Fermentation process of microbial strain

Abstract

The invention relates to the technical field of food processing, in particular to a fermentation process of microbial strains. Comprising the following steps: pretreating a brown rice fermentation substrate; expanding culture of strains and fermentation of the psyllium seed husk powder; and performing efficient fermentation and post-treatment on the brown rice. The brown rice and the citric acid powder are mixed for plasma treatment, part of water in the brown rice is evaporated in the plasma treatment process, the water is combined with citric acid to generate a weak acid environment, cellulose on the surface of the brown rice can be softened, and the surface structure of the brown rice is etched and damaged in combination with plasma, so that the surface structure of the brown rice is improved. The method can effectively reduce the crystallinity of cellulose, enables the surface structure of brown rice to be looser, can absorb and adsorb more amino acids in the subsequent soaking process of an amino acid solution, also can improve the rate and effect of subsequent microbial fermentation, improves the water absorption rate of the finished product of fermented brown rice, and improves the quality of the fermented brown rice. And the hardness of the surface cortex of the finished fermented brown rice is reduced, so that the cooking quality of the fermented brown rice is improved.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, in particular to a fermentation process of microbial strains. Background Art

[0002] Brown rice is rice that retains the rough outer layer after the rice grains are husked. In other words, brown rice is the rice after the husk is removed, which is the caryopsis of the rice grain. Although brown rice is rich in starch, protein, fat, vitamins, minerals, cellulose and trace elements, compared with polished rice, brown rice retains the cortex, which contains more crude cellulose, resulting in brown rice being difficult to cook during the steaming process and having a residue-like taste when chewed. There is also a waxy layer in the cortex of brown rice, which makes it difficult for water to enter the endosperm, limiting the gelatinization of starch.

[0003] At present, the main methods for improving the edible quality of brown rice include milling, soaking, extrusion and enzyme treatment. The milling method is to use a rice mill to remove the cortex of brown rice to enhance the water absorption performance of brown rice and improve the cooking quality, but this method causes a large loss of nutrients in brown rice; the soaking method is to soak brown rice in water or other solutions. Soaking can soften the cortex of brown rice to shorten the cooking time of brown rice, but in actual operation, the soaking temperature is generally 50-60℃, and it needs to be soaked for 4 hours at this temperature, which is inefficient. The product quality is poor; the extrusion puffing method is a modern processing technology that integrates mixing, stirring, crushing, heating, cooking, sterilization, puffing and forming. It is simple and safe to operate and does not pollute the environment. However, after extrusion puffing, the shape of brown rice changes greatly and is not suitable for processing brown rice into a staple food; the enzyme treatment method mainly utilizes endogenous enzymes, exogenous enzymes and complex enzymes to degrade cellulose, phytic acid and pectin in brown rice to improve the edibility of brown rice. However, the enzyme treatment method must add a specific catalyst and react at a specific pH value. The processing is complicated, and the rate and time of the enzymatic reaction are difficult to control, which significantly increases the production cost of brown rice. Summary of the invention

[0004] In order to solve the above-mentioned process difficulties, the present invention has developed a fermentation process of microbial strains, which includes first treating the surface of brown rice, then soaking it in a nutrient solution, and finally fermenting it. This process can not only greatly improve the cooking quality of brown rice and reduce its hardness, but also improve the sensory quality of the fermented brown rice.

[0005] A fermentation process of a microbial strain comprises the following steps: S1: Pretreatment of brown rice fermentation substrate The brown rice is washed and air-dried, and then mixed with citric acid powder, and then placed in a DBD plasma cleaning machine for plasma treatment to obtain plasma-treated brown rice; lecithin, aspartic acid, lysine and deionized water are mixed and stirred, and then ultrasonically treated to obtain an amino acid solution; the plasma-treated brown rice is soaked in the amino acid solution, and then refrigerated and drained to obtain amino acid-containing brown rice; the amino acid-containing brown rice is filled in a space bag for steam sterilization, and the brown rice space bag is obtained after natural cooling; S2: Propagation of bacteria and fermentation of psyllium husk powder The frozen Lactobacillus plantarum and Aspergillus oryzae strains are thawed, and then inoculated into culture medium for shaking culture, and then sterile water is added to dilute them to obtain Lactobacillus plantarum and Aspergillus oryzae liquids, which are refrigerated for later use; psyllium husk powder and sterile water are mixed and placed in a container, and then the Lactobacillus plantarum and Aspergillus oryzae liquids are added, and the psyllium husk fermentation liquid is obtained after sealing and fermentation; S3: Efficient fermentation and post-processing of brown rice In a sterile environment, psyllium husk fermentation liquid is added to a brown rice space bag, and the air in the brown rice space bag is discharged and then sealed and fermented to obtain a fermented brown rice space bag, and the outer layer of the fermented brown rice space bag is removed in a clean and dust-free environment, and the space bag is degassed and sealed after air drying, and refrigerated and stored to obtain a finished fermented brown rice.

