A method for preparing an animal protein hydrolysate

Abstract

This invention relates to the field of harmless treatment and resource utilization of diseased and dead livestock and poultry, and particularly to a method for preparing animal proteolytic hydrolysate. The method includes: crushing livestock and poultry raw materials, spraying them with a compound enzyme preparation solution, and pumping them to a processing tank; sterilizing after enzymatic hydrolysis; pumping the sterilized liquid into a storage tank through a disinfection pipeline; pumping it back to the processing tank for secondary sterilization; separating solids and liquids after sterilization, using a high temperature of not less than 140°C for the liquid, and controlling the switching of the oil and liquid discharge paths by a four-way valve through a conductivity sensor in the drain pipeline to separate oil and water; concentrating the defatted enzymatic hydrolysate and mixing it with the solid, then drying and packaging it. This invention places the enzymatic hydrolysis step in the pre-process to avoid protein thermal denaturation, achieving 99.32% of peptides below 3000 Da and 81.56% of small peptides; double sterilization combined with closed transport ensures biosafety; and energy-saving separation is achieved by utilizing the material's own high temperature coupled with conductivity self-control, thus unifying the harmless treatment and high-value-added resource utilization of diseased and dead livestock and poultry.

Description

Technical Field

[0001] This invention relates to the field of harmless treatment and resource utilization of diseased and dead livestock and poultry, and particularly to a method for preparing animal proteolytic hydrolysate. Background Technology

[0002] The harmless disposal of diseased and dead animals is a crucial aspect of animal disease prevention and control and ensuring public health safety. The "Technical Specifications for Harmless Disposal of Diseased and Dead Animals" (Agricultural Medical Document

[2017] No. 25) clearly stipulates the applicable objects, technical processes, and operational precautions for various disposal methods, including incineration, rendering, and sulfuric acid decomposition. Rendering, in particular, involves introducing high-temperature saturated steam into a sealed, high-pressure container, either through the container's jacket or within the container itself, to treat diseased and dead animals and related animal products under the combined effects of dry heat and pressure, or steam and pressure. Rendering can completely kill pathogenic microorganisms under high temperature and pressure conditions, while simultaneously utilizing byproducts, and has become one of the mainstream technologies for the harmless disposal of diseased and dead livestock and poultry.

[0003] Currently, the common process route for further resource utilization based on the rendering method is high-temperature rendering, enzymatic hydrolysis, separation, and drying. A typical process is as follows: Diseased and dead livestock and poultry are crushed and fed into a rendering tank for sterilization and rendering under high temperature and high pressure conditions. The core temperature of the material needs to reach above 160℃, and the pressure needs to reach above 0.5MPa. After rendering, oil, water, and sludge are separated through processes such as pressure filtration and centrifugation. The separated aqueous phase material is the protein-containing material, which is then added with enzymes for enzymatic hydrolysis, catalyzing large protein molecules into small peptides and amino acids. Finally, after drying and other processes, products such as meat and bone meal are produced.

[0004] However, the existing processes described above have significant technical drawbacks. During high-temperature processing, animal proteins undergo severe thermal denaturation at temperatures above 160°C. Denatured proteins have a compact molecular structure, with encapsulated enzyme cleavage sites, hindering the release of free amino acids and small peptides. This results in a significant reduction in subsequent enzymatic hydrolysis efficiency, with the content of small peptides below 3000 Da in the hydrolysate typically only reaching around 33%. Simultaneously, the oils and proteins in the high-temperature processed material are emulsified or encapsulated, especially in the water-sludge phase where a large amount of meat fibers are present. Conventional centrifugation is insufficient to completely remove the oils, and the residual oils further affect the contact efficiency between the enzyme and the substrate, thus impacting the molecular weight distribution and functional properties of the product. Furthermore, the process sequence of high-temperature processing followed by enzymatic hydrolysis necessitates that the hydrolysis step be performed only after high-temperature sterilization and cooling, extending the overall processing cycle and increasing energy consumption and production costs.

[0005] Therefore, there is an urgent need in this field for a method to prepare animal protease hydrolysates that can avoid protein thermal denaturation, improve enzymatic hydrolysis efficiency and lipid separation effect, and obtain high content of small molecule peptides. Summary of the Invention

[0006] Therefore, the present invention provides a method for preparing animal protease hydrolysate, which solves the technical problems of low enzymatic hydrolysis efficiency and low small peptide content caused by high-temperature sterilization in existing high-temperature processing processes, as well as the difficulty in separating oil and protein due to oil and protein encapsulation, long production cycle and high energy consumption.

[0007] To achieve the above objectives, the present invention provides a method for preparing animal protease hydrolysates, characterized by comprising the following steps: Step S1: After crushing the raw materials of diseased and dead livestock and poultry, spray them with compound enzyme preparation solution and mix them evenly, then pump them into the processing tank. Step S2: Seal the chemical preparation tank and control the temperature to 55℃~65℃, stir and enzymatically hydrolyze for 2h~6h, then raise the temperature to the center temperature of the material not lower than 160℃ and the pressure not lower than 0.5MPa, and keep it at the temperature for not less than 0.5h for sterilization. Step S3: The sterilized enzymatic hydrolysate is unloaded under pressure into a tanker through a closed pipeline. A sterilization device is installed at the unloading interface, and the enzymatic hydrolysate is pumped to the storage tank through a sterilization pipeline. Step S4: Pump the enzymatic hydrolysate in the storage tank back to the chemical preparation tank, and heat it again to a core temperature of not less than 160°C and a pressure of not less than 0.5 MPa, and keep it at that temperature for not less than 0.5 h for secondary sterilization; Step S5: After secondary sterilization, the material undergoes solid-liquid separation. The separated liquid is pumped to an oil-water separation tank. The material's own high temperature of not less than 140°C creates pressure inside the tank, causing the oil-water interface to clearly separate. A conductivity sensor installed in the drain pipe controls a four-way valve to switch between oil and liquid draining paths according to a preset threshold, thereby achieving automatic oil-water separation and obtaining oil and enzymatic hydrolysate.

