Method for producing soy sauce by using termitomyces albuminosus

Abstract

The invention discloses a method for producing soy sauce by using termitomyces albuminosus, and belongs to the technical field of soy sauce production. Aspergillus oryzae and aspergillus niger are subjected to multi-generation domestication screening through a termitomyces albuminosus powder culture medium, the adaptability of the strain to a termitomyces albuminosus substrate is remarkably improved, termitomyces albuminosus has antioxidant activity, the domesticated strain can fully utilize nutritional ingredients in the termitomyces albuminosus in the fermentation process, generation of termitomyces albuminosus flavor substances is promoted, and the yield of the termitomyces albuminosus flavor substances is increased. A compound enzyme system of neutral protease, cellulase, flavourzyme and laccase is adopted, gradient enzyme deactivation and ultrasonic-assisted treatment are combined, cell walls and protein of termitomyces albuminosus are fully decomposed, free amino acid, polysaccharide and flavoring substances are released, the enzymolysis efficiency is improved, and the flavor of the termitomyces albuminosus is improved; through secondary saccharification of the red date polysaccharide extract and beta-glucanase, the content of functional polysaccharide and soluble sugar in the soy sauce is increased, the sour taste of the soy sauce is balanced, and the taste roundness is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of soy sauce production, and particularly relates to a method for producing soy sauce using Termitomyces albuminosus. Background Art

[0002] Traditional soy sauce mostly uses soybeans and wheat as the main raw materials, relying on the enzymes produced by Aspergillus fermentation to decompose the proteins and starches in the raw materials, thereby forming the unique flavor and components of soy sauce. However, this production mode has many shortcomings. From the perspective of raw materials, the sources are relatively single, resulting in relatively fixed product flavors and nutritional components, and it is unable to meet the increasingly diverse taste requirements of consumers. In terms of technology, the traditional fermentation process takes a long time and has low production efficiency.

[0003] Termitomyces albuminosus, a rare fungus that can be used both as medicine and food, its fruiting body is rich in 18 kinds of amino acids (including 7 essential amino acids for the human body), β-glucan, ergosterol, polyphenolic compounds and trace elements such as selenium and germanium. Research shows that the extract of Termitomyces albuminosus has antioxidant activity with a DPPH free radical scavenging rate of over 85%, as well as significant immunomodulatory and anti-tumor effects. Its unique volatile components such as 1-octen-3-ol and 2,3-butanediol endow the product with a unique mushroom freshness, and can form a compound flavor system after being combined with the traditional soy sauce flavor. Introducing Termitomyces albuminosus into soy sauce production can not only break through the limitations of traditional raw materials, but also develop high-end soy sauce products with both functionality and flavor innovation. Summary of the Invention

[0004] In view of the above situation, in order to overcome the defects of the prior art, the present invention optimizes the performance of the strains, improves the enzymatic hydrolysis and fermentation efficiency, realizes the efficient utilization of Termitomyces albuminosus raw materials, and improves the quality of soy sauce.

[0005] To achieve the above object, the following technical solutions are adopted: The present invention provides a method for producing soy sauce using Termitomyces albuminosus, comprising the following steps:

[0006] S1. After drying and pulverizing the fruiting body of Termitomyces albuminosus, add it to the basic medium at a mass fraction of 5% to obtain a Termitomyces albuminosus powder medium. Take the original strains of Aspergillus oryzae and Aspergillus niger, and inoculate them into the Termitomyces albuminosus powder medium respectively. Culture them in a constant temperature incubator at 30°C for 5-7 days, observe the colony growth situation, select the colonies with fast growth rate, dense mycelium and strong adaptability, and inoculate them for further culture. Repeat the domestication and screening 5 times to obtain the domesticated strains of Aspergillus oryzae and Aspergillus niger adapted to the Termitomyces albuminosus environment;

