A method for synergic bioconversion of feedstock by cooking, expansion, coupling of enzymatic hydrolysis and fermentation

Abstract

The application discloses a kind of feed raw materials of cooking expansion coupled enzymatic fermentation synergistic bioconversion methods, belong to feed processing technical field.The conversion method includes raw material pretreatment, cooking expansion, enzymolysis, fermentation and post-processing.For three kinds of raw materials of mixed meal, food processing by-products, food leftovers, set up targeted cooking expansion parameters and compound enzyme ratio respectively, and construct the recycling system of heat energy coupling, carbon source coupling, metabolic heat reuse coupling.The method can effectively reduce anti-nutritional factors, increase acid-soluble protein and small peptide content, enrich probiotics, reduce energy consumption, suitable for soybean meal reduction substitution and no-antibiotic breeding.

Description

Technical Field

[0001] This invention relates to the field of feed processing technology, and in particular to a method for the synergistic biotransformation of feed ingredients through steaming, expansion, coupled with enzymatic hydrolysis and fermentation. Background Technology

[0002] With the continued advancement of policies aimed at reducing and replacing soybean meal consumption, the feed processing industry faces three core challenges: livestock and poultry health maintenance, cost reduction and efficiency improvement in livestock farming, and feed raw material supply. Traditional feed processing technologies often employ single processes such as cooking, extrusion, or simple grinding and mixing, which are insufficient to simultaneously address multiple needs, including deep removal of anti-nutritional factors, efficient protein utilization, and resource utilization of low-value raw materials.

[0003] Currently, while heat treatment processes such as steaming and puffing can destroy some anti-nutritional factors to a certain extent, high-temperature treatment easily leads to the loss of heat-sensitive nutrients. Enzymatic hydrolysis can specifically degrade certain anti-nutritional factors, but its ability to break down the complex structure of raw materials is limited. Although fermentation technology can produce beneficial metabolites such as probiotics and organic acids, the fermentation cycle is relatively long. Currently, some technologies are attempting to combine gas explosion (steam explosion) with enzymatic hydrolysis and bio-fermentation for biotransformation. For example, Chinese patent CN104905013A discloses a method of mixing steam-exploded material with fermentation broth and enzyme preparations for enzymatic hydrolysis and bio-fermentation, achieving a series of three processes: "steam explosion + enzymatic hydrolysis + fermentation." Chinese patent CN104904993A similarly discloses a technical solution for steam explosion followed by mixing with mixed broth and enzyme preparations for enzymatic hydrolysis and fermentation. Chinese patent CN105104773A discloses a method for steam-exploded cottonseed meal followed by mixing with mixed broth, molasses, and enzyme preparations for enzymatic hydrolysis and fermentation. However, the aforementioned existing technologies still have the following drawbacks: First, the above process combinations do not achieve closed-loop coupling of matter and energy, resulting in direct loss of sensible heat from steam explosion and metabolic heat from fermentation, leading to low thermal energy utilization and creating a heat dissipation problem for large-scale solid-state fermentation. Second, the reducing sugars and other products generated by enzymatic hydrolysis cannot be supplied to the fermentation process, requiring the addition of external carbon sources such as molasses. Third, the process adaptability is limited; most of the above processes are only suitable for single raw materials such as liquor lees and straw, and have poor applicability to various low-value non-grain raw materials such as miscellaneous meals and food processing by-products.

[0004] Therefore, how to achieve efficient utilization of various non-grain resources for feed through technological innovation, and alleviate the strategic risks to my country's feed grain supply from the source, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a method for the synergistic bioconversion of feed ingredients through steaming, expansion, coupled with enzymatic hydrolysis and fermentation, in order to solve the problems in the prior art.