[0008] Step S6: The defatted enzymatic hydrolysate is concentrated and mixed with the separated solid portion, dried, packaged, and stored.

[0009] Further, in step S1, the complex enzyme preparation is one or a mixture of several of neutral protease, acidic protease and alkaline protease.

[0010] Further, in step S1, the compound enzyme preparation is first completely dissolved in water to prepare a solution with a mass concentration of 20% to 60%.

[0011] Further, in step S1, the amount of the compound enzyme preparation used is 0.01% to 1% of the raw material mass.

[0012] Furthermore, in step S1, the diseased and dead livestock raw materials are crushed into meat pieces of 2-5 cm by a crusher.

[0013] Furthermore, in step S1, the compound enzyme preparation solution is uniformly sprayed onto the surface of the minced meat using a pump spraying process, and then uniformly mixed by roller shearing.

[0014] Furthermore, in step S5, a mesh filter conveying device is used for the solid-liquid separation.

[0015] Furthermore, in step S5, the conductivity sensor is installed at the drain pipe of the oil-water separator to control the four-way valve to discharge the grease into the oil storage tank based on the comparison result of the detected conductivity value and the preset threshold.

[0016] Furthermore, in step S6, the defatted enzymatic hydrolysate is concentrated to a solid content of 45% to 65% by low-temperature residual heat, then mixed with the solid portion ground by a colloid mill, dried, packaged, and stored.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: By placing the enzymatic hydrolysis step in advance, spraying the compound enzyme preparation immediately after crushing and performing low-temperature enzymatic hydrolysis at 55℃~65℃, followed by high-temperature and high-pressure sterilization, the present invention avoids the problem of severe thermal denaturation of animal proteins caused by high-temperature processing in traditional processes. This fully exposes the enzyme cleavage sites, significantly improves the enzymatic hydrolysis efficiency, and achieves a small peptide content of less than 3000Da of up to 81.56%, while the traditional process can only achieve about 33%. This effectively solves the technical problems of protein denaturation, low enzymatic hydrolysis efficiency, and low small molecule peptide content caused by high-temperature sterilization in the prior art.

[0018] Furthermore, in the low-temperature enzymatic hydrolysis process, the present invention simultaneously decomposes nitrogen- and sulfur-containing odorous gases with the compound enzyme preparation, thereby reducing the generation of malodorous pollutants such as ammonia and hydrogen sulfide from the source, reducing the load on subsequent waste gas treatment, and effectively solving the technical problems of large malodorous gas generation and high end-of-pipe treatment costs in existing processes.

[0019] Furthermore, this invention employs a two-stage high-temperature and high-pressure sterilization process combined with pressurized closed pipeline transportation. After the first sterilization, the enzymatic hydrolysate is unloaded under pressure into a tanker truck via an interface equipped with a disinfection and sterilization device. Upon arrival at the storage plant, the tanker truck does not enter the plant but directly pumps the enzymatic hydrolysate into the storage tank via a disinfection pipeline. This achieves closed and aseptic transportation throughout the entire process, effectively preventing the risk of contamination by pathogens and bacteria during transportation. It solves the technical problems of lack of biosafety control, easy spread of pathogens, and secondary pollution in the material transportation process of existing technologies.

[0020] Furthermore, this invention employs a mesh filter conveying device for solid-liquid separation after the second sterilization. The separated liquid is pumped to an oil-water separation tank, where the material's own high temperature of not less than 140°C creates pressure within the tank, causing clear stratification of the oil-water interface. A conductivity sensor located in the drain pipe controls a four-way valve to switch between oil and liquid draining paths based on a preset threshold, achieving automatic oil-water separation without the need for additional heating. This reduces separation energy consumption and manual intervention costs, and solves the technical problems of long production cycles and high energy consumption caused by the process sequence of high temperature followed by enzymatic hydrolysis in the prior art.

[0021] Furthermore, this invention concentrates the enzymatic hydrolysate after oil separation to a solid content of 45%–65% using low-temperature residual heat, significantly reducing the heat requirement for subsequent drying. It is then mixed with the solid portion ground by a colloid mill, allowing the small molecule peptides in the liquid to fully combine with components such as fibrin in the solid residue. After drying, it is packaged and stored in a workshop equipped with an ultraviolet sterilization device, which is continuously sterilized by turning on the ultraviolet sterilization device. This ensures that the product is not subject to secondary contamination during storage, thereby improving the quality stability and biosafety of the final product.

