Rice straw fermentation method and fermented feed

Abstract

The invention discloses a rice straw fermentation method and a fermented feed. The invention discloses a rice straw fermentation method. The method comprises the following steps: (1) cutting coarse straws into pieces of 2-3cm; (2) cooking the straws at high temperature and high pressure to remove moisture; (3) mixing the coarse straw with 25% ammonia water according to a mass ratio of 1: 6; (4) performing ultrasonic treatment on the coarse straw; (5) keeping the temperature at 30 DEG C for 18 hours; (6) washing the pH value of the straw with deionized water until the pH value is 7.0-7.3, drying at 105 DEG C for 4 hours, crushing and uniformly mixing; and (7) inoculating strains and a compound enzyme preparation into the uniformly mixed straws, adjusting the moisture, performing aerobic fermentation at 37 DEG C for 72 hours, and performing anaerobic fermentation for 72 hours. The method is easy to operate, mild in condition, free of waste water and waste gas and suitable for industrial production. According to the invention, low-value straws can be converted into high-value fermented straws, so that feed utilization of the straws is realized, and meanwhile, the application effects of reducing cost and increasing efficiency are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of straw utilization, and in particular relates to a rice straw fermentation method and fermented feed. Background Art

[0002] my country is a major rice-growing country in the world. In 2023, China's rice planting area will be 299.20 thousand hectares, and the rice output will be 212.84 million tons. According to statistics, my country can produce 900 million tons of straw each year, of which rice straw is about 200 million tons, and the resources are abundant. As people's demand for meat, milk and eggs increases, the demand for food has also increased significantly. In this way, more and more food is used to feed livestock, affecting the food self-sufficiency rate. However, the prices of food resources such as corn and soybeans remain high. The development of non-grain feed resources is one of the effective means to alleviate the contradiction of "people and animals competing for food".

[0003] Dry straw has a rough texture and poor palatability. It has almost no value in feeding monogastric animals directly. Dry straw is often fed directly to ruminants as roughage, mainly to maintain the normal function of the rumen. The utilization rate is low and the feeding potential has not been fully tapped. According to measurements, the dry matter content of naturally air-dried rice straw is 89.2-91.4%, with 3.7-4.1% crude protein, 2.7-3.3% crude fat, and 61.5-64.1% crude fiber on a dry matter basis. Reducing the fiber content and improving the feed conversion rate have become urgent problems to be solved in the conversion of straw into a grain.

[0004] Straw pretreatment mainly changes the physical and chemical properties of straw, increases the surface area of ​​straw, destroys the chemical bonds between cellulose, hemicellulose and lignin, and reduces the crystallization of cellulose, thereby improving the degradation efficiency of straw. Physical methods mainly include mechanical treatment (grinding and extrusion), irradiation treatment, high temperature and electrolysis, etc., which can effectively increase the contact area of ​​straw, but are still limited in improving the fiber degradation rate. Chemical pretreatment mainly includes acid pretreatment, alkali pretreatment, ionic liquid pretreatment, etc., which can effectively break the structure of lignocellulose, but acid and alkali liquids are easy to pollute the environment and cause difficulties for subsequent biological utilization. Biological pretreatment mainly treats straw through microorganisms, shortens the subsequent anaerobic fermentation time, and increases the amount of straw products generated.

[0005] Chinese patent application CN109938158A discloses a method for preparing biological feed by micro-storage fermentation of rice straw, which uses rice straw as raw material, obtains fermented feed after fermentation treatment, and the feed can be stored for a long time. However, CN109938158A does not effectively solve the problem of excessively high cellulose and lignin content in rice straw, and the preparation time is relatively long. The strains of the above method need to be cultured for 2-10 days, and the rice is cut into 3 cm pieces, and then the bacterial solution is inoculated and mixed evenly, and then anaerobic fermentation is carried out, and the fermentation takes 25-30 days. The obtained fermented feed can be stored for a long time, but it does not solve the problem of high crude fiber content in rice straw, which is time-consuming and has low resource utilization. Summary of the invention

[0006] In order to solve the above technical problems, the present invention proposes a fermented straw production method. The present invention not only effectively removes crude fiber, hemicellulose and lignin components, but also makes the fermented rice straw feed fragrant in sensory evaluation, and the production method is simple, time-saving and cost-effective.

