Bio-fermented feed, preparation method and application thereof

Abstract

The application provides a biological fermentation feed, a preparation method and application thereof. The preparation method comprises the following steps: inoculating mold into a biological fermentation feed culture medium to perform first fermentation, and obtaining a first fermentation product; inoculating yeast into the first fermentation product to perform second fermentation after the first fermentation, and obtaining the biological fermentation feed; the biological fermentation feed culture medium comprises straw products and supplementary materials; the straw products comprise 40-70% of instantaneous steam explosion straw products and 30-60% of continuous steam explosion straw products in terms of mass content; and the supplementary materials comprise a nitrogen source, potassium dihydrogen phosphate and magnesium sulfate. The culture medium obtained has sufficient space structure and higher reducing sugar content, and provides a better growth fermentation environment for microorganisms.

Description

Technical Field

[0001] This invention relates to the field of bio-feed technology, and more specifically, to a bio-fermented feed, its preparation method, and its application. Background Technology

[0002] Biomass energy is a renewable energy source. Generally, biomass energy refers to the energy converted and stored by plants through photosynthesis using solar energy, making it the fourth largest energy source after coal, oil, and natural gas. However, the complex and stable structure of plant lignocellulose cell walls, with its tightly cross-linked cellulose, hemicellulose, and lignin, hinders microbial utilization and enzymatic degradation of cellulose. It does not hydrolyze at room temperature, and even at high temperatures, hydrolysis is minimal, severely limiting the application of biomass raw materials in industrial production. This seriously restricts the resource utilization of biomass raw materials, leading to resource waste and increasing environmental pollution control pressures.

[0003] Approximately 988 million tons of crop straw are produced annually, of which 215 million tons remain unused, equivalent to 64.5 million tons of starch or 99.23 million tons of corn. Such a vast biomass resource could be transformed into single-cell protein through solid-state fermentation using steam explosion pretreatment technology and cellulase-producing microorganisms such as Aspergillus niger, Aspergillus oryzae, and yeast. This could alleviate the shortage of protein feed resources and the problem of competition between humans and livestock for grain.

[0004] By altering the compact "three elements" structure of straw raw materials through various pretreatment technologies, the utilization efficiency of microorganisms can be improved. Currently, straw pretreatment methods mainly include chemical methods (acid method, alkali method), physical methods (high-temperature cooking, mechanical crushing, microwave treatment, and high-energy radiation), and steam explosion pretreatment methods. Among these, physical pretreatment technology has limited effectiveness in separating the "three elements" of straw, consumes a lot of energy, and has high operating costs. Chemical pretreatment technology involves hemicellulose hydrolysis, yielding the largest amount of sugar and having low catalytic costs, but it suffers from slow hydrolysis rates, acid recovery problems, severe equipment corrosion, and environmental pollution. Steam explosion pretreatment includes instantaneous steam explosion pretreatment technology and continuous steam explosion pretreatment technology.

[0005] Instantaneous steam explosion pretreatment technology can effectively separate the three elements (cellulose, hemicellulose, and lignin) in straw raw materials, but it does not significantly alter the properties of the straw raw materials and has limited effects on the degradation of cellulose, hemicellulose, and lignin. Using instantaneously steam-exploded straw raw materials as a solid-state fermentation medium, without the addition of an exogenous carbon source, affects the growth of microorganisms in the early stages of solid-state fermentation. Furthermore, the larger size and porosity of instantaneously steam-exploded straw raw materials not only reduce the specific surface area provided for microbial growth but also affect the mass transfer of nutrients required by microorganisms, reducing the efficiency of mixed-culture solid-state fermentation and impacting microbial growth and reproduction.

[0006] Continuous steam explosion pretreatment technology can effectively separate the three elements (cellulose, hemicellulose, and carbon) in straw raw materials, altering their properties and transforming them into a fine powder structure. Simultaneously, it can degrade some cellulose and hemicellulose into monosaccharides. However, continuously steam-exploded straw raw materials have small particle sizes and low porosity, making them prone to clumping and sandwiching. Using continuously steam-exploded straw raw materials as a solid-state fermentation medium can negatively impact heat and mass transfer, hindering microbial respiration and aeration, ultimately leading to microbial failure and bio-fermentation failure.

[0007] Even when instantaneous steam explosion pretreatment technology and continuous steam explosion pretreatment technology are used in combination, the existing technologies still have problems such as complex operation, low repeatability, and difficulty in scaling up production. In addition, the fermentation effect is poor, and the effective components of the fermented feed, such as protein content, are low. Therefore, it is of great significance to provide a simple method for preparing fermented feed with high content of effective components for the recycling of straw. Summary of the Invention

[0008] The main objective of this invention is to provide a bio-fermented feed, its preparation method, and its application, in order to solve the problem that the effective ingredient content of fermented feed prepared from straw in the prior art is low.

[0009] To achieve the above objectives, according to a first aspect of the present invention, a method for preparing bio-fermented feed is provided. The method includes: inoculating mold into a bio-fermented feed culture medium and carrying out a first fermentation to obtain a first fermentation product; after the first fermentation, inoculating yeast into the first fermentation product and carrying out a second fermentation to obtain the bio-fermented feed; wherein the bio-fermented feed culture medium includes: straw products and supplementary feed; the straw products, by mass content, include: 40%-70% instantaneously explosive straw products and 30%-60% continuously explosive straw products; the supplementary feed includes: a nitrogen source, potassium dihydrogen phosphate, and magnesium sulfate; by mass content, the amount of nitrogen source added is 3.5-5% of the total mass of the straw products; the amount of potassium dihydrogen phosphate added is 0.1%-1% of the total mass of the straw products; and the amount of magnesium sulfate added is 0.1-1% of the total mass of the straw products.

[0010] Further, the mold is the product obtained by inoculating mold spore liquid into a mold seed culture medium and then culturing the mold; wherein, the mold seed culture medium includes: main materials and auxiliary materials; by mass content, the main materials include: 30%-60% of instantaneously steam-exploded straw products and 40%-70% of continuously steam-exploded straw products as substrates; the auxiliary materials include: nitrogen source, potassium dihydrogen phosphate and magnesium sulfate; by mass content, the amount of nitrogen source added is 1-3% of the total mass of straw products; the amount of potassium dihydrogen phosphate added is 0.1%-1% of the total mass of straw products; the amount of magnesium sulfate added is 0.1-1% of the total mass of straw products; preferably, the nitrogen source in the bio-fermentation feed culture medium and the mold seed culture medium is independently selected from one or more of the following: urea, ammonium sulfate or ammonium phosphate; preferably, the humidity of the mold seed culture medium is 40-70%; preferably, the mold is selected from one or more of the following: Aspergillus niger or Aspergillus oryzae; preferably, the spore concentration in the mold spore liquid is 1×10⁻¹⁰. 6 -10 7 CFU / mL; preferably, the inoculation amount of mold spore solution to the volume-to-mass ratio of mold seed culture medium is 1-5%; preferably, the mold culture time is 2-2.5 days; preferably, the mold culture temperature is 25-35℃.

