High-activity feather hydrolyzed amino acid water-soluble fertilizer and preparation method thereof

Abstract

The invention relates to a high-activity feather hydrolyzed amino acid water-soluble fertilizer and a preparation method thereof. The preparation method comprises the steps of pretreatment, complex enzyme stepped hydrolysis, nanofiltration separation, chelation and stabilization, spray drying and the like. Feather keratin is hydrolyzed step by step through a compound enzyme, small molecule peptide and amino acid are separated in combination with a nanofiltration membrane, trace elements are added for chelation, and a drying process is optimized, so that the activity and stability of the fertilizer are remarkably improved. The feather keratin can be efficiently degraded, the problem of amino acid racemization caused by a traditional strong acid / alkali method is solved, meanwhile, energy consumption is reduced, and the requirements of modern agriculture for environment-friendly and efficient fertilizer are met.

Description

Technical Field

[0001] The invention relates to the field of agricultural biotechnology, and in particular to a high-activity feather hydrolyzed amino acid water-soluble fertilizer and a preparation method thereof. Background Art

[0002] With the continuous development of agricultural technology, amino acid water-soluble fertilizers have been widely used in modern agriculture due to their easy absorption and crop growth-promoting properties. However, existing feather hydrolysis technologies often use strong acid / alkali treatments, which lead to amino acid racemization and loss of activity, affecting the fertilizer's effectiveness. In addition, commercially available amino acid fertilizers generally suffer from large molecular weights and low crop absorption rates, limiting their further promotion in high-efficiency agriculture. Therefore, the development of a highly active, low-molecular-weight feather hydrolyzed amino acid water-soluble fertilizer and its preparation method are of great significance.

[0003] Publication number CN110042129B discloses a method for preparing γ-polyglutamic acid for agricultural use. This patent prepares γ-polyglutamic acid through three steps: microbial fermentation, membrane filtration, and spray drying, simplifying post-processing and reducing production costs. However, this technical solution primarily focuses on the extraction and preparation of γ-polyglutamic acid and does not address how to maintain the high activity of amino acids during feather hydrolysis or control the molecular weight of the product. Furthermore, the membrane filtration process, primarily used for separating macromolecules, has a low retention rate for small peptides, making it difficult to meet the demand for highly efficient amino acid water-soluble fertilizers.

[0004] Publication number CN105367137B discloses a multi-element chelated fertilizer and a preparation method thereof. The patent provides a multi-element chelated fertilizer comprising p-hydroxyphenylglycine salt, which has a simple production process and low cost, and can be degraded by microorganisms in the soil. However, the core of this technical solution lies in the chelation of trace elements, rather than the extraction and activation of amino acids from feather hydrolysis. Its preparation process does not involve directed enzymatic hydrolysis technology, and cannot effectively solve the problem of amino acid racemization caused by the traditional strong acid / alkali method. At the same time, the molecular weight distribution of the fertilizer is relatively wide, and it fails to achieve effective enrichment of small molecule peptides, thereby limiting its application in high-efficiency agriculture.

[0005] The above problems indicate that the existing feather hydrolysis technology and amino acid fertilizer preparation methods still have certain shortcomings in retaining amino acid activity, controlling product molecular weight, and improving crop absorption rate. Summary of the Invention

[0006] In order to solve the above problems, the present invention proposes a highly active feather hydrolyzed amino acid water-soluble fertilizer and a preparation method thereof. By combining a composite enzyme step-by-step hydrolysis process, an activity protection system and green manufacturing technology, the activity of amino acids in feather hydrolyzates is significantly improved, and efficient enrichment of small molecule peptides is achieved, thereby meeting the demand of modern agriculture for efficient and environmentally friendly fertilizers.

[0007] To achieve the above object, the technical solution of the present invention is: A high-activity feather hydrolyzed amino acid water-soluble fertilizer is prepared by the following steps: Step (1) pretreatment of feather raw materials; Step (2) complex enzyme step hydrolysis; Step (3) nanofiltration separation; Step (4) chelation and stabilization; Step (5) spray drying.

[0008] Preferably, the feather raw material pretreatment comprises the following steps: Step 1.1, Cleaning and Shearing: Rinse 10 feathers three times with clean water to remove surface impurities, then rinse twice with 3% Na2CO3 solution to remove grease and blood stains, and then cut them into lengths ranging from 0.5 to 1 cm using a mechanical shearing device; Step 1.2, Penetrant Addition and Mixing: Place the sheared feather material into a mixing container, add 0.5-1 part of a nonionic surfactant as a penetrant, and simultaneously start a low-speed agitator at 100-200 rpm for 5-10 minutes to evenly distribute the penetrant. Step 1.3, antioxidant introduction and soaking: add 0.1-0.2 parts of antioxidant to the stirring container, continue stirring for 2-3 minutes, and then let it stand at room temperature for 30-60 minutes to complete the pretreatment process.

[0009] Preferably, the penetrant is alkyl polyglycoside (APG0810).

[0010] Preferably, the antioxidant is L-ascorbic acid or EDTA-2Na.