[0007] S2. Mix the fruiting bodies and mycelia of Termitomyces albuminosus in a mass ratio of 3:1, crush them, and mix them with distilled water at a solid-liquid ratio of 1:25 - 35 to obtain a Termitomyces albuminosus mixture. After inactivating enzymes at gradient temperatures, adjust the pH to 7.0 - 7.5, then add a complex enzyme preparation accounting for 0.5% of the mass of the Termitomyces albuminosus mixture, and perform ultrasonic-assisted enzymatic hydrolysis at 45 - 50 °C for 2 h to obtain an enzymatic hydrolysate. The complex enzyme preparation contains neutral protease, cellulase, flavor protease, and laccase;

[0008] S3. Compound the enzymatic hydrolysate with sorghum bran in a mass ratio of 2 - 3:1 to obtain a compound, and then add β-glucanase accounting for 0.5% of the mass of the compound for secondary saccharification treatment;

[0009] S4. Mix the domestically screened Aspergillus oryzae and Aspergillus niger with lactic acid bacteria to obtain a mixed starter culture. Inoculate the mixed starter culture into the matrix after secondary saccharification at an inoculation amount of 1.5%, and control it with gradient salt concentration, and perform fermentation at 38 - 45 °C for 28 - 32 days;

[0010] S5. Perform membrane separation on the product after fermentation in step S4 using a 100 kDa ultrafiltration membrane, and then obtain the finished soy sauce through low-temperature vacuum concentration.

[0011] Furthermore, the complex enzyme preparation in step S2 contains the following components in mass percentages: 60 - 70% of neutral protease, 15 - 20% of cellulase, 5 - 15% of flavor protease, and 5 - 15% of laccase.

[0012] Furthermore, the enzyme activity of the neutral protease is 80000 - 120000 U / g, the enzyme activity of the cellulase is 10000 - 15000 U / g, the enzyme activity of the flavor protease is 5000 - 8000 U / g, and the enzyme activity of the laccase is 200 - 500 U / g.

[0013] Furthermore, the mixed starter culture contains 60 - 75% of Aspergillus oryzae, 20 - 30% of Aspergillus niger, and 5 - 15% of lactic acid bacteria.

[0014] Furthermore, the preparation method of the jujube polysaccharide extract is as follows: Take pitted jujubes and the Termitomyces albuminosus fermentation broth for extraction at a ratio of 1:5, perform compound enzymatic hydrolysis with pectinase:xylanase = 3:1, and perform microwave-assisted extraction under the conditions of 600 W, 60 °C, and 15 min, and then use ceramic membrane for separation and purification.

[0015] Furthermore, the basal medium in step S1 contains 2% of glucose, 1% of peptone, 0.5% of yeast extract, 2% of agar, and the balance is distilled water.

[0016] Furthermore, the conditions for inactivating enzymes at gradient temperatures in step S2 are: first heat up to 50 °C, then heat up to 70 °C, and finally heat up to 90 °C, with each stage lasting for 5 min.

[0017] Furthermore, the gradient salt concentration in step S4 is controlled as follows: the salt concentration is 12% in the first 5 days, 15% in the middle 7 days, and 18% in the last 8 days.

[0018] Furthermore, the secondary saccharification treatment specifically includes: after compounding the enzymolysis liquid and sorghum bran in a ratio of 2:1, adding 0.5% of β-glucanase, and performing a saccharification reaction at 50 - 55°C for 3 - 4 hours, with stirring every 30 minutes during this period, and the stirring speed being 100 - 120 revolutions per minute.

[0019] Furthermore, the concentration of the low-temperature vacuum concentration is as follows: the vacuum degree is -0.08 MPa to -0.09 MPa, the temperature is controlled at 45°C - 50°C. During the concentration process, the volume change of the liquid and the content of amino acid nitrogen are continuously monitored. When the amino acid nitrogen content of the product reaches ≥1.2 g / 100 mL, the concentration is stopped to obtain the finished soy sauce.