[0006] Furthermore, step S1 pretreatment of the brown rice fermentation substrate comprises the following steps: S1.1: fresh brown rice without mildew or deterioration is placed in a cleaning tank and washed with clean water for 8-10 minutes, taken out and air-dried to obtain washed brown rice, the washed brown rice and citric acid powder are mixed and stirred evenly at a mass ratio of 1: (0.1-0.15), and then placed in a DBD plasma cleaning machine chamber, the volume of the washed brown rice and citric acid powder accounts for 1 / 3-1 / 2 of the volume of the DBD plasma cleaning machine chamber, and then the output voltage of the DBD plasma cleaning machine is adjusted to 26-28kV, the duty cycle is 45-60%, and the frequency is 45-50Hz, and air is used as the discharge gas source for 4-5 minutes of plasma treatment to obtain plasma-treated brown rice; S1.2: Place lecithin, aspartic acid, lysine and deionized water in a container at a mass ratio of 1: (2-3): (4-5): (45-50), stir for 10-15 minutes, transfer to an ultrasonic disperser, perform ultrasonic treatment at an ultrasonic frequency of 20-25 kHz for 8-10 minutes to obtain an amino acid solution, soak the plasma-treated brown rice in the amino acid solution at a solid-liquid ratio of 1: (10-12), and then transfer them together to a cold room, adjust the temperature of the cold room to 3-4°C, refrigerate for 12-15 hours, take out and drain at room temperature using a filter screen, control the water content at 30-40%, and obtain amino acid-containing brown rice; S1.3: Fill the amino acid-containing brown rice into a space bag, tightly close the opening of the space bag after it is full, and then place it in a steam sterilizer, sterilize it at a steam temperature of 121-125°C for 20-25 minutes, and then place it in a clean and dust-free environment to naturally cool down to 30-38°C to obtain a brown rice space bag.

[0007] Furthermore, step S2 of expanding the culture of the bacteria and fermenting the psyllium husk powder comprises the following steps: S2.1: Thaw the frozen Lactobacillus plantarum and Aspergillus oryzae, inoculate 1-2% of Lactobacillus plantarum into 20-40mL MSR medium, and inoculate 1-2% of Aspergillus oryzae into 20-40mL mashed potato medium, then place them in a shaking incubator, shake and culture at 30-37℃, 180-200r / min for 20-24 hours, add sterile water to dilute the OD 600 The OD value was 0.41-0.46, and the Lactobacillus plantarum culture was obtained. Sterile water was added to the mashed potato culture medium to dilute the OD 600 is 0.21-0.25, and the Aspergillus oryzae liquid is obtained, and all are refrigerated at 3-4°C for use; S2.2: Psyllium husk powder and sterile water are mixed in a solid-liquid ratio of 1: (6-8) and placed in a high-pressure sterilized container, and then 2-3wt% of Lactobacillus plantarum solution and 0.8-1wt% of Aspergillus oryzae solution are added, and the mixture is thoroughly stirred. The container is then sealed with a breathable sealing film, and fermented at 35-37°C for 10-12 hours to obtain psyllium husk fermentation liquid.

[0008] Furthermore, step S3, efficient fermentation and post-treatment of brown rice, comprises the following steps: S3.1: Place the brown rice space bag on a sterile operating table, open the opening and add 4-6wt% psyllium husk fermentation liquid, expel the air in the brown rice space bag and then close the opening, ferment at a temperature of 30-37°C, and turn the brown rice space bag over and over after fermenting for 6-8 hours, and then turn it over every 2-3 hours. After fermenting for 20-24 hours, obtain the fermented brown rice space bag; S3.2: Place the fermented brown rice space bag in a dust-free clean environment, remove the outer layer of the space bag, first blow dry it at a temperature of 40-45°C, then degas and seal it, and store it in a cold storage room at minus 18°C ​​to minus 20°C to obtain the finished fermented brown rice.

[0009] Furthermore, in step S1.1, the particle size of the citric acid powder is 0.1-0.2 mm.

[0010] Further, the DBD plasma cleaning machine chamber in step S1.1 is a rotating drum chamber, which rotates at a speed of 20-25 rpm during the plasma treatment process.

[0011] Furthermore, the space bag in step S1.3 is made of 2.5 mil polypropylene, has a length×width×height of 8 inches×5 inches×15 inches when fully filled, and has a one-way exhaust valve.