[0022] This invention integrates five measures through a synergistic process in steps S1 to S6: low-temperature pre-enzymatic hydrolysis to improve small peptide yield, low-temperature enzymatic hydrolysis with simultaneous deodorization, double sterilization combined with closed pressurized transport to ensure biosafety, high-temperature coupling of the material's own conductivity for energy-saving separation, and low-temperature waste heat concentration to reduce energy consumption. These steps create a positive synergistic effect. Experimental results show that the enzymatic hydrolysate prepared by this invention contains up to 81.56% small peptides below 3000 Da, an increase of approximately 147% compared to the 33% of the traditional process. The product has a high content of functional small molecule peptides, which are easily absorbed and transformed by plants and animals, effectively improving their nutrient absorption capacity and immunity. This achieves a unified approach to the harmless treatment of dead livestock and poultry and the high-value-added resource utilization, overcoming the technical defects of poor synergy and low product added value caused by the simple sequential connection of processes in existing technologies. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the steps of the method for preparing animal protease hydrolysates in this embodiment; Figure 2 This is a flowchart of the crushing and enzymatic mixing steps in step S1 of this embodiment; Figure 3 This is a flowchart of the low-temperature enzymatic hydrolysis and high-temperature sterilization steps in step S2 of this embodiment; Figure 4 This is a flowchart of the pressurized closed transfer process in step S3 of this embodiment; Figure 5 This is a flowchart of the solid-liquid separation and automatic oil-water separation steps in step S5 of this embodiment; Figure 6This is a flowchart of the concentration, drying, packaging, and storage steps in step S6 of this embodiment. Detailed Implementation

[0024] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0025] Please see Figure 1 The diagram shown is a flowchart of the steps for preparing the animal protease hydrolysate in this embodiment.

[0026] This invention provides a method for preparing animal protease hydrolysates, comprising: Step S1: After crushing the raw materials of diseased and dead livestock and poultry, spray them with compound enzyme preparation solution and mix them evenly, then pump them into the processing tank.

[0027] Specifically, the diseased and dead livestock and poultry raw materials are crushed into meat pieces of 2-5 cm by a crusher; the compound enzyme preparation is one or more of neutral protease, acidic protease and alkaline protease, which are first completely dissolved in water to prepare a solution with a mass concentration of 20%-60%, and the amount of enzyme preparation used is 0.01%-1% of the mass of the raw materials; the compound enzyme preparation solution is evenly sprayed onto the surface of the meat pieces by a pump spraying process, and then mixed evenly by roller shearing.

[0028] Please see Figure 2 As shown, it is a flowchart of the crushing and enzymatic mixing steps in step S1 of this embodiment.

[0029] In this embodiment, the specific process of step S1 includes: Step S11: The collected diseased and dead livestock raw materials are weighed and then transported to the crusher, where they are crushed into meat pieces of 2-5cm in a closed environment under negative pressure. Step S12: Dissolve the compound enzyme preparation completely in water to prepare a solution with a mass concentration of 20% to 60%. The compound enzyme preparation is one or a mixture of several of neutral protease, acidic protease and alkaline protease. The amount of enzyme preparation used is 0.01% to 1% of the mass of the raw materials. Step S13: The prepared compound enzyme preparation solution is evenly sprayed onto the surface of the minced meat using a pump spraying process, and then mixed evenly by roller shearing. In step S14, the mixed material is pumped to the chemical tank through a closed pipeline by a feed pump.

[0030] It is understandable that the particle size of diseased and dead livestock and poultry raw materials directly affects the efficiency of subsequent enzymatic hydrolysis. If the particle size is too large, the enzyme preparation cannot penetrate the material, resulting in incomplete hydrolysis; if the particle size is too small, it increases crushing energy consumption and dust generation. This application controls the crushed particle size to 2-5 cm, ensuring sufficient contact between the enzyme preparation and the material while also considering crushing efficiency and equipment durability. The neutral protease, acidic protease, and alkaline protease in the compound enzyme preparation act on protein peptide bonds under different pH conditions. Their synergistic use achieves comprehensive protein degradation, maximizing the generation efficiency of small molecule peptides. The enzyme preparation dosage is controlled within the range of 0.01% to 1% of the raw material mass. Too low a dosage results in insufficient hydrolysis, while too high a dosage increases production costs and may cause over-hydrolysis, producing bitter peptides. Through the combination of pump spraying and roller shearing, the enzyme preparation solution is evenly distributed on the surface of each piece of minced meat and fully penetrates, ensuring sufficient contact between the enzyme and the substrate, laying a material foundation for efficient enzymatic hydrolysis in the subsequent processing tank.

[0031] Step S2: Seal the chemical treatment tank and control the temperature to 55℃~65℃, stir and enzymatically hydrolyze for 2h~6h, then raise the temperature to the center temperature of the material not lower than 160℃ and the pressure not lower than 0.5MPa, and keep it at the temperature for not less than 0.5h for sterilization.

[0032] Specifically, the inner layer of the chemical treatment tank is equipped with a thermocouple device and a multi-point temperature sensor for real-time measurement of the material's center temperature, and is equipped with a temperature recording system to monitor and record the temperature throughout the entire chemical treatment process; the chemical treatment tank is equipped with a stirring device that continuously stirs the material during the heating and heat preservation process, so that the material inside the tank is heated evenly.

[0033] Please see Figure 3 As shown, it is a flowchart of the steps of low-temperature enzymatic hydrolysis and high-temperature sterilization in step S2 of this embodiment.

