Aspergillus oryzae vpa06 and application thereof

Abstract

The present application relates to the technical field of microorganisms, and particularly relates to a strain of aspergillus oryzae (vpa06) and application thereof. Aspergillus oryzae The aspergillus oryzae vpa06 strain provided by the present application has high neutral protease and amino peptidase production, and the produced compound protease has good heat resistance, and is very suitable for a high-temperature enzymolysis system. The strain can be used for preparing enzyme preparations, and can meet the application requirements of high-temperature scenes such as food processing, especially low-salt food production, can effectively improve the protein utilization rate, increase the amino acid nitrogen and amino acid content, and improve the product flavor and quality.

Description

Technical Field

[0001] This invention relates to the field of microbial technology, specifically to a strain of Aspergillus oryzae vpa06 and its applications. Background Technology

[0002] Proteases are an important class of hydrolases, accounting for over 60% of total industrial enzyme production, and are widely used in food, pharmaceuticals, detergents, textiles, and leather processing. In food processing, especially when proteases hydrolyze animal and plant proteins, a high concentration of salt is often added to inhibit the proliferation of harmful microorganisms. However, high salt content inhibits protease activity, reduces hydrolysis efficiency, and prolongs the hydrolysis cycle. Furthermore, excessive salt intake can damage organs such as the heart, brain, and kidneys, increasing the incidence of hypertension and the risk of depression. Increasing the reaction temperature of a low-salt hydrolysis system can effectively inhibit microbial growth and reduce the microbial risk of the product.

[0003] Aspergillus oryzae secretes a rich protease system, with endopeptidases mainly being neutral proteases and exopeptidases mainly being aminopeptidases. This makes it highly suitable as a production strain for proteases and it is a production strain for endopeptidases such as neutral proteases and exopeptidases such as aminopeptidases as specified in the National Food Safety Standard for the Use of Food Additives (GB2760-2024). However, Aspergillus oryzae proteases suffer from the common heat intolerance of fungal proteases; after heating at 55°C for 1 hour, more than 80% of the neutral protease is lost, making it unsuitable for reaction systems with enzymatic hydrolysis temperatures exceeding 55°C.

[0004] Currently, domestic literature reports on Aspergillus oryzae proteases mainly focus on strain selection and fermentation condition optimization, without addressing the heat resistance of Aspergillus oryzae proteases. Patent 202411190034.1 discloses an Aspergillus oryzae strain ZA304, whose acidic protease, neutral protease, aminopeptidase, and total protease activities are significantly improved, but its heat resistance is not discussed. Patent 201210559100.9 discloses a high-yield neutral protease Aspergillus oryzae mutant strain and its liquid fermentation method. The neutral protease produced by this Aspergillus oryzae strain has an activity above 20821 U / mL, and after incubation at 40℃ for 1 hour, the remaining enzyme activity is 91%, exhibiting good heat resistance. However, 40℃ cannot inhibit microbial proliferation during food processing. Therefore, developing a high-activity and heat-resistant Aspergillus oryzae complex protease can meet the high-temperature application requirements of food processing, especially suitable for the production of low-salt foods and improving enzymatic hydrolysis efficiency, which is of great significance. Summary of the Invention

[0005] Based on the above technical problems, the main purpose of this invention is to overcome the shortcomings of the above-mentioned background technology. Using Aspergillus oryzae Hu Niang 3.042 as the starting strain, an Aspergillus oryzae vpa06 strain was obtained through ARTP mutagenesis screening. This strain produces high yields of neutral protease and aminopeptidase, and the compound protease produced has good heat resistance, making it very suitable for high-temperature enzymatic hydrolysis systems. It has broad application prospects in food production, especially in the production of low-salt foods.

[0006] To achieve the above objectives, the inventors conducted in-depth research and, through repeated studies and demonstrations, obtained the solution of this invention, as detailed below:

[0007] In a first aspect, the present invention provides a strain of Aspergillus oryzae vpa06, the preservation number of which is GDMCC No: 68006.

[0008] The strain was deposited on March 27, 2026 at the Guangdong Microbial Culture Collection Center, located at 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, Guangdong Province.

[0009] Secondly, the present invention provides a fermentation agent comprising Aspergillus oryzae vpa06.

[0010] Thirdly, the present invention provides the application of Aspergillus oryzae VPA06 or the above-mentioned fermentation agent in food processing. Specifically, the application is for the degradation of proteins and peptide chains, and the food is a low-salt food.