[0012] Further, the MSR medium in step S2.1 is prepared by 10-20 g / L peptone, 10-15 g / L beef extract, 5-10 g / L yeast extract, 15-20 g / L glucose, 1-5 g / L sodium acetate, 0.5-2 g / L diammonium citrate, 0.5-1 mL / L Tween 80, 0.5-2 g / L K2HPO4, 0.1-0.5 g / LMgSO4·7H2O, 10-20 g / L CaCO3 and 15-20 g / L agar, supplemented with deionized water to 1000 mL with a pH of 6.3-6.8, and sterilized at 121°C for 20 min.

[0013] Further, the mashed potato culture medium in step S2.1 is prepared by 50-100 g / L mashed potato, 5-10 g / L peptone, 10-15 g / L glucose, 10-20 g / L maltose, 10-30 g / L mannitol, 1-5 g / L yeast extract and 1-5 g / L sodium chloride, supplemented with deionized water to 1000 mL, pH natural, and sterilized at 121°C for 20 min.

[0014] Furthermore, the moisture content after air drying in step S3.2 is 8-12%.

[0015] The beneficial effects are as follows: 1. The present invention mixes brown rice and citric acid powder and performs plasma treatment. During the plasma treatment, part of the water in the brown rice evaporates, and the water combines with citric acid to generate a weak acid environment, which can soften the cellulose on the surface of the brown rice. In combination with the etching and destruction of the surface structure of the brown rice by plasma, the crystallinity of the cellulose can be effectively reduced, so that the surface structure of the brown rice is looser, more amino acids can be absorbed and adsorbed during the subsequent soaking process of the amino acid solution, and the rate and effect of the subsequent microbial fermentation can be improved, so that the water absorption rate of the finished fermented brown rice is improved, and the surface cortex hardness of the finished fermented brown rice is reduced, thereby improving the cooking quality of the finished fermented brown rice.

[0016] 2. The present invention prepares an amino acid solution by mixing lecithin, aspartic acid, lysine and deionized water for ultrasonic dispersion, and then immerses the plasma-treated brown rice in the amino acid solution for refrigeration. First, the bilayer or micellar structure formed by lecithin as a natural surfactant in the solution can reduce the interfacial tension between the aqueous solution and the surface of the brown rice, so that the solution can be better spread on the surface of the brown rice, and the contact area between the brown rice and the solution is increased, so that aspartic acid and lysine can better penetrate into the brown rice, not only can the content of bound water of the finished fermented brown rice be enhanced, but also hydrogen bonds or salt bridges can be formed with other amino acid side chains in the brown rice protein molecule during the fermentation process, so that the structure is more stable, thereby reducing the cooking loss of the finished fermented brown rice, and the alkalinity shown by aspartic acid and lysine themselves can also reduce the acidity of the finished fermented brown rice, so that it can obtain better sensory quality.

[0017] 3. The present invention prepares psyllium husk fermentation liquid by fermenting Lactobacillus plantarum, Aspergillus oryzae and psyllium husk powder together, and then ferments brown rice with the psyllium husk fermentation liquid. During the mixed fermentation process, Aspergillus oryzae can decompose part of the psyllium husk powder to produce some oligosaccharides and organic acids, which can not only promote the growth of Lactobacillus plantarum and improve the fermentation efficiency, but also combine with starch and protein in the brown rice to change its physical properties, which helps to improve the texture of the fermented brown rice, making it softer and easier to cook. In addition, the undecomposed psyllium husk powder dietary fiber has good water absorption, which further improves the cooking quality of the finished fermented brown rice. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is a flow chart of the fermentation process of the microbial strains used in the embodiment of the present invention. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The Lactobacillus plantarum strains and Aspergillus oryzae strains described in the following examples are both from commercial sources, wherein the Lactobacillus plantarum strain is the second-generation glycerol liquid strain of Lactobacillus plantarum ATCC8014, and the Aspergillus oryzae strain is the standard strain of Aspergillus oryzae CGMCC3.951, both of which were purchased from Taobao.