[0007] To achieve the above object, the present invention provides the following technical solutions: A rice straw fermentation method comprises the following steps: (1) Cut the coarse straw into pieces of 2-3 cm; (2) Steaming the straw at high temperature and high pressure to remove moisture; (3) Mix the crude straw with 25% ammonia water in a mass ratio of 1:6; (4) ultrasonically treating the crude straw; (5) Constant temperature at 30°C for 18 hours; (6) Wash the straw with deionized water to a pH of 7.0 - 7.3, dry at 105 °C for 4 h, and then crush and mix; (7) Inoculate the above mixed straw with bacteria and complex enzyme preparation, adjust the moisture content, and ferment aerobically at 37°C for 72 hours or anaerobic fermentation for 72 hours.

[0008] The chopped rice straw in step (2) is placed in a high-temperature and high-pressure sterilization bag with air holes, and steamed at 121° C. for 20 minutes. After steaming, the straw is wrung dry to remove most of the moisture.

[0009] In step (4), the temperature is 23° C., ultrasound is used for assistance, and the process is carried out with a plastic wrap for 1 hour.

[0010] In step (7), the moisture content of the crude straw is adjusted to 55%.

[0011] In step (7), the bacterial species are Bacillus subtilis, Saccharomyces cerevisiae and Enterococcus faecalis. After activation and purification, single colonies of Bacillus subtilis and Saccharomyces cerevisiae are picked and cultured in LB medium or YPD medium at 37°C and 200 rpm for 12 h to obtain Bacillus subtilis fermentation broth and Saccharomyces cerevisiae fermentation broth. After activation and purification of Enterococcus faecalis, a single colony was picked and placed in MRS medium for static culture for 12 hours, and then the activated fermentation broth was added to 5% of the total system and mixed, the enzyme preparation was added in an amount of 0.1%, the enzyme activity was 10U / g, and an appropriate amount of water was added and mixed evenly to obtain a mixed fermentation broth; Bacillus subtilis ZJUFA-1 is an existing strain, which is deposited in the General Microbiology Center of China National Microbiological Culture Collection Administration, and the deposit number is CGMCC NO: 12823; the brewer's yeast is an existing strain, purchased from the General Microbiology Center of China National Microbiological Culture Collection Administration, and the strain catalog number is: 2.3973; Enterococcus faecalis ZJUAF-4 is an existing strain, and the deposit number of the General Microbiology Center of China National Microbiological Culture Collection Administration is CGMCC NO: 16767; the complex enzyme preparation is composed of the following enzymes: xylanase 8000 IU / g, protease 11000 IU / g, β-glucanase 5000 IU / g, cellulase 3000 IU / g, pectinase 1500 IU / g, mannanase 300 IU / g, and galactosidase 200 IU / g.

[0012] A fermented feed obtained according to the method, wherein the removal rate of crude fiber in the fermented straw reaches 27.21%, the removal rate of hemicellulose reaches 10.17%, and the removal rate of lignin reaches 31.08%, the enzymatic hydrolysis efficiency of cellulose is improved, and the bioavailability is improved; the crude protein of the feed increases by 6.90% after fermentation; the pH of the feed gradually decreases to 6.73; the number of Bacillus subtilis and Enterococcus faecalis reaches 1.048×10 9 and 1.1×10 8 cfu / g.

[0013] Beneficial effects of the present invention: The crushed rice straw is first cooked at high temperature and high pressure, then mixed with ammonia water and deionized water in a certain proportion, and the pH value of the rice straw is adjusted to neutral after ultrasonic and constant temperature treatment. After drying and crushing, the mixed fermentation agent is inoculated for aerobic-anaerobic two-step fermentation to obtain fermented rice straw. The method of the present invention is simple to operate, has mild conditions, does not produce wastewater and waste gas, and is suitable for industrial production. In addition, the crude fiber removal rate of the fermented rice straw reached 27.21%, the lignin removal rate was as high as 31.08%, the crude protein increased by 6.90%, and the number of Bacillus and Enterococcus faecalis reached 1.048×10 9 and 1.1×10 8The present invention can convert low-value straw into high-value fermented straw, realize the utilization of straw as feed, and achieve the application effect of reducing costs and increasing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The results show that the crude fiber, cellulose and hemicellulose of crude straw are compared with those of pretreated and fermented straw. Pretreatment and microbial fermentation significantly reduced the contents of crude fiber, cellulose and hemicellulose in straw (P < 0.01). DETAILED DESCRIPTION