[0011] This pretreatment solution effectively improves the water absorption and chemical stability of feather raw materials through a combination of penetrant micropore construction and antioxidant free radical scavenging. The hydrophilic end of the penetrant adsorbs onto the feather surface, while the hydrophobic end embeds within the fiber, forming microporous channels that accelerate water diffusion. The antioxidant captures free radicals, inhibiting amino acid oxidation and reducing activity loss.

[0012] Preferably, the complex enzyme step hydrolysis comprises the following steps: Step 2.1, first stage hydrolysis: Place the pretreated feathers in a reactor, add 30-50 parts of deionized water, adjust the pH to 7.5-8.5, raise the temperature to 40-50°C, add 0.1-0.2 parts of keratinase, and start stirring at 300-500 rpm for 2-4 hours. The keratinase acts on the disulfide bonds and peptide bonds in the feathers, initially releasing amino acids and short peptides. Step 2.2, second stage hydrolysis: adjust the pH of the reaction system to 8.5-9.5, raise the temperature to 50-60°C, add 0.2-0.3 parts of alkaline protease, increase the stirring speed to 800-1000 rpm, and continue the reaction for 4-6 hours. The alkaline protease further decomposes the long-chain polypeptide to generate small molecule peptides and free amino acids.

[0013] The complex enzymatic stepwise hydrolysis process achieves efficient degradation of feather proteins through the synergistic action of a two-stage process: initial hydrolysis by keratinase followed by deep cleavage by alkaline protease. The first stage of hydrolysis primarily targets disulfide bonds and some peptide bonds in the feathers, generating high-molecular-weight polypeptide fragments. The second stage of hydrolysis further cleaves the polypeptide chains, generating small-molecule peptides and free amino acids, thereby reducing the molecular weight of the product.

[0014] Preferably, the nanofiltration separation comprises the following steps: Step 3.1: The hydrolyzate is passed through a nanofiltration membrane with a pore size of 200-500 Da, and separated at an operating pressure of 1-2 MPa and a flow rate of 5-10 L / min. The permeate is collected and the macromolecular substances are retained to obtain a concentrate rich in small molecular peptides; Step 3.2: The retentate was returned to the reactor and the above separation process was repeated 1-2 times to ensure that the recovery rate of the small molecule peptide was not less than 90%.

[0015] Nanofiltration separation achieves selective enrichment of small peptides by precisely controlling membrane pore size and operating conditions. Nanofiltration membranes with pore sizes of 200-500 Da can effectively retain large peptides and incompletely hydrolyzed proteins, while the permeate is enriched in small peptides with a molecular weight less than 500 Da and free amino acids, significantly improving the bioactivity and absorption efficiency of the product.

[0016] Preferably, the chelation and stabilization comprises the following steps: Step 4.1, preparing a trace element solution: dissolving zinc, iron, manganese, and copper sulfates in deionized water at a mass ratio of 1-2:0.5-1:0.3-0.5:0.3-0.5 to prepare a trace element solution with a concentration of 0.5-1%; Step 4.2, chelation reaction: slowly add 0.1-0.3 parts of the trace element solution to the concentrate, and simultaneously start the stirrer at 500-800 rpm for 5-10 minutes to allow the trace elements to chelate with the amino acids and small molecule peptides; Step 4.3, Stabilizer addition and pH adjustment: Add 0.05-0.1 parts of stabilizer to the system, continue stirring for 2-3 minutes, then adjust the pH to 5.5-6.5 with dilute hydrochloric acid or sodium hydroxide solution, and let it stand for 10-20 minutes to complete the stabilization process.

[0017] Preferably, the stabilizer is sodium polyaspartate (PASP).

[0018] Chelation and stabilization further enhance the product's bioactivity and storage stability. Chelates formed by trace elements with amino acids and small peptides have higher bioavailability, while stabilizers prevent product aggregation or precipitation during storage through intermolecular forces.

[0019] Preferably, the spray drying comprises the following steps: The chelating liquid is dried by spray drying equipment, with the air inlet temperature set at 150-180°C, the air outlet temperature set at 70-90°C, the atomization pressure set at 0.2-0.3MPa, and the feed rate at 5-10mL / min to obtain a powdered finished product with a particle size of 50-200μm.

[0020] Spray drying avoids thermal damage to amino acids and small molecule peptides caused by high temperatures by rapidly evaporating water, while obtaining evenly dispersed powdered products that are convenient for subsequent packaging and application.

[0021] Feathers are the primary raw material, selected from clean, mildew-free poultry feathers. To enhance hydrolysis efficiency and product activity, non-ionic surfactants and antioxidants are introduced during the pretreatment stage to improve the physical and chemical properties of the feathers through micropore formation and free radical scavenging, respectively. Simultaneously, a two-stage, synergistic enzymatic stepwise hydrolysis process achieves efficient degradation of feather proteins, generating small peptides and free amino acids.

[0022] To further enhance the product's biological activity, this solution incorporates trace element chelation technology. Zinc, iron, manganese, and copper ions in the trace element solution chelate with amino acids and small peptides to form stable chelates, significantly improving crop absorption of trace elements. Furthermore, the addition of stabilizers prevents product aggregation or precipitation during storage through intermolecular forces, extending the product's shelf life.