[0034] In this embodiment, the specific process of step S2 includes: Step S21: Seal the chemical tank, start the stirring device, and introduce a circulating heat source through the jacket to raise the temperature of the material in the tank to 55℃~65℃; Step S22: Enzymatic hydrolysis is carried out at a constant temperature of 55℃~65℃ for 2h~6h, so that the compound enzyme preparation can fully catalyze the hydrolysis of protein into small molecule peptides. Step S23: After enzymatic hydrolysis is completed, a high-temperature circulating heat source is introduced through a jacket to heat the material to a core temperature of not less than 160°C and a pressure of not less than 0.5MPa. Step S24: The enzyme hydrolysate is subjected to high-temperature and high-pressure sterilization at a temperature of 160°C or above and a pressure of 0.5 MPa or above for no less than 0.5 h.

[0035] It is understandable that enzymatic hydrolysis requires suitable temperature conditions. 55℃~65℃ is the optimal operating temperature range for the composite enzyme preparation selected in this application, where enzyme activity is highest and catalytic efficiency is optimal. The hydrolysis time of 2h~6h balances hydrolysis depth and production efficiency. Too short a time results in insufficient hydrolysis and low yields of small peptides below 3000Da; too long a time causes the hydrolysis reaction to reach equilibrium, leading to decreased marginal yield and increased production cycle and energy consumption. Unlike traditional processes that involve high-temperature curing followed by enzymatic hydrolysis, this application places the enzymatic hydrolysis step before high-temperature sterilization. At this time, the protein has not yet undergone heat denaturation, its molecular structure remains in its natural extended state, and the enzyme cleavage sites are fully exposed, allowing the enzyme preparation to efficiently catalyze large protein molecules into small peptides. Simultaneously, during the low-temperature enzymatic hydrolysis process, the composite enzyme preparation simultaneously decomposes nitrogen- and sulfur-containing compounds, reducing the generation of malodorous gases such as ammonia and hydrogen sulfide at the source, and lowering the load on subsequent waste gas treatment. After enzymatic hydrolysis, the chemical treatment tank is heated to above 160℃ and pressure above 0.5MPa for high-temperature and high-pressure sterilization, which can effectively kill pathogenic microorganisms. This step completes low-temperature enzymatic hydrolysis and high-temperature sterilization sequentially in the same chemical treatment tank, ensuring both enzymatic hydrolysis efficiency and sterilization effect. It avoids heat loss and contamination risks caused by transferring materials between different equipment, and achieves efficient integration of the two processes of enzymatic hydrolysis and sterilization.

[0036] Step S3: The sterilized enzymatic hydrolysate is unloaded under pressure into a tanker through a closed pipeline. A sterilization device is installed at the unloading interface, and the enzymatic hydrolysate is pumped to the storage tank through a sterilization pipeline.

[0037] Please see Figure 4 As shown, it is a flowchart of the pressurized closed transfer step S3 in this embodiment.

[0038] In this embodiment, the specific process of step S3 includes: Step S31: After sterilization, the discharge port of the chemical tank is connected to the feed pipe of the tank truck through a sealed pipe. Before the connection, the feed pipe of the tank truck is disinfected and sterilized. Step S32: Open the discharge valve of the chemical treatment tank and use the residual pressure in the chemical treatment tank to discharge the enzymatic hydrolysate into the tank truck through a closed pipeline under pressure. During the unloading process, the unloading interface is continuously disinfected and sterilized. Step S33: After unloading, the feed pipe head of the tank truck is disinfected and sterilized a second time, the tank truck is sealed, and the tank truck transports the enzymatic hydrolysate to the storage plant area. Step S34: After the tanker arrives at the storage plant, it does not enter the plant. Instead, the tanker's discharge pipe is connected to the plant's disinfection pipeline. A disinfection and sterilization device is installed at the connection point, and the enzymatic hydrolysate is pumped to the storage tank through the disinfection pipeline.

[0039] It is understandable that there is a risk of pathogen spread and secondary contamination during the material transfer process in the harmless treatment of diseased and dead animals. This application employs a pressurized, closed pipeline to directly unload the sterilized enzymatic hydrolysate from the preparation tank to a tank truck. A disinfection and sterilization device is installed at the unloading interface to ensure microbial safety at the interface. After arriving at the storage plant, the tank truck does not enter the plant; instead, the material is directly pumped to the storage tank through a disinfection pipeline. The entire process achieves closed and aseptic transfer, with no direct contact between the tank truck and the plant area, fundamentally eliminating the biosafety risks during the transfer process.

[0040] Step S4: Pump the enzymatic hydrolysate in the storage tank back to the chemical treatment tank, and heat it again to a core temperature of not less than 160°C and a pressure of not less than 0.5 MPa, and keep it at this temperature for not less than 0.5 hours for secondary sterilization.

[0041] Understandably, although airtight and high-temperature maintenance measures were taken during the transportation and storage of the enzymatic hydrolysate, this application included a secondary high-temperature and high-pressure sterilization process to ensure absolute product safety. The secondary sterilization conditions were the same as the primary sterilization, sufficient to kill all possible pathogens from diseased or dead animals, ensuring the biosafety of the final product and meeting the requirements of harmless treatment standards.

[0042] Step S5: After secondary sterilization, the material undergoes solid-liquid separation. The separated liquid is pumped to an oil-water separation tank. The material's own high temperature of not less than 140°C creates pressure inside the tank, causing the oil-water interface to clearly separate. A conductivity sensor installed in the drain pipe controls a four-way valve to switch between oil and liquid draining paths according to a preset threshold, thereby achieving automatic oil-water separation and obtaining oil and enzymatic hydrolysate.