[0006] To achieve the above objectives, this invention provides a method for the synergistic biotransformation of feed ingredients through steaming, expansion, coupled with enzymatic hydrolysis and fermentation, comprising the following steps: Step S1, Raw material pretreatment: The feed raw materials are crushed and pretreated. The feed raw materials are selected from one or more of the following: miscellaneous oilseed meals, food processing by-products, and food waste. Step S2, Cooking and Expansion Treatment: The material obtained in Step S1 is subjected to cooking and expansion treatment at a temperature of 110-150℃, a pressure of 0.15-0.5MPa, and a treatment time of 5-15min. After the treatment is completed, the pressure is quickly released to atmospheric pressure to make the material expand instantaneously. Step S3, Enzymatic hydrolysis: After cooling the material obtained in step S2 to 30-55℃, add the compound enzyme preparation for enzymatic hydrolysis; the enzymatic hydrolysis pH value is 4.0-7.0, the total amount of compound enzyme preparation added is 0.1-5% of the dry weight of the raw material, and the enzymatic hydrolysis time is 30min-4h; Step S4, Fermentation Treatment: Inoculate the material obtained in Step S3 with a compound microbial strain for fermentation treatment; the inoculation amount is 0.5-10% of the wet weight of the material, the fermentation temperature is 25-45℃, the fermentation time is 12-72h, and the fermentation moisture content is 35-60%; Step S5, Post-processing: The fermented material obtained in step S4 is dried, crushed, and granulated to obtain the bioconverted feed product; Steps S2, S3, and S4 form a coupled and cyclical system, including: Thermal coupling: The sensible heat released by the material after the cooking and expansion treatment in step S2 is recovered and used to preheat the heat preservation medium of the enzymatic hydrolysis process in step S3 and / or the fermentation process in step S4. Carbon source coupling: The concentration of reducing sugar in the enzymatic hydrolysis system in step S3 is detected. When the concentration of reducing sugar is ≥3.0 g / L, a portion of the enzymatic hydrolysate is exported and transferred to the fermentation process in step S4 as a supplementary carbon source. Metabolic heat recovery coupling: The metabolic heat generated in step S4 fermentation is recovered and used to preheat the insulation medium of step S3 enzymatic hydrolysis and / or step S4 fermentation in subsequent production batches.

[0007] Preferably, in step S1, the particle size of the feed raw material is 20-100 mesh, and the moisture content is 25-45%.

[0008] Preferably, in step S1, the mixed meal raw materials are one or more of rapeseed meal, cottonseed meal, palm kernel meal, and peanut meal; the food processing by-products are one or more of distillers' grains, wheat bran, corn husks, and corn germ meal; and the food waste is one or more of fruit pomace and vegetable pomace.

[0009] Preferably, in step S2, the cooking expansion treatment adopts a gradient heating mode, first heating to 70-80% of the target temperature at 5-15℃ / min, holding for 1-3min, then continuing to heat to the target temperature, and then holding for the set time; after the treatment is completed, the pressure is quickly released to atmospheric pressure within 0.5-2s.

[0010] Preferably, in step S2, the processing temperature for miscellaneous meal raw materials is 130-150℃, the pressure is 0.3-0.5MPa, and the processing time is 5-10min; the processing temperature for food processing by-product raw materials is 120-135℃, the pressure is 0.2-0.3MPa, and the processing time is 8-15min; and the processing temperature for food waste raw materials is 110-125℃, the pressure is 0.15-0.25MPa, and the processing time is 10-15min.

[0011] Preferably, a shearing emulsification step is included between step S2 and step S3: the cooked and expanded material is sheared and emulsified at 5000-10000 rpm for 5-30 min to refine the material particles to 10-50 μm.

[0012] Preferably, in step S3, The compound enzyme preparations used for miscellaneous oilseed meals are mainly composed of protease, combined with cellulase and xylanase. Protease accounts for 40-85% of the total mass of the compound enzyme preparation. The compound enzyme preparations used for food processing by-product raw materials include saccharifying enzymes and non-starch polysaccharide enzymes. The non-starch polysaccharide enzymes are selected from at least one of cellulase, β-glucanase, and xylanase. The saccharifying enzymes account for 20-70% of the total mass of the compound enzyme preparation. The compound enzyme preparations used in food by-products are mainly pectinase, combined with cellulase and protease. Pectinase accounts for 30-80% of the total mass of the compound enzyme preparation.

[0013] Preferably, in step S4, the compound microbial strain is selected from one or more of lactic acid bacteria, yeast, Bacillus subtilis, Bacillus licheniformis, Aspergillus niger, Aspergillus oryzae, Trichoderma reesei, and Candida utilis.

[0014] Preferably, in step S5, the drying temperature is 50-65℃, and the material is dried until the moisture content is ≤12%; the particle size is 40-80 mesh.

[0015] Preferably, in a coupled recycling system: Thermal energy coupling and heat recovery account for 10-30% of the total heat input for cooking expansion; In carbon source coupling, the carbon source corresponding to the transferred enzyme hydrolysate accounts for 5-30% of the total carbon source requirement of the fermentation material; The metabolic heat recovery coupling was implemented starting from the second production batch.