[0021] Example 1: A fermentation process of a microbial strain, as shown in FIG1 , comprises the following steps: S1: Pretreatment of brown rice fermentation matrix S1.1: Place fresh brown rice without mildew or deterioration in a cleaning tank and wash it with clean water for 8 minutes, take it out and air-dry it to obtain the washed brown rice, mix the washed brown rice and citric acid powder with a particle size of 0.1 mm in a mass ratio of 1:0.1 and stir evenly, then place it in the rotating drum chamber of a DBD plasma cleaning machine, the volume of the washed brown rice and citric acid powder accounts for 1 / 3 of the volume of the DBD plasma cleaning machine chamber, then adjust the output voltage of the DBD plasma cleaning machine to 26kV, the duty cycle to 45%, the frequency to 45Hz, the drum speed to 20rpm, and use air as the discharge gas source for 4 minutes of plasma treatment to obtain plasma-treated brown rice; S1.2: Place lecithin, aspartic acid, lysine and deionized water in a container in a mass ratio of 1:2:4:45, stir for 10 minutes, then transfer to an ultrasonic disperser, and perform ultrasonic dispersion at a frequency of 20kHz for 8 The plasma-treated brown rice was ultrasonically treated for 10 minutes to obtain an amino acid solution, and the plasma-treated brown rice was immersed in the amino acid solution at a solid-liquid ratio of 1:10, and then transferred to a cold room together, and the temperature of the cold room was adjusted to 3°C, and the brown rice was refrigerated for 12 hours. After being taken out, the brown rice was drained at room temperature using a filter screen, and the water content was controlled at 30%, thereby obtaining brown rice containing amino acids; S1.3: The amino acid-containing brown rice is filled into a space bag made of 2.5 mil polypropylene. When full, the length × width × height of the space bag is 8 inches × 5 inches × 15 inches. The space bag has a one-way exhaust valve. After filling, the opening of the space bag is tightly closed and then placed in a steam sterilizer for sterilization at a steam temperature of 121°C for 20 minutes. Then, the space bag is placed in a clean and dust-free environment and naturally cooled to 30°C to obtain a brown rice space bag.

[0022] S2: Propagation of bacteria and fermentation of psyllium husk powder S2.1: Thaw the frozen Lactobacillus plantarum and Aspergillus oryzae, inoculate 1% of Lactobacillus plantarum into 20 mL of MSR medium, and inoculate 1% of Aspergillus oryzae into 20 mL of mashed potato medium. Then, place them in a shaking incubator and shake and culture them at 30°C and 180 r / min for 20 h. Add sterile water to dilute the OD value in the MSR medium. 600 The OD value was 0.41, and the Lactobacillus plantarum culture was obtained. Sterile water was added to the mashed potato culture medium to dilute the OD 600 is 0.21, and the Aspergillus oryzae liquid is obtained, and all are refrigerated at 3°C ​​for later use; S2.2: Psyllium husk powder and sterile water are mixed in a solid-liquid ratio of 1:6 and placed in a high-pressure sterilized container. Then, 2wt% of Lactobacillus plantarum solution and 0.8wt% of Aspergillus oryzae solution are added, and the mixture is thoroughly stirred. The container is sealed with a breathable sealing film, and fermented at 35°C for 10 hours to obtain psyllium husk fermentation liquid.

[0023] S3: Efficient fermentation and post-processing of brown rice S3.1: Place a brown rice bag on a sterile operating table, open the bag and add 4 wt% psyllium husk fermentation liquid, expel the air in the bag and then close the bag, ferment at 30°C, turn the bag over once after 6 hours of fermentation, and then turn it over every 2 hours, and obtain a fermented brown rice bag after 20 hours of fermentation; S3.2: Place the fermented brown rice bag in a dust-free clean environment, remove the outer bag, and first perform air drying at 40°C to control the moisture content to 8%, then degas and seal the bag, and store it in a cold storage room at -18°C to obtain the finished fermented brown rice.

[0024] Example 2: A fermentation process of a microbial strain, as shown in FIG1 , comprises the following steps: S1: Pretreatment of brown rice fermentation substrate S1.1: fresh brown rice without mildew or deterioration is placed in a cleaning tank and washed with clean water for 8 minutes, taken out and air-dried to obtain washed brown rice, washed brown rice and citric acid powder with a particle size of 0.1 mm are mixed and stirred evenly at a mass ratio of 1:0.15, and then placed in the rotating drum chamber of a DBD plasma cleaning machine, the volume of washed brown rice and citric acid powder accounts for 1 / 3 of the volume of the DBD plasma cleaning machine chamber, and then the output voltage of the DBD plasma cleaning machine is adjusted to 26kV, the duty cycle is 45%, the frequency is 45Hz, and the drum speed is 20rpm, and air is used as the discharge gas source for 4 minutes of plasma treatment to obtain plasma-treated brown rice; S1.2: lecithin, aspartic acid, lysine and deionized water are placed in a container at a mass ratio of 1:3:5:50, stirred for 10 minutes, and then transferred to an ultrasonic disperser, and ultrasonically treated at an ultrasonic frequency of 20kHz for 8 minutes to obtain an amino acid solution, and the plasma-treated brown rice is placed in a container at a mass ratio of 1:12 The brown rice is soaked in an amino acid solution with a solid-liquid ratio of 100%, and then transferred to a cold storage room together. The temperature of the cold storage room is adjusted to 3°C, and the brown rice is refrigerated for 12 hours. After being taken out, the brown rice is drained at room temperature using a filter screen, and the water content is controlled at 30%, thereby obtaining brown rice containing amino acids. S1.3: The amino acid-containing brown rice is filled into a space bag made of 2.5 mil polypropylene. When full, the length × width × height of the space bag is 8 inches × 5 inches × 15 inches. The space bag has a one-way exhaust valve. After filling, the opening of the space bag is tightly closed and then placed in a steam sterilizer for sterilization at a steam temperature of 121°C for 20 minutes. Then, the space bag is placed in a clean and dust-free environment and naturally cooled to 30°C to obtain a brown rice space bag.

