Method for synergistically fermenting wheat bran by saccharomycetes and cellulase

Abstract

The invention relates to a method for synergistically fermenting wheat bran by saccharomycetes and cellulase. The technology relates to the fields of fermentation engineering and food processing. The problems of low product nutrition and poor taste caused by many anti-nutritional factors and difficult degradation of macromolecules in the traditional fermentation technology are solved. According to the technical scheme, the method comprises the steps of yeast activation, pretreatment before wheat bran fermentation, cellulose enzymolysis, yeast fermentation and the like. In the whole process, sterile operation is ensured, the temperature, the humidity, the PH value and the oxygen amount are accurately regulated and controlled, and optimal fermentation conditions are created. When the technology is applied to the food or feed industry, high-quality food or feed raw materials can be obtained, antinutritional factors in the wheat bran are reduced, digestion and absorption of nutrient substances in the wheat bran are improved, and the cost is reduced; when being applied to food and feed processing, the feed additive can improve the flavor and taste of raw materials, increase the nutritional value of the raw materials and promote intestinal digestion; meanwhile, waste is turned into wealth, resources are recycled, food waste is reduced, and the win-win situation of environmental protection and benefits is achieved.

Description

Technical Field

[0001] Fermentation engineering and food processing Background Technology

[0002] Wheat bran is the main byproduct of wheat flour milling. It is rich in bioactive substances such as active polysaccharides, phenolic compounds, amino acids, and minerals. It can also serve as an inexpensive and abundant source of dietary fiber, providing various nutrients for animals and humans and maintaining gut health. Solid-state fermentation is a biotransformation process in which the substrate exists in a solid form, and microorganisms use the substrate as a substrate for growth and metabolism. Compared to liquid fermentation, solid-state fermentation has advantages such as requiring less water, lower cost, higher product purity, and simpler operation, and is therefore widely used in various industries, including the food industry, bioenergy production, and feed preparation. Adding unfermented wheat bran directly to food means that some beneficial components are not easily absorbed and utilized by the human body, and the insoluble fiber in wheat bran has strong resistance to degradation in the intestines. To address the negative issues of low utilization value resulting from directly adding wheat bran and to improve its nutritional value, enzyme-co-fermentation of wheat bran is employed. This process positively impacts the bioavailability of several functional compounds in the bran, leading to an increase in the content of bound peptides after fermentation. It also improves the sensory, quality, and nutritional characteristics of bran-containing products, including increased total free phenol content, increased water-holding capacity, decreased soluble pentosan and phytic acid content, and enhanced DDPH scavenging rate and hydroxyl radical scavenging ability. Summary of the Invention

[0003] This invention relates to a method for utilizing cellulase (100,000 U / g) and fruit wine yeast ( SC A method for co-fermenting wheat bran (8532-RW).

[0004] A method for co-fermenting wheat bran using cellulase and fruit wine yeast, comprising the following steps: 60 g (dry weight) of wheat bran was crushed, passed through an 80-mesh sieve, sterilized at 121°C for 20 minutes, and then cooled to room temperature. A yeast strain previously screened and preserved from fruit wine in the laboratory was used... SC -8532) was subjected to secondary activation screening in YPD medium, with each incubation lasting 24 h. After the secondary activation, the sample was centrifuged at 8000 r / min for 10 min, and the precipitate was washed twice with 10 ml of sterile water. A 0.02% (dry weight) cellulase aqueous solution was added to wheat bran at a 1:1 ratio and treated for 18 h. Then, 2 g (calculated based on the dry weight of wheat bran) of the centrifuged yeast precipitate was inoculated into the wheat bran and treated for another 18 h. Simultaneously, sterile water (1:1 by weight of deionized water based on the dry weight of wheat bran) was added and stirred thoroughly. After each mixing, three replicate samples were taken, and the indicators of each recombinant sample were measured twice as parallel measurements.