[0016] This invention utilizes the instantaneous pressure relief during cooking expansion to disrupt the dense structure of raw materials, thereby fully exposing anti-nutritional factors. A targeted complex enzyme system acts on the anti-nutritional factors and fiber components, releasing fermentable sugars. The anti-nutritional factors are further transformed by fermentation with a complex microbial strain, generating probiotics, organic acids, and other active substances. Simultaneously, the sensible heat of cooking expansion, the carbon source from enzymatic hydrolysis, and the metabolic heat of fermentation are recycled between processes, enhancing the transfer of matter and energy and forming a triple coupling synergistic effect.

[0017] This invention enables the efficient utilization of various low-value raw materials such as miscellaneous meals, food processing by-products, and food scraps for feed production. Anti-nutritional factors are effectively reduced, and the product is rich in acid-soluble proteins, small peptides, and active probiotics, which can support antibiotic-free aquaculture. The coupled utilization of heat energy, carbon source, and metabolic heat helps to reduce energy consumption, improve the stability of continuous production batches, shorten the production cycle, and has strong process adaptability.

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 This is a comparison chart of the content of major anti-nutritional factors before and after treatment of three different raw materials in Examples 1-3 of the present invention; Figure 2 This is a comparison diagram of the effects of triple coupling and single coupling in Embodiment 1 and Comparative Examples 1-3 of the present invention. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims and are all within the protection scope of the present invention.

[0021] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0022] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0023] Unless otherwise specified, the raw materials, reagents, enzyme preparations, strains, etc. used in this invention are all conventional products that can be obtained through commercial channels, and the testing standards all use national or international standards commonly used in this field, which will not be further explained here.

[0024] In this invention, "insulating medium" refers to a heat carrier used to maintain the temperature of the enzymatic hydrolysis process and / or fermentation process, such as circulating water, hot air, heat transfer oil, etc.; "preheating insulating medium" refers to using recovered heat to increase the initial temperature of the above-mentioned heat carrier, thereby reducing the external heating energy consumption required to maintain the process temperature.

[0025] In this invention, the “processing time” in step S2 refers to the heat preservation time after the material reaches the target temperature, excluding the intermediate heat preservation time during the gradient heating process; the intermediate heat preservation during the gradient heating process is to make the material temperature uniform and is part of the heating stage.

[0026] For the main anti-nutritional factors in various raw materials, their contents before and after treatment were determined according to the relevant national or industry standard methods, and the elimination rate of anti-nutritional factors was calculated using the following formula: Factor elimination rate = (content before treatment - content after treatment) / content before treatment × 100%.

[0027] Example 1 This embodiment provides a method for the co-bioconversion of feed ingredients using mixed oilseed meals as the main raw material. The mixed oilseed meals used are a mixture of rapeseed meal and cottonseed meal. This embodiment is a continuous batch production, running for a total of 5 batches, fully implementing heat energy coupling, carbon source coupling, and metabolic heat recovery coupling, specifically including the following steps: Step S1: Raw material pretreatment Rapeseed meal and cottonseed meal were mixed at a mass ratio of 1:1. The mixed raw material had a lignocellulose content of 22% and a crude protein content of 34%. The main anti-nutritional factors were glucosinolates, gossypol, and phytic acid. Glucosinolates were derived from rapeseed meal, gossypol from cottonseed meal, and phytic acid was shared by both. The mixture was then pulverized through a 40-mesh sieve, and the moisture content was adjusted to 30%.

[0028] Step S2, Steaming and Expansion Treatment The pretreated material was fed into a cooking and expansion equipment, with the temperature controlled at 138℃ and the pressure at 0.4MPa. A gradient heating mode was used: first, the temperature was increased to 104℃ (75% of the target temperature) at a rate of 10℃ / min, and held for 2 minutes; then, the temperature was increased to 138℃ at a rate of 10℃ / min, and held at the target temperature for another 7 minutes. After treatment, the pressure was rapidly released within 1 second, causing the material to expand instantaneously. The material temperature after cooking and expansion was 88℃.