[0025] S2: Propagation of bacteria and fermentation of psyllium husk powder S2.1: Thaw the frozen Lactobacillus plantarum and Aspergillus oryzae, inoculate 1% of Lactobacillus plantarum into 20 mL of MSR medium, and inoculate 1% of Aspergillus oryzae into 20 mL of mashed potato medium. Then, place them in a shaking incubator and shake and culture them at 30°C and 180 r / min for 20 h. Add sterile water to dilute the OD value in the MSR medium. 600 The OD value was 0.41, and the Lactobacillus plantarum culture was obtained. Sterile water was added to the mashed potato culture medium to dilute the OD 600 is 0.21, and the Aspergillus oryzae liquid is obtained, and all are refrigerated at 3°C ​​for later use; S2.2: Psyllium husk powder and sterile water are mixed in a solid-liquid ratio of 1:8 and placed in a high-pressure sterilized container. Then, 3wt% of Lactobacillus plantarum solution and 1wt% of Aspergillus oryzae solution are added, and the mixture is thoroughly stirred. The container is then sealed with a breathable sealing film, and fermented at 35°C for 10 hours to obtain psyllium husk fermentation liquid.

[0026] S3: Efficient fermentation and post-processing of brown rice S3.1: Place a brown rice bag on a sterile operating table, open the bag and add 6 wt% psyllium husk fermentation liquid, expel the air in the bag and then close the bag, ferment at 30°C, turn the bag over once after 6 hours of fermentation, and then turn it over every 2 hours, and obtain a fermented brown rice bag after 20 hours of fermentation; S3.2: Place the fermented brown rice bag in a dust-free clean environment, remove the outer bag, and first perform air drying at 40°C to control the moisture content to 8%, then degas and seal the bag, and store it in a cold storage room at -18°C to obtain the finished fermented brown rice.

[0027] Example 3: A fermentation process of a microbial strain, as shown in FIG1 , comprises the following steps: S1: Pretreatment of brown rice fermentation substrate S1.1: fresh brown rice without mildew or deterioration is placed in a cleaning tank and washed with clean water for 10 minutes, taken out and air-dried to obtain washed brown rice, washed brown rice and citric acid powder with a particle size of 0.2 mm are mixed and stirred evenly at a mass ratio of 1:0.1, and then placed in the rotating drum chamber of a DBD plasma cleaning machine, the volume of washed brown rice and citric acid powder accounts for 1 / 2 of the volume of the DBD plasma cleaning machine chamber, and then the output voltage of the DBD plasma cleaning machine is adjusted to 28kV, the duty cycle is 60%, the frequency is 50Hz, and the drum speed is 25rpm, and air is used as the discharge gas source for 5 minutes of plasma treatment to obtain plasma-treated brown rice; S1.2: lecithin, aspartic acid, lysine and deionized water are placed in a container at a mass ratio of 1:2:4:45, stirred for 15 minutes, and then transferred to an ultrasonic disperser, and ultrasonically treated at an ultrasonic frequency of 25kHz for 10 minutes to obtain an amino acid solution, and the plasma-treated brown rice is placed in a container at a mass ratio of 1:12 The brown rice is soaked in an amino acid solution with a solid-liquid ratio of 100%, and then transferred to a cold storage room together. The temperature of the cold storage room is adjusted to 4°C, and the brown rice is refrigerated for 15 hours. After being taken out, the brown rice is drained at room temperature using a filter screen to control the water content at 40%, thereby obtaining brown rice containing amino acids. S1.3: The amino acid-containing brown rice is filled into a space bag made of 2.5 mil polypropylene. When full, the length × width × height of the space bag is 8 inches × 5 inches × 15 inches. The space bag has a one-way exhaust valve. After filling, the opening of the space bag is tightly closed and then placed in a steam sterilizer for sterilization at a steam temperature of 125°C for 25 minutes. Then, the space bag is placed in a clean and dust-free environment and naturally cooled to 38°C to obtain a brown rice space bag.