[0011] Furthermore, the preparation method of the instantaneous steam explosion straw product includes: pre-degrading the straw raw material and then subjecting it to instantaneous steam explosion to obtain the instantaneous steam explosion straw product; preferably, the pressure of the instantaneous steam explosion is 0.5-1.2 MPa; preferably, the instantaneous steam explosion time is 0.5-10 min; preferably, the straw raw material is selected from at least one of the following: rice straw, rapeseed straw, wheat straw, corn straw, corn cob, bagasse or sugarcane leaves; preferably, the length of the straw raw material is 1-30 cm; preferably, the pre-degradation includes: soaking or spraying the straw raw material with water, an acid solution with a mass concentration of 1-10% or an alkaline solution with a mass concentration of 1-10%; preferably, the pre-degradation time is 10-60 min.

[0012] Further, the preparation method of the continuous steam-exploded straw product includes: pre-degrading the straw raw material and then subjecting it to continuous steam explosion to obtain the continuous steam-exploded straw product; preferably, the temperature of the continuous steam explosion is 150-220℃; preferably, the pressure of the continuous steam explosion is 0.5-1.2 MPa; preferably, the time of the continuous steam explosion is 5-40 min; preferably, the straw raw material is selected from at least one of the following: rice straw, rapeseed straw, wheat straw, corn straw, corn cob, bagasse or sugarcane leaves; preferably, the length of the straw raw material is 1-10 cm; preferably, the pre-degradation includes: soaking or spraying the straw raw material with water, an acid solution with a mass concentration of 1-10% or an alkaline solution with a mass concentration of 1-10%; preferably, the pre-degradation time is 10-60 min.

[0013] Further, the yeast is a product obtained by inoculating sucrose medium and culturing it; preferably, the yeast is selected from one or more of the following: Saccharomyces cerevisiae, Kluyveromyces martensii, or Candida utilis; preferably, the pH value of the yeast culture is 4.8-5.0; preferably, the temperature of the yeast culture is 30-32℃; preferably, the yeast culture time is 1-2 days.

[0014] Furthermore, the humidity of the bio-fermented feed culture medium is 40-70%; preferably, the mass ratio of the inoculation amount of mold to the bio-fermented feed culture medium is 3-5%; preferably, the volume-mass ratio of the inoculation amount of yeast to the first fermentation product is 1-5%.

[0015] Furthermore, the first fermentation time is 24h-48h; preferably, the temperature of the first fermentation is 25-35℃; preferably, the second fermentation time is 3d-7d; preferably, the temperature of the second fermentation is 25-35℃.

[0016] Furthermore, the preparation method also includes: drying the product after the second fermentation to obtain bio-fermented feed; preferably, the drying temperature is 50-60℃.

[0017] To achieve the above objectives, according to a second aspect of the present invention, a bio-fermented feed prepared by the above-described preparation method is provided, wherein the crude protein content of the bio-fermented feed is >26%; preferably, the amino acid content of the bio-fermented feed is >21%.

[0018] To achieve the above objectives, according to a third aspect of the present invention, an application of bio-fermented feed prepared using the above-described preparation method in animal husbandry is provided.

[0019] By applying the technical solution of this invention, adding a specific ratio of instantaneously vapor-exploded straw and continuously vapor-exploded straw to the culture medium for preparing bio-fermented feed can produce a culture medium with sufficient spatial structure and pores and a high reducing sugar content. This provides a better growth and fermentation environment for the subsequently added microorganisms, enabling efficient utilization of the difficult-to-degrade straw material and achieving the recycling of straw. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 A schematic diagram of untreated straw raw material is shown;

[0022] Figure 2A schematic diagram of straw after instantaneous steam explosion treatment is shown;

[0023] Figure 3 A schematic diagram of straw after continuous steam explosion treatment is shown. Detailed Implementation

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0025] Definitions:

[0026] Instantaneous steam explosion: Instantaneous steam explosion pretreatment technology can effectively separate the three elements (cellulose, hemicellulose, and lignin) in straw raw materials, but it does not significantly change the properties of the straw raw materials and has limited effects on the degradation of cellulose, hemicellulose, and lignin. In addition, the straw raw materials produced by instantaneous steam explosion have a larger size and porosity, which not only provides a smaller unit surface area for microbial growth, but also affects the mass transfer of nutrients required by microorganisms, reduces the efficiency of mixed solid-state fermentation, and affects the growth and reproduction of microorganisms.

[0027] Continuous steam explosion: Continuous steam explosion pretreatment technology can effectively separate the three elements in straw raw materials, change the properties of straw raw materials, turn straw raw materials into a fine powder structure, and at the same time degrade some cellulose and hemicellulose into monosaccharides. Continuous steam explosion straw raw materials have small particle size and low porosity, making them prone to clumping and sandwiching. Using continuously steam-exploded straw raw materials as a solid fermentation medium will adversely affect heat and mass transfer, hinder microbial respiration and aeration, and ultimately lead to the failure of bio-fermentation due to the inability of microorganisms to grow normally.

[0028] The working principles of instantaneous steam explosion and continuous steam explosion are different. Instantaneous steam explosion systems cannot be continuously fed. Material is introduced into the system and maintained at a specific pressure for a set period before instantaneous detonation, with a detonation time of less than 0.1 seconds. Instantaneous steam explosion systems release high-pressure steam, which has penetrated into the fiber, through closed pores in the form of a gas stream. This causes some mechanical breakage in the fiber. Simultaneously, the intensified high temperature and pressure break the hydrogen bonds within the cellulose, releasing new hydroxyl groups. The ordered structure within the cellulose changes, but the material's external shape remains largely unchanged.

[0029] By using a continuous steam explosion system, biomass raw materials can be continuously fed into the system. The internal pressure of the pressure-maintaining equipment is constant. The material is continuously pushed and squeezed forward by the screw inside the pressure-maintaining equipment. The material can be continuously discharged from the outlet. Under the action of high-pressure steam and physical extrusion, the material will be transformed into fine particles.

[0030] As mentioned in the background section, due to the relatively compact structure of cellulose, hemicellulose, and lignin in straw raw materials, it is difficult to efficiently degrade and utilize them. Existing methods for degrading and utilizing biomass straw, whether physical, chemical, or steam explosion methods, all have certain drawbacks, including low efficiency, complex operation, and low content of effective components (such as protein) in the resulting fermentation products. Therefore, this application aims to protect a method for preparing bio-fermented feed with a high content of effective components using straw with high efficiency.