[0011] Fourthly, the present invention provides the application of Aspergillus oryzae vpa06 or the above-mentioned fermentation agent in the preparation of enzyme preparations.

[0012] Fifthly, the present invention provides an enzyme preparation, which is obtained by filtering and concentrating the fermentation broth of the above-mentioned Aspergillus oryzae vpa06 or fermentation agent.

[0013] Sixthly, the present invention provides the application of the above-mentioned enzyme preparation in food processing, specifically, the application is for the degradation of proteins and peptide chains, and the food is a low-salt food.

[0014] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0015] 1. The Aspergillus oryzae vpa06 provided in this application has the advantage of high production of complex protease. The neutral protease activity in its fermentation broth is 6.5 times that of the Aspergillus oryzae 3.042 fermentation broth, and the aminopeptidase activity is 7.2 times that of the Aspergillus oryzae 3.042 fermentation broth. The neutral protease activity of the crude enzyme solution of the complex protease prepared by it exceeds 110,000 U / mL, and the aminopeptidase activity exceeds 25,000 U / mL.

[0016] 2. The Aspergillus oryzae vpa06 strain provided by this invention produces a complex protease with good heat resistance. After heating at 60°C for 1 hour, the neutral protease activity retention rate exceeds 25%, and the aminopeptidase activity retention rate exceeds 99%, making it very suitable for high-temperature enzymatic hydrolysis systems.

[0017] 3. The Aspergillus oryzae vpa06 strain provided by this invention can be used to prepare enzyme preparations, meeting the application requirements of high-temperature scenarios such as food processing, especially in the production of low-salt foods, which can effectively improve protein utilization, increase amino acid nitrogen and amino acid content, and improve product flavor and quality. Attached Figure Description

[0018] Figure 1 The results of the optimal reaction temperature test for complex proteases and commercially available proteases;

[0019] Figure 2 The results are from heat resistance tests on compound proteases and commercially available proteases.

[0020] The Aspergillus oryzae vpa06 provided by this invention was deposited at the Guangdong Microbial Culture Collection Center on March 27, 2026, at the address: 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, Guangdong Province, with accession number GDMCC NO: 68006. This strain was received and registered by the collection center on March 27, 2026, and was confirmed to be a viable strain by the collection center on March 27, 2026. Detailed Implementation

[0021] To facilitate understanding of the present invention, a more comprehensive description will be given below. However, 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 thorough and complete understanding of the disclosure of the present invention.

[0022] 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.

[0023] Unless otherwise specified, the reagents, methods and equipment used in this invention are conventional food-grade reagents, methods and equipment in the art.

[0024] The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] The culture medium formulation and enzyme activity detection method used in the following examples are as follows:

[0026] Casein medium: 10g glucose, 10g casein, 1g potassium dihydrogen phosphate, 0.5g magnesium sulfate heptahydrate, 0.5g sodium chloride, 20g agar, 1000mL distilled water, pH 7.0-7.2. Sterilize at 121℃ for 20min.

[0027] PDA medium: Weigh 200g of potatoes, wash and chop them, add an appropriate amount of water and boil, filter, add water to the filtrate to a final volume of 1000mL, add 20g of glucose and 20g of agar, heat to dissolve the agar, and control the pH naturally. Sterilize at 121℃ for 20min.

[0028] PDY medium: Weigh 200g of potatoes, wash and chop them, add an appropriate amount of water and boil, filter, add water to the filtrate to a final volume of 1000mL, add 2% glucose, and control the pH naturally. Sterilize at 121℃ for 20min.

[0029] Fermentation medium: 50g glucose, 50g soybean flour, 5g corn steep liquor powder, 5g yeast powder, 10g citric acid, 8g disodium hydrogen phosphate, 8g ammonium sulfate, 1000mL distilled water, pH 6.0-7.0. Sterilize at 121℃ for 30min.

[0030] Neutral protease activity assay method: The assay method is based on Appendix A of GB / T23527.1-2023, Determination of Protease Activity - Folin Method. One unit of neutral protease activity is defined as the amount of protease required to hydrolyze casein to produce 1 μg of tyrosine in 1 minute at 40℃ and pH 7.5.

[0031] Aminopeptidase activity assay: Under conditions of (40±0.2)℃ and pH 8.0, the amount of enzyme required to hydrolyze the Leu-pNA substrate within 1 min to produce 1 μg of p-NA is defined as 1 enzyme activity unit, expressed as U / g (or U / mL).