[0043] Specifically, a mesh filter conveying device is used for solid-liquid separation; the conductivity sensor is installed at the drain pipe of the oil-water separator and is used to control the four-way valve to switch between oil drain and liquid drain paths based on the comparison result of the detected conductivity value and the preset threshold.

[0044] Please see Figure 5 As shown, it is a flowchart of the solid-liquid separation and automatic oil-water separation steps in step S5 of this embodiment.

[0045] In this embodiment, the specific process of step S5 includes: Step S51: After secondary sterilization, the material enters the mesh filter conveyor to trap solid residue, and the liquid part is pumped to the oil-water separator. Step S52: Use the material's own high temperature of not less than 140°C to create pressure in the oil-water separator, and let it stand to allow the oil-water interface to clearly separate into layers. Step S53: The conductivity sensor monitors the conductivity value of the discharged liquid in real time. When the detected conductivity value is lower than the first set threshold, it is determined to be an oil layer. The four-way valve is automatically controlled to open the oil discharge passage and discharge the upper oil layer to the oil storage tank. When the conductivity value is higher than the second set threshold, it is determined to be an enzymatic hydrolysate layer. The four-way valve is automatically controlled to switch to the discharge passage and discharge the lower enzymatic hydrolysate. In step S54, after the oil is completely discharged, the four-way valve automatically closes, and the lower layer of enzymatic hydrolysate is pumped out to enter the next process.

[0046] Understandably, during secondary sterilization, the core temperature of the material is no lower than 160℃. After discharge, pipeline transportation, and solid-liquid separation, the material temperature will decrease, but it will still remain above 140℃. Utilizing the residual heat of the material itself (no lower than 140℃), pressure is created within the oil-water separator, resulting in clear stratification of the oil and water interface without the need for additional heating, thus reducing separation energy consumption. A conductivity sensor located in the drain pipeline controls a four-way valve to switch between oil and liquid draining paths based on a preset threshold, achieving automatic oil-water separation. This avoids errors from manual judgment and operation, improving separation efficiency and oil purity. Solid residues retained by the mesh filter conveyor enter the subsequent grinding process, realizing tiered separation and full component utilization of the material.

[0047] Step S6: The defatted enzymatic hydrolysate is concentrated and mixed with the separated solid portion, dried, packaged, and stored.

[0048] Specifically, the defatted enzymatic hydrolysate is concentrated to a solid content of 45% to 65% by low-temperature residual heat, and then mixed with the solid portion ground by a colloid mill. After the mixture is dried, it is packaged and stored in a workshop equipped with an ultraviolet sterilization device, and the ultraviolet sterilization device is turned on to continuously sterilize the storage environment.

[0049] Please see Figure 6 As shown, it is a flowchart of the concentration, drying, packaging and storage steps in step S6 of this embodiment.

[0050] In this embodiment, the specific process of step S6 includes: Step S61: Pump the defatted enzymatic hydrolysate into a low-temperature waste heat concentration device to concentrate the enzymatic hydrolysate to a solid content of 45% to 65% using the waste heat resources of the plant. Step S62: Grind the solid residue obtained from solid-liquid separation in step S5 into fine powder using a colloid mill; Step S63: The concentrated enzymatic hydrolysate and the ground solid part are thoroughly mixed in a mixer to fully combine the small molecule peptides in the liquid with the fibrin in the solid residue. In step S64, the mixture is sent to a drying device for drying. The dried product is then weighed and packaged in the packaging workshop and transferred to a storage workshop equipped with an ultraviolet disinfection device for storage. During storage, the ultraviolet disinfection device is turned on to continuously sterilize the storage environment.

[0051] Understandably, the degreased enzymatic hydrolysate has a high water content, making direct drying energy-intensive. This application utilizes low-temperature waste heat for concentration, concentrating the hydrolysate to a solid content of 45%–65% using waste heat resources from the plant, significantly reducing the heat requirements for subsequent drying and lowering energy consumption. The concentrated hydrolysate is mixed with the solid fraction ground in a colloid mill, allowing the small molecule peptides in the liquid to fully combine with components such as fibrin in the solid residue. After drying, the final product is obtained. The product is stored in a workshop equipped with an ultraviolet sterilization device. During storage, the ultraviolet sterilization device is continuously activated to sterilize the storage environment, ensuring that the product is not subject to secondary contamination during storage.

[0052] Example 1

[0053] This embodiment provides a method for preparing animal protease hydrolysate, the specific steps of which are as follows: Step S1: The collected diseased and dead livestock raw materials are weighed and transported to a crusher, where they are crushed into 2-5 cm pieces in a negative pressure, closed environment. Equal amounts of neutral protease, acidic protease, and alkaline protease are mixed as a compound enzyme preparation, completely dissolved in water to prepare a 40% (w / w) solution. The total amount of the compound enzyme preparation is 0.4% (baseline) of the raw material mass. The prepared compound enzyme preparation solution is evenly sprayed onto the surface of the meat pieces using a pump spraying process, and then uniformly mixed by roller shearing. The mixed material is then pumped to a rendering tank via a closed pipeline by a feed pump.