[0029] Thermal coupling operation: The sensible heat released from the cooking and expanding material is recovered through a shell-and-tube heat exchanger located at the discharge end of the cooking and expanding equipment, using circulating water as the medium. The hot side of the heat exchanger is connected to the discharge port of the cooking and expanding equipment, while the cold side is a closed-loop circulating water circuit. The recovered heat is transported to the jacketed heating system of the enzymatic hydrolysis tank and the insulation system of the fermentation chamber by a circulating pump. In this embodiment, the recovered heat accounts for 20% of the total input heat, which is used to preheat the circulating water in the enzymatic hydrolysis tank in step S3 from 25°C to 38°C; at the same time, it preheats the insulation circulating water in the fermentation chamber in step S4 from 25°C to 35°C, thereby reducing external steam consumption.

[0030] Step S3, Enzymatic hydrolysis Cool the expanded material after cooking to 45℃. Prepare the compound enzyme preparation: mix alkaline protease, cellulase, and xylanase in a mass ratio of 4:1:1; the alkaline protease activity is 100,000 U / g, the cellulase activity is 10,000 U / g, and the xylanase activity is 50,000 U / g. The total amount of the compound enzyme preparation added is 2.0% of the dry weight of the raw material. Add the compound enzyme preparation to the cooled material, control the enzymatic hydrolysis temperature at 45℃, the enzymatic hydrolysis pH at 5.5, and the enzymatic hydrolysis time at 2 hours. The solid-liquid ratio of the enzymatic hydrolysate is 1:1.5, and the total volume of the hydrolysate is 500L, based on 1000kg of raw material.

[0031] Carbon source coupling operation: After 1.5 hours of enzymatic hydrolysis, a sample was taken via the sampling-exit pipeline on the enzymatic hydrolysis reactor. The online biosensor detected a reducing sugar concentration of 5.2 g / L, meeting the threshold requirement of not less than 3.0 g / L. The outlet pipeline valve was opened, and 20% of the total enzymatic hydrolysate, i.e., 100 L, was introduced into the fermentation material mixer in step S4. After thorough mixing with the fermentation material, it was introduced into the fermentation chamber as a supplementary carbon source. This portion of reducing sugar totaled 520 g, accounting for 17.3% of the total carbon source requirement of the fermentation material.

[0032] Step S4: Fermentation treatment Inoculate the enzymatically hydrolyzed material with a compound microbial strain. The compound microbial strain consists of Bacillus subtilis, Saccharomyces cerevisiae, and lactic acid bacteria in a volume ratio of 1:1:1, and the inoculation amount is 5% of the wet weight of the material. Adjust the moisture content of the material to 50% and ferment it in a solid state at 32℃ for 48 hours.

[0033] Metabolic heat recovery coupled operation: In batches 2 to 5, after 24 hours of fermentation, metabolic heat is recovered through stainless steel heat exchange coils embedded in the fermentation material layer. At this time, the material temperature spontaneously rises to 38℃, a temperature rise of 6℃. The recovered metabolic heat, after passing through a heat exchanger, is used to preheat the jacketed circulating water of the enzymatic hydrolysis tank in step S3 of the next batch, from 25℃ to 35℃; simultaneously, it preheats the insulation circulating water of the fermentation tank in step S4, from 25℃ to 32℃. In batch 1, metabolic heat is not recovered for preheating but is discharged through conventional cooling; the metabolic heat generated in this batch is only used to verify the operational reliability of the heat exchange coils. After step S2, the cooling rate of the material is controlled by an independent conventional cooling water system at 2℃ / min. This cooling system is independent of the metabolic heat recovery system, avoiding the influence of low-grade heat sources on the cooling control of high-temperature materials.

[0034] Step S5, Post-processing The fermentation material was dried at 60°C to a moisture content of 12%, pulverized through a 60-mesh sieve, and then granulated at 50°C to obtain the final product.

[0035] The bioconverted feed product obtained in Example 1 was tested for various indicators. The average value was taken from three repeated experiments, and the test results are shown in Table 1 below. In addition, the content before treatment refers to the initial content after the raw material pretreatment; the content after treatment refers to the content in the product after the post-treatment; "—" indicates that it is not applicable or not measured.

[0036] Table 1: Test results of various indicators of the product obtained in Example 1

[0037] Example 2 This embodiment provides a method for the co-bioconversion of feed ingredients using food processing by-products as the main raw material. The food processing by-products used are a mixture of distillers' grains and wheat bran. This embodiment is a continuous batch production method, running for a total of 5 batches, fully implementing thermal energy coupling, carbon source coupling, and metabolic heat recovery coupling, specifically including the following steps: Step S1: Raw material pretreatment Distillers' grains and wheat bran were mixed at a mass ratio of 2:1. The mixed raw material had a lignocellulose content of 33%, a crude protein content of 18%, and its main anti-nutritional factor was non-starch polysaccharide (NSP), while its secondary anti-nutritional factor was phytic acid. The mixture was then pulverized through a 60-mesh sieve, and the moisture content was adjusted to 35%.