[0005] The present invention relates to a method that utilizes cellulase and fruit wine yeast to synergistically ferment wheat bran, which can significantly increase the content of total free phenols, soluble pentosans, DDPH scavenging rate and hydroxyl radical scavenging capacity of wheat bran, reduce the content of phytic acid, and improve the nutritional quality of wheat bran. Detailed Implementation

[0006] The present invention will now be described in conjunction with specific embodiments: Example

[0007] The specific steps are as follows: (1) Preparation of YPD medium: Weigh 1g of yeast extract, 2g of peptone, and 2g of glucose, dissolve them in 100ml of deionized water, and seal the flask with sealing film after complete dissolution. Place the sealed conical flask in a high-pressure steam sterilizer (100kPa, 121℃, 20 min) for sterilization. When the pressure gauge drops to "0", pause briefly and allow the temperature to continue to drop below 90℃. Open the exhaust valve, unscrew the fixing screw, open the cap, remove the conical flask, and place it in a sterile table to cool to room temperature of about 30℃. The YPD medium is now ready.

[0008] (2) Two activations of yeast: First activation: In a clean bench or sterile room, add the yeast strain to the culture medium solution. SC -8532), the addition amount is 10% (v / v, the strain preserved in glycerol is thoroughly mixed), and it is placed in a shaker and cultured at 30℃ for 24 h. Secondary activation: Repeat step (1) to prepare YPD liquid medium, take 2 ml of the yeast suspension after the first activation (shake well before taking), inoculate it into YPD liquid medium, and culture it again in a shaker at 30℃ for 24 h, thus completing the secondary activation of yeast. Centrifuge the yeast after secondary activation in an 8000r / min centrifuge for 5 min, take 2 g of the lower precipitate and inoculate it into wheat bran for wheat bran fermentation in step (3).

[0009] (3) Pretreatment of wheat bran before fermentation: Wheat bran was crushed using a 1600W high-speed multi-functional pulverizer and passed through an 80-mesh sieve. The moisture content of wheat bran was determined according to the method of GB5009.3-2016. 60g of wheat bran with a moisture content of w% after crushing (W = 60 ÷ (1-w%)) was weighed into a 500ml conical flask, sealed with sealing film, and placed in a high-pressure steam sterilizer (100 kPa, 121℃, 20 min). After cooling, sterile water was added to the sterile operating table at a mass ratio of 1:1 based on the dry matter content of wheat bran.

[0010] (4) Cellulase activation treatment: Weigh 0.12g of cellulase and dissolve it in 60ml of sterile water to prepare the cellulase aqueous solution. Add the cellulase aqueous solution to the sterilized conical flask in (3) on a sterile operating table, and incubate at 85% humidity and 48℃ for 18 hours for enzymatic hydrolysis.

[0011] (5) Wheat bran fermentation: After cooling the wheat bran treated in (4) to room temperature, add 2g of the centrifuged yeast precipitate mentioned in step (2), stir evenly with a glass rod, seal with a sealing film, and ferment in a constant temperature and humidity fermentation box at 30℃ and 85% relative humidity for 24 hours. The wheat bran fermentation is now complete.

[0012] (6) Drying and storage of fermented wheat bran: After fermentation by yeast and cellulase, the wheat bran is dried in an oven at 60°C for 24 hours. The fermented wheat bran is then stored in a well-sealed container or bag at low temperature.