[0031] In a first typical embodiment of this application, a method for preparing bio-fermented feed is provided. The method includes: inoculating mold into a bio-fermented feed culture medium and carrying out a first fermentation to obtain a first fermentation product; after carrying out the first fermentation, inoculating yeast into the first fermentation product and carrying out a second fermentation to obtain bio-fermented feed.

[0032] The bio-fermented feed culture medium includes: straw products and supplementary feed; by mass content, the straw products include: 40%-70% instantaneous steam-explosion straw products and 30%-60% continuous steam-explosion straw products; the supplementary feed includes: nitrogen source, potassium dihydrogen phosphate and magnesium sulfate; by mass content, the amount of nitrogen source added is 3.5-5% of the total mass of straw products; the amount of potassium dihydrogen phosphate added is 0.1%-1% of the total mass of straw products; and the amount of magnesium sulfate added is 0.1-1% of the total mass of straw products.

[0033] It should be noted that the molds and yeasts mentioned in this application are all commercially available products or existing publicly disclosed strains.

[0034] This invention configures continuously steam-exploded straw raw materials and instantaneously steam-exploded straw raw materials in a certain proportion to form a bio-fermentation feed culture medium. This can better combine the characteristics of different steam-exploded materials, so that the bio-fermentation feed has sufficient spatial structure and pores, reducing clumping or sandwiching in the culture medium, which is more conducive to aeration and heat transfer. It also enables the culture medium to have a high reducing sugar content and a large specific surface area, which is more conducive to the early growth and reproduction of microorganisms. Thus, while achieving efficient degradation of straw raw materials, it also produces bio-fermentation feed with a high content of effective components (such as protein), realizing the effective reuse of straw.

[0035] Any mold with good activity is suitable for this application. The mold can degrade cellulose, hemicellulose and lignin in the Platycodon grandiflorus raw material. To further improve the degradation efficiency of the mold on Platycodon grandiflorus, the mold is activated and propagated in a culture medium containing Platycodon grandiflorus raw material beforehand. In a preferred embodiment, the mold is obtained by inoculating mold spore liquid into a mold seed culture medium and then culturing the mold. The mold seed culture medium includes: main material and auxiliary material. By mass content, the main material includes: 30%-60% instantaneous steam-exploded straw product and 40%-70% continuous steam-exploded straw product as substrate. The auxiliary material includes: nitrogen source, potassium dihydrogen phosphate and magnesium sulfate. By mass content, the amount of nitrogen source added is 1-3% of the total mass of straw product; the amount of potassium dihydrogen phosphate added is 0.1%-1% of the total mass of straw product; and the amount of magnesium sulfate added is 0.1-1% of the total mass of straw product.

[0036] To further improve the growth efficiency of mold, in a preferred embodiment, the nitrogen source in both the bio-fermentation feed culture medium and the mold seed culture medium is independently selected from one or more of the following: urea, ammonium sulfate, or ammonium phosphate, wherein the amount of nitrogen source added is calculated based on nitrogen atomic content; preferably, the humidity of the mold seed culture medium is 40-70%. Any mold suitable for this application is applicable to this application. In a preferred embodiment, the mold is selected from one or more of the following: Aspergillus niger or Aspergillus oryzae. It should be noted that Aspergillus niger and Aspergillus oryzae mentioned in this application are commercially available products or existing publicly disclosed strains. Preferably, the spore concentration in the mold spore solution is 1 x 10⁻⁶. 6 -10 7 CFU / mL; preferably, the inoculation amount of mold spore solution to the volume-to-mass ratio of mold seed culture medium is 1-5%; preferably, the mold culture time is 2-2.5 days; preferably, the mold culture temperature is 25-35℃.

[0037] Any method capable of instantaneously steam-exploding the raw material of Platycodon grandiflorus is applicable to this application. To further improve the efficiency of instantaneous steam explosion, in a preferred embodiment, the method for preparing the instantaneously steam-exploded straw product includes: pre-degrading the straw raw material and then subjecting it to instantaneous steam explosion to obtain the instantaneously steam-exploded straw product; preferably, the pressure of the instantaneous steam explosion is 0.5-1.2 MPa; preferably, the time of the instantaneous steam explosion is 0.5-10 min; preferably, the straw raw material is selected from at least one of the following: rice straw, rapeseed straw, wheat straw, corn straw, corn cob, bagasse, or sugarcane leaves; preferably, the length of the straw raw material is 1-30 cm.

[0038] To further efficiently achieve instantaneous steam explosion, the cellulose, hemicellulose, and lignin in the Platycodon grandiflorus raw material are pretreated. In a preferred embodiment, the pre-degradation includes: soaking or spraying the straw raw material with water, an acid solution with a mass concentration of 1-10%, or an alkaline solution with a mass concentration of 1-10%. Preferably, the pre-degradation time is 10-60 minutes.

[0039] Any method capable of continuously steam-exploding the raw material of Platycodon grandiflorus is applicable to this application. To further improve the efficiency of continuous steam explosion, in a preferred embodiment, the method for preparing the continuously steam-exploded straw product includes: pre-degrading the straw raw material and then subjecting it to continuous steam explosion to obtain the continuously steam-exploded straw product; preferably, the temperature of the continuous steam explosion is 150-220℃; preferably, the pressure of the continuous steam explosion is 0.5-1.2 MPa; preferably, the time of the continuous steam explosion is 5-40 min; preferably, the straw raw material is selected from at least one of the following: rice straw, rapeseed straw, wheat straw, corn straw, corn cob, bagasse, or sugarcane leaves; preferably, the length of the straw raw material is 1-10 cm.

[0040] To further efficiently complete continuous steam explosion, the cellulose, hemicellulose and lignin in the Platycodon grandiflorus raw material are pretreated. In a preferred embodiment, the pre-degradation includes: soaking or spraying the straw raw material with water, an acid solution with a mass concentration of 1-10% or an alkaline solution with a mass concentration of 1-10%; preferably, the pre-degradation time is 10-60 minutes.

[0041] To obtain yeast with good activity, in a preferred embodiment, the yeast is the product obtained by inoculating it in a sucrose medium and culturing it. Any yeast suitable for this application is applicable. In a preferred embodiment, the yeast is selected from one or more of the following: *Saccharomyces cerevisiae*, *Kluyveromyces martensii*, or *Candida utilis*. It should be noted that *Saccharomyces cerevisiae*, *Kluyveromyces martensii*, and *Candida utilis* mentioned in this application are all commercially available products or existing publicly disclosed strains. Preferably, the pH value for yeast culture is 4.8-5.0; preferably, the temperature for yeast culture is 30-35°C; preferably, the culture time is 1-2 days.

[0042] To efficiently prepare bio-fermented feed, in a preferred embodiment, the humidity of the bio-fermented feed culture medium is 40-70%; preferably, the mass ratio of mold inoculation amount to bio-fermented feed culture medium is 3-5%; preferably, the volume-mass ratio of yeast inoculation amount to the first fermentation product is 1-5%.