[0038] Step S2, Steaming and Expansion Treatment The pretreated material is fed into a cooking and expansion equipment, with the temperature controlled at 128℃ and the pressure at 0.25MPa. A gradient heating mode is used: first, the temperature is increased to 96℃ (75% of the target temperature) at a rate of 8℃ / min, and held for 2 minutes; then, the temperature is increased to 128℃ at a rate of 8℃ / min, and held at the target temperature for another 12 minutes. After processing, the pressure is rapidly released within 1.5 seconds, causing the material to expand instantaneously.

[0039] The thermal coupling operation is the same as in Example 1, except that the recovered heat accounts for 18% of the total input heat and is used to preheat the circulating water in the enzymatic hydrolysis tank and fermentation chamber.

[0040] Step S3, shearing emulsification treatment The expanded material after cooking was subjected to shear emulsification at a speed of 8000 rpm for 15 minutes. After treatment, the material particles were refined to 30 μm, and the material temperature rose by 3.5℃. This heat was used to reduce the external heating required for the enzymatic hydrolysis process.

[0041] Step S4, Enzymatic hydrolysis Cool the sheared and emulsified material to 40℃. Prepare the compound enzyme preparation: mix saccharifying enzyme, cellulase, and β-glucanase in a mass ratio of 2.5:1.8:1.2; wherein the saccharifying enzyme activity is 100,000 U / g, the cellulase activity is 10,000 U / g, and the β-glucanase activity is 50,000 U / g. The total amount of the compound enzyme preparation added is 1.8% of the dry weight of the raw material. Add the compound enzyme preparation to the cooled material, control the enzymatic hydrolysis temperature at 40℃, the enzymatic hydrolysis pH at 5.0, and the enzymatic hydrolysis time at 3 hours. The solid-liquid ratio of the enzymatic hydrolysate is 1:1.4, and the total volume of the hydrolysate is 450L, based on 1000kg of raw material.

[0042] The carbon source coupling operation is the same as in Example 1, except that when the enzymatic hydrolysis is carried out for 2 hours, the online detection of the reducing sugar concentration is 6.0 g / L, which meets the threshold requirement. 20% of the total amount of enzymatic hydrolysate, i.e., 90 L, is introduced into the fermentation process. The total amount of reducing sugar is 540 g, accounting for 18% of the total carbon source requirement of the fermentation material.

[0043] Step S5: Fermentation treatment Inoculate the enzymatically hydrolyzed material with a compound microbial strain. The compound microbial strain consists of Aspergillus niger, Candida utilis, and lactic acid bacteria in a volume ratio of 1:1:0.5, and the inoculation amount is 4% of the wet weight of the material. Adjust the moisture content of the material to 45% and ferment it in a semi-solid state at 30℃ for 60 hours.

[0044] The metabolic heat recovery coupling operation is the same as in Example 1, and is performed in batches 2 to 5. The recovered metabolic heat is used to preheat the circulating water in the enzymatic hydrolyzer and fermentation tank for the next batch.

[0045] Step S6, Post-processing The fermentation material was dried at 60°C to a moisture content of 12%, pulverized through a 60-mesh sieve, and then granulated at 50°C to obtain the final product.

[0046] The bioconversion feed product obtained in Example 2 was tested for various indicators. The average value was taken from three repeated experiments. The test results are shown in Table 2 below.

[0047] Table 2: Test results of various indicators of the product obtained in Example 2

[0048] Example 3 This embodiment provides a method for the co-bioconversion of feed ingredients using food by-products as the main raw material. The food by-products used are a mixture of fruit pomace and vegetable pomace. This embodiment is a continuous batch production method, running for a total of 5 batches, fully implementing thermal energy coupling, carbon source coupling, and metabolic heat recovery coupling, specifically including the following steps: Step S1: Raw material pretreatment Fruit pomace and vegetable pomace were mixed at a mass ratio of 1:1. The mixed raw material contained 15% lignocellulose and 7% crude protein, with pectin and organic acids as the main anti-nutritional factors. The mixture was then pulverized and passed through a 20-mesh sieve, and the moisture content was adjusted to 40%.