[0020] The beneficial effects of the present invention are as follows: Through multi-generation domestication and screening of Aspergillus oryzae and Aspergillus niger with the termite mushroom powder culture medium, the adaptability of the strains to the termite mushroom substrate is significantly improved, the mycelial growth rate is accelerated and the metabolic activity is enhanced. The termite mushroom contains polyphenolic compounds, proteins and polypeptides, making the termite mushroom and its extracts have antioxidant activity. The domesticated strains can make more full use of the nutritional components in the termite mushroom during the fermentation process, promote the generation of flavor substances of the termite mushroom, and make the soy sauce fermentation process more efficient. The finished soy sauce has antioxidant ability. The present invention also adopts a composite enzyme system of neutral protease, cellulase, flavor protease and laccase, combined with gradient enzyme inactivation and ultrasonic-assisted treatment, to fully decompose the cell wall and proteins of the termite mushroom, release free amino acids, polysaccharides and flavor substances, improving the enzymolysis efficiency. By introducing microwave-assisted enzyme extraction of jujube polysaccharide extract and β-glucanase for secondary saccharification, the content of functional polysaccharides and soluble sugars in the soy sauce is increased, further balancing the sour taste of the soy sauce and enhancing the roundness of the taste. Description of the Drawings

[0021] Figure 1 It is the determination result of the free amino acid content in the finished soy sauce of each example and comparative example of the present invention;

[0022] Figure 2 It is the determination result of the DPPH free radical scavenging ability of the soy sauce of each example and comparative example of the present invention.

[0023] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. Detailed Embodiments

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to the described content can be applied to the present invention. The preferred implementation methods and materials described herein are only for illustrative purposes and do not limit the content of this application.

[0026] The experimental methods in the following embodiments are all conventional methods unless otherwise specified. The test materials used in the following embodiments are all obtained from commercial channels unless otherwise specified.

[0027] Example 1

[0028] A method for producing soy sauce using Termitomyces albuminosus, comprising the following steps:

[0029] S1. After drying and pulverizing the fruiting bodies of Termitomyces albuminosus, add them to the basal medium (the basal medium contains 2% glucose, 1% peptone, 0.5% yeast extract, 2% agar, and the balance is distilled water) at a mass fraction of 5% to obtain a Termitomyces albuminosus powder medium; take the original strains of Aspergillus oryzae and Aspergillus niger, inoculate them into the Termitomyces albuminosus powder medium respectively, culture them in a constant temperature incubator at 30°C for 7 days, observe the colony growth situation, select the colonies with fast growth rate, dense mycelia and strong adaptability, and conduct re-inoculation and culture. Repeat the domestication and screening 5 times to obtain the domesticated strains of Aspergillus oryzae and Aspergillus niger adapted to the Termitomyces albuminosus environment;

[0030] S2. Mix and pulverize the fruiting bodies and mycelia of Termitomyces albuminosus at a mass ratio of 3:1, mix them with distilled water at a liquid-to-solid ratio of 1:35 to obtain a Termitomyces albuminosus mixture. After inactivating enzymes at gradient temperatures (first raise the temperature to 50°C, then to 70°C, and finally to 90°C, each stage for 5 minutes), adjust the pH to 7.5, and then add a compound enzyme preparation accounting for 0.5% of the mass of the Termitomyces albuminosus mixture (the compound enzyme preparation contains 70% neutral protease, 20% cellulase, 5% flavor protease, 5% laccase, the enzyme activity of neutral protease is 120000 U / g, the enzyme activity of cellulase is 15000 U / g, the enzyme activity of flavor protease is 8000 U / g, and the enzyme activity of laccase is 500 U / g), and carry out ultrasonic-assisted enzymatic hydrolysis at 50°C for 2 hours to obtain an enzymatic hydrolysate;

[0031] S3. The enzymatic hydrolysate and sorghum bran are compounded at a mass ratio of 3:1 to obtain a compound, and then β-glucanase accounting for 0.5% of the mass of the compound is added, and saccharification reaction is carried out at 55°C for 4 hours, with stirring every 30 minutes during this period, the stirring speed is 120 revolutions per minute, and secondary saccharification treatment is carried out.