[0043] To further improve the efficiency of the first and second fermentation, in a preferred embodiment, the first fermentation time is 24-48 hours; preferably, the temperature of the first fermentation is 25-35°C; preferably, the second fermentation time is 3-7 days; preferably, the temperature of the second fermentation is 25-35°C.

[0044] To obtain feed that is easy to preserve, it is dried. In a preferred embodiment, the preparation method further includes drying the product after the second fermentation to obtain bio-fermented feed; preferably, the drying temperature is 50-60°C.

[0045] In a second typical embodiment of this application, a bio-fermented feed prepared using the above-described preparation method is provided, wherein the crude protein content of the bio-fermented feed is >26%. In a preferred embodiment, the amino acid content of the bio-fermented feed is >21%. Because the culture medium for preparing the feed in the above method contains instantaneously vapor-exploded and continuously vapor-exploded bellflower products mixed in a specific ratio, the cellulose, hemicellulose, and lignin in the bellflower are more easily utilized to obtain a feed with higher protein content.

[0046] In a third typical embodiment of this application, an application of the bio-fermented feed prepared using the above-described method in animal husbandry is provided. This application, while obtaining feed with high protein content, also achieves effective utilization of Platycodon grandiflorus.

[0047] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0048] The sucrose culture medium used in the embodiments of this application consists of 10% sucrose, 2% yeast extract, 0.1% potassium dihydrogen phosphate, 0.1% magnesium sulfate, and the remainder is water, with a pH of 5.0.

[0049] The Aspergillus niger strain used in the embodiments and comparative examples of this application was selected from: Aspergillus niger strain Q270-C6, accession number: CCTCC NO:M 20231261, and Aspergillus niger strain ESP1023, accession number: CCTCC NO:M 2018829.

[0050] The Aspergillus oryzae strain used in the embodiments and comparative examples of this application is selected from Aspergillus oryzae C1, accession number: CCTCC NO:M 20231260.

[0051] The Candida utilis used in the embodiments and comparative examples of this application is selected from Candida C1.7, classified as Wickerhamomyces anomalus, with accession number CCTCC NO:M 2017782.

[0052] The brewing yeasts used in the embodiments and comparative examples of this application are selected from: Saccharomyces cerevisiae Hansen Z2.2, with accession number CCTCC NO:M205128; Saccharomyces cerevisiae FX-2, with accession number CCTCC NO:M2016418; and Saccharomyces cerevisiae Hansen Z2.4, with accession number CCTCC NO:M205130.

[0053] The Kluyveromyces marxianus used in the embodiments and comparative examples of this application are selected from: Kluyveromyces KW-6, accession number CCTCC NO:M 2020173; and Kluyveromyces marxianus AMCC 30634, accession number CCTCC NO:M 2023217.

[0054] The patent document numbers cited for the strains with the specific accession numbers mentioned above are shown in Table 1 below:

[0055]

[0056] Table 2. Raw materials used in the embodiments and comparative examples of this application.

[0057]

[0058]

[0059] Example 1

[0060] I. Different steam explosion treatments for straw

[0061] 1. Cut rice straw into 10cm segments, soak the cut rice straw in a 5% acid solution for 20 minutes to complete the pretreatment, add the pretreated rice straw into a continuous steam explosion device, steam at 150℃ and 0.5Mpa for 40 minutes, and then quickly depressurize to obtain the continuous steam explosion straw product.

[0062] 2. Cut the rice straw into 30cm segments, soak the cut rice straw in a 5% acid solution for 20 minutes to complete the pretreatment, add the pretreated rice straw to an instantaneous steam explosion device, maintain at 0.5 MPa for 10 minutes, and quickly detonate to obtain instantaneous steam explosion straw products.

[0063] II. Microbial Culture

[0064] 1. Yeast seed culture: Take the preserved brewer's yeast and inoculate it into sucrose medium for yeast culture. The pH value is 4.8 and the temperature is 30℃. Culture for 1 day.

[0065] 2. Mold seed culture:

[0066] Preparation of mold seed culture medium: The main materials consist of 30% instantaneously detonated straw products and 70% continuously detonated straw products, with urea as the nitrogen source, supplemented by 1% nitrogen source, 1% potassium dihydrogen phosphate, and 1% magnesium sulfate. These are mixed evenly in proportion, and distilled water is added to adjust the humidity to 70%. The proportions of nitrogen source, potassium dihydrogen phosphate, and magnesium sulfate added are based on the total mass of the instantaneously detonated and continuously detonated straw products.

[0067] Mold inoculation: Prepare Aspergillus niger spore solution (spore concentration of 10). 6 The inoculum (CFU / mL) was inoculated into the mold seed culture medium at an inoculum size of 5% (V / W) and cultured at 25°C for 2 days.

[0068] III. Preparation of Bio-fermented Feed

[0069] Preparation of bio-fermented feed culture medium: The straw product portion of the culture medium consists of 40% instantaneously steam-exploded straw products and 60% continuously steam-exploded straw products. Urea is used as the nitrogen source, with the addition of 3.5% nitrogen source, 0.5% potassium dihydrogen phosphate, and 0.5% magnesium sulfate. These are mixed thoroughly in the specified proportions, and distilled water is added to adjust the humidity to 70%. The proportions of nitrogen source, potassium dihydrogen phosphate, and magnesium sulfate are based on the total mass of the instantaneously and continuously steam-exploded straw products.

[0070] Microbial inoculation: The Aspergillus niger obtained from the above-mentioned mold seed culture was inoculated into the bio-fermented feed culture medium at an inoculation amount of 5% (W / W) for the first fermentation at 35℃ for 24 hours. Then, the Saccharomyces cerevisiae obtained from the above-mentioned yeast seed culture was inoculated at an inoculation amount of 5% (V / W) for the second fermentation at 35℃ for 7 days. After the second fermentation was completed, the feed was dried at 60℃ to obtain the bio-fermented feed.

[0071] Example 2

[0072] I. Different steam explosion treatments for straw

[0073] 1. Cut wheat straw into 1cm pieces, soak the cut wheat straw in water for 10 minutes to complete the pretreatment, add the pretreated wheat straw into a continuous steam explosion device, steam at 180℃ and 0.8Mpa for 10 minutes, and then quickly release the pressure to obtain the continuous steam explosion straw product.

[0074] 2. Cut the wheat straw into 1cm pieces, soak the cut wheat straw in water for 10 minutes to complete the pretreatment, add the pretreated wheat straw to the instantaneous steam explosion equipment, 0.8Mpa, maintain for 5 minutes, and quickly detonate to obtain instantaneous steam explosion straw products.

[0075] II. Microbial Culture

[0076] 1. Yeast seed culture: Take the preserved Kluyveromyces macrocarpa and inoculate it into sucrose medium for yeast culture. The pH value is 4.9 and the temperature is 35℃. The culture time is 2 days.