[0049] Step S2, Steaming and Expansion Treatment The pretreated material is fed into a cooking and expansion equipment, with the temperature controlled at 118℃ and the pressure at 0.18MPa. A gradient heating mode is used: first, the temperature is increased to 88℃ (75% of the target temperature) at a rate of 6℃ / min, and held for 2 minutes; then, the temperature is increased to 118℃ at a rate of 6℃ / min, and held at the target temperature for another 14 minutes. After processing, the pressure is rapidly released within 2 seconds, causing the material to expand instantaneously.

[0050] The thermal coupling operation is the same as in Example 1, except that the recovered heat accounts for 16% of the total input heat and is used to preheat the circulating water in the enzymatic hydrolysis tank and fermentation chamber.

[0051] Step S3, Enzymatic hydrolysis Cool the expanded material after cooking to 50℃. Prepare a compound enzyme preparation: mix pectinase, cellulase, and protease in a mass ratio of 2.5:1.2:1.2; wherein the activity of pectinase is 50,000 U / g, the activity of cellulase is 10,000 U / g, and the activity of protease is 100,000 U / g. The total amount of the compound enzyme preparation added is 2.5% of the dry weight of the raw materials. Add the compound enzyme preparation to the cooled material, control the enzymatic hydrolysis temperature at 50℃, the enzymatic hydrolysis pH at 4.5, and the enzymatic hydrolysis time at 1.5h. The solid-liquid ratio of the enzymatic hydrolysate is 1:1.6, and the total volume of the hydrolysate is 600L, based on 1000kg of raw materials.

[0052] The carbon source coupling operation is the same as in Example 1, except that when the enzymatic hydrolysis is carried out for 1 hour, the online detection of the reducing sugar concentration is 3.8 g / L, which meets the threshold requirement. 15% of the total amount of enzymatic hydrolysate, i.e., 90 L, is introduced into the fermentation process. The total amount of reducing sugar is 342 g, which accounts for 11.4% of the total carbon source requirement of the fermentation material.

[0053] Step S4: Fermentation treatment Inoculate the enzymatically hydrolyzed material with a compound microbial strain. The compound microbial strain consists of yeast, lactic acid bacteria, and Aspergillus oryzae in a volume ratio of 1:1:0.5, and the inoculation amount is 4% of the wet weight of the material. Adjust the moisture content of the material to 55% and ferment it in a solid state at 28℃ for 72 hours.

[0054] The metabolic heat recovery coupling operation is the same as in Example 1, and is performed in batches 2 to 5. The recovered metabolic heat is used to preheat the circulating water in the enzymatic hydrolyzer and fermentation tank for the next batch.

[0055] Step S5, Post-processing The fermentation material was dried at 60°C to a moisture content of 12%, pulverized through a 60-mesh sieve, and then granulated at 50°C to obtain the final product.

[0056] The bioconversion feed product obtained in Example 3 was tested for various indicators. The average value was taken from three repeated experiments. The test results are shown in Table 3 below.

[0057] Table 3: Test results of various indicators of the product obtained in Example 3

[0058] Comparative Example 1 The only difference between this comparative example and Example 1 is that no thermal coupling, carbon source coupling, or metabolic heat recovery coupling is implemented; all other steps and conditions are the same as in Example 1.

[0059] Comparative Example 2 The only difference between this comparative example and Example 1 is that thermal coupling is implemented, but carbon source coupling and metabolic heat recovery coupling are not implemented. All other steps and conditions are the same as in Example 1.

[0060] Comparative Example 3 The only difference between this comparative example and Example 1 is that carbon source coupling is implemented, but thermal energy coupling and metabolic heat recovery coupling are not implemented. All other steps and conditions are the same as in Example 1.

[0061] Comparative Example 4 The only difference between this comparative example and Example 1 is that step S4 fermentation is not performed, and no thermal coupling, carbon source coupling, or metabolic heat recovery coupling is implemented. All other steps and conditions are the same as in Example 1.

[0062] Comparative Example 5 The only difference between this comparative example and Example 1 is that step S3 enzymatic hydrolysis is not performed, and no thermal coupling, carbon source coupling, or metabolic heat recovery coupling is implemented. All other steps and conditions are the same as in Example 1.

[0063] Comparative Example 6 The only difference between this comparative example and Example 1 is that step S2 uses conventional atmospheric pressure cooking, i.e., cooking at 130°C for 30 minutes under atmospheric pressure without rapid depressurization expansion. Step S4 fermentation is not performed, and no thermal energy coupling, carbon source coupling, or metabolic heat recovery coupling is implemented. All other steps and conditions are the same as in Example 1.