[0023] Nanofiltration separation technology uses nanofiltration membranes with pore sizes of 200-500Da. By precisely controlling operating conditions, it achieves the selective enrichment of small-molecule peptides. This technology not only increases the degree of product molecular weight reduction, but also significantly reduces the amount of residual macromolecules, thereby improving the biological activity of the fertilizer and crop absorption rate.

[0024] The present invention also utilizes a spray drying process to convert the liquid chelate solution into a powdered product. Spray drying rapidly evaporates water, avoiding heat damage to amino acids and small peptides caused by high temperatures, while also producing a uniformly dispersed powdered product that is convenient for subsequent packaging and application.

[0025] This proposal also proposes a method for preparing the above-mentioned high-activity feather hydrolyzed amino acid water-soluble fertilizer.

[0026] The working principle and beneficial effects of the present invention are: 1. Components: This solution utilizes a compound enzymatic step-by-step hydrolysis process to efficiently decompose feather proteins, generating small-molecule peptides and free amino acids. Trace element chelation further enhances the product's bioactivity and crop absorption efficiency. The addition of stabilizers prevents product aggregation or precipitation during storage through intermolecular forces, extending its shelf life. These three elements work synergistically to form a multi-level optimization system: compound enzymatic hydrolysis provides the foundation for small-molecule synthesis, trace element chelation enhances bioactivity, and stabilizers protect and extend storage time, significantly improving the fertilizer's overall performance.

[0027] 2. Process: This solution improves the physical and chemical properties of feather raw materials through pretreatment, while achieving efficient decomposition through a composite enzymatic step-by-step hydrolysis process. The nanofiltration separation process utilizes precisely controlled operating conditions to ensure the efficient enrichment of small-molecule peptides. The chelation and stabilization process further enhances the product's biological activity and storage stability through the dual effects of trace element chelation and stabilizer protection. The spray drying process rapidly evaporates water, avoiding heat damage and producing a uniformly dispersed powdered product. These processes precisely control the formation and assembly of the product, ensuring stable output of macroscopic properties. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example

[0029] A high-activity feather hydrolyzed amino acid water-soluble fertilizer is prepared by the following steps, calculated by weight: Step (1) Feather raw material pretreatment: Step 1.1, cleaning and cutting: Rinse 10 parts of feather raw materials with clean water three times, then rinse with 3% Na2CO3 solution twice, and then cut them into lengths ranging from 0.5 to 1 cm using a mechanical shearing device; Step 1.2, penetrant addition and mixing: Place the sheared feather material into a stirring container, add 0.5-1 parts of alkyl polyglycoside, and simultaneously start a low-speed stirrer at 100-200 rpm for 5-10 minutes; Step 1.3, introduction and soaking of antioxidants: Add 0.1-0.2 parts of L-ascorbic acid or EDTA-2Na to a stirring container, continue stirring for 2-3 minutes, and then let it stand at room temperature for 30-60 minutes to obtain pretreated feathers.

[0030] Step (2) complex enzyme step hydrolysis: Step 2.1, first stage hydrolysis: Place the pretreated feathers in a reactor, add 30-50 parts of deionized water, adjust the pH to 7.5-8.5, raise the temperature to 40-50°C, add 0.1-0.2 parts of keratinase, start the agitator at 300-500 rpm and stir for 2-4 hours; Step 2.2, second stage hydrolysis: adjust the pH of the reaction system to 8.5-9.5, raise the temperature to 50-60° C., add 0.2-0.3 parts of alkaline protease, increase the stirring speed to 800-1000 rpm, continue the reaction for 4-6 hours, and obtain a hydrolyzate.

[0031] Step (3) Nanofiltration separation: Step 3.1: The hydrolyzate is passed through a nanofiltration membrane with a pore size of 200-500 Da, and separated at an operating pressure of 1-2 MPa and a flow rate of 5-10 L / min. The permeate is collected and the macromolecular substances are retained to obtain a concentrate rich in small molecular peptides; Step 3.2: Return the retentate to the reactor and repeat the above separation process 1-2 times.

[0032] Step (4) Chelation and stabilization: Step 4.1, preparing a trace element solution: dissolving zinc, iron, manganese, and copper sulfates in deionized water at a mass ratio of 1-2:0.5-1:0.3-0.5:0.3-0.5 to prepare a trace element solution with a concentration of 0.5-1%; Step 4.2, chelation reaction: slowly add 0.1-0.3 parts of the trace element solution to the concentrate, and start the stirrer at 500-800 rpm for 5-10 minutes; Step 4.3, Stabilizer addition and pH adjustment: Add 0.05-0.1 parts of sodium polyaspartate to the system, continue stirring for 2-3 minutes, then adjust the pH to 5.5-6.5 with dilute hydrochloric acid or sodium hydroxide solution, and let it stand for 10-20 minutes to complete the stabilization process.