[0077] 2. Mold seed culture:

[0078] Preparation of mold seed culture medium: The main materials consist of 60% instantaneously detonated straw products and 40% continuously detonated straw products. Ammonium sulfate is used as the nitrogen source, supplemented with 2% nitrogen source, 0.1% potassium dihydrogen phosphate, and 0.1% magnesium sulfate. The mixture is thoroughly mixed in the specified proportions, and distilled water is added to adjust the humidity to 50%. The proportions of nitrogen source, potassium dihydrogen phosphate, and magnesium sulfate are based on the total mass of the instantaneously detonated and continuously detonated straw products.

[0079] Mold inoculation: Prepare Aspergillus niger spore solution (spore concentration of 10). 6 The inoculum (CFU / mL) was inoculated into the mold seed culture medium at an inoculum size of 3% (V / W) and cultured at 28°C for 2.5 days.

[0080] III. Preparation of Bio-fermented Feed

[0081] Preparation of bio-fermented feed culture medium: The straw product portion of the culture medium consists of 70% instantaneously steam-exploded straw products and 30% continuously steam-exploded straw products. Ammonium sulfate is used as the nitrogen source, supplemented with 4% nitrogen source, 0.1% potassium dihydrogen phosphate, and 0.1% magnesium sulfate. These are mixed evenly in proportion, and distilled water is added to adjust the humidity to 50%. The proportions of nitrogen source, potassium dihydrogen phosphate, and magnesium sulfate added are based on the total mass of the instantaneously and continuously steam-exploded straw products.

[0082] Microbial inoculation: The Aspergillus niger obtained from the above-mentioned mold seed culture was inoculated into the bio-fermented feed culture medium at an inoculation amount of 3% (W / W) for the first fermentation at 25°C for 48 hours. Then, the Kluyveromyces macrocarpa obtained from the above-mentioned yeast seed culture was inoculated at an inoculation amount of 1% (V / W) for the second fermentation at 25°C for 5 days. After the second fermentation was completed, the feed was dried at 55°C to obtain the bio-fermented feed.

[0083] Example 3

[0084] I. Different steam explosion treatments for straw

[0085] 1. Cut the corn cobs into 5cm particles, soak the cut corn cobs in a 5% alkaline solution for 60 minutes to complete the pretreatment, add the pretreated corn cobs into a continuous steam explosion device, steam at 220℃ and 1.2 MPa for 5 minutes, and then quickly release the pressure to obtain the continuous steam explosion straw product.

[0086] 2. Cut the corn cobs into 5cm particles, soak the cut corn cobs in a 5% alkaline solution for 60 minutes to complete the pretreatment, add the pretreated corn cobs to an instantaneous steam explosion device, apply 1.2 MPa for 0.5 minutes, and quickly detonate to obtain instantaneous steam-exploded straw products.

[0087] II. Microbial Culture

[0088] 1. Yeast seed culture: Take the preserved Candida utilis and inoculate it into sucrose medium for yeast culture. The pH value is 5.0 and the temperature is 30℃. The culture time is 1 day.

[0089] 2. Mold seed culture:

[0090] Preparation of mold seed culture medium: The main materials consist of 50% instantaneously detonated straw products and 50% continuously detonated straw products, with ammonium phosphate as the nitrogen source, supplemented with 3% nitrogen source, 0.5% potassium dihydrogen phosphate, and 0.5% magnesium sulfate. These are mixed thoroughly in the specified proportions, and distilled water is added to adjust the humidity to 40%. The proportions of nitrogen source, potassium dihydrogen phosphate, and magnesium sulfate added are based on the total mass of the instantaneously detonated and continuously detonated straw products.

[0091] Mold inoculation: Prepare Aspergillus oryzae spore solution (spore concentration of 10). 7 The inoculum (CFU / mL) was inoculated into the mold seed culture medium at an inoculation amount of 1% (V / W) and cultured at 35°C for 2 days.

[0092] III. Preparation of Bio-fermented Feed

[0093] The culture medium for bio-fermented feed consisted of 50% instantaneously steam-exploded straw products and 50% continuously steam-exploded straw products as the straw product portion. Ammonium phosphate was used as the nitrogen source, supplemented with 5% nitrogen source, 1% potassium dihydrogen phosphate, and 1% magnesium sulfate. These were mixed evenly in proportion, and distilled water was added to adjust the humidity to 40%. The proportions of nitrogen source, potassium dihydrogen phosphate, and magnesium sulfate added were based on the total mass of the instantaneously and continuously steam-exploded straw products.

[0094] Microbial inoculation: Aspergillus oryzae obtained from the above-mentioned mold seed culture was inoculated into the bio-fermented feed culture medium at an inoculation amount of 4% (W / W) for the first fermentation at 30°C for 36 hours. Then, Candida utilis obtained from the above-mentioned yeast seed culture was inoculated at an inoculation amount of 3% (V / W) for the second fermentation at 30°C for 3 days. After the second fermentation was completed, the feed was dried at 50°C to obtain the bio-fermented feed.

[0095] Example 4

[0096] Except for "I. Different steam explosion treatments of straw" which differs from Example 1, all other steps are the same as in Example 1. The "I. Different steam explosion treatments of straw" in this comparative example is as follows:

[0097] 1. Cut rice straw into 10cm segments and soak the cut rice straw in a 5% acid solution for 20 minutes to complete the pretreatment. Add the pretreated rice straw into a continuous steam explosion device and steam it at 140℃ and 0.3MPa for 50 minutes. Then, quickly release the pressure to obtain the continuous steam explosion straw product.

[0098] 2. Cut the rice straw into 10cm segments, soak the cut rice straw in a 5% acid solution for 20 minutes to complete the pretreatment, add the pretreated rice straw to an instantaneous steam explosion device, maintain at 0.3 MPa for 2 minutes, and quickly detonate to obtain instantaneous steam explosion straw products.

[0099] Comparative Example 1

[0100] Except for "III. Preparation of Bio-fermented Feed," which differs from Example 1, all other steps are the same as in Example 1. The "III. Preparation of Bio-fermented Feed" in this comparative example is as follows:

[0101] Preparation of bio-fermented feed culture medium: The straw product portion of the culture medium consists of 80% instantaneously steam-exploded straw products and 20% continuously steam-exploded straw products. Urea is used as the nitrogen source, supplemented with 3.5% nitrogen source, 2% potassium dihydrogen phosphate, and 2% magnesium sulfate. These are mixed evenly in proportion, and distilled water is added to adjust the humidity to 70%. The proportions of nitrogen source, potassium dihydrogen phosphate, and magnesium sulfate added are based on the total mass of the instantaneously and continuously steam-exploded straw products.

