Method for producing functional clostridium butyricum culture by using clostridium butyricum centrifugate

Abstract

The invention discloses a method for producing a functional clostridium butyricum culture by using a clostridium butyricum centrifugate. The method comprises the following steps: (1) adding a protein raw material and a compound enzyme into the clostridium butyricum centrifugate, and reacting at 40-60 DEG C for 1-5 hours to finish a primary enzymolysis process; (2) compound strains are inoculated into the preliminary enzymolysis product, meanwhile, a carbon source is supplemented, a reaction is conducted for 6-18 h at the temperature of 25-40 DEG C, a secondary fermentation process is completed, an enzymolysis reaction is conducted in the process, the compound strains are composed of multiple lactic acid bacteria and saccharomycetes, and the lactic acid bacteria comprise lactobacillus casei, lactobacillus plantarum, lactobacillus acidophilus and enterococcus faecium; the saccharomycetes are kluyveromyces marxianus; and (3) carrying out spray drying on the fermented product to obtain the functional clostridium butyricum culture. The beneficial metabolites of the clostridium butyricum, the lactic acid bacteria and the saccharomycetes in the product not only have a very strong food calling effect and can promote digestion and absorption of feed, but also can effectively improve the immune level of livestock and poultry and inhibit livestock and poultry diseases.

Description

Technical Field

[0001] This invention belongs to the field of feed additive production technology, and in particular relates to a method for producing functional Clostridium butyricum cultures from Clostridium butyricum centrifuged liquid. Background Technology

[0002] Intensive livestock farming has led to a serious conflict between humans and livestock over feed, making it imperative to improve the utilization rate of feed ingredients. Protein feed accounts for a large proportion of farming costs, making it crucial to explore ways to improve protein utilization. Soybean meal is an ideal animal protein source due to its high protein content and amino acid profile that meets animal growth requirements, but it is relatively expensive. Cottonseed meal has a similar protein content to soybean meal but is cheaper; however, its nutritional balance is less than ideal, containing less lysine and more arginine. Excessive arginine can hinder lysine absorption. Combining the two can reduce costs while achieving nutritional balance. However, both feed ingredients contain anti-nutritional factors. Trypsin inhibitors, phytic acid, and oligosaccharides in soybean meal, and gossypol in cottonseed meal, severely impact their nutritional value. Enzymatic hydrolysis combined with microbial fermentation can not only destroy these anti-nutritional factors but also produce functional oligopeptides, digestive enzymes, organic acids, vitamins, and other beneficial substances, making it an ideal technical solution.

[0003] In addition, the incidence of intestinal and respiratory diseases in livestock and poultry is increasing, leading to decreased production performance and increased breeding costs. To address this issue, "antibiotic alternatives" have emerged, with probiotics being a leading example. Probiotics improve animal production performance through multiple mechanisms, including balancing the intestinal microecological environment, enhancing animal immunity, and promoting nutrient absorption. Commonly used probiotics include Bacillus and yeast, which promote digestion, and lactic acid bacteria, which inhibit the growth of pathogenic bacteria.

[0004] Clostridium butyricum, a rising star among Bacillus species, was included in the list of probiotics for animal feed in 2013. A strict anaerobe, Clostridium butyricum readily colonizes the intestines. It not only produces proteases, lipases, amylases, cellulases, and glycosidases that promote feed digestion and absorption, but also possesses a strong conditioning effect on the gut: its secreted butyric acid and other antimicrobial peptides inhibit the growth of pathogenic bacteria, and its butyric acid is a major energy source for intestinal epithelial cells. Its metabolites also promote the proliferation of beneficial bacteria such as Bifidobacteria and Lactobacilli. Furthermore, Clostridium butyricum has an appetite-stimulating effect. Therefore, Clostridium butyricum is widely used in livestock, poultry, and aquaculture. The production process of Clostridium butyricum generates a large amount of centrifuged liquid. This liquid, in addition to being rich in nutrients, also contains a high concentration of bacterial cells. Its recycling can greatly conserve resources and reduce environmental pressure. Summary of the Invention