[0033] Step (5) spray drying: The chelating liquid is dried by spray drying equipment, with the air inlet temperature set at 150-180°C, the air outlet temperature set at 70-90°C, the atomization pressure set at 0.2-0.3MPa, and the feed rate at 5-10mL / min to obtain a powdered finished product with a particle size of 50-200μm.

[0034] Example 1: A high-activity feather hydrolyzed amino acid water-soluble fertilizer is prepared by the following steps, calculated by weight: Step (1) Feather raw material pretreatment: Step 1.1, cleaning and cutting: Rinse 10 parts of feather raw materials with clean water three times, rinse with 3% Na2CO3 solution twice, and then cut them into 0.8 cm using a mechanical shearing device; Step 1.2, penetrant addition and mixing: Place the sheared feather material into a stirring container, add 0.8 parts of alkyl polyglycoside, and simultaneously start a low-speed stirrer at 150 rpm for 8 minutes; Step 1.3, Antioxidant Introduction and Soaking: Add 0.15 parts of antioxidant (L-ascorbic acid: EDTA-2Na = 1:1) to a stirring container, continue stirring for 2.5 minutes, and then let it stand at room temperature for 45 minutes to obtain pretreated feathers; Step (2) complex enzyme step hydrolysis: Step 2.1, first stage hydrolysis: Place the pretreated feathers in a reactor, add 40 parts of deionized water, adjust the pH to 8, raise the temperature to 45°C, add 0.15 parts of keratinase, and start the agitator at 400 rpm for 3 hours; Step 2.2, second stage hydrolysis: adjust the pH of the reaction system to 9, raise the temperature to 55°C, add 0.25 parts of alkaline protease, increase the stirring speed to 900 rpm, and continue the reaction for 5 hours to obtain a hydrolyzate; Step (3) Nanofiltration separation: Step 3.1: The hydrolyzate was passed through a nanofiltration membrane with a pore size of 300 Da and separated at an operating pressure of 1.8 MPa and a flow rate of 7.5 L / min. The permeate was collected and the macromolecular substances were retained to obtain a concentrate rich in small molecular peptides; Step 3.2: The retentate was returned to the reactor and the above separation process was repeated twice; Step (4) Chelation and stabilization: Step 4.1, preparation of trace element solution: dissolve zinc, iron, manganese, and copper sulfates in deionized water at a mass ratio of 1.5:0.75:0.4:0.4 to prepare a solution with a concentration of 0.75%; Step 4.2, chelation reaction: slowly add 0.2 parts of the trace element solution to the concentrate, and start the stirrer at 650 rpm for 7.5 minutes; Step 4.3, Stabilizer Addition and pH Adjustment: Add 0.08 parts of sodium polyaspartate to the system and continue stirring for 2.5 minutes. Then adjust the pH to 6 with dilute hydrochloric acid or sodium hydroxide solution and let it stand for 15 minutes to complete the stabilization process. Step (5) spray drying: The chelating liquid was dried by spray drying equipment, with the inlet air temperature set at 170°C, the outlet air temperature set at 85°C, the atomization pressure set at 0.25 MPa, and the feed rate set at 7.5 mL / min to obtain a powdered finished product.

[0035] Example 2: A high-activity feather hydrolyzed amino acid water-soluble fertilizer is prepared by the following steps, calculated by weight: Step (1) Feather raw material pretreatment: Step 1.1, cleaning and cutting: Rinse 10 parts of feather raw materials with clean water three times, rinse with 3% Na2CO3 solution twice, and then cut them into 0.8 cm using a mechanical shearing device; Step 1.2, penetrant addition and mixing: Place the sheared feather material into a stirring container, add 0.5 parts of alkyl polyglycoside, and start a low-speed stirrer at 150 rpm for 8 minutes; Step 1.3, antioxidant introduction and soaking: 0.1 parts of EDTA-2Na were added to the stirring container, and the mixture was stirred for 2.5 minutes, and then allowed to stand at room temperature for 30 minutes to obtain pretreated feathers; Step (2) complex enzyme step hydrolysis: Step 2.1, first stage hydrolysis: Place the pretreated feathers in a reactor, add 40 parts of deionized water, adjust the pH to 8, raise the temperature to 45°C, add 0.1 parts of keratinase, and start the stirrer at 400 rpm for 3 hours; Step 2.2, second stage hydrolysis: adjust the pH of the reaction system to 8.5, raise the temperature to 5°C, add 0.2 parts of alkaline protease, increase the stirring speed to 900 rpm, and continue the reaction for 4 hours to obtain a hydrolyzate; Step (3) Nanofiltration separation: Step 3.1: The hydrolyzate was passed through a nanofiltration membrane with a pore size of 500 Da and separated under the conditions of an operating pressure of 1 MPa and a flow rate of 7.5 L / min. The permeate was collected and the macromolecular substances were retained to obtain a concentrate rich in small molecular peptides; Step 3.2: The retentate was returned to the reactor and the above separation process was repeated once; Step (4) Chelation and stabilization: Step 4.1, preparation of trace element solution: dissolve zinc, iron, manganese, and copper sulfates in deionized water at a mass ratio of 1:0.5:0.3:0.3 to prepare a solution with a concentration of 0.75%; Step 4.2, chelation reaction: slowly add 0.1 parts of the trace element solution to the concentrate, and start the stirrer at 650 rpm for 7.5 minutes; Step 4.3, Stabilizer Addition and pH Adjustment: Add 0.05 parts of sodium polyaspartate to the system and continue stirring for 2.5 minutes. Then adjust the pH to 5.5 with dilute hydrochloric acid or sodium hydroxide solution and let it stand for 15 minutes to complete the stabilization process. Step (5) spray drying: The chelating liquid was dried by spray drying equipment, with the inlet air temperature set at 150°C, the outlet air temperature set at 70°C, the atomization pressure set at 0.2 MPa, and the feed rate set at 7.5 mL / min to obtain a powdered finished product.