[0102] Microbial inoculation: The Aspergillus niger obtained from the above-mentioned mold seed culture was inoculated into the bio-fermented feed culture medium at an inoculation amount of 5% (W / W) for the first fermentation at 35℃ for 24 hours. Then, the Saccharomyces cerevisiae obtained from the above-mentioned yeast seed culture was inoculated at an inoculation amount of 5% (V / W) for the second fermentation at 35℃ for 7 days. After the second fermentation was completed, the feed was dried at 60℃ to obtain the bio-fermented feed.

[0103] Comparative Example 2

[0104] In this comparative example, only straw raw materials were subjected to continuous steam explosion, and the culture medium used contained only the continuously steam-exploded straw products as a carbon source. The specific steps are as follows:

[0105] 1. Continuous steam explosion treatment of straw

[0106] 1. Cut rice straw into 10cm segments, soak the cut rice straw in a 5% acid solution for 20 minutes to complete the pretreatment, add the pretreated rice straw into a continuous steam explosion device, steam at 150℃ and 0.5Mpa for 40 minutes, and then quickly depressurize to obtain the continuous steam explosion straw product.

[0107] II. Microbial Culture

[0108] 1. Yeast seed culture: Take the preserved brewer's yeast and inoculate it into sucrose medium for yeast culture. The pH value is 4.8 and the temperature is 30℃. Culture for 1 day.

[0109] 2. Mold seed culture:

[0110] Preparation of mold seed culture medium: 100% of continuously steam-exploded straw products were used as the main material, with urea as the nitrogen source, supplemented with 1% nitrogen source, 1% potassium dihydrogen phosphate, and 1% magnesium sulfate. The mixture was thoroughly mixed in proportion, and distilled water was added to adjust the humidity to 70%. The proportions of nitrogen source, potassium dihydrogen phosphate, and magnesium sulfate added were based on the total mass of both instantaneously and continuously steam-exploded straw products.

[0111] Mold inoculation: Prepare Aspergillus niger spore solution (spore concentration of 10). 6 The inoculum (CFU / mL) was inoculated into the mold seed culture medium at an inoculum size of 5% (V / W) and cultured at 25°C for 2 days.

[0112] III. Preparation of Bio-fermented Feed

[0113] Preparation of bio-fermented feed culture medium: The culture medium consists of 100% continuously steam-exploded straw products, with urea as the nitrogen source, supplemented with 3.5% nitrogen source, 0.5% potassium dihydrogen phosphate, and 0.5% magnesium sulfate. These are mixed thoroughly in the specified proportions, and distilled water is added to adjust the humidity to 70%. The proportions of nitrogen source, potassium dihydrogen phosphate, and magnesium sulfate added are based on the total mass of both instantaneously and continuously steam-exploded straw products.

[0114] Microbial inoculation: The Aspergillus niger obtained from the above-mentioned mold seed culture was inoculated into the bio-fermented feed culture medium at an inoculation amount of 5% (W / W) for the first fermentation at 35℃ for 24 hours. Then, the Saccharomyces cerevisiae obtained from the above-mentioned yeast seed culture was inoculated at an inoculation amount of 5% (V / W) for the second fermentation at 35℃ for 7 days. After the second fermentation was completed, the feed was dried at 60℃ to obtain the bio-fermented feed.

[0115] Comparative Example 3

[0116] In this comparative example, only the straw raw material underwent instantaneous steam explosion, and the culture medium used contained only the instantaneous steam explosion straw products as a carbon source. The specific steps are as follows:

[0117] I. Instantaneous steam explosion treatment of straw

[0118] 1. Cut rice straw into 10cm segments, soak the cut rice straw in a 5% acid solution for 20 minutes to complete the pretreatment, add the pretreated rice straw to an instantaneous steam explosion device, maintain at 0.5 MPa for 10 minutes, and quickly detonate to obtain instantaneous steam explosion straw products.

[0119] II. Microbial Culture

[0120] 1. Yeast seed culture: Take the preserved brewer's yeast and inoculate it into sucrose medium for yeast culture. The pH value is 4.8 and the temperature is 30℃. Culture for 1 day.

[0121] 2. Mold seed culture:

[0122] Preparation of mold seed culture medium: 100% of the instantaneously steam-exploded straw products were used as the main material, with urea as the nitrogen source, supplemented with 1% nitrogen source, 1% potassium dihydrogen phosphate, and 1% magnesium sulfate. The mixture was thoroughly mixed in proportion, and distilled water was added to adjust the humidity to 70%. The proportions of nitrogen source, potassium dihydrogen phosphate, and magnesium sulfate added were based on the total mass of the instantaneously and continuously steam-exploded straw products.

[0123] Mold inoculation: Prepare Aspergillus niger spore solution (spore concentration of 10). 6 The inoculum (CFU / mL) was inoculated into the mold seed culture medium at an inoculum size of 5% (V / W) and cultured at 25°C for 2 days.

[0124] III. Preparation of Bio-fermented Feed

[0125] Preparation of bio-fermented feed culture medium: The culture medium consists of 100% instantaneously steam-exploded straw products, with urea as the nitrogen source, supplemented with 3.5% nitrogen source, 0.5% potassium dihydrogen phosphate, and 0.5% magnesium sulfate. These are mixed thoroughly in the specified proportions, and distilled water is added to adjust the humidity to 70%. The proportions of nitrogen source, potassium dihydrogen phosphate, and magnesium sulfate added are based on the total mass of both instantaneously and continuously steam-exploded straw products.

[0126] Microbial inoculation: The Aspergillus niger obtained from the above-mentioned mold seed culture was inoculated into the bio-fermented feed culture medium at an inoculation amount of 5% (W / W) for the first fermentation at 35℃ for 24 hours. Then, the Saccharomyces cerevisiae obtained from the above-mentioned yeast seed culture was inoculated at an inoculation amount of 5% (V / W) for the second fermentation at 35℃ for 7 days. After the second fermentation was completed, the feed was dried at 60℃ to obtain the bio-fermented feed.

[0127] Comparative Example 4

[0128] In this comparative example, the straw raw material was not treated and was directly added to the culture medium for use as a carbon source. The specific steps are as follows:

[0129] Preparation of bio-fermented feed

[0130] Preparation of bio-fermented feed culture medium: 100% rice straw was used as the straw product portion of the culture medium, with urea as the nitrogen source, supplemented with 3.5% nitrogen source, 0.5% potassium dihydrogen phosphate, and 0.5% magnesium sulfate. The mixture was thoroughly mixed in proportion, and distilled water was added to adjust the humidity to 70%. The proportions of nitrogen source, potassium dihydrogen phosphate, and magnesium sulfate were based on the total mass of the straw products from both instantaneous and continuous steam explosions.

[0131] Microbial inoculation: The preserved Aspergillus niger was inoculated into the bio-fermented feed culture medium at an inoculation amount of 5% (W / W) for the first fermentation at 35℃ for 24 hours. Then, the preserved Saccharomyces cerevisiae was inoculated at an inoculation amount of 5% (V / W) for the second fermentation at 35℃ for 7 days. After the second fermentation was completed, the feed was dried at 60℃ to obtain the bio-fermented feed.