[0028] S2: Propagation of bacteria and fermentation of psyllium husk powder S2.1: Thaw the frozen Lactobacillus plantarum and Aspergillus oryzae, inoculate 2% of Lactobacillus plantarum into 40 mL of MSR medium, and inoculate 2% of Aspergillus oryzae into 40 mL of mashed potato medium. Then, place them in a shaking incubator and shake and culture them at 37°C and 200 r / min for 24 hours. Add sterile water to dilute the bacterial solution in the MSR medium, and add sterile water to dilute the OD value in the mashed potato medium. 600 is 0.25, and the Aspergillus oryzae liquid is obtained, and all are refrigerated at 4°C for later use; S2.2: Psyllium husk powder and sterile water are mixed in a solid-liquid ratio of 1:6 and placed in a high-pressure sterilized container. Then, 2wt% of Lactobacillus plantarum solution and 1wt% of Aspergillus oryzae solution are added, and the mixture is thoroughly stirred. The container is then sealed with a breathable sealing film, and fermented at 37°C for 12 hours to obtain psyllium husk fermentation liquid.

[0029] S3: Efficient fermentation and post-processing of brown rice S3.1: Place a brown rice bag on a sterile operating table, open the bag and add 4 wt% psyllium husk fermentation liquid, expel the air in the bag and then close the bag, ferment at 37°C, turn the bag over once after 8 hours of fermentation, and then turn it over every 3 hours, and obtain a fermented brown rice bag after 24 hours of fermentation; S3.2: Place the fermented brown rice bag in a dust-free clean environment, remove the outer bag, and first perform air drying at 45°C to control the moisture content to 12%, then degas and seal the bag, and store it in a cold storage room at -20°C to obtain the finished fermented brown rice.

[0030] Comparative Example 1: Compared with Example 1, the difference of Comparative Example 1 is that the plasma treatment operation of brown rice in step S1.1 is removed in Comparative Example 1, and the subsequent plasma treatment of brown rice is replaced by washing brown rice. The remaining steps are the same as those in Example 1 to obtain fermented brown rice, which is recorded as Comparative Example 1.

[0031] Comparative Example 2: Compared with Example 1, the difference of Comparative Example 2 is that citric acid powder is not added in step S1.1 of Comparative Example 2, and the remaining steps are the same as those of Example 1 to prepare fermented brown rice, which is recorded as Comparative Example 2.

[0032] Comparative Example 3: Compared with Example 1, the difference of Comparative Example 3 is that step S1.2 is removed in Comparative Example 3, and the subsequent amino acid-containing brown rice is replaced with plasma-treated brown rice. The remaining steps are the same as those in Example 1 to obtain fermented brown rice, which is recorded as Comparative Example 3.

[0033] Comparative Example 4: Compared with Example 1, the difference of Comparative Example 4 is that, in Comparative Example 4, Aspergillus oryzae liquid is not prepared in step S2.1, and Aspergillus oryzae liquid is not added in S2.2. The remaining steps are the same as those in Example 1 to obtain fermented brown rice, which is recorded as Comparative Example 4.

[0034] Comparative Example 5: Compared with Example 1, the difference of Comparative Example 5 is that step S2.2 is removed in Comparative Example 5, and psyllium husk fermentation liquid is not added in step S3.1. Instead, 2-3wt% of Lactobacillus plantarum liquid and 0.8-1wt% of Aspergillus oryzae liquid are added, and the remaining steps are the same as those in Example 1 to obtain fermented brown rice, which is recorded as Comparative Example 5.

[0035] Cooking time test: 6 g of the finished fermented brown rice prepared in Example 1, Comparative Example 2, Comparative Example 4 and Comparative Example 5 were taken respectively, and each was divided into three equal samples, and then the cooking test was carried out in sequence. The test process was to place the sample on a sieve covered with a layer of gauze with a mesh size of 20, and the sieve was placed on the surface of continuously boiling water to cook the brown rice. After cooking for 25 minutes, 10 grains of brown rice were taken out every 1 minute, pressed between two glass plates, and observed whether a white core appeared. When 90% of the brown rice did not have a white core after being pressed, it was considered that the brown rice was fully cooked, which was the optimal cooking time. The optimal cooking time of each sample was recorded, as shown in Table 1;

[0036] Water absorption test: 6 g of the finished fermented brown rice prepared in Example 1, Comparative Example 2 and Comparative Example 5 were taken, divided into three equal parts, placed in test tubes, and 20 mL of distilled water was added. The test tubes were placed in an incubator (25° C.) for 1 hour, and then the moisture content was measured. Water absorption (dry basis) = (M1-M0) / [M0×(1-moisture content)]×100%, where M0 is the initial weight of the brown rice, and M1 is the weight of the brown rice after soaking for 1 hour. The data were recorded and tabulated as shown in Table 2.