[0054] Step S2: Seal the chemical treatment tank, start the stirring device, and introduce a circulating heat source through the jacket to raise the temperature of the material inside the tank to 60°C. Maintain the temperature at 60°C and stir for 2 hours for enzymatic hydrolysis. After enzymatic hydrolysis, continue to introduce a high-temperature circulating heat source through the jacket to raise the temperature of the material to a core temperature of not less than 160°C and a pressure of not less than 0.5 MPa. Hold the temperature for not less than 0.5 hours for high-temperature and high-pressure sterilization.

[0055] Step S3: After sterilization, the discharge port of the chemical treatment tank is connected to the feed pipe of the tank truck via a sealed pipeline. Before connection, the feed pipe of the tank truck is disinfected and sterilized. The discharge valve of the chemical treatment tank is opened, and the residual pressure inside the tank is used to discharge the enzymatic hydrolysate into the tank truck through the sealed pipeline under pressure. During the unloading process, the discharge interface is continuously disinfected and sterilized. After unloading, the feed pipe of the tank truck is disinfected and sterilized a second time, and the tank truck is sealed. After transporting the enzymatic hydrolysate to the storage plant area, the tank truck does not enter the plant. The discharge pipe of the tank truck is connected to the plant's disinfection pipeline. A disinfection and sterilization device is installed at the connection point, and the enzymatic hydrolysate is pumped to the storage tank through the disinfection pipeline.

[0056] Step S4: Pump the enzymatic hydrolysate from the storage tank back to the chemical processing tank, and heat it again to a material center temperature of not less than 160°C and a pressure of not less than 0.5MPa. Keep it at this temperature for not less than 0.5h for secondary sterilization.

[0057] In step S5, the material after secondary sterilization undergoes solid-liquid separation via a mesh filter conveyor. The separated liquid is pumped to an oil-water separator, where the material's high temperature creates pressure within the separator, allowing the oil and water to separate into distinct layers. A conductivity sensor monitors the oil-water interface in real time. When the interface temperature drops to a set threshold, a four-way valve automatically opens, discharging the upper layer of oil into a storage tank and pumping out the lower layer of enzymatic hydrolysate.

[0058] Step S6: The defatted enzymatic hydrolysate is pumped into a low-temperature waste heat concentration device to concentrate the hydrolysate to a solid content of 55% using the waste heat resources of the plant. The solid residue obtained from the solid-liquid separation in step S5 is ground into a fine powder using a colloid mill. The concentrated enzymatic hydrolysate and the ground solid portion are thoroughly mixed in a mixer, and the mixture is sent to a drying device for drying. The dried product is then metered, packaged, and stored in a workshop equipped with an ultraviolet sterilization device.

[0059] Example 2

[0060] The difference between this embodiment and embodiment 1 is that the enzymatic hydrolysis time in step S2 is 4 hours, while the remaining steps and parameters are the same as in embodiment 1.

[0061] Example 3

[0062] The difference between this embodiment and Embodiment 1 is that the total amount of the compound enzyme preparation used in step S1 is 0.6% of the raw material mass, which is 1.5 times the baseline amount. The remaining steps and parameters are the same as in Embodiment 1.

[0063] Example 4

[0064] The difference between this embodiment and Embodiment 1 is that: in step S1, the total amount of the compound enzyme preparation is 0.6% of the raw material mass, which is 1.5 times the baseline amount; in step S2, the enzymatic hydrolysis time is 4 hours, and the remaining steps and parameters are the same as in Embodiment 1.

[0065] Comparative Example 1 The difference between this comparative example and Example 1 is that no compound enzyme preparation is added in step S1, that is, the amount of enzyme preparation used is 0, and the remaining steps and parameters are the same as in Example 1.

[0066] Comparative Example 2 The difference between this comparative example and Example 2 is that no compound enzyme preparation is added in step S1, that is, the amount of enzyme preparation used is 0, and the remaining steps and parameters are the same as in Example 2.

[0067] Comparative Example 3 The difference between this comparative example and Example 3 is that no compound enzyme preparation is added in step S1, that is, the amount of enzyme preparation used is 0, and the remaining steps and parameters are the same as in Example 3.

[0068] Comparative Example 4 The difference between this comparative example and Example 4 is that no compound enzyme preparation is added in step S1, that is, the amount of enzyme preparation used is 0, and the remaining steps and parameters are the same as in Example 4.

[0069] Enzymatic hydrolysis effect verification Samples of the enzymatic hydrolysates prepared in Examples 1-4 and Comparative Examples 1-4 were taken, and the proportion of peptides below 3000 Da in the enzymatic hydrolysates was determined by high performance gel size exclusion chromatography. The results are shown in Table 1.

