wheat flour are mixed evenly at a mass ratio of 9:1, and inoculated with Aspergillus oryzae spores (3.042 spores) at an inoculation amount of 10... 7 One spore / g of koji is added, and the koji is made in a ventilated environment at 30℃ for 36 hours. After the koji is made, brine is added to make the ratio of raw material mass to brine mass 1:1.9. Fermentation is carried out for 6 months to obtain crude soy sauce.

[0079] Comparative Example 3

[0080] The only difference between this comparative example and Example 4 is that the koji was inoculated with Aspergillus oryzae 3.042 spores.

[0081] A method for preparing soy sauce includes the following steps:

[0082] After thoroughly mixing steamed soybeans and roasted wheat flour (soybeans to wheat in a 9:1 mass ratio), inoculate with Aspergillus oryzae spores (3.042 spores) at a rate of 10. 7 One spore / g of koji. After inoculation, the koji is ventilated at 30℃ for 36 hours. After the koji is made, brine is added at a mass ratio of raw material mass to brine mass = 1:1.9. Soy sauce crude oil is added to the brine to adjust the water activity of the brine to 0.83 and the salt content to 20%. Soy sauce crude oil is obtained after 6 months of fermentation. The parameters of soy sauce are measured.

[0083] The preparation method of soy sauce crude oil added to the initial brine is as follows: Steamed soybeans and roasted wheat flour are mixed evenly at a mass ratio of 9:1, and inoculated with Aspergillus oryzae spores (3.042 spores) at an inoculation amount of 10... 7 One spore / g of koji is added, and the koji is made in a ventilated environment at 30℃ for 36 hours. After the koji is made, brine is added to make the ratio of raw material mass to brine mass 1:1.9. Fermentation is carried out for 6 months to obtain crude soy sauce.

[0084] Comparative Example 4

[0085] The only difference between this comparative example and Example 4 is that the salt content of the brine is adjusted to 22%.

[0086] A method for preparing soy sauce includes the following steps:

[0087] After thoroughly mixing steamed soybeans and roasted wheat flour (soybeans to wheat in a 9:1 mass ratio), inoculate with Aspergillus oryzae QHJ005 spores at a rate of 10. 7 One spore / g of koji. After inoculation, the koji is ventilated at 30℃ for 36 hours. After the koji is made, brine is added at a mass ratio of raw material mass to brine mass = 1:1.9. Soy sauce crude oil is added to the brine to adjust the water activity of the brine to 0.83 and the salt content to 22%. Soy sauce crude oil is obtained after 6 months of fermentation, and the parameters of soy sauce are measured.

[0088] The preparation method of soy sauce crude oil added to the initial brine is as follows: Steamed soybeans and roasted wheat flour are mixed evenly at a mass ratio of 9:1, and inoculated with Aspergillus oryzae QHJ005 spores at an inoculation amount of 10... 7 One spore / g of koji is added, and the koji is made in a ventilated environment at 30℃ for 36 hours. After the koji is made, brine is added to make the ratio of raw material mass to brine mass 1:1.9. Fermentation is carried out for 6 months to obtain crude soy sauce.

[0089] The test results of the soy sauce prepared in the above embodiments and comparative examples are shown in Table 2.

[0090] Table 2. Measurement results of soy sauce prepared in the examples and comparative examples.

[0091] Example 2 53.7 2.07 14.5 Example 3 48.6 3.28 14.9 Example 4 46.3 3.95 14.2 Example 5 50.5 2.94 14.0 Example 6 51.9 2.86 15.1 Comparative Example 1 58.4 1.72 14.3 Comparative Example 2 56.4 1.93 14.7 Comparative Example 3 55.9 2.34 14.6 Comparative Example 4 47.5 3.98 16.3

[0092] The data comparison in the table above shows that:

[0093] 1. From the fermentation results of adding different Aspergillus oryzae in Example 1, and from the comparison of data between Example 2 and Comparative Example 1, the comparison of data between Example 3 and Comparative Example 2, and the comparison of data between Example 4 and Comparative Example 3, it can be seen that:

[0094] Under the same preparation process parameters, compared with the conventional Shanghai brewing strain 3.042, the total peptide content of soy sauce prepared using Aspergillus oryzae QHJ005 of this invention is significantly improved, and the total peptide content can be increased while reducing the brine concentration. The quality of soy sauce prepared by the production method of this invention is significantly improved.