[0032] Example 1: Screening of the target strain

[0033] 1. Preliminary screening of bacterial strains

[0034] Weigh 0.1g of Aspergillus oryzae 3.042 spore powder into a clean test tube, dissolve in 2 mL of sterile water, mix well, and then spread the diluted spore solution onto PDA agar plates using the dilution spread method. Incubate at 30℃ until spores mature. Add 2 mL of sterile physiological saline to the agar plate, scrape off the spores using a sterile L-shaped spreader to suspend them, and collect them into 2 mL centrifuge tubes. Dilute the spore suspension to an appropriate factor, count the spores using a hemocytometer, and then dilute the spore concentration in the original solution to 2×10⁻⁶. 8CFU / mL. Prepare a sterile 10% (v / v) glycerol and spore suspension by thoroughly mixing at a 1:1 ratio. Apply 10 μL of the mixture to a sterile slide, then transfer the slide to a sterile stage. Use helium as the working gas, setting the power to 120 W, the gas flow rate to 10 SLM, and the mutagenesis times to 0, 60, 90, 120, 150, 180, 210, and 240 seconds.

[0035] The mutagenized slides were placed in centrifuge tubes containing 200 μL of sterile physiological saline. 100 μL of the solution was spread onto PDA medium and incubated at 30°C for 72 h. Single colonies of the mold were then picked and inoculated onto casein medium. After incubation at 30°C for 72 h, the growth of the strains was observed. Mutant strains with normal mycelial growth, large clear zones, large colony diameters, and larger H / C ratios compared to Aspergillus oryzae 3.042 were selected. The results are recorded in Table 1.

[0036] Table 1. Results of ARTP mutagenesis screening for Aspergillus oryzae 3.042.

[0037] Aspergillus oryzae 3.042 21.5 18.5 1.16 AO-01 23.4 19.3 1.21 AO-02 25.9 19.2 1.35 AO-03 38.5 20.9 1.84 AO-04 29.3 18.8 1.56

[0038] As shown in Table 1, four mutant strains had higher clear zone diameter, colony diameter, and H / C ratio than the control strain Hu Niang 3.042, which was not treated with ARTP. Among them, strain AO-03 had a colony diameter of 20.9 mm, a clear zone diameter of 38.5 mm, and an H / D ratio of 1.84, which were significantly higher than those of the control strain Hu Niang 3.042. Therefore, the mutant strain AO-03 may have higher protease activity, and this strain was selected for further ARTP mutagenesis screening.

[0039] 2. Secondary screening of strains

[0040] Weigh 0.1g of Aspergillus oryzae AO-03 spore powder into a clean test tube, and perform ARTP mutagenesis using the same method as the initial screening. Then, screen for mutant strains with normal mycelial growth, large clear zone, large colony diameter, and large H / C ratio. The results are recorded in Table 2.

[0041] Table 2 Results of ARTP mutagenesis screening of Aspergillus oryzae AO-03

[0042] AO-03 38.2 20.1 1.9 AO-05 40.6 20.8 1.95 AO-06 43.2 21.2 2.04 AO-07 48.4 21.7 2.23

[0043] As shown in Table 2, three mutant strains had higher clear zone diameter, colony diameter, and H / C ratio than the control strain AO-03. These mutant strains were named AO-05, AO-06, and AO-07, respectively.

[0044] The three strains AO-05, AO-06, and AO-07, along with the starting strain Hu Niang 3.042, were activated and transferred to PDA slant culture medium in test tubes and incubated at 30℃ for 5 days. After activation, they were transferred to Erlenmeyer PDY medium and cultured at 30℃ with a stirring speed of 150 r / min for 48 h. The cultured liquid culture was then inoculated into fermentation medium for fermentation, with the fermentation temperature controlled at 30℃, a stirring speed of 150 r / min, a fermentation pH of 6.5, and a fermentation time of 72 h. After fermentation, the fermentation broth was centrifuged at 10000 r / min for 5 min, and the supernatant was used to detect the activity of neutral protease and aminopeptidase. The supernatant was then heated in a 60℃ water bath for 1 h, and samples were taken again to detect the activity of neutral protease and aminopeptidase. The results are shown in Table 3.

[0045] Table 3. Enzyme activity detection results of fermentation supernatant of the strain before and after heating.