[0070] Table 1. Comparison of enzymatic hydrolysis effects between different embodiments and comparative examples. Moisture (%) 79.77 72.51 77.66 77.11 83.50 73.81 75.21 77.25 Crude protein (%) 4.99 6.93 7.04 6.84 5.48 6.03 6.35 7.27 Small peptides (acid-soluble proteins, as a percentage of crude protein) 58.72 78.02 70.79 81.56 15.73 12.36 12.54 11.55 More than 10000Da (%) 0.61 0.26 0.32 0.26 27.56 33.44 36.38 35.01 5000-10000Da (%) 0.84 1.88 0.52 0.42 0.28 0.23 0.20 0.20 3000-5000Da (%) 1.77 0 0 0 0 0 1 0 2000-3000Da (%) 9.82 9.37 9.16 8.49 0 0 0 0 1000-2000Da (%) 14.45 13.98 13.35 13.00 0.07 0.06 0.05 0.06 500-1000Da (%) 33.18 32.92 33.08 32.99 0 0 0 0 180-500Da (%) 27.66 28.34 28.99 29.29 62.40 57.50 54.76 55.45 Less than 180 Da (%) 11.67 13.25 14.58 15.55 9.69 8.77 8.61 9.28 As shown in Table 1, under the same enzymatic hydrolysis time conditions, the small peptide content of the examples with added enzyme was significantly higher than that of the corresponding control group without added enzyme. The small peptide content of Example 4 reached 81.56%, while that of Comparative Example 4 was only 11.55%, indicating that the addition of enzyme is a necessary condition for the degradation of large protein molecules into small peptides. In Comparative Examples 1–4 without added enzyme, the proportion of large protein molecules with a molecular weight greater than 10000 Da was as high as 27.56%–36.38%, further confirming that high temperature and high pressure treatment cannot effectively degrade large protein molecules into small peptides without the addition of enzyme.

[0071] Under the same enzymatic hydrolysis time of 2 hours, when the enzyme dosage was 1.5 times the baseline amount, the small peptide content was 70.79%, an increase of 12.07 percentage points compared to the baseline of 58.72%; the total proportion of peptides below 3000 Da increased from 96.78% to 99.16%. Under the same enzymatic hydrolysis time of 4 hours, when the enzyme dosage was 1.5 times the baseline amount, the small peptide content was 81.56%, an increase of 3.54 percentage points compared to the baseline of 78.02%. These results indicate that increasing the enzyme dosage can effectively improve the degree of protein hydrolysis, especially under conditions of shorter enzymatic hydrolysis time, where the improvement effect is more significant.

[0072] Under the same enzyme dosage baseline, when the enzymatic hydrolysis time was extended from 2 hours to 4 hours, the small peptide content increased from 58.72% to 78.02%, an increase of 19.30 percentage points; the total proportion of peptides below 3000 Da increased from 96.78% to 97.86%. Under the same enzyme dosage 1.5 times the baseline, when the enzymatic hydrolysis time was extended from 2 hours to 4 hours, the small peptide content increased from 70.79% to 81.56%, an increase of 10.77 percentage points; the total proportion of peptides below 3000 Da increased from 99.16% to 99.32%. This indicates that extending the enzymatic hydrolysis time is beneficial for the deep hydrolysis of proteins, allowing more large protein molecules to be degraded into small peptide molecules.

[0073] In Example 4, peptides below 3000 Da accounted for 99.32% of the total, small peptides accounted for 81.56%, large proteins above 10000 Da accounted for only 0.26%, and free amino acids below 180 Da accounted for 15.55%, all of which were optimal levels among all samples. This indicates that the combination of process parameters used in Example 4—1.5 times the baseline amount of enzyme preparation, 60℃ hydrolysis temperature, and 4h hydrolysis time—can achieve the most complete hydrolysis of proteins, with the hydrolysis products mainly consisting of small peptides and free amino acids, which are easily absorbed and utilized by plants and animals.

[0074] In summary, both enzyme dosage and hydrolysis time have a significant positive impact on protein hydrolysis efficiency. Increasing enzyme dosage and extending hydrolysis time work synergistically to ensure the complete degradation of large protein molecules into functional small peptides. Hydrolysis time has a more significant impact on hydrolysis efficiency, but the hydrolysis reaction is nearly complete after 4 hours, and further extending the hydrolysis time has limited marginal benefits. The preferred embodiment of this invention is Example 4, where the enzyme dosage is 1.5 times the baseline amount, the hydrolysis temperature is 60°C, and the hydrolysis time is 4 hours. Under these conditions, the content of functional small peptides in the hydrolysis product is the highest.

[0075] This invention integrates five measures through the synergistic process of steps S1 to S6: low-temperature pre-enzymatic hydrolysis to improve small peptide yield, low-temperature enzymatic hydrolysis with simultaneous deodorization, double sterilization combined with closed pressurized transport to ensure biosafety, high-temperature coupling of the material itself to achieve energy-saving separation, and low-temperature waste heat concentration to reduce energy consumption. These measures create a positive synergistic effect among the steps.

[0076] Step S1, the pre-enzymatic hydrolysis, involves spraying the compound enzyme preparation directly onto the surface of the crushed fresh meat chunks and mixing it evenly. The enzymatic reaction begins before the proteins undergo heat denaturation, maintaining the natural extended molecular structure and fully exposing the enzyme cleavage sites, significantly improving hydrolysis efficiency. Simultaneously, the compound enzyme preparation decomposes nitrogen- and sulfur-containing compounds during hydrolysis, reducing the generation of malodorous gases at the source. Step S2 sequentially completes low-temperature enzymatic hydrolysis and high-temperature sterilization in the same processing tank. After hydrolysis, sterilization is directly achieved by heating, avoiding heat loss and contamination risks during material transfer between different equipment while ensuring sterilization effectiveness. Step S3 achieves aseptic transfer of the hydrolysate from the processing tank to the tanker truck via pressurized closed pipelines and interface sterilization devices. The tanker truck does not enter the factory; instead, it is directly pumped to the storage tank via sterilization pipelines, ensuring a completely closed and aseptic transfer process and eliminating biosafety risks during transport. Step S4, the secondary sterilization, provides double protection for the biosafety of the final product, sufficient to kill all potentially contaminating pathogens from diseased or dead animals. Step S5 utilizes the material's own high temperature for oil-water separation, and an automatic four-way valve controlled by a conductivity sensor achieves automatic oil-water separation without additional heating, reducing separation energy consumption and manual intervention costs. Step S6 employs low-temperature waste heat concentration to significantly reduce drying energy consumption. After grinding in a colloid mill, the mixture is mixed with the concentrate and dried, achieving full utilization of the material's components.