[0132] Testing experiment:

[0133] 1. Detect the products obtained from different steam explosion treatments of straw.

[0134] Using the NY-T3494-2019 method to treat untreated rice straw (such as...) Figure 1 The cellulose, hemicellulose, and lignin of the products obtained from Comparative Examples 2 and 3 (as shown) were tested, and the reducing sugar content in the samples was determined using the GB 5009.7-2016 method.

[0135] The results are shown in Table 3. In Comparative Example 3, after instantaneous steam explosion pretreatment, cellulose and hemicellulose were partially degraded, generating monosaccharides. The reducing sugar content reached 1.7% after instantaneous steam explosion treatment. Figure 2 As shown, instantaneous steam explosion treatment does not change the straw.

[0136] Appearance and shape of the raw materials. The product of Comparative Example 2, after continuous steam explosion treatment, showed partial degradation of cellulose and most degradation of hemicellulose, producing monosaccharides. After continuous steam explosion treatment, its reducing sugar content reached 12.1%. Figure 3 As shown, the straw raw material treated with continuous steam explosion becomes smaller in shape and finer in particle size.

[0137] Table 3. Physicochemical properties of straw obtained from different steam explosion treatments.

[0138] Unprocessed 36 17 24 0.1 Comparative Example 2 35.3 2.5 26.7 12.1 Comparative Example 3 35.5 15.5 24.1 1.7

[0139] 2. The bio-fermented feeds obtained from different embodiments and comparative treatments were tested.

[0140] The crude protein content in bio-fermented feed was determined using the GB / T 6432-2018 method, the amino acid content in bio-fermented feed was determined using the GB / T 18246-2019 method, the cellulase activity of samples from bio-fermented feed prepared in different examples and comparative examples after the second fermentation was determined using the NY / T 912-2020 method, and the xylanase activity of samples from bio-fermented feed prepared in different examples and comparative examples after the second fermentation was determined using the GB / T23874-2009 method.

[0141] Table 4. Physicochemical properties of bio-fermented feed from different embodiments and comparative examples.

[0142]

[0143]

[0144] The bio-fermented feed prepared in Comparative Example 4 failed to utilize the tightly bound cellulose, hemicellulose, and lignin structures in the straw raw material, making it difficult for microorganisms to operate. Even with mixed fermentation using Aspergillus niger and Saccharomyces cerevisiae, the microorganisms struggled to utilize the cellulose and hemicellulose in the straw, hindering their growth and reproduction, leading to fermentation failure. The resulting bio-fermented feed exhibited low cellulase and xylanase activities, with a crude protein content of 21.84% and an amino acid content of 1.36%. This indicates that the bio-fermented feed prepared using the method in Comparative Example 4 suffers from microbial instability and fermentation failure, resulting in low microbial protein content and low nutritional value in the post-fermentation sample.

[0145] The bio-fermented feed prepared in Comparative Example 3 used only the straw raw material after instantaneous steam explosion as the substrate for the culture medium. Due to its low reducing sugar content, it was insufficient to provide the nutrients required for the early growth of microorganisms. In addition, the straw raw material after instantaneous steam explosion had a large size and porosity, resulting in a small unit surface area for microbial growth, which affected the mass transfer of nutrients required by microorganisms. Furthermore, water was easily lost during the fermentation process, reducing the efficiency of mixed solid-state fermentation and affecting the growth and reproduction of microorganisms. After fermentation, the bio-fermented feed had low levels of cellulase and xylanase, with a crude protein content of 22.01% and an amino acid content of 2.05%. This indicates that using only the straw raw material after instantaneous steam explosion as the substrate for the culture medium for bio-fermented feed made it difficult for microorganisms to reproduce and grow, leading to fermentation failure. After fermentation, the sample had low microbial protein content and low nutritional value.

[0146] The bio-fermented feed prepared in Comparative Example 2 used only the straw raw material after continuous steam explosion as the substrate for the culture medium. Due to the small particle size and low porosity of the continuously steam-exploded straw raw material, it was prone to clumping and sandwiching, which adversely affected heat and mass transfer, hindered the respiration and ventilation of microorganisms, and ultimately led to the failure of bio-fermentation. The bio-fermented feed obtained after fermentation had low levels of cellulase and xylanase, with a crude protein content of 21.93% and an amino acid content of 3.14%. This indicates that the bio-fermented feed prepared using Comparative Example 2 had low microbial protein content and low nutritional value.

[0147] The bio-fermented feed prepared in Comparative Example 1 had a different ratio of continuously steam-exploded straw products and instantaneously steam-exploded straw products in its culture medium compared to the example. Consequently, the mixing effect of the two was poor, resulting in a poor nutritional and structural environment for microbial fermentation, which affected the growth and reproduction of microorganisms. After fermentation, the bio-fermented feed had low levels of cellulase and xylanase, a crude protein content of 22.05%, and an amino acid content of 4.24%. This indicates that the bio-fermented feed prepared using Comparative Example 1 had low microbial protein content and low nutritional value.

[0148] The bio-fermented feed prepared in Example 4 had a poor effect on the straw raw material due to the different specific parameter values ​​for continuous and instantaneous steam explosion compared to this application. Microorganisms had difficulty utilizing the cellulose and hemicellulose in the straw raw material, which affected the growth and reproduction of microorganisms and led to fermentation failure. The bio-fermented feed obtained after fermentation had low levels of cellulase and xylanase, with a crude protein content of 23.07% and an amino acid content of 4.34%. This indicates that the bio-fermented feed prepared using Example 4 has low microbial protein content and low nutritional value.

[0149] The bio-fermented feeds prepared in Examples 1-3 were processed using both instantaneous steam explosion and continuous steam explosion techniques on Platycodon grandiflorus raw materials. The Platycodon grandiflorus products from these two different treatments were used as components of the bio-fermented feed culture medium in a specific ratio. Instantaneous steam explosion of the Platycodon grandiflorus raw materials provided sufficient spatial structure and pores to the culture medium, reducing the risk of agglomeration and core formation in solid-state fermentation substrates, and facilitating aeration and heat transfer. Continuous steam explosion treatment of the Platycodon grandiflorus raw materials resulted in higher reducing sugar content, smaller particle size, and lower porosity, providing the necessary nutrients for early microbial growth and reproduction. Furthermore, the larger specific surface area facilitated nutrient mass transfer and the secretion of cellulase by enzyme-producing microorganisms, as well as yeast growth. After fermentation, the feed had a crude protein content greater than 26%, an amino acid content greater than 21%, a cellulase activity reaching a maximum of 153 U / g, and a xylanase activity reaching a maximum of 26 U / g, indicating that the bio-fermented feeds prepared using Examples 1-3 had high microbial protein content and high nutritional value.