[0005] This invention provides a method for producing functional Clostridium butyricum cultures using Clostridium butyricum centrifuge broth. The method involves using Clostridium butyricum centrifuge broth as the main component, adding soybean meal powder and cottonseed meal powder, followed by preliminary enzymatic hydrolysis to destroy anti-nutritional factors. Then, yeast and lactic acid bacteria are added for secondary fermentation to produce beneficial metabolites such as lactic acid, butyric acid, and digestive enzymes. Simultaneously, this process further destroys anti-nutritional factors and degrades large protein molecules into small oligopeptides that can enhance immunity, reduce the risk of intestinal inflammation, resist stress, provide antioxidant effects, promote intestinal microecological balance, regulate endocrine function, and promote growth and reproduction.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for producing functional Clostridium butyricum cultures from Clostridium butyricum centrifuged broth includes the following steps: (1) After adding protein raw materials and complex enzymes to the Clostridium butyricum centrifuged liquid, the mixture is reacted at 40℃~60℃ for 1~5 h to complete the preliminary enzymatic hydrolysis process. The concentration of Clostridium butyricum in the centrifuged liquid is (2.0~3.0)×10 7 CFU / mL, wherein the complex enzyme includes acidic protease, neutral protease, alkaline protease, cellulase, pectinase, and a complex enzyme composed of two or more of the above enzymes. (2) After the enzymatic hydrolysis is completed, a compound microbial strain is inoculated into the enzymatic hydrolysis product, and a carbon source is added at the same time. The reaction is carried out at 25℃~40℃ for 6~18 h to complete the two fermentation processes. During this process, the enzymatic hydrolysis reaction occurs simultaneously. The compound microbial strain is composed of a variety of lactic acid bacteria and yeast. The lactic acid bacteria include Lactobacillus casei, Lactobacillus plantarum, Lactobacillus acidophilus and Enterococcus faecalis; the yeast is Kluyveromyces martensii. (3) The fermented product was spray-dried to obtain a functional Clostridium butyricum culture.

[0007] Furthermore, the protein raw material is at least one of soybean meal powder, fermented soybean meal powder, cottonseed meal powder, soybean protein concentrate, chicken meal, puffed urea, and lysine.

[0008] Furthermore, the protein raw material is soybean meal powder.

[0009] Furthermore, the amount of protein raw material added is 400-600 g / L.

[0010] Furthermore, the complex enzyme is an alkaline protease, a neutral protease, and a cellulase in a mass ratio of 1:1:1.

[0011] Furthermore, the amount of the compound enzyme added is 3-5 g / L.

[0012] Furthermore, the compound bacterial strain is a compound bacterial strain with a mass ratio of Lactobacillus casei: Lactobacillus acidophilus and Enterococcus faecalis of 1:1:1.

[0013] Furthermore, the viable bacteria concentration of the lactic acid bacteria seed solution is (1-5)×10⁻⁶. 9 The viable cell concentration of the yeast seed culture is (2-4) × 10 CFU / mL. 9 CFU / mL; the inoculation amount is 8-10% (V / V).

[0014] Furthermore, the carbon source is glucose and wheat bran powder, wherein the amount of glucose added is 1-3 g / L and the amount of wheat bran powder added is 5-10 g / L.

[0015] Furthermore, the drying process is spray drying, and the inlet temperature of the spray dryer is 150℃~190℃. Beneficial effects

[0016] 1. This method involves adding protein raw materials to the centrifuged broth of Clostridium butyricum for enzymatic hydrolysis and secondary fermentation, thus turning waste into treasure. The resulting product is a highly efficient "antibiotic alternative" rich in various functional components such as bacteria, enzymes, acids, peptides, and prebiotics. It has functions such as improving appetite, promoting digestion, reducing stress, preventing diarrhea, and promoting growth. The beneficial metabolites of Clostridium butyricum, lactic acid bacteria, and yeast in the product not only have a strong appetite-stimulating effect and promote feed digestion and absorption, but also effectively improve the immune level of livestock and poultry and inhibit livestock and poultry diseases.