[0015] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0016] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0017] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0018] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0019] The calculation formula of the moisture content in the embodiment of the present invention is moisture content (%) = (wet weight - dry weight) / wet weight * 100%. Example

[0020] A method for preparing fermented rice straw feed comprises the following steps: (1) Weigh 50g of dry straw, adjust the moisture content of the fermented feed to 45%, and inoculate 5% of Bacillus subtilis, 5% of Saccharomyces cerevisiae, and 5% of Enterococcus faecalis. The fermentation groups were inoculated with 0.1% of compound enzymes (xylanase 8000IU / g, protease 11000IU / g, β-glucanase 5000IU / g, cellulase 3000IU / g, pectinase 1500IU / g, mannanase 300IU / g, galactosidase 200IU / g, enzyme activity 10U / g). The high enzyme-producing Bacillus subtilis in the present invention belongs to Bacillus subtilis subsp. subtilis, named ZJUFA-1, and is deposited in the General Microbiological Center of China National Microbiological Culture Collection Administration (address: Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing, zip code 100101), the deposit date is August 8, 2016, and the deposit number is CGMCC NO: 12823. The brewer's yeast was purchased from the General Microbiological Center of China National Microbiological Culture Collection Administration, with a strain catalog number of 2.3973; Enterococcus faecalis ZJUAF-4 is an existing strain, and the deposit number of the General Microbiological Center of China National Microbiological Culture Collection Administration is CGMCC NO: 16767.

[0021] 2) Anaerobic fermentation at 37 degrees Celsius for 6 days.

[0022] The moisture, crude protein, acid-soluble protein, ADF, NDF, pH value, Bacillus subtilis, Saccharomyces cerevisiae, Enterococcus faecalis and other indicators of unfermented rice straw and fermented rice straw were measured respectively.

[0023] Table 1

[0024] The results are shown in Table 1. The acid-soluble protein of fermented rice straw increased by 58.03% compared with that of unfermented rice straw. NDF and ADF did not change significantly. The pH value decreased and the Bacillus subtilis reached 8×10 6 cfu / g, Saccharomyces cerevisiae reached 2×10 5 cfu / g, Enterococcus faecalis reached 6×10 6 cfu / g, and the probiotic content is rich. Since the fiber content does not change significantly after fermentation, the rice straw is pretreated as shown in Example 2.

[0025] Example 2 A method for preparing fermented straw, comprising the following steps: (1) Cut 400 g of rice straw into pieces of 2-3 cm; (2) Place 400 g of rice straw into a high-temperature and high-pressure sterilization bag (with the bag tied) and steam at 121°C for 20 min.

[0026] (3) Prepare 25% ammonia water: add 25 ml of ammonia water (analytical grade) to 75 ml of deionized water and place in a conical flask.

[0027] (4) Squeeze out the moisture from the straw and add 2336 ml of deionized water and 64 ml of 25% ammonia water in a solid-liquid ratio of 1:6.

[0028] (5) 23℃, 300W ultrasonic assistance, cover with plastic wrap to retain heat for 1 hour. Then transfer to a constant temperature box and treat at 30℃ for 18 hours.

[0029] (6) The next day, soak and wash the straw in deionized water until the pH is 7.0-7.3 (or adjust the pH of the straw with HCl or NaOH).

[0030] (7) Dry at 105°C for 4 hours and crush uniformly after drying.

[0031] (8) Using high enzyme-producing Bacillus subtilis, Saccharomyces cerevisiae, Enterococcus faecalis, and complex enzymes as shown in Example 1.

[0032] (9) The water content was adjusted to 50%, the temperature to 37 °C, the fermentation time to 5 days, and a two-step fermentation process of aerobic fermentation for 72 hours and anaerobic fermentation for 72 hours was adopted.

[0033] Table 2

[0034] The contents of cellulose, hemicellulose and lignin in straw raw material and fermented rice straw (144h) were measured respectively.

[0035] The results are shown in Table 2 and Appendix Figure 1 The results show that the combination of pretreatment and fermentation can effectively destroy the wood fiber structure of rice straw. The crude fiber removal rate reached 27.21% (P < 0.01), the hemicellulose removal rate reached 10.17% (P < 0.01), and the lignin removal rate reached 31.08% (P < 0.01), which can improve the enzymatic efficiency of cellulase and improve the bioavailability.