[0036] Example 3: A high-activity feather hydrolyzed amino acid water-soluble fertilizer is prepared by the following steps, calculated by weight: Step (1) Feather raw material pretreatment: Step 1.1, cleaning and cutting: Rinse 10 parts of feather raw materials with clean water three times, rinse with 3% Na2CO3 solution twice, and then cut them into 0.8 cm using a mechanical shearing device; Step 1.2, penetrant addition and mixing: Place the sheared feather material into a mixing container, add 1 part of alkyl polyglycoside, and start a low-speed stirrer at 150 rpm for 8 minutes; Step 1.3, antioxidant introduction and soaking: 0.2 parts of L-ascorbic acid were added to the stirring container, and the mixture was stirred for 2.5 minutes, and then allowed to stand at room temperature for 60 minutes to obtain pretreated feathers; Step (2) complex enzyme step hydrolysis: Step 2.1, first stage hydrolysis: Place the pretreated feathers in a reactor, add 40 parts of deionized water, adjust the pH to 8.5, raise the temperature to 50°C, add 0.2 parts of keratinase, and start the stirrer at 400 rpm for 4 hours; Step 2.2, second stage hydrolysis: adjust the pH of the reaction system to 9, raise the temperature to 60°C, add 0.3 parts of alkaline protease, increase the stirring speed to 900 rpm, and continue the reaction for 6 hours to obtain a hydrolyzate; Step (3) Nanofiltration separation: Step 3.1: The hydrolyzate was passed through a nanofiltration membrane with a pore size of 200 Da and separated under the conditions of an operating pressure of 2 MPa and a flow rate of 7.5 L / min. The permeate was collected and the macromolecular substances were retained to obtain a concentrate rich in small molecular peptides; Step 3.2: The retentate was returned to the reactor and the above separation process was repeated twice; Step (4) Chelation and stabilization: Step 4.1, preparation of trace element solution: dissolve zinc, iron, manganese, and copper sulfates in deionized water at a mass ratio of 2:1:0.5:0.5 to prepare a solution with a concentration of 0.75%; Step 4.2, chelation reaction: slowly add 0.3 parts of the trace element solution to the concentrate, and start the stirrer at 650 rpm for 7.5 minutes; Step 4.3, Stabilizer Addition and pH Adjustment: Add 0.1 parts of sodium polyaspartate to the system and continue stirring for 2.5 minutes. Then adjust the pH to 6.5 with dilute hydrochloric acid or sodium hydroxide solution and let it stand for 15 minutes to complete the stabilization process. Step (5) spray drying: The chelating liquid was dried by spray drying equipment, with the inlet air temperature set at 180°C, the outlet air temperature set at 90°C, the atomization pressure set at 0.3 MPa, and the feed rate set at 7.5 mL / min to obtain a powdered finished product.

[0037] Example 4: A high-activity feather hydrolyzed amino acid water-soluble fertilizer is prepared by the following steps, calculated by weight: Step (1) Feather raw material pretreatment: Step 1.1, cleaning and cutting: Rinse 10 parts of feather raw materials with clean water three times, rinse with 3% Na2CO3 solution twice, and then cut them into 0.8 cm using a mechanical shearing device; Step 1.2, penetrant addition and mixing: Place the sheared feather material into a stirring container, add 0.5 parts of alkyl polyglycoside, and start a low-speed stirrer at 150 rpm for 8 minutes; Step 1.3, antioxidant introduction and soaking: Add 0.1 parts of antioxidant (L-ascorbic acid: EDTA-2Na = 1:3) to the stirring container, continue stirring for 2.5 minutes, and then let it stand at room temperature for 30 minutes to obtain pretreated feathers; Step (2) complex enzyme step hydrolysis: Step 2.1, first stage hydrolysis: Place the pretreated feathers in a reactor, add 40 parts of deionized water, adjust the pH to 8, raise the temperature to 45°C, add 0.1 parts of keratinase, and start the stirrer at 400 rpm for 2.5 hours; Step 2.2, second stage hydrolysis: adjust the pH of the reaction system to 8.5, raise the temperature to 55°C, add 0.2 parts of alkaline protease, increase the stirring speed to 900 rpm, and continue the reaction for 3.5 hours to obtain a hydrolyzate; Step (3) Nanofiltration separation: The hydrolyzate was passed through a nanofiltration membrane with a pore size of 500Da and separated under the conditions of an operating pressure of 1MPa and a flow rate of 7.5L / min. The permeate was collected and the macromolecular substances were retained to obtain a concentrate rich in small molecular peptides. The retained liquid was refluxed into the reactor and the above separation process was repeated once. Step (4) Chelation and stabilization: Step 4.1, preparation of trace element solution: dissolve zinc, iron, manganese, and copper sulfates in deionized water at a mass ratio of 1:0.5:0.3:0.3 to prepare a solution with a concentration of 0.75%; Step 4.2, chelation reaction: slowly add 0.15 parts of the trace element solution to the concentrate while starting the stirrer at 650 rpm for 7.5 minutes; Step 4.3, Stabilizer Addition and pH Adjustment: Add 0.05 parts of sodium polyaspartate to the system and continue stirring for 2.5 minutes. Then adjust the pH to 5.5 with dilute hydrochloric acid or sodium hydroxide solution and let it stand for 15 minutes to complete the stabilization process. Step (5) spray drying: The chelating liquid was dried by spray drying equipment, with the inlet air temperature set at 160°C, the outlet air temperature set at 75°C, the atomization pressure set at 0.2 MPa, and the feed rate set at 7.5 mL / min to obtain a powdered finished product.