[0032] S4. Steps: The domestically screened Aspergillus oryzae and Aspergillus niger are mixed with lactic acid bacteria to obtain a mixed koji species (the mixed koji species contains 60% Aspergillus oryzae, 30% Aspergillus niger, and 10% lactic acid bacteria). The mixed koji species is inoculated into the matrix after secondary saccharification at an inoculation amount of 1.5%, and gradient salt concentration control is adopted (the salt concentration is 12% in the first 5 days, 15% in the middle 7 days, and 18% in the last 8 days), and fermentation is carried out at 45°C for 32 days.

[0033] S5. The product after fermentation in step S4 is subjected to membrane separation using a 100 kDa ultrafiltration membrane, and then low-temperature vacuum concentration is carried out under the conditions of a vacuum degree of -0.09 MPa and a temperature controlled at 50°C. During the concentration process, the volume change and amino acid nitrogen content of the liquid are continuously monitored. When the amino acid nitrogen content of the product reaches ≥1.2 g / 100 mL, the concentration is stopped to obtain the finished soy sauce.

[0034] Example 2

[0035] A method for producing soy sauce using Termitomyces albuminosus, comprising the following steps:

[0036] S1. After drying and pulverizing the fruiting bodies of Termitomyces albuminosus, they are added to the basic medium (the basic medium contains 2% glucose, 1% peptone, 0.5% yeast extract, 2% agar, and the balance is distilled water) at a mass fraction of 5% to obtain a Termitomyces albuminosus powder medium. The original strains of Aspergillus oryzae and Aspergillus niger are taken and inoculated into the Termitomyces albuminosus powder medium respectively, and cultured in a constant temperature incubator at 30°C for 5 days. Observe the colony growth situation, select the colonies with fast growth rate, dense mycelium and strong adaptability, and carry out re-inoculation and culture. Repeat the domestication and screening 5 times to obtain the domesticated strains of Aspergillus oryzae and Aspergillus niger adapted to the Termitomyces albuminosus environment.

[0037] S2. Mix the fruiting bodies and mycelia of Termitomyces albuminosus at a mass ratio of 3:1, and mix them with distilled water at a solid-liquid ratio of 1:25 to obtain a Termitomyces albuminosus mixture. After inactivating enzymes at gradient temperatures (first heating to 50 °C, then to 70 °C, and finally to 90 °C, each stage for 5 min), adjust the pH to 7.0, and then add a compound enzyme preparation accounting for 0.5% of the mass of the Termitomyces albuminosus mixture (the compound enzyme preparation contains 60% neutral protease, 15% cellulase, 10% flavor protease, and 15% laccase, with the enzyme activity of neutral protease being 80000 U / g, cellulase being 10000 U / g, flavor protease being 5000 U / g, and laccase being 200 U / g), and perform ultrasonic-assisted enzymatic hydrolysis at 45 °C for 2 h to obtain an enzymatic hydrolysate;

[0038] S3. Compound the enzymatic hydrolysate and sorghum bran at a mass ratio of 2:1 to obtain a compound, and then add β-glucanase accounting for 0.5% of the mass of the compound, and perform saccharification reaction at 50 °C for 3 h, stirring once every 30 minutes during the period, with the stirring speed being 100 r / min for secondary saccharification treatment;

[0039] S4. Mix the domestically screened Aspergillus oryzae and Aspergillus niger with lactic acid bacteria to obtain a mixed starter culture (the mixed starter culture contains 70% Aspergillus oryzae, 20% Aspergillus niger, and 10% lactic acid bacteria), inoculate the mixed starter culture into the matrix after secondary saccharification at an inoculation amount of 1.5%, and control with gradient salt concentrations (the salt concentration is 12% in the first 5 days, 15% in the middle 7 days, and 18% in the last 8 days), and perform fermentation at 38 °C for 28 days.

[0040] S5. Perform membrane separation on the product after fermentation in step S4 using a 100 kDa ultrafiltration membrane, and then perform low-temperature vacuum concentration under the conditions of a vacuum degree of -0.08 MPa and a temperature controlled at 45 °C. During the concentration process, continuously monitor the volume change and amino acid nitrogen content of the liquid. When the amino acid nitrogen content of the product reaches ≥1.2 g / 100 mL, stop concentration to obtain the finished soy sauce.