[0036] The moisture, crude protein, pH value, Bacillus, Enterococcus faecalis and other indicators of unfermented rice straw, unfermented rice straw after pretreatment, fermented rice straw after pretreatment (72h), and fermented rice straw (144h) were measured respectively.

[0037] It can be seen that compared with the unfermented feed, the crude protein of the fermented feed increased by 6.90%; the pH of the feed gradually decreased to 6.73; the number of Bacillus and Enterococcus faecalis reached 1.05×10 9 cfu / g and 1.1×10 8 cfu / g. In summary, the obtained fermented feed is rich in crude protein and probiotics.

[0038] The characteristic of this embodiment is that the combined physical and chemical pretreatment and microbial treatment and fermentation of rice straw can effectively remove cellulose, hemicellulose and lignin, increase the crude protein content of rice straw and enrich the probiotic content.

[0039] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, all of which belong to the protection scope of the present invention. The protection scope of the present invention is given by the attached claims and any equivalent technical solutions thereof.

Claims

1. A rice straw fermentation method, characterized in that: The following steps are involved: (1) Cut the coarse straw into pieces of 2-3 cm; (2) Steaming the straw at high temperature and high pressure to remove moisture; (3) Mix the crude straw with 25% ammonia water in a mass ratio of 1:6; (4) ultrasonically treating the crude straw; (5) Constant temperature at 30°C for 18 hours; (6) Wash the straw with deionized water to a pH of 7.0 - 7.3, dry at 105 °C for 4 h, and then crush and mix; (7) Inoculate the above mixed straw with bacteria and complex enzyme preparation, adjust the moisture content, and ferment aerobically at 37°C for 72 hours or anaerobic fermentation for 72 hours.

2. The method according to claim 1, characterized in that The chopped rice straw in step (2) is placed in a high-temperature and high-pressure sterilization bag with air holes, and steamed at 121° C. for 20 minutes. After steaming, the straw is wrung dry to remove most of the moisture.

3. The method for producing fermented straw according to claim 1, characterized in that: In step (4), the temperature is 23° C., ultrasound is used for assistance, and the process is carried out with a plastic wrap for 1 hour.

4. The method according to claim 1, characterized in that: In step (7), the moisture content of the crude straw is adjusted to 55%.

5. The method according to claim 1, characterized in that: In step (7), the bacterial species are Bacillus subtilis, Saccharomyces cerevisiae and Enterococcus faecalis. After activation and purification, single colonies of Bacillus subtilis and Saccharomyces cerevisiae are picked and cultured in LB medium or YPD medium at 37°C and 200 rpm for 12 h to obtain Bacillus subtilis fermentation broth and Saccharomyces cerevisiae fermentation broth. After activation and purification of Enterococcus faecalis, single colonies were picked and placed in MRS medium for static culture for 12 hours, and then the activated fermentation broth was added to 5% of the total system and mixed, the enzyme preparation was added in an amount of 0.1%, the enzyme activity was 10U / g, and an appropriate amount of water was added and mixed evenly to obtain a mixed fermentation broth; Bacillus subtilis is an existing strain, which is deposited in the General Microbiology Center of China National Microbiological Culture Collection Administration, and the deposit number is CGMCC NO: 12823; the brewer's yeast is an existing strain, purchased from the General Microbiology Center of China National Microbiological Culture Collection Administration, and the strain catalog number is: 2.3973; Enterococcus faecalis ZJUAF-4 is an existing strain, and the deposit number of the General Microbiology Center of China National Microbiological Culture Collection Administration is CGMCC NO: 16767; the complex enzyme preparation is composed of the following enzymes: xylanase 8000 IU / g, protease 11000 IU / g, β-glucanase 5000 IU / g, cellulase 3000 IU / g, pectinase 1500 IU / g, mannanase 300 IU / g, and galactosidase 200 IU / g.

6. A fermented feed obtained by the method according to claims 1-5, characterized in that: The removal rate of crude fiber, hemicellulose and lignin in fermented straw reached 27.21%, 10.17% and 31.08%, respectively, which improved the enzymatic efficiency of cellulase and bioavailability. The crude protein content of feed increased by 6.90% after fermentation. The pH of feed gradually decreased to 6.

73. The number of Bacillus subtilis and Enterococcus faecalis reached 1.048×10 9 and 1.1×10 8 cfu / g.

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