[0038] Example 5: A high-activity feather hydrolyzed amino acid water-soluble fertilizer is prepared by the following steps, calculated by weight: Step (1) Feather raw material pretreatment: Step 1.1, cleaning and cutting: Rinse 10 parts of feather raw materials with clean water three times, rinse with 3% Na2CO3 solution twice, and then cut them into 0.8 cm using a mechanical shearing device; Step 1.2, penetrant addition and mixing: Place the sheared feather material into a mixing container, add 1 part of alkyl polyglycoside, and start a low-speed stirrer at 150 rpm for 8 minutes; Step 1.3, Antioxidant Introduction and Soaking: Add 0.2 parts of antioxidant (L-ascorbic acid: EDTA-2Na = 3:1) to a stirring container, continue stirring for 2.5 minutes, and then let it stand at room temperature for 60 minutes to obtain pretreated feathers; Step (2) complex enzyme step hydrolysis: Step 2.1, first stage hydrolysis: Place the pretreated feathers in a reactor, add 40 parts of deionized water, adjust the pH to 8.5, raise the temperature to 55°C, add 0.2 parts of keratinase, and start the stirrer at 400 rpm for 3.5 hours; Step 2.2, second stage hydrolysis: adjust the pH of the reaction system to 9, raise the temperature to 60°C, add 0.3 parts of alkaline protease, increase the stirring speed to 900 rpm, and continue the reaction for 5.5 hours to obtain a hydrolyzate; Step (3) Nanofiltration separation: The hydrolyzate was passed through a nanofiltration membrane with a pore size of 200 Da and separated under the conditions of an operating pressure of 2 MPa and a flow rate of 7.5 L / min. The permeate was collected and the macromolecular substances were retained to obtain a concentrate rich in small molecular peptides. The retained liquid was refluxed into the reactor and the above separation process was repeated twice; Step (4) Chelation and stabilization: Step 4.1, preparation of trace element solution: dissolve zinc, iron, manganese, and copper sulfates in deionized water at a mass ratio of 2:1:0.5:0.5 to prepare a solution with a concentration of 0.75%; Step 4.2, chelation reaction: slowly add 0.25 parts of the trace element solution to the concentrate while starting the stirrer at 650 rpm for 7.5 minutes; Step 4.3, Stabilizer Addition and pH Adjustment: Add 0.1 parts of sodium polyaspartate to the system and continue stirring for 2.5 minutes. Then adjust the pH to 6.5 with dilute hydrochloric acid or sodium hydroxide solution and let it stand for 15 minutes to complete the stabilization process. Step (5) spray drying: The chelating liquid was dried by spray drying equipment, with the inlet air temperature set to 175°C, the outlet air temperature set to 90°C, the atomization pressure set to 0.3 MPa, and the feed rate set to 7.5 mL / min to obtain a powdered finished product.

[0039] Comparative Example 1 The difference from Example 1 is that the feather pretreatment is only rinsing with sodium carbonate, without pretreatment with a penetrant.

[0040] Comparative Example 2 The difference from Example 1 is that only alkaline protease is used in the single-enzyme hydrolysis.

[0041] Comparative Example 3 The difference from Example 1 is that the spray drying temperature is increased, and the parameters are set to 220°C for inlet air and 120°C for outlet air.

[0042] Comparative Example 4 The difference from Example 1 is that the nanofiltration separation is replaced by vacuum concentration at 60° C. to a solid content of 25%.

[0043] Comparative Example 5 The difference from Example 1 is that only keratinase is used for single-enzyme hydrolysis.

[0044] Comparative Example 6 The difference from Example 1 is that the penetrant is added in excess, 1.2 parts.

[0045] Comparative Example 7 The difference from Example 1 is that the sulfates of zinc, iron, manganese and copper are dissolved in deionized water at a mass ratio of 0.8:0.8:0.6:0.3.