[0041] Example 3

[0042] A method for producing soy sauce using Termitomyces albuminosus, comprising the following steps:

[0043] S1. After drying and pulverizing the fruiting bodies of Termitomyces albuminosus, add them to the basal medium at a mass fraction of 5% (the basal medium contains 2% glucose, 1% peptone, 0.5% yeast extract, 2% agar, and the balance is distilled water) to obtain a Termitomyces albuminosus powder medium. Take the original strains of Aspergillus oryzae and Aspergillus niger, inoculate them into the Termitomyces albuminosus powder medium respectively, culture them in a constant temperature incubator at 30 °C for 6 days, observe the colony growth situation, select the colonies with fast growth rate, dense mycelia and strong adaptability, and perform re-inoculation and culture. Repeat the domestication and screening 5 times to obtain the domesticated strains of Aspergillus oryzae and Aspergillus niger adapted to the Termitomyces albuminosus environment;

[0044] S2. Mix the fruiting bodies and mycelia of Termitomyces albuminosus at a mass ratio of 3:1, pulverize them, and mix them with distilled water at a solid-liquid ratio of 1:30 to obtain a Termitomyces albuminosus mixture. After inactivating enzymes at gradient temperatures (first heating to 50 °C, then to 70 °C, and finally to 90 °C, 5 minutes for each stage), adjust the pH to 7.2, and then add a compound enzyme preparation accounting for 0.5% of the mass of the Termitomyces albuminosus mixture (the compound enzyme preparation contains 65% neutral protease, 20% cellulase, 10% flavor protease, and 5% laccase; the enzyme activity of neutral protease is 100000 U / g, the enzyme activity of cellulase is 12500 U / g, the enzyme activity of flavor protease is 6500 U / g, and the enzyme activity of laccase is 350 U / g). Carry out ultrasonic-assisted enzymatic hydrolysis at 47.5 °C for 2 h to obtain an enzymatic hydrolysate;

[0045] S3. Compound the enzymatic hydrolysate and sorghum bran at a mass ratio of 2.5:1 to obtain a compound, and then add β-glucanase accounting for 0.5% of the mass of the compound. Carry out saccharification reaction at 52.5 °C for 3.5 h, stir once every 30 minutes during this period, and the stirring speed is 110 revolutions per minute for secondary saccharification treatment;

[0046] S4. Mix the domesticated and screened Aspergillus oryzae and Aspergillus niger with lactic acid bacteria to obtain a mixed starter culture (the mixed starter culture contains 65% Aspergillus oryzae, 25% Aspergillus niger, and 10% lactic acid bacteria). Inoculate the mixed starter culture into the matrix after secondary saccharification at an inoculation amount of 1.5%, and adopt gradient salt concentration control (the salt concentration is 12% in the first 5 days, 15% in the middle 7 days, and 18% in the last 8 days), and carry out fermentation at 41.5 °C for 30 days;

[0047] S5. Carry out membrane separation on the product after fermentation in step S4 using a 100 kDa ultrafiltration membrane, and then carry out low-temperature vacuum concentration under the conditions of a vacuum degree of -0.085 MPa and a temperature controlled at 47.5 °C. During the concentration process, continuously monitor the volume change and amino acid nitrogen content of the liquid. When the amino acid nitrogen content of the product reaches ≥1.2 g / 100 mL, stop concentration to obtain the finished soy sauce.

[0048] Comparative Example 1

[0049] In this comparative example, the original strains of Aspergillus oryzae and Aspergillus niger were directly used, and the other steps in Example 3 were followed for soy sauce production, that is, without going through the domestication and screening process in the Termitomyces albuminosus powder medium

[0050] Comparative Example 2

[0051] In this comparative example, in step S2, the compound enzyme preparation was replaced with an equal amount of single neutral protease, and the other steps were the same as in Example 3.