[0017] 2. The protein raw materials undergo enzymatic and fermentation processes to destroy anti-nutritional factors such as trypsin inhibitors, phytic acid, and gossypol. The small-molecule oligopeptides produced by enzymatic hydrolysis are high-quality nutritional products suitable for young livestock: they can promote nutrient absorption and improve feed utilization; alleviate lactose intolerance; activate macrophages and T lymphocytes, enhance non-specific immune responses, and strengthen immunity; reduce pathogen invasion and lower the risk of intestinal inflammation by maintaining the integrity of the intestinal mucosa; they also have anti-stress, antioxidant, and meat quality-improving effects; and can act as prebiotics to provide nutrition for beneficial bacteria (such as lactic acid bacteria and bifidobacteria), inhibit the proliferation of harmful bacteria, promote intestinal microecological balance, and reduce diarrhea rates. Some peptide fragments can promote the release of growth hormone (GH) and insulin-like growth factor (IGF-1), accelerating muscle synthesis. In breeding livestock, it may improve reproductive rates by regulating reproductive hormone levels. Feeding this patented product can also reduce nitrogen and phosphorus content in feces, alleviating livestock pollution. Attached Figure Description

[0018] Figure 1 This invention demonstrates the feeding-inducing effect of the product on pig herds. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Source of the strains for this invention: Clostridium butyricum is a patented strain preserved by our company, with accession number CCTCC NO. M 20231636; The yeast strain is *Kluyveromyces martensii*, with accession number CGMCC 24455; Lactobacillus casei, Lactobacillus plantarum, Lactobacillus acidophilus, and Enterococcus faecalis were all purchased from Beijing Bio-Bio Biotechnology Co., Ltd., with bio-67166, bio-67299, bio-67164, and bio-67103, respectively.

[0021] Culture medium formulation Ferrous sulfite agar medium (g / L): tryptone 15.0, soybean peptone 5.0, yeast extract 5.0, sodium metabisulfite 1.0, ferric ammonium citrate 1.0, agar 20.0, pH 7.5±0.2.

[0022] Ordinary broth culture medium (g / L): peptone 20, beef extract 5, sodium chloride 5, pH 7.5±0.2.

[0023] Clostridium butyricum activation medium (g / L): includes: peptone 10, beef extract 10, yeast extract 3, glucose 5, soluble starch 1, sodium chloride 5, sodium acetate 3, L-cysteine ​​hydrochloride 0.5, pH 6.8. Fermentation medium components (g / L): molasses 20, glucose 10, yeast extract 10, peptone 20, magnesium sulfate 1, dipotassium hydrogen phosphate 0.5, sodium citrate 1.

[0024] MRS medium, with the following composition (g / L): peptone 10, beef extract 10, yeast extract 5, K2HPO4 2, diammonium citrate 2, sodium acetate 5, glucose 20, MgSO4·7H2O 0.5, MnSO4·4H2O 0.2, Tween 80, pH 6.3 (natural).

[0025] The composition of the activated and seed culture medium for Kluwer Maximilian yeast is as follows (g / L): glucose 20, peptone 20, yeast extract 10, pH 6.8.

[0026] Preparation of seed liquid Preparation method of lactic acid bacteria seed culture: Slant cultures of *Lactobacillus casei*, *Lactobacillus plantarum*, and *Enterococcus faecalis* were inoculated separately into sterile MRS medium, with a liquid volume of 40% in shake flasks, and activated by incubation at 180 rpm and 42℃ for 24 h. The activated solution was then inoculated into MRS medium at a 4% inoculation rate and fermented under the activated conditions for 8 h to obtain the seed culture. The viable cell concentrations of the obtained *Lactobacillus casei*, *Lactobacillus plantarum*, and *Enterococcus faecalis* seeds were 2.21 × 10⁻⁶. 9 CFU / mL, 1.58 × 10 9 CFU / mL and 3.25×10 9 CFU / mL.

[0027] Kluyveromyces martensii culture method: Kluyveromyces martensii slant culture was inoculated into activation medium (30% capacity) and cultured at 30℃ and 180 rpm for 24 h to obtain the activated solution. Then, 4% of the activated solution was inoculated into expansion medium and cultured under activation conditions for 18 h to obtain the Kluyveromyces martensii seed culture. The viable cell concentration of the obtained seed culture was 2.71 × 10⁻⁶. 9 CFU / mL.