[0077] The steps described above are interconnected and progressively build upon each other. Step S1 provides a material base rich in small molecule peptides for Step S2; the first sterilization in Step S2 ensures the safety of the closed-loop transfer in Step S3; the pressurized closed-loop transfer in Step S3 reduces the bioburden for the second sterilization in Step S4; the solid-liquid separation and conductivity-controlled oil-water separation in Step S5 provide uniform intermediate materials for the concentration and drying in Step S6; and the low-temperature waste heat concentration in Step S6 fully utilizes the waste heat resources of the plant, reducing the overall energy consumption. These steps are not simply sequential processes, but rather form a cascading amplification effect: "enzymatic hydrolysis efficiency improvement → odor source reduction → enhanced biosafety → energy-saving separation → full resource utilization."

[0078] Experimental results show that the enzymatic hydrolysate prepared in the preferred embodiment of this invention contains 99.32% peptides below 3000 Da, 81.56% small peptides, and only 0.26% large molecular proteins above 10000 Da. This represents a significant increase in small peptide content compared to the traditional process of high-temperature curing followed by enzymatic hydrolysis (approximately 33%). The product has a high content of functional small molecular peptides, which are easily absorbed and transformed by plants and animals, effectively improving their nutrient absorption capacity and immunity. It achieves the unity of harmless treatment of diseased and dead livestock and poultry and high-value-added resource utilization, overcoming the technical defects of poor synergy and low product added value caused by the simple sequential connection of various processes in the prior art.

[0079] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for preparing animal protease hydrolysate, characterized in that, Includes the following steps: Step S1: After crushing the raw materials of diseased and dead livestock and poultry, spray them with compound enzyme preparation solution and mix them evenly, then pump them into the processing tank. Step S2: Seal the chemical preparation tank and control the temperature to 55℃~65℃, stir and enzymatically hydrolyze for 2h~6h, then raise the temperature to the center temperature of the material not lower than 160℃ and the pressure not lower than 0.5MPa, and keep it at the temperature for not less than 0.5h for sterilization. Step S3: The sterilized enzymatic hydrolysate is unloaded under pressure into a tanker through a closed pipeline. A sterilization device is installed at the unloading interface, and the enzymatic hydrolysate is pumped to the storage tank through a sterilization pipeline. Step S4: Pump the enzymatic hydrolysate in the storage tank back to the chemical preparation tank, and heat it again to a core temperature of not less than 160°C and a pressure of not less than 0.5 MPa, and keep it at that temperature for not less than 0.5 h for secondary sterilization; Step S5: After secondary sterilization, the material undergoes solid-liquid separation. The separated liquid is pumped to an oil-water separation tank. The material's own high temperature of not less than 140°C creates pressure inside the tank, causing the oil-water interface to clearly separate. A conductivity sensor installed in the drain pipe controls a four-way valve to switch between oil and liquid draining paths according to a preset threshold, thereby achieving automatic oil-water separation and obtaining oil and enzymatic hydrolysate. Step S6: The defatted enzymatic hydrolysate is concentrated and mixed with the separated solid portion, dried, packaged, and stored.

2. The method for preparing animal protease hydrolysate according to claim 1, characterized in that, In step S1, the complex enzyme preparation is one or a mixture of several of neutral protease, acidic protease and alkaline protease.

3. The method for preparing animal protease hydrolysate according to claim 2, characterized in that, In step S1, the compound enzyme preparation is first completely dissolved in water to prepare a solution with a mass concentration of 20% to 60%.

4. The method for preparing animal protease hydrolysate according to claim 3, characterized in that, In step S1, the amount of the compound enzyme preparation used is 0.01% to 1% of the raw material mass.

5. The method for preparing animal protease hydrolysate according to claim 4, characterized in that, In step S1, the diseased and dead livestock raw materials are crushed into meat pieces of 2-5cm by a crusher.

6. The method for preparing animal protease hydrolysate according to claim 5, characterized in that, In step S1, the compound enzyme preparation solution is uniformly sprayed onto the surface of the minced meat using a pump spraying process, and then mixed evenly by roller shearing.

7. The method for preparing animal protease hydrolysate according to claim 6, characterized in that, In step S5, a mesh filter conveying device is used for solid-liquid separation.

8. The method for preparing animal protease hydrolysate according to claim 7, characterized in that, In step S5, the conductivity sensor is installed at the drain pipe of the oil-water separator and is used to control the four-way valve to discharge the grease into the oil storage tank based on the comparison result of the detected conductivity value and the preset threshold.

9. The method for preparing animal protease hydrolysate according to claim 8, characterized in that, In step S6, the defatted enzymatic hydrolysate is concentrated to a solid content of 45% to 65% by low-temperature residual heat, then mixed with the solid portion ground by a colloid mill, dried, packaged, and stored.

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