[0150] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects: by utilizing instantaneous steam explosion and continuous steam explosion technologies respectively, the dense cellulose, hemicellulose, and lignin in straw raw materials are separated, and some of the cellulose and hemicellulose are degraded into monosaccharides. Furthermore, by configuring the substances obtained from the two different steam explosion treatment methods in a certain proportion into a culture medium, which serves as nutrients in the culture medium for bio-fermented feed, it is more conducive to the growth and fermentation of microorganisms inoculated therein. It also effectively adjusts the spatial structure and pores of the particles in the culture medium, reducing clumping or sandwiching of the particle raw materials, and facilitating aeration and heat transfer. The prepared bio-fermented feed has a crude protein content greater than 26% and an amino acid content greater than 21%.

[0151] The preparation method of this application is applicable to a wide range of straw sources, utilizing straw resources from major agricultural by-products in different regions of China, thereby reducing the environmental pollution caused by straw-based agricultural waste. Furthermore, the bio-fermented feed cultivation process of this application does not require the addition of any exogenous carbon source; it uses only continuously steam-exploded and instantaneously steam-exploded straw raw materials as a solid substrate, undergoing solid-state fermentation with microorganisms to convert straw into high-quality protein raw materials, thus alleviating the shortage of protein feed resources.

[0152] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a bio-fermented feed, characterized in that, The preparation method includes: The mold was inoculated into the bio-fermented feed culture medium and subjected to the first fermentation to obtain the first fermentation product. After the first fermentation, yeast is inoculated into the first fermentation product to carry out a second fermentation, thereby obtaining the bio-fermented feed. The bio-fermented feed culture medium includes: straw products and supplementary feed; The straw products, by mass content, include: 40%-70% instantaneous steam-explosion straw products and 30%-60% continuous steam-explosion straw products; The supplementary materials include: a nitrogen source, potassium dihydrogen phosphate, and magnesium sulfate; The amount of nitrogen source added, by mass content, is 3.5-5% of the total mass of the straw product; the amount of potassium dihydrogen phosphate added is 0.1%-1% of the total mass of the straw product; and the amount of magnesium sulfate added is 0.1-1% of the total mass of the straw product. The method for preparing the instantaneous steam explosion straw product includes: After pre-degradation, the straw raw material is subjected to instantaneous steam explosion to obtain the instantaneous steam explosion straw product. The method for preparing the continuously steam-exploded straw product includes: After pre-degradation, the straw raw material is subjected to continuous steam explosion to obtain the continuous steam-exploded straw product. The pre-degradation includes: soaking or spraying the straw raw material with water, an acid solution with a mass concentration of 1-10%, or an alkaline solution with a mass concentration of 1-10%. The pressure of the instantaneous steam explosion is 0.5-1.2 MPa; The instantaneous steam explosion time is 0.5-10 minutes; The temperature of the continuous steam explosion is 150-220℃; The pressure of the continuous steam explosion is 0.5-1.2 MPa; The duration of the continuous steam explosion is 5-40 minutes.

2. The preparation method according to claim 1, characterized in that, The mold is a product obtained by inoculating mold spore liquid into a mold seed culture medium and then culturing the mold. The mold seed culture medium includes: main material and auxiliary material; Based on mass content, the main material includes: 30%-60% of the instantaneous steam-exploded straw product and 40%-70% of the continuous steam-exploded straw product as substrate; The excipients include: the nitrogen source, the potassium dihydrogen phosphate, and the magnesium sulfate; The amount of nitrogen source added is 1-3% of the total mass of the straw product, based on mass content; the amount of potassium dihydrogen phosphate added is 0.1%-1% of the total mass of the straw product; and the amount of magnesium sulfate added is 0.1%-1% of the total mass of the straw product.

3. The preparation method according to claim 2, characterized in that, The nitrogen source in the bio-fermented feed culture medium and the mold seed culture medium is independently selected from one or more of the following: urea, ammonium sulfate or ammonium phosphate.

4. The preparation method according to claim 2, characterized in that, The humidity of the mold seed culture medium is 40-70%.

5. The preparation method according to claim 2, characterized in that, The mold is selected from one or more of the following: Aspergillus niger or Aspergillus oryzae.

6. The preparation method according to claim 2, characterized in that, The spore concentration in the mold spore solution is 1×10⁻⁶. 6 -10 7 CFU / mL.

7. The preparation method according to claim 2, characterized in that, The volume-to-mass ratio of the inoculum of the mold spore solution to the mold seed culture medium is 1-5%.

8. The preparation method according to claim 2, characterized in that, The mold culture time is 2-2.5 days.

9. The preparation method according to claim 2, characterized in that, The temperature for mold culture is 25-35℃.

10. The preparation method according to claim 1, characterized in that, The straw raw material is selected from at least one of the following: rice straw, rapeseed straw, wheat straw, corn straw, bagasse or sugarcane leaves.

11. The preparation method according to claim 1, characterized in that, The length of the straw raw material is 1-30cm.

12. The preparation method according to claim 1, characterized in that, The pre-degradation time is 10-60 min.

13. The preparation method according to claim 1, characterized in that, The length of the straw raw material is 1-10cm.

14. The preparation method according to claim 1, characterized in that, The yeast is a product obtained by inoculating yeast in a sucrose medium and then culturing it.

15. The preparation method according to claim 14, characterized in that, The yeast strain is selected from one or more of the following: Saccharomyces cerevisiae, Kluyveromyces martensii, or Candida utilis.

16. The preparation method according to claim 14, characterized in that, The pH value of the yeast culture is 4.8-5.

0.

17. The preparation method according to claim 14, characterized in that, The yeast was cultured at a temperature of 30-32℃.

18. The preparation method according to claim 14, characterized in that, The yeast is cultured for 1-2 days.

19. The preparation method according to claim 1, characterized in that, The humidity of the bio-fermented feed culture medium is 40-70%.

20. The preparation method according to claim 19, characterized in that, The inoculation amount of the mold is 3-5% of the mass of the bio-fermented feed culture medium.

21. The preparation method according to claim 20, characterized in that, The inoculation amount of the yeast is 1-5% of the volume mass of the first fermentation product.

22. The preparation method according to claim 1, characterized in that, The first fermentation time is 24h-48h.

23. The preparation method according to claim 22, characterized in that, The temperature of the first fermentation is 25-35℃.

24. The preparation method according to claim 22, characterized in that, The second fermentation period is 3-7 days.

25. The preparation method according to claim 22, characterized in that, The temperature for the second fermentation is 25-35℃.

26. The preparation method according to claim 1, characterized in that, The preparation method further includes drying the product after the second fermentation to obtain the bio-fermented feed.

27. The preparation method according to claim 26, characterized in that, The drying temperature is 50-60℃.

28. The application of bio-fermented feed prepared by any one of claims 1-27 in animal husbandry.

Images