[0064] Comparative Example 7 The only difference between this comparative example and Example 1 is that step S2 uses conventional puffing treatment, puffing at 130°C and 0.35 MPa for 8 minutes, without using gradient heating mode and instantaneous pressure relief expansion. Step S3 enzymatic hydrolysis is not performed, and no thermal energy coupling, carbon source coupling, or metabolic heat recovery coupling is implemented. All other steps and conditions are the same as in Example 1.

[0065] Comparative Example 8 The only difference between this comparative example and Example 1 is that step S2 (cooking and expansion) and step S3 (enzymatic hydrolysis) are omitted. The pretreated raw materials are directly fermented. Due to the lack of pretreatment, the substrate has poor fermentability, so the fermentation time is extended to 72 hours to achieve full fermentation. No thermal coupling, carbon source coupling, or metabolic heat recovery coupling is implemented. All other steps and conditions are the same as in Example 1.

[0066] The bioconversion feed products obtained in Example 1 and each comparative example were tested for various indicators. The average value ± standard deviation of three repeated experiments is shown in Table 4 below.

[0067] Table 4: Test results of various indicators of the products obtained from the examples and comparative examples

[0068] Depend on Figure 1 , Figure 2As shown in Tables 1-4, the cooking and expansion parameters and compound enzyme ratios set by this invention for three types of raw materials—meal meals, food processing by-products, and food waste—all exhibit good adaptability. Major anti-nutritional factors are effectively reduced, and the content of acid-soluble proteins, small peptides, and probiotics in the product is at a high level. Under identical process conditions, the embodiment implementing heat energy coupling, carbon source coupling, and metabolic heat recovery coupling is superior to the uncoupled three-stage process in terms of anti-nutritional factor removal, protein degradation, and small peptide generation. While implementing heat energy coupling or carbon source coupling alone provides some improvement, the effect is limited; only simultaneous implementation of all three couplings achieves the best synergistic effect. The product indicators significantly decrease when the enzymatic hydrolysis or fermentation process is missing, indicating that these two processes are irreplaceable. Compared with traditional atmospheric pressure cooking, traditional puffing, and direct fermentation, the cooking and expansion coupling process of this invention has significant advantages in the removal of anti-nutritional factors and the generation of active substances.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for the synergistic biotransformation of feed ingredients through steaming, expansion, coupled with enzymatic hydrolysis and fermentation, characterized in that, Includes the following steps: Step S1, Raw material pretreatment: The feed raw materials are crushed and pretreated. The feed raw materials are selected from one or more of the following: miscellaneous oilseed meals, food processing by-products, and food waste. Step S2, Cooking and Expansion Treatment: The material obtained in Step S1 is subjected to cooking and expansion treatment at a temperature of 110-150℃, a pressure of 0.15-0.5MPa, and a treatment time of 5-15min. After the treatment is completed, the pressure is quickly released to atmospheric pressure to make the material expand instantaneously. Step S3, Enzymatic hydrolysis: After cooling the material obtained in step S2 to 30-55℃, add the compound enzyme preparation for enzymatic hydrolysis; the enzymatic hydrolysis pH value is 4.0-7.0, the total amount of compound enzyme preparation added is 0.1-5% of the dry weight of the raw material, and the enzymatic hydrolysis time is 30min-4h; Step S4, Fermentation Treatment: Inoculate the material obtained in Step S3 with a compound microbial strain for fermentation treatment; the inoculation amount is 0.5-10% of the wet weight of the material, the fermentation temperature is 25-45℃, the fermentation time is 12-72h, and the fermentation moisture content is 35-60%; Step S5, Post-processing: The fermented material obtained in step S4 is dried, crushed, and granulated to obtain the bioconverted feed product; Steps S2, S3, and S4 form a coupled and cyclical system, including: Thermal coupling: The sensible heat released by the material after the cooking and expansion treatment in step S2 is recovered and used to preheat the heat preservation medium of the enzymatic hydrolysis process in step S3 and / or the fermentation process in step S4. Carbon source coupling: The concentration of reducing sugar in the enzymatic hydrolysis system in step S3 is detected. When the concentration of reducing sugar is ≥3.0 g / L, a portion of the enzymatic hydrolysate is exported and transferred to the fermentation process in step S4 as a supplementary carbon source. Metabolic heat recovery coupling: The metabolic heat generated in step S4 fermentation is recovered and used to preheat the insulation medium of step S3 enzymatic hydrolysis and / or step S4 fermentation in subsequent production batches.