Claims

1. A method for solid-state fermentation of wheat bran using cellulase and fruit wine yeast. Characterized by, Includes the following steps: (1) Preparation of YPD culture medium: Weigh 1g of yeast extract and 2g of peptone, dissolve them in 100ml of deionized water, then weigh 15g of glucose, dissolve them in 250ml of deionized water, and seal them with sealing film after complete dissolution. Place the sealed conical flask in a high-pressure steam sterilizer (100kPa, 121℃, 20min) for sterilization. When the pressure gauge drops to "0", pause briefly, and allow the temperature to continue to drop below 90℃. Open the exhaust valve, unscrew the fixing screw, open the cap and take out the conical flask. Place it in a sterile table to cool to about 50℃. The YPD culture medium is now ready. (2) Two activations of yeast: First activation: In a clean bench or sterile room, add 0.2g of yeast strain selected from fruit wine to the culture medium solution and incubate on a shaker at 30℃ for 24h. Second activation: Repeat step (1) to prepare YPD liquid culture medium, take 2ml of the yeast suspension after the first activation (shake well before taking), inoculate it into YPD liquid culture medium, and incubate on a shaker at 30℃ for 24h again. This completes the second activation of yeast. Centrifuge the yeast after the second activation at 8000r / min for 10min, take 2g of the lower precipitate and inoculate it into wheat bran for fermentation in step (3). (3) Pretreatment of wheat bran before fermentation: Wheat bran was crushed using a 1600W high-speed multi-functional pulverizer and passed through an 80-mesh sieve. 60g of wheat bran with a moisture content of 11.38% after crushing was weighed into a 500ml conical flask, sealed with sealing film, and placed in a high-pressure steam sterilizer (100kPa, 121℃, 20min). After cooling, sterile water was added at a mass ratio of 1:1 on a sterile operating table. (4) Cellulase activation treatment: Weigh 0.04g of cellulase and dissolve it in 200ml of water to prepare a 0.02% cellulase aqueous solution. Add the cellulase aqueous solution to the sterilized conical flask in (3) at a mass ratio of 1:1 under sterile conditions, and mix and ferment for 18h; (5) Wheat bran fermentation: Add 2g of the centrifuged yeast precipitate mentioned in step (2), stir evenly with a glass rod, seal with a sealing film, and ferment in a constant temperature and humidity fermentation box at 30℃ and 70% relative humidity for 24 hours. The wheat bran fermentation is now complete. (6) Drying and storage of fermented wheat bran: After fermentation with microorganisms and enzymes for 24 hours, the wheat bran is dried in an oven at 60°C for 24 hours. The fermented wheat bran is then placed in a well-sealed container or packaging bag and stored at low temperature.

2. The method according to claim 1, utilizing cellulase and fruit wine yeast in synergy, is characterized in that... The glucose produced by cellulase hydrolysis provides carbon and energy for yeast, while the metabolites such as ethanol produced by yeast fermentation will have a feedback effect on cellulase activity. The two work together to achieve efficient cellulase conversion and ethanol fermentation.

3. The solid-state fermentation method as described in claim 1, characterized in that... In a solid-state fermentation system, microorganisms can grow and reproduce in the loose porous structure of wheat bran, providing a large contact area for enzymatic hydrolysis.

4. A wheat bran product, characterized by wheat bran treated with a combination of microbial enzymes and fermentation, in which some insoluble dietary fiber is converted into soluble fiber, the content of anti-nutritional factors is reduced, the texture is softer and more delicate than ordinary wheat bran products, and the antibacterial substances produced by fermentation can extend its shelf life.

5. Limit the scope of protection Fermentation method protection: Primarily based on claim 1, it covers the entire process and related parameters of wheat bran pretreatment, cellulase solution preparation, fruit wine yeast activation, mixed inoculation, and solid-state fermentation, including the degree of wheat bran grinding, cellulase solution activity concentration, fruit wine yeast activation conditions, inoculation ratio of each material, fermentation temperature, humidity, and duration. It includes further limitations on some technical features, such as the sieve mesh size of the ground wheat bran and the composition of the yeast activation culture medium. These dependent claims further narrow and clarify the scope of protection. Scope of protection for fermented wheat bran products: Fermented wheat bran products prepared by the above method with enzyme synergistic fermentation, emphasizing that the products are rich in specific components (such as oligosaccharides, amino acids, etc.) and have specific characteristics (such as improved antioxidant properties, improved flavor, etc.), are all within the scope of protection as long as the products are prepared by this method and meet these characteristics.