[0046]

[0047] Table 3 shows that the neutral protease and aminopeptidase activities of the AO-07 mutant strain were highest before and after heating, and significantly higher than those of the Aspergillus oryzae 3.042 fermentation broth. The neutral protease activity of the AO-07 mutant strain fermentation broth was 6.5 times that of the Aspergillus oryzae 3.042 fermentation broth, and the aminopeptidase activity was 7.2 times that of the Aspergillus oryzae 3.042 fermentation broth. After heating in a 60℃ water bath for 1 hour, the retention rate of its neutral protease activity was 27%, significantly better than that of the Aspergillus oryzae 3.042 fermentation broth, and the retention rate of its aminopeptidase activity was 99%, comparable to that of the Aspergillus oryzae 3.042 fermentation broth. The above results indicate that the mutant strain AO-07 can produce high levels of neutral protease and aminopeptidase, and the produced enzymes have good heat resistance. The strain was identified by sequencing as an Aspergillus oryzae strain, renamed vpa06, and deposited at the Guangdong Provincial Microbial Culture Collection Center on March 27, 2026, with accession number GDMCC NO: 68006.

[0048] Example 2: Genetic stability test of Aspergillus oryzae vpa06

[0049] The *Aspergillus oryzae* vpa06 strain obtained in Example 1 was passaged 10 times on PDA slant culture medium. The growth of each generation was observed and recorded. The 1st, 5th, and 10th generation slant cultures were inoculated into Erlenmeyer PDY medium and cultured at 30°C with a stirring speed of 150 rpm for 48 h. The cultured liquid culture was then inoculated into fermentation medium for fermentation at 30°C with a stirring speed of 150 rpm and a pH of 6.5 for 72 h. After fermentation, the fermentation broth was centrifuged at 10,000 rpm for 5 min, and the supernatant was used to detect the activities of neutral protease and aminopeptidase. The genetic stability of the *Aspergillus oryzae* vpa06 strain was determined based on the activities of neutral protease and aminopeptidase in the fermentation supernatant. If the changes in neutral protease and aminopeptidase activities were within 10% after ten generations, the genetic stability of the strain was considered good. The test results are shown in Table 4.

[0050] Table 4. Results of genetic stability testing of Aspergillus oryzae strain VPA06

[0051] 1 Normal colony characteristics 3767.1 1017.2 5 Normal colony characteristics 3995.4 997.1 10 Normal colony characteristics 3843.2 1037.4

[0052] As shown in Table 4, the colony characteristics of Aspergillus oryzae vpa06 strains of different generations were normal, and the enzyme activities of neutral protease and aminopeptidase in the fermentation supernatant were within 10%, indicating that the strain had good genetic stability.

[0053] Example 3: Method for preparing complex protease from Aspergillus oryzae vpa06

[0054] (1) Activation of strain: The freeze-dried Aspergillus oryzae vpa06 strain was transferred to PDA slant medium and cultured at 30℃ for 5 days to activate the strain.

[0055] (2) Shake flask liquid culture: The activated strain was inoculated into Erlenmeyer PDY medium for expansion culture. The culture temperature was set at 30℃, the stirring speed was 150r / min, and the culture time was 48h.

[0056] (3) Fermentation in a fermenter: The liquid inoculum cultured in the seed tank is transferred to the fermentation medium in the fermenter for fermentation. The fermentation temperature is set at 30℃. Ammonia or phosphoric acid is added to control the fermentation pH at 6.5. The stirring speed is 200 r / min for the first 4 hours of fermentation and 500 r / min for the later stage. The aeration ratio is 1.5 (V / V·min). During the fermentation process, when the reducing sugar content of the fermentation liquid in the fermenter decreases to 5 g / L, glucose solution is added to control the reducing sugar content of the fermentation liquid at 3-7 g / L. The fermentation cycle is 144 hours.

[0057] (4) Plate and frame filter press: Add 100% of the fermentation liquid mass of tap water to the fermentation liquid, then add 1% of the fermentation liquid mass of calcium chloride, 1% of polyacrylamide, 1% of diatomaceous earth and 4% of perlite, stir for 0.5 h and then perform plate and frame filter press to obtain clear liquid.

[0058] (5) Membrane concentration: The supernatant was concentrated using a 10KD filter membrane, and then sterilized using a 0.22μm filter membrane to obtain a crude enzyme solution of the complex protease. Samples were taken to test the activity of neutral protease and aminopeptidase. The test results are shown in Table 5.

[0059] Table 5. Results of enzyme activity detection for the compound protease prepared from Aspergillus oryzae vpa06

[0060] crude enzyme solution 111178.0 25793.3

[0061] Example 4: Heat resistance test of the complex protease produced by Aspergillus oryzae vpa06

[0062] The crude enzyme solution of the complex protease prepared in Example 3 was used as the experimental group sample; a commercially available protease derived from Aspergillus oryzae was used as the control sample. After adjusting the neutral protease activity of the samples to 10000 U / mL using phosphate buffer (pH 7.5), the optimal reaction temperature and heat resistance were studied.