[0095] 2. As can be seen from the comparison between Comparative Example 4 and Example 4, the salt content of the brine in Example 4 decreased from 22% to 20% compared to Comparative Example 4, while the total peptide content remained almost unchanged. However, the salt content in the soy sauce was significantly reduced, which is more conducive to the preparation of low-sodium soy sauce. This proves that under the premise of comparable total peptide content, the salt content of the finished soy sauce can be significantly reduced. While meeting the flavor requirements, it reduces sodium intake, which is in line with the trend of low-sodium healthy diet.

[0096] 3. A comparison of Examples 2 with Examples 3 and 4 shows that Examples 3 and 4 further adjusted the water activity of the brine based on Example 2. The salt content in the prepared soy sauce remained almost unchanged, but the total peptide content increased significantly. This proves that by controlling the water activity of the brine, the present invention can significantly enhance the richness and smoothness of the soy sauce.

[0097] 4. A comparison of the data from Examples 4, 5, and 6 shows that Example 4 has the best technical effect under different parameters.

[0098] Finally, it should be noted that the above specific embodiments are only used to describe the purpose, technical solution, and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation of the present invention and is not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the foregoing specific embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions or improvements can be made to some or all of the technical features. These modifications, equivalent substitutions, and improvements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A type of Aspergillus oryzae QHJ005, characterized in that, The Aspergillus oryzae QHJ005 was deposited at the China General Microbiological Culture Collection Center (CGMCC) on March 27, 2026, with accession number CGMCC No. 42543.

2. The application of Aspergillus oryzae QHJ005 as described in claim 1 in the fermentation of soy sauce koji.

3. A method for preparing a high-peptide, low-salt soy sauce, characterized in that, Includes the following steps: Steamed soybeans and roasted wheat flour are mixed evenly at a mass ratio of (8~10):1, and then inoculated with Aspergillus oryzae QHJ005 spores as described in claim 1, with an inoculation amount of 1×10⁻⁶. 6 ~1×10 7 One spore / g of koji is added, and the koji is made in a ventilated environment at 28~32℃ for 32~40h. After the koji is made, brine is added so that the mass ratio of raw material to brine is 1:(1.8~2.0). Fermentation is carried out for 3~12 months to obtain crude soy sauce. The brine has a water activity of 0.83~0.85 and a salt content of 18~21%.

4. The method for preparing a high-peptide, low-salt soy sauce according to claim 3, characterized in that, The mass ratio of soybeans to wheat flour is 9:

1.

5. The method for preparing a high-peptide, low-salt soy sauce according to claim 3, characterized in that, The salt content of the brine is 18% to 20%.

6. The method for preparing a high-peptide, low-salt soy sauce according to claim 3, characterized in that, The method for adjusting the initial water activity of brine is as follows: add crude soy sauce to the brine to adjust the water activity to 0.83~0.

85.

7. The method for preparing a high-peptide, low-salt soy sauce according to claim 3, characterized in that, The inoculum size of Aspergillus oryzae QHJ005 spores was 1×10⁻⁶. 6 ~5×10 6 spores / g of koji.

8. The method for preparing a high-peptide, low-salt soy sauce according to claim 3, characterized in that, The ratio of raw material mass to brine mass is 1:1.

9.

9. The method for preparing a high-peptide, low-salt soy sauce according to claim 3, characterized in that, The ventilation and fermentation conditions are as follows: 30℃ for 36 hours.

10. The method for preparing a high-peptide, low-salt soy sauce according to claim 3, characterized in that, The fermentation time is 6 to 10 months.