[0052] Comparative Example 3

[0053] In step S3, without adding β-glucanase for secondary saccharification, directly after the enzymatic hydrolysate and sorghum bran are compounded in the ratio in Example 3, they enter the fermentation process in step S4, and other steps are the same as in Example 3.

[0054] Result analysis

[0055] Detect the free amino acid content in the finished soy sauce of each example and comparative example, so as to evaluate the enzymatic hydrolysis efficiency and quality of the soy sauce of each example and comparative example. The results are shown in Figure 1 .

[0056] It can be seen from Figure 1 : Since in the examples, Termitomyces albuminosus powder medium was used to domesticate and screen Aspergillus oryzae and Aspergillus niger, the adaptability of the strains to the Termitomyces albuminosus matrix was enhanced. At the same time, a compound enzyme preparation containing multiple enzymes was used, combined with gradient enzyme inactivation and ultrasonic-assisted treatment, to fully decompose the cell wall and protein of Termitomyces albuminosus, releasing more free amino acids. In Comparative Example 1, without domestication and screening with Termitomyces albuminosus powder medium, Aspergillus oryzae and Aspergillus niger had poor adaptability to the Termitomyces albuminosus matrix and low enzymatic hydrolysis efficiency, resulting in a relatively low content of free amino acids. In Comparative Example 2, a single neutral protease was used, which could not fully decompose the cell wall and protein of Termitomyces albuminosus like the compound enzyme preparation, and the enzymatic hydrolysis was insufficient, so the content of free amino acids was low. In Comparative Example 3, the secondary saccharification treatment with β-glucanase was lacking, which affected the soluble sugar content in the soy sauce, and further might affect some sugar-related metabolic processes and the formation of flavor substances, and also had a certain adverse effect on the release of free amino acids, and its content was lower than that of the example group.

[0057] Measure the DPPH free radical scavenging ability of the soy sauce of each example and comparative example. The results are shown in Figure 2 .

[0058] It can be seen from Figure 2 : The soy sauce produced in the examples has strong DPPH free radical scavenging ability. This is because Termitomyces albuminosus contains polyphenolic compounds, proteins, polypeptides, etc., which have antioxidant activity. The domesticated strains can make more full use of the nutrients in Termitomyces albuminosus during the fermentation process, promoting the formation of flavor substances and antioxidant substances. At the same time, processes such as the adopted compound enzyme system, microwave-assisted enzymatic extraction of jujube polysaccharide extract, and secondary saccharification with β-glucanase increase the content of functional polysaccharides and soluble sugars in the soy sauce, further enhancing the antioxidant ability of the soy sauce.

[0059] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

[0060] The above describes the present invention and its embodiments. Such description is not restrictive. What is shown in the drawings is only one of the embodiments of the present invention, and the actual application is not limited thereto. In summary, if those of ordinary skill in the art are inspired by it and, without departing from the gist of the present invention, design in a non-creative way similar methods and embodiments to this technical solution, they shall fall within the protection scope of the present invention.