[0063] (1) Optimal reaction temperature test: The buffer solution and reaction solution were preheated to 30, 35, 40, 45, 50, 55, 60, 70, 80, and 85 °C, respectively, and the enzyme activity of the samples at different temperatures was measured. The enzyme activity at the optimal temperature was taken as 100%, and the relative enzyme activity at each temperature was calculated. The results are shown in Table 6 and Figure 1 As shown.

[0064] Table 6. Optimal reaction temperature test results of the complex protease prepared from Aspergillus oryzae vpa06 and the commercially available protease.

[0065]

[0066] From Table 6 and Figure 1 It can be seen that the optimal reaction temperature for the neutral protease of the complex protease prepared by Aspergillus oryzae vpa06 is 55℃, and the optimal reaction temperature for the aminopeptidase is 70℃; the optimal reaction temperature for the neutral protease of commercially available proteases is 50℃, and the optimal reaction temperature for the aminopeptidase is 70℃. The optimal temperature for the neutral protease of the complex protease prepared by Aspergillus oryzae vpa06 is higher than that of the neutral protease of commercially available proteases, while the optimal temperatures for the aminopeptidase of the two are not significantly different.

[0067] (2) Heat resistance test: The samples were incubated at 30, 35, 40, 45, 50, 60, 70, and 80℃ for 1 hour, respectively, and then rapidly cooled to room temperature. The enzyme activity was then measured under the enzyme activity assay conditions (40℃, pH 7.5). The enzyme activity measured without heat treatment was taken as 100%, and the corresponding enzyme activity retention rate was calculated after each temperature treatment. The results are shown in Table 7. Figure 2 As shown.

[0068] Table 7. Heat resistance test results of the complex protease prepared by Aspergillus oryzae vpa06 and commercially available protease.

[0069]

[0070] From Table 7 and Figure 2 It was found that the compound protease prepared by *Aspergillus oryzae* VPA06 retained 48.3% of its neutral protease activity and 100.6% of its aminopeptidase activity after heating at 55℃ for 1 hour; after heating at 60℃ for 1 hour, the retention rates were 26.1% and 102.4%. Commercially available proteases, after heating at 55℃ for 1 hour, retained 19.3% of their neutral protease activity and 99.2% of their aminopeptidase activity; after heating at 60℃ for 1 hour, the retention rates were 2.6% and 99.5%. The neutral protease activity retention rate of the compound protease prepared by *Aspergillus oryzae* VPA06 after heating at 55℃ for 1 hour was 2.5 times that of the commercially available protease; and the neutral protease activity retention rate of the compound protease prepared by heating at 60℃ for 1 hour was 10 times that of the commercially available protease.

[0071] In summary, the heat resistance of the neutral protease in the complex protease prepared by *Aspergillus oryzae* vpa06 is significantly better than that of commercially available neutral proteases, while the heat resistance of the aminopeptidase is slightly better. Therefore, the heat resistance of the complex protease prepared by *Aspergillus oryzae* vpa06 is superior to that of commercially available proteases.

[0072] Example 5: Test on the enzymatic hydrolysis effect of the compound protease produced by Aspergillus oryzae vpa06 on oyster juice.

[0073] (1) Thaw the oyster meat, grind it into powder, and then homogenize it to ensure that the oyster paste is uniform.

[0074] (2) The complex protease prepared by Aspergillus oryzae vpa06 and the commercially available protease were diluted to control the activity of the neutral protease after dilution to 30000U / mL.

[0075] (3) Weigh 100g of oyster paste into a 250mL Erlenmeyer flask, and add two diluted proteases for enzymatic hydrolysis. The amount of protease added is 1% of the substrate mass. Place the Erlenmeyer flask in a constant temperature water bath and shake it. Control the hydrolysis temperature at 55℃, the shaking speed at 200rpm, and the hydrolysis time at 16 hours. After the hydrolysis is completed, place the hydrolysate in boiling water for 10 minutes to inactivate the enzyme.

[0076] (4) After the enzymatic hydrolysate cools to room temperature, samples are taken to test amino acid nitrogen, total nitrogen, and salt content. The enzymatic hydrolysis efficiency of the oyster meat is calculated. Enzymatic hydrolysis efficiency (%) = amino acid nitrogen / total nitrogen × 100%. The results are recorded in Table 8.