[0028] Product detection methods: Butyric acid, acetic acid, and lactic acid concentrations were determined by gas chromatography; total acid was determined by acid-base titration; bacterial concentration was determined by dilution-spreading method; crude protein was determined by Kjeldahl method; acid-soluble protein content was obtained by analyzing the protein content dissolved in 15% trichloroacetic acid; free amino acid content was analyzed by ninhydrin method; small peptide content was obtained by subtracting free amino acid content from acid-soluble protein content. Viable bacterial concentration was analyzed by dilution plating method. The viable bacterial concentration measured after heating at 85℃ for 10 min was the spore concentration (clostridium butyricum concentration was analyzed using ferrous sulfite agar medium, and the total concentration of other bacteria was analyzed using ordinary broth medium); other indicators were detected by national standard methods.

[0029] Example 1: Preparation of Clostridium butyricum centrifuged solution An appropriate amount of slant culture was inoculated into the activation medium and incubated statically at 37℃ for 16 h in an anaerobic incubator to obtain the seed culture. Clostridium butyricum fermentation was carried out in a 50 L fermenter under the following conditions: 70% fill factor, 4% inoculum (v / v), 37℃, 36 h fermentation time, 100 rpm rotation speed, 0.05 MPa pressure, and 0.2 VVM nitrogen flow rate. After fermentation, the fermentation broth was centrifuged at 5000 rpm for 10 min to prepare the supernatant. The concentration of residual Clostridium butyricum in the supernatant was 2.2 × 10⁻⁶. 7 CFU / mL.

[0030] Example 2: Preliminary Enzyme Process Optimization 1. Enzyme Combination Selection 400 g / L soybean meal powder and 200 g / L cottonseed meal powder were added to the Clostridium butyricum fermentation centrifuge broth, along with 5 g / L enzyme. After reacting at 55℃ for 2 h, a 10% inoculation ratio of a cheese-plant-feces sausage (mass ratio 1:1:1) composite microbial culture was added, and fermentation was continued at 37℃ for 10 h. The reaction was then terminated by immediately raising the temperature to 85℃ and holding for 10 min to inactivate the enzyme. The contents of crude protein, acid-soluble protein, and small peptides were measured. The specific enzyme combinations and experimental results are shown in Table 1. The specific activities of acidic protease, alkaline protease, neutral protease, and cellulase were all 100,000 U / g.

[0031]

[0032] As shown in Table 1, the alkaline protease-neutral protease-cellulase ratio of 1:1:1 exhibits the highest efficiency in the initial hydrolysis process.

[0033] 2. Selection of raw materials for enzymatic protein hydrolysis The effects of different protein raw materials on the content of acid-soluble proteins and small peptides after hydrolysis were investigated. The specific experimental steps and parameters were the same as those for enzyme combination selection. The difference was that the compound enzyme used in this example was alkaline protease-neutral protease-cellulase in a weight ratio of 1:1:1. While ensuring that the total amount of protein raw materials added remained unchanged, the combination of protein raw materials was adjusted. The results are shown in Table 2.

[0034]

[0035] Note: Total protein content is 600 g / L.

[0036] As shown in Table 2, the higher the soybean meal content, the higher the content of acid-soluble protein and small peptides in the hydrolysate. This patent selects soybean meal as the protein raw material. However, soybean meal is more expensive than cottonseed meal. In future product development, product quality and price can be considered comprehensively, and cottonseed meal or chicken meal can be used in appropriate proportions to replace soybean meal.

[0037] 3. Preliminary investigation of enzymatic hydrolysis time The effect of initial enzymatic hydrolysis time on the composition of the final product was investigated. The specific experimental steps and parameters were the same as those for the selection of raw materials for enzymatic hydrolysis of protein. The difference was that the compound enzyme used in this example was alkaline protease-neutral protease-cellulase in a weight ratio of 1:1:1, and the protein raw material was soybean meal powder with an addition amount of 600 g / L. The results are shown in Table 3.

[0038]

[0039] As can be seen from the results in Table 3, the combination of 2 hours of initial hydrolysis with two fermentation processes yielded the best results, with the highest contents of total protein, acid-soluble protein, and small peptides. As the time increased, all indicators decreased, indicating that excessively long enzyme time caused the protein to be hydrolyzed into amino acids, or even lost as gas through denitrification.