2. The method for synergistic bioconversion of feed ingredients through steaming, expansion, coupled enzymatic hydrolysis, and fermentation according to claim 1, characterized in that, In step S1, the feed raw materials are ground to a particle size of 20-100 mesh and have a moisture content of 25-45%.

3. The method for synergistic bioconversion of feed ingredients through steaming, expansion, coupled enzymatic hydrolysis, and fermentation according to claim 1, characterized in that, In step S1, the raw materials for miscellaneous meals are one or more of rapeseed meal, cottonseed meal, palm kernel meal, and peanut meal; the food processing by-products are one or more of distillers' grains, wheat bran, corn husks, and corn germ meal; and the food wastes are one or more of fruit pomace and vegetable pomace.

4. The method for synergistic bioconversion of feed ingredients through steaming, expansion, coupled enzymatic hydrolysis, and fermentation according to claim 1, characterized in that, In step S2, the cooking expansion treatment adopts a gradient heating mode. First, the temperature is increased to 70-80% of the target temperature at a rate of 5-15℃ / min, and then held for 1-3 minutes. Then, the temperature is increased to the target temperature and held for the set time. After the treatment is completed, the pressure is rapidly released to atmospheric pressure within 0.5-2 seconds.

5. The method for synergistic bioconversion of feed ingredients through steaming, expansion, coupled enzymatic hydrolysis, and fermentation according to claim 1, characterized in that, In step S2, the processing temperature for miscellaneous meal raw materials is 130-150℃, the pressure is 0.3-0.5MPa, and the processing time is 5-10min; the processing temperature for food processing by-product raw materials is 120-135℃, the pressure is 0.2-0.3MPa, and the processing time is 8-15min; and the processing temperature for food waste raw materials is 110-125℃, the pressure is 0.15-0.25MPa, and the processing time is 10-15min.

6. The method for synergistic bioconversion of feed ingredients through steaming, expansion, coupled enzymatic hydrolysis, and fermentation according to claim 1, characterized in that, Between steps S2 and S3, there is also a shearing emulsification process: the cooked and expanded material is sheared and emulsified at 5000-10000 rpm for 5-30 min to refine the material particles to 10-50 μm.

7. The method for synergistic bioconversion of feed ingredients through steaming, expansion, coupled enzymatic hydrolysis, and fermentation according to claim 1, characterized in that, In step S3, The compound enzyme preparations used for miscellaneous oilseed meals are mainly composed of protease, combined with cellulase and xylanase. Protease accounts for 40-85% of the total mass of the compound enzyme preparation. The compound enzyme preparations used for food processing by-product raw materials include saccharifying enzymes and non-starch polysaccharide enzymes. The non-starch polysaccharide enzymes are selected from at least one of cellulase, β-glucanase, and xylanase. The saccharifying enzymes account for 20-70% of the total mass of the compound enzyme preparation. The compound enzyme preparations used in food by-products are mainly pectinase, combined with cellulase and protease. Pectinase accounts for 30-80% of the total mass of the compound enzyme preparation.

8. The method for synergistic bioconversion of feed ingredients through steaming, expansion, coupled enzymatic hydrolysis, and fermentation according to claim 1, characterized in that, In step S4, the compound microbial strain is selected from one or more of the following: lactic acid bacteria, yeast, Bacillus subtilis, Bacillus licheniformis, Aspergillus niger, Aspergillus oryzae, Trichoderma reesei, and Candida utilis.

9. The method for synergistic bioconversion of feed ingredients through steaming, expansion, coupled enzymatic hydrolysis, and fermentation according to claim 1, characterized in that, In step S5, the drying temperature is 50-65℃, and the material is dried until the moisture content is ≤12%; the particle size is 40-80 mesh.

10. The method for synergistic bioconversion of feed ingredients through steaming, expansion, coupled enzymatic hydrolysis, and fermentation according to claim 1, characterized in that, In a coupled cyclical system: Thermal energy coupling and heat recovery account for 10-30% of the total heat input for cooking expansion; In carbon source coupling, the carbon source corresponding to the transferred enzyme hydrolysate accounts for 5-30% of the total carbon source requirement of the fermentation material; The metabolic heat recovery coupling was implemented starting from the second production batch.

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