[0046] Comparative Example 8 The difference from Example 1 is that 0.15 parts of sodium polyaspartate is added to the system.

[0047] Comparative Example 9 The difference from Example 1 is that, in step 4.3, the pH is adjusted to 7.

[0048] Comparative Example 10 The difference from Example 1 is that, in step 4.3, the pH is adjusted to 5.

[0049] Comparative Example 11 The difference from Example 1 is that no trace element solution is added.

[0050] Comparative Example 12 The difference from Example 1 is that, in step 4.2, chelation reaction: 0.35 parts of the trace element solution is slowly added to the concentrated solution.

[0051] Comparative Example 13 The difference from Example 1 is that 0.12 parts of sodium polyaspartate is added to the system.

[0052] Comparative Example 14 The difference from Example 1 is that sodium polyaspartate is not added to the system.

[0053] Performance testing method: Small molecule peptide (<500Da) content: Protein purity was determined using SEC-HPLC.

[0054] Free amino acid content: The free amino acid content was determined by ninhydrin colorimetry.

[0055] Foliar absorption rate: using N 15 Isotope tracer method, N 15 The isotope enrichment rate of leaves was measured 24 hours after spraying labeled amino acids.

[0056] The test results are shown in Table 1.

[0057] Table 1 Performance test results of the embodiments and comparative examples

[0058]

[0059] The significant advantages of the high-activity feather hydrolyzed amino acid water-soluble fertilizer of the embodiment of the present invention in terms of small molecule peptide content, free amino acid content and foliar absorption rate are due to the synergistic optimization of its pretreatment-enzymatic hydrolysis-separation-chelation-drying process: in the pretreatment stage, 0.8 parts of alkyl polysaccharide are used as non-ionic penetrants to construct microporous channels by adsorbing the hydrophilic end on the feather surface and embedding the hydrophobic end into the fiber interior, which significantly improves the water absorption of the feathers, and the water absorption rate is increased from the traditional 30% to more than 60%. In combination with 0.15 parts of L-ascorbic acid, free radicals are scavenged and amino acid oxidation is inhibited (the oxidation rate is reduced from the traditional 15-20% to <5%), creating an ideal environment with easy penetration and low oxidation for subsequent enzymatic hydrolysis; in the complex enzyme ladder hydrolysis, keratinase first specifically destroys the disulfide bonds and some β-folded peptide bonds that account for 25% of the feather keratin to generate large molecular polypeptide fragments (50 The two stages synergistically increase the production rate of small-molecule peptides (<500Da) from 30% in traditional enzymatic hydrolysis to 92.3%; nanofiltration separation (200-500Da membrane) accurately intercepts large molecular impurities (retention rate >95%), enriches small-molecule peptides, and significantly reduces absorption barriers; in the chelation and stabilization stage, zinc, iron, manganese, and copper sulfate form stable chelates with amino acids / small-molecule peptides in a ratio of 1.5:0.75:0.4:0.4 (bioavailability is 2-3 times higher than that of inorganic salts), and 0.08 parts of sodium polyaspartate (PASP) are added to prevent aggregation and precipitation through intermolecular forces; low-temperature spray drying quickly evaporates water to avoid high-temperature damage, ultimately forming a highly active, small-molecule, and easily absorbed high-quality fertilizer.

[0060] The performance disadvantages of each comparative example compared with Example 1 are essentially due to the lack of key processes or components / imbalance that destroys the collaborative optimization system of the entire process: Comparative Example 1 lacks microporous construction, the contact between the enzyme and the feather fiber is hindered, the hydrolysis efficiency is reduced, and insufficient antioxidants lead to increased oxidation losses; Comparative Example 2 lacks keratinase to destroy the disulfide bond, the long peptide chain cannot be effectively cleaved, the small molecule peptide is 54.1%, and the incomplete hydrolysis leads to low free amino acids and absorption rate; Comparative Example 3 destroys the active structure of amino acids and small molecule peptides due to the high temperature of 220 ° C, the oxidation loss is aggravated, the free amino acid is 27.3%, and the absorption rate is greatly reduced; In Example 4, due to the inability to selectively enrich small molecule peptides, large molecular impurities remained and hindered absorption; in Comparative Example 5 (only keratinase), due to the lack of deep cleavage by alkaline protease, the amount of small molecule peptides produced was still lower than that of Example 1 with dual enzyme synergy; in Comparative Example 6, the amount of penetrant was excessive, the viscosity of the solution increased, the diffusion rate of the enzyme and substrate decreased, and the absorption rate decreased slightly; in Comparative Example 7, the ratio of trace elements was unbalanced, the ratio of zinc and iron was too high (0.8:0.8), and the ratio of manganese and copper was too low (0.6:0.3), the chelation was incomplete and the stability decreased, and the absorption rate decreased; in Comparative Example 8, the amount of stabilizer was excessive, forming steric hindrance that prevented the components from contacting with the plant, and the absorption rate decreased; in Comparative Example 9, the amount of stabilizer was excessive, forming steric hindrance that prevented the components from contacting with the plant, and the absorption rate decreased. The pH value of 7 deviates from the optimal chelation range, the amino acid carboxyl group dissociates less (pKa≈2-3), the chelation ability is weak, and the absorption rate is reduced; the pH value of comparative example 10 is 5, which is excessively dissociated, and the amino acid carboxyl group dissociates excessively (-COO⁻) to form insoluble salts, resulting in loss of effective ingredients; comparative example 11 lacks chelation supplementation of essential trace elements such as zinc, iron, manganese, and copper, and the fertilizer contains only free amino acids and small molecule peptides, which cannot meet the plant's demand for comprehensive nutrients; comparative example 12 has an excess of 0.35 parts of trace elements, the chelate is unstable, precipitates or inactivates, and the absorption rate decreases; comparative example 13 has insufficient stabilizer, the components are easily aggregated and precipitated, and the storage stability is poor; comparative example 14 has no stabilizer, aggregation and precipitation are serious, and effective ingredients are lost. In summary, each comparative example destroys the synergistic optimization system of pretreatment-enzymatic hydrolysis-separation-chelation-drying due to the lack / imbalance of key processes or components, resulting in a comprehensive performance significantly lower than that of Example 1.