[0040] Example 3: Optimization of Secondary Fermentation Conditions Optimization of strain combinations 600 g / L soybean meal powder and 5 g / L compound enzyme were added to the Clostridium butyricum fermentation centrifuge broth. After reacting at 55℃ for 2 h, different combinations of compound bacterial strains were inoculated at 10% (v / v) and incubated at 37℃ for 24 h. The pH value and lactic acid bacteria concentration were measured, as shown in Table 4. The compound enzyme was a combination of alkaline protease, neutral protease, and cellulase in a mass ratio of 1:1:1. The specific activities of alkaline protease, neutral protease, and cellulase were all 100,000 U / g.

[0041]

[0042] As shown in Table 4, the lactic acid bacteria exhibited the best growth when the compound strain consisted of Lactobacillus casei, Lactobacillus acidophilus, and Enterococcus faecalis in a mass ratio of 1:1:1.

[0043] 2. Optimization of incubator gas atmosphere conditions The influence of the gas atmosphere conditions of the incubator on the composition of the final product was investigated. The specific experimental steps and parameters were the same as those for the optimization of the bacterial strain combination. The difference was that the compound strain was composed of Lactobacillus casei, Lactobacillus acidophilus and Enterococcus faecalis in a mass ratio of 1:1:1. The strains were cultured in conventional incubators and anaerobic incubators for 20 h, with 5 replicates. The results are shown in Table 5.

[0044]

[0045] As can be seen from the results in Table 5, there is no significant difference in the growth of lactic acid bacteria in ordinary incubators and anaerobic incubators, indicating that ordinary incubators are sufficient for the production of this product.

[0046] 3. Supplementing the selection of carbon sources The effects of supplementing different carbon sources during the secondary fermentation process on acid production and the growth of Clostridium butyricum and lactic acid bacteria were investigated. The specific experimental steps and parameters were the same as those for optimizing the gas atmosphere conditions of the incubator. The difference was that a regular incubator was used for fermentation, and carbon sources were supplemented during the secondary fermentation process. The results are shown in Table 6.

[0047]

[0048] Taking into account the concentrations of Clostridium butyricum and lactic acid bacteria, as well as their acid production, 2 g of glucose plus 5 g of wheat bran powder is a more ideal carbon source supplement.

[0049] Example 4 Spray drying 600 g / L soybean meal powder and 5 g / L compound enzyme were added to the Clostridium butyricum fermentation centrifuge broth. After reacting at 55℃ for 2 h, different combinations of compound strains were inoculated at 10% (v / v). Simultaneously, 2 g / L glucose and 5 g / L wheat bran powder were added as carbon sources. The mixture was then statically cultured at 37℃ for 24 h. The fermented material was then spray-dried at an inlet temperature of 160℃ to obtain the final product. The product was sent to Henan Hairui Zheng Testing Technology Co., Ltd. for analysis, and the results are shown in Table 7. The compound enzyme was a combination of alkaline protease, neutral protease, and cellulase in a mass ratio of 1:1:1. The specific activities of alkaline protease, neutral protease, and cellulase were all 100,000 U / g. The compound strains consisted of Lactobacillus casei, Lactobacillus acidophilus, and Enterococcus faecalis in a mass ratio of 1:1:1.

[0050]

[0051] As can be seen from Table 7, this product has a very low content of anti-nutritional factors, is rich in nutrients, and also contains probiotics, organic acids, and proteases.

[0052] Example 5 Feeding Trial feeding test One hundred 45-day-old pigs from the Yanjin Yechang Pig Farm in Henan Province were selected, and two feed trays were prepared for the experiment. The two trays contained nursery feed and nursery feed supplemented with 5% of the product prepared in Example 4, respectively. The pigs were allowed to freely choose their feed, and their feeding rate was recorded. The experiment lasted for 10 days, and the results are as follows: Figure 1 As shown.

[0053] Depend on Figure 1 It can be seen that 5% of this patented product has a very significant effect on attracting pigs to eat.

[0054] 2. Feeding trial of weaned piglets One hundred and twenty 21-day-old weaned piglets (approximately 6.5 kg) from the Yechang Pig Farm in Yanjin County, Henan Province, were randomly divided into two treatment groups, with three replicates per group and twenty piglets per replicate. 25 kg of yeast hydrolysate or 25 kg of the product prepared in Example 4 was added to each ton of nursery feed to serve as the control group and the experimental group, respectively. Feeding was ad libitum for 14 days. Initial weight, final weight, ADG (average daily gain), ADFI (average feed intake), feed conversion ratio, and diarrhea rate were recorded during the experiment. The results are shown in Table 8.