[0077] Table 8 Results of enzymatic hydrolysis of oyster juice by the compound protease prepared from Aspergillus oryzae vpa06 and commercially available protease.

[0078] Complex protease hydrolyzes oyster juice 0.82 1.45 56.4% 2.74 Commercially available protease-hydrolyzed oyster juice 0.68 1.43 47.4% 2.68

[0079] Table 8 shows that, under the same conditions of oyster paste raw materials, when the same amount of compound protease prepared by Aspergillus oryzae VPA06 and commercially available protease with the same enzyme activity were added to the oyster paste for enzymatic hydrolysis, the amino acid nitrogen content of the compound protease group was increased by 21% and the enzymatic hydrolysis efficiency was increased by 19% compared with the commercially available protease group. Sensory evaluation results showed that the oyster juice hydrolyzed by the compound protease had a weaker fishy smell and better flavor than that hydrolyzed by the commercially available protease.

[0080] Example 6: Test on the enzymatic hydrolysis effect of the complex protease produced by Aspergillus oryzae vpa06 on chicken meat

[0081] (1) After grinding the chicken into a paste, add twice the amount of distilled water, boil for 10 minutes, and then cool for later use.

[0082] (2) The complex protease prepared by Aspergillus oryzae vpa06 and the commercially available protease were diluted to control the activity of the neutral protease after dilution to 30000U / mL.

[0083] (3) Weigh 100g of cooked chicken into a 250mL Erlenmeyer flask, and add two diluted proteases for enzymatic hydrolysis. The amount of protease added is 2% of the substrate mass. Place the Erlenmeyer flask in a constant temperature water bath and shake it. Control the hydrolysis temperature at 55℃, the shaker speed at 200rpm, and the hydrolysis time at 5 hours. After the hydrolysis is completed, place the hydrolysate in boiling water for 10 minutes to inactivate the enzyme.

[0084] (4) After the enzyme hydrolysate cools to room temperature, take a sample to test for amino acid nitrogen and glutamic acid.

[0085] Table 9. Results of enzymatic hydrolysis of chicken meat by the complex protease prepared from Aspergillus oryzae vpa06 and commercially available protease.

[0086] Chicken meat hydrolyzed by complex protease 0.49 3.90 Commercially available protease-hydrolyzed chicken 0.33 1.17

[0087] Table 9 shows that, under the same conditions of chicken raw materials, when oyster paste was hydrolyzed with the same amount and enzyme activity of a compound protease prepared from Aspergillus oryzae VPA06 and a commercially available protease, the amino acid nitrogen content of the compound protease group was increased by 48% and the glutamic acid content was increased by 233% compared with the commercially available protease group. Sensory evaluation results showed that the chicken hydrolyzed with the compound protease had a more prominent umami and salty taste and a better flavor than the chicken hydrolyzed with the commercially available protease.

[0088] In summary, Aspergillus oryzae vpa06 produces high yields of neutral protease and aminopeptidase, and the enzymes produced have good heat resistance. Compared with commercially available proteases, the complex protease prepared by Aspergillus oryzae vpa06 can better meet the application needs of high-temperature scenarios such as food processing, especially in the production of low-salt foods. It can effectively improve protein utilization, increase amino acid nitrogen and amino acid content, and enhance product flavor and quality.

[0089] 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 strain of Aspergillus oryzae ( Aspergillus oryzae vpa06, characterized in that, The preservation number of Aspergillus oryzae vpa06 is GDMCC No: 68006.

2. A fermentation agent, characterized in that, The fermentation agent comprises Aspergillus oryzae vpa06 as described in claim 1.

3. The application of Aspergillus oryzae VPA06 as described in claim 1 or the fermentation agent as described in claim 2 in food processing.

4. The application as described in claim 3, characterized in that, The application is for the degradation of proteins and peptide chains.

5. The application as described in claim 3 or 4, characterized in that, The food in question is a low-sodium food.

6. The use of Aspergillus oryzae VPA06 as described in claim 1 or the fermentation agent as described in claim 2 in the preparation of enzyme preparations.

7. An enzyme preparation, characterized in that, The enzyme preparation is obtained by filtering and concentrating the fermentation broth of Aspergillus oryzae vpa06 as described in claim 1 or the fermentation agent as described in claim 2.

8. The application of the enzyme preparation as described in claim 7 in food processing.

9. The application as described in claim 8, wherein the application is for protein and peptide chain degradation.

10. The application as described in claim 8 or 9, characterized in that, The food in question is a low-sodium food.

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