[0037] It can be seen from the examples, comparative examples 1 and 2 in Table 1 and Table 2 that the optimal cooking time without the plasma treatment step is greater than the optimal cooking time without the citric acid powder, and the water absorption rate of comparative example 2 is greater than that of comparative example 1, which can prove that plasma treatment of washed brown rice can reduce the optimal cooking time and improve the water absorption rate, thereby improving the cooking quality of the finished fermented brown rice. At the same time, it can be proved that adding citric acid powder to the washed brown rice for plasma treatment can also improve the cooking quality of the finished fermented brown rice. It can be seen from the examples, comparative examples 4 and comparative examples 5 that the optimal cooking time without adding Aspergillus oryzae liquid increases, while the optimal cooking time without preparing psyllium husk fermentation liquid increases and the water absorption rate decreases. It can be proved that fermenting Lactobacillus plantarum, Aspergillus oryzae and psyllium husk powder into a fermentation liquid and then fermenting the brown rice can improve the cooking quality of the finished fermented brown rice.

[0038] Cooking loss test: 6 g of the finished fermented brown rice prepared in Example 1 and Comparative Example 3 were taken, each divided into three equal parts, placed in 20 mL of distilled water, and cooked in a boiling water bath for 38 min. The rice porridge was transferred to a 50 mL beaker, which had been heated to constant weight in an oven at 110° C. before use. The cooked brown rice was washed three times with 10 mL of distilled water to collect the solids adhering to the surface of the brown rice. The beaker containing the rice porridge was dried in an oven at 110° C. until the weight no longer changed. The beaker was then weighed and the cooking loss was calculated, cooking loss = 1000 × (M2-M1) / M0 × 100%, M0 is the weight of the brown rice, M1 is the weight of the beaker, M2 is the weight of the beaker and the rice porridge after drying, the data were recorded and tabulated, as shown in Table 3, it can be seen that the cooking loss of the embodiment is less than the cooking loss of the comparative example 3, which can prove that the preparation of the amino acid solution for soaking the plasma-treated brown rice can reduce the cooking loss of the finished fermented brown rice and improve its cooking quality.

[0039]

Claims

1. A fermentation process of a microbial strain, characterized in that: The following steps are involved: S1: Pretreatment of brown rice fermentation substrate The brown rice is washed and air-dried, and then mixed with citric acid powder, and then placed in a DBD plasma cleaning machine for plasma treatment to obtain plasma-treated brown rice; lecithin, aspartic acid, lysine and deionized water are mixed and stirred, and then ultrasonically treated to obtain an amino acid solution; the plasma-treated brown rice is soaked in the amino acid solution, refrigerated and then drained to obtain amino acid-containing brown rice; the amino acid-containing brown rice is filled in a space bag for steam sterilization, and the brown rice space bag is obtained after natural cooling; S2: Propagation of bacteria and fermentation of psyllium husk powder The frozen Lactobacillus plantarum and Aspergillus oryzae strains are thawed, and then inoculated into culture medium for shaking culture, and then sterile water is added to dilute them to obtain Lactobacillus plantarum and Aspergillus oryzae liquids, which are refrigerated for later use; psyllium husk powder and sterile water are mixed and placed in a container, and then the Lactobacillus plantarum and Aspergillus oryzae liquids are added, and the psyllium husk fermentation liquid is obtained after sealing and fermentation; S3: Efficient fermentation and post-processing of brown rice In a sterile environment, psyllium husk fermentation liquid is added to a brown rice space bag, and the air in the brown rice space bag is discharged and then sealed and fermented to obtain a fermented brown rice space bag, and the outer layer of the fermented brown rice space bag is removed in a clean and dust-free environment, and the space bag is degassed and sealed after air drying, and refrigerated and stored to obtain a finished fermented brown rice.

2. The fermentation process of a microbial strain according to claim 1, characterized in that: Step S1: pretreatment of the brown rice fermentation substrate, comprising the following steps: S1.1: fresh brown rice without mildew or deterioration is placed in a cleaning tank and washed with clean water for 8-10 minutes, taken out and air-dried to obtain washed brown rice, washed brown rice and citric acid powder are mixed and stirred evenly at a mass ratio of 1: (0.1-0.15), and then placed in the chamber of a DBD plasma cleaning machine, the volume of washed brown rice and citric acid powder accounts for 1 / 3-1 / 2 of the volume of the chamber of the DBD plasma cleaning machine, and then the output voltage of the DBD plasma cleaning machine is adjusted to 26-28kV, the duty cycle is 45-60%, and the frequency is 45-50Hz, and air is used as the discharge gas source for 4-5 minutes of plasma treatment to obtain plasma-treated brown rice; S1.2: Place lecithin, aspartic acid, lysine and deionized water in a container at a mass ratio of 1: (2-3): (4-5): (45-50), stir for 10-15 minutes, transfer to an ultrasonic disperser, perform ultrasonic treatment at an ultrasonic frequency of 20-25kHz for 8-10 minutes to obtain an amino acid solution, soak the plasma-treated brown rice in the amino acid solution at a solid-liquid ratio of 1: (10-12), and then transfer them together to a cold room, adjust the temperature of the cold room to 3-4°C, refrigerate for 12-15 hours, take out and drain at room temperature using a filter screen, control the water content at 30-40%, and obtain amino acid-containing brown rice; S1.3: Fill the amino acid-containing brown rice into a space bag, close the opening of the space bag after it is full, and then place it in a steam sterilizer, sterilize it at a steam temperature of 121-125℃ for 20-25 minutes, and then place it in a clean and dust-free environment to naturally cool down to 30-38℃ to obtain a brown rice space bag.