Claims

1. A method for producing soy sauce using Album albuminum, characterized in that: The following steps are involved: S1. After the fruiting body of Alternaria albuminosa was dried and crushed, it was added to the basal culture medium at a mass fraction of 5% to obtain an Alternaria albuminosa powder culture medium, and the original strains of Aspergillus oryzae and Aspergillus niger were taken and inoculated into the Alternaria albuminosa powder culture medium respectively, and cultured in a constant temperature incubator at 30°C for 5-7 days, and the growth of the colonies was observed, and colonies with fast growth rate, dense mycelium and strong adaptability were selected, and inoculated and cultured again, and the domestication screening was repeated 5 times to obtain domesticated strains of Aspergillus oryzae and Aspergillus niger adapted to the Alternaria albuminosa environment; S2. The fruiting bodies and mycelium of Albizia albuminosa are mixed and crushed in a mass ratio of 3:1, and mixed with distilled water in a solid-liquid ratio of 1:25-35 to obtain a mixture of Albizia albuminosa, and after the enzyme is inactivated by gradient temperature, the pH is adjusted to 7.0-7.5, and then 0.5% of the mass of the composite enzyme preparation of the mixture of Albizia albuminosa is added, and ultrasonic-assisted enzymolysis is performed at 45-50°C for 2h to obtain an enzymatic solution, wherein the composite enzyme preparation comprises neutral protease, cellulase, flavor protease and laccase; S3. The enzymatic hydrolysate and sorghum bran are compounded in a mass ratio of 2-3:1 to obtain a compound, and then 0.5% of the mass of the compound is added to perform a secondary saccharification treatment with β-glucanase; S4. The acclimated and screened Aspergillus oryzae and Aspergillus niger were mixed with lactic acid bacteria to obtain a mixed koji, and the mixed koji was inoculated in the matrix after secondary saccharification at an inoculum amount of 1.5%, and the salt concentration was controlled by gradient, and fermented at 38-45 ℃ for 28-32 days; S5. The product after fermentation in step S4 is subjected to membrane separation using a 100 kDa ultrafiltration membrane, and then concentrated at low temperature and vacuum to obtain finished soy sauce.

2. A method for producing soy sauce utilizing Album albuminum according to claim 1, characterized in that: The composite enzyme preparation in step S2 comprises the following components in percentage by mass: 60-70% of neutral protease, 15-20% of cellulase, 5-15% of flavor protease and 5-15% of laccase.

3. A method for producing soy sauce utilizing Album albuminum according to claim 2, characterized in that: The neutral protease has an enzymatic activity of 80000-120000 U / g, the cellulase has an enzymatic activity of 10000-15000 U / g, the flavor protease has an enzymatic activity of 5000-8000 U / g, and the laccase has an enzymatic activity of 200-500 U / g.

4. A method for producing soy sauce utilizing Album albuminum according to claim 3, characterized in that: The mixed koji contains 60-75% of Aspergillus oryzae, 20-30% of Aspergillus niger and 5-15% of lactic acid bacteria.

5. A method for producing soy sauce utilizing Album albuminum according to claim 4, characterized in that: The preparation method of the red date polysaccharide extract is as follows: pitted red dates and Alternaria album fermentation liquid are extracted in a ratio of 1:5, subjected to composite enzymatic hydrolysis with pectinase:xylanase=3:1, subjected to microwave-assisted extraction at 600W, 60°C, 15min, and then separated and purified using a ceramic membrane.

6. A method for producing soy sauce utilizing Album albuminum according to claim 5, characterized in that: The basic culture medium in step S1 comprises 2% glucose, 1% peptone, 0.5% yeast extract, 2% agar, and the remainder is distilled water.

7. A method for producing soy sauce utilizing Album albuminum according to claim 6, characterized in that: The gradient temperature inactivation conditions of step S2 are: first heating to 50° C., then heating to 70° C., and finally heating to 90° C., with each stage lasting 5 minutes.

8. A method for producing soy sauce utilizing Album albuminum according to claim 7, characterized in that: The gradient salt concentration in step S4 is controlled as follows: the salt concentration is 12% in the first 5 days, 15% in the middle 7 days, and 18% in the last 8 days.

9. A method for producing soy sauce utilizing Album albuminum according to claim 8, characterized in that: The secondary saccharification treatment specifically includes: mixing the enzymatic hydrolysate with sorghum bran at a ratio of 2:1, adding 0.5% beta-glucanase, and carrying out saccharification reaction at 50-55°C for 3-4 hours, stirring every 30 minutes during the reaction, and the stirring speed is 100-120 rpm.

10. A method for producing soy sauce using Album albuminum according to claim 9, characterized in that: The concentration of the low-temperature vacuum concentration is: the vacuum degree is -0.08MPa to -0.09MPa, the temperature is controlled at 45°C-50°C, and during the concentration process, the volume change of the liquid and the amino acid nitrogen content are continuously monitored. When the amino acid nitrogen content of the product reaches ≥1.2g / 100mL, the concentration is stopped to obtain the finished soy sauce.

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