[0055]

[0056] As shown in Table 8, compared with feeding the same amount of yeast hydrolysate, feeding this patented product resulted in a 37 g / day increase in daily weight gain, a 0.13 decrease in feed conversion ratio, and a 3.59% decrease in diarrhea rate, indicating that the effect of this patented product is better than that of yeast hydrolysate.

[0057] 3. Feeding trial of nursery pigs One hundred piglets weighing 10-20 kg from Yechang Pig Farm in Yanjin, Henan Province, were randomly divided into two groups. The control group was fed with a formula feed from Guang'an Feed Factory in Henan Province, while the experimental group was fed with 2% of the product prepared in Example 4. The piglets were allowed free access to feed for 15 days. After the experiment, the effects of this patented product on daily weight gain and meat production cost were compared. The results are shown in Table 9.

[0058]

[0059] As shown in Table 9, after a 15-day trial, the average daily weight gain from adding this patented product significantly increased, the feed conversion ratio and diarrhea rate significantly decreased, and the cost of meat production decreased by 0.49 yuan / kg.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing functional Clostridium butyricum cultures from Clostridium butyricum centrifuged broth, characterized in that, Includes the following steps: (1) After adding protein raw materials and complex enzymes to the Clostridium butyricum centrifuged liquid, the reaction is carried out at 40℃~60℃ for 1~5 h to complete the preliminary enzymatic hydrolysis process. The concentration of Clostridium butyricum in the Clostridium butyricum centrifuged liquid is 2.0~3.0×10 7 CFU / mL, wherein the complex enzyme includes acidic protease, neutral protease, alkaline protease, cellulase, pectinase, and a complex enzyme composed of two or more of the above enzymes. (2) The preliminary enzymatic hydrolysis product is inoculated with a compound microbial strain and a carbon source is added. The reaction is carried out at 25℃~40℃ for 6~18 h to complete the two fermentation processes. During this process, the enzymatic hydrolysis reaction occurs simultaneously. The compound microbial strain is composed of a variety of lactic acid bacteria and yeast. The lactic acid bacteria include Lactobacillus casei, Lactobacillus plantarum, Lactobacillus acidophilus and Enterococcus faecalis. The yeast is Kluyveromyces martensii. (3) The fermented product was spray-dried to obtain a functional Clostridium butyricum culture.

2. The method according to claim 1, characterized in that: The protein raw material is at least one of soybean meal powder, fermented soybean meal powder, cottonseed meal powder, soybean protein concentrate, chicken meal, puffed urea, and lysine.

3. The method according to claim 2, characterized in that: The protein raw material is soybean meal powder.

4. The method according to any one of claims 1 to 3, characterized in that: The amount of protein raw material added is 400-600 g / L.

5. The method according to claim 1, characterized in that: The complex enzyme is composed of alkaline protease, neutral protease, and cellulase in a mass ratio of 1:1:

1.

6. The method according to claim 1 or 5, characterized in that: The amount of the compound enzyme added is 3-5 g / L.

7. The method according to claim 1, characterized in that: The aforementioned compound bacterial strain is a compound bacterial strain consisting of Lactobacillus casei, Lactobacillus acidophilus, and Enterococcus faecalis in a mass ratio of 1:1:

1.

8. The method according to claim 1 or 7, characterized in that: The viable bacteria concentration of the lactic acid bacteria seed solution is 1–5 × 10⁻⁶. 9 The viable cell concentration of the yeast seed culture is 2–4 × 10⁻⁶ CFU / mL. 9 CFU / mL; the inoculation amount is 8-10% V / V.

9. The method according to claim 1, characterized in that: The carbon source is glucose and wheat bran powder, wherein the amount of glucose added is 1-3 g / L and the amount of wheat bran powder added is 5-10 g / L.

10. The method according to claim 1, characterized in that: The drying process is spray drying, and the inlet temperature of the spray dryer is 150℃~190℃.

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