3. The fermentation process of a microbial strain according to claim 2, characterized in that: Step S2: Proliferation of bacterial strains and fermentation of psyllium husk powder, comprising the following steps: S2.1: The frozen Lactobacillus plantarum and Aspergillus oryzae strains were thawed respectively, and the Lactobacillus plantarum strains were inoculated into 20-40mL MSR medium at an inoculum size of 1-2%, and the Aspergillus oryzae strains were inoculated into 20-40mL mashed potato medium at an inoculum size of 1-2%, and then placed in a shaking incubator, and cultured for 20-24 hours at 30-37°C and 180-200r / min, and sterile water was added to the MSR medium to dilute the OD600 to 0.41-0.46 to obtain a Lactobacillus plantarum bacterial solution, and sterile water was added to the mashed potato medium to dilute the OD600 to 0.21-0.25 to obtain an Aspergillus oryzae liquid, and both were refrigerated at 3-4°C for use; S2.2: Psyllium husk powder and sterile water are mixed in a solid-liquid ratio of 1: (6-8) and placed in a high-pressure sterilized container, and then 2-3wt% of Lactobacillus plantarum solution and 0.8-1wt% of Aspergillus oryzae solution are added, and the mixture is thoroughly stirred. The container is then sealed with a breathable sealing film, and fermented at 35-37°C for 10-12 hours to obtain psyllium husk fermentation liquid.

4. The fermentation process of a microbial strain according to claim 3, characterized in that: Step S3: efficient fermentation and post-processing of brown rice, comprising the following steps: S3.1: Place the brown rice space bag on a sterile operating table, open the opening and add 4-6wt% psyllium husk fermentation liquid, expel the air in the brown rice space bag and then close the opening, ferment at a temperature of 30-37°C, and turn the brown rice space bag over and over after fermenting for 6-8 hours, and then turn it over every 2-3 hours. After fermenting for 20-24 hours, obtain the fermented brown rice space bag; S3.2: Place the fermented brown rice space bag in a dust-free clean environment, remove the outer layer of the space bag, first blow dry it at a temperature of 40-45°C, then degas and seal it, and store it in a cold storage room at minus 18°C ​​to minus 20°C to obtain the finished fermented brown rice.

5. The fermentation process of a microbial strain according to claim 2, characterized in that: The particle size of the citric acid powder in step S1.1 is 0.1-0.2 mm.

6. The fermentation process of a microbial strain according to claim 2, characterized in that: The DBD plasma cleaning machine chamber in step S1.1 is a rotating drum chamber, which rotates at a speed of 20-25 rpm during the plasma treatment process.

7. The fermentation process of a microbial strain according to claim 2, characterized in that: The space bag in step S1.3 is made of 2.5 mil polypropylene, has a length × width × height of 8 inches × 5 inches × 15 inches when full, and has a one-way exhaust valve.

8. The fermentation process of a microbial strain according to claim 3, characterized in that: The MSR medium in step S2.1 is prepared by 10-20 g / L peptone, 10-15 g / L beef extract, 5-10 g / L yeast extract, 15-20 g / L glucose, 1-5 g / L sodium acetate, 0.5-2 g / L diammonium citrate, 0.5-1 mL / L Tween 80, 0.5-2 g / L K2HPO4, 0.1-0.5 g / LMgSO4·7H2O, 10-20 g / L CaCO3 and 15-20 g / L agar, supplemented with deionized water to 1000 mL, pH 6.3-6.8, and sterilized at 121°C for 20 min.

9. The fermentation process of a microbial strain according to claim 3, characterized in that: The mashed potato medium in step S2.1 is prepared by adding 50-100 g / L mashed potato, 5-10 g / L peptone, 10-15 g / L glucose, 10-20 g / L maltose, 10-30 g / L mannitol, 1-5 g / L yeast extract and 1-5 g / L sodium chloride, supplemented with deionized water to 1000 mL, pH natural, and sterilized at 121°C for 20 min.

10. The fermentation process of a microbial strain according to claim 4, characterized in that: Step S3.2 The moisture content after forced air drying is 8-12%.

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