Claims

1. A high-activity feather hydrolyzed amino acid water-soluble fertilizer, characterized in that: By mass, it is prepared by the following steps: Step (1) Feather raw material pretreatment: Step 1.1, cleaning and cutting; Step 1.2, penetrant addition and mixing: Place the sheared feather material into a mixing container, add 0.5-1 parts of alkyl polysaccharide, and stir evenly; Step 1.3, antioxidant introduction and soaking: add 0.1-0.2 parts of antioxidant to the stirring container, continue stirring for 2-3 minutes, and then stand at room temperature for 30-60 minutes to obtain pretreated feathers; Step (2) complex enzyme step hydrolysis: Step 2.1, first stage hydrolysis: Place the pretreated feathers in a reactor, add 30-50 parts of deionized water, adjust the pH to 7.5-8.5, raise the temperature to 40-50°C, add 0.1-0.2 parts of keratinase, and stir the reaction for 2-4 hours; Step 2.2, second stage hydrolysis: adjust the pH of the reaction system to 8.5-9.5, raise the temperature to 50-60°C, add 0.2-0.3 parts of alkaline protease, and react at high speed stirring for 4-6 hours to obtain a hydrolyzate; Step (3) Nanofiltration separation: Step 3.1: The hydrolyzate is passed through a nanofiltration membrane with a pore size of 200-500 Da to obtain a concentrate rich in small molecular peptides; Step 3.2: Return the retentate to the reactor and repeat the above separation process 1-2 times; Step (4) Chelation and stabilization: Step 4.1, preparing a trace element solution: dissolving zinc, iron, manganese, and copper sulfates in deionized water at a mass ratio of 1-2:0.5-1:0.3-0.5:0.3-0.5 to prepare a trace element solution with a concentration of 0.5-1%; Step 4.2, chelation reaction: slowly add 0.1-0.3 parts of the trace element solution to the concentrate and stir to homogenize; Step 4.3, Stabilizer Addition and pH Adjustment: Add 0.05-0.1 parts of sodium polyaspartate to the system, continue stirring for 2-3 minutes, then adjust the pH to 5.5-6.5, and let it stand for 10-20 minutes to complete the stabilization process; Step (5) spray drying: The chelating liquid is dried by spray drying equipment, with the air inlet temperature set at 150-180°C, the air outlet temperature set at 70-90°C, the atomization pressure set at 0.2-0.3MPa, and the feed rate at 5-10mL / min to obtain a powdered finished product with a particle size of 50-200μm.

2. The highly active feather hydrolyzed amino acid water-soluble fertilizer according to claim 1, wherein In step 1.1, the cleaning and shearing process is as follows: 10 parts of the feather raw material are rinsed with clean water three times, then rinsed twice with a 3% Na2CO3 solution, and then cut into lengths ranging from 0.5 to 1 cm using a mechanical shearing device. In step 1.2, the specific process for uniform stirring is: stirring at 100 to 200 rpm for 5 to 10 minutes.

3. The highly active feather hydrolyzed amino acid water-soluble fertilizer according to claim 1, wherein The antioxidant in step 1.3 is L-ascorbic acid or EDTA-2Na.

4. The highly active feather hydrolyzed amino acid water-soluble fertilizer according to claim 1, wherein In step 2.1, the rotation speed of the stirring reaction is 300-500 rpm; in step 2.2, the rotation speed of the high-speed stirring reaction is 800-1000 rpm.

5. The highly active feather hydrolyzed amino acid water-soluble fertilizer according to claim 1, characterized in that: In step 3.1, the hydrolyzate is passed through a nanofiltration membrane with a pore size of 200-500 Da at an operating pressure of 1-2 MPa and a hydrolyzate flow rate of 5-10 L / min.

6. The highly active feather hydrolyzed amino acid water-soluble fertilizer according to claim 1, characterized in that: In step 4.2, the stirring rate of the homogenization is 500-800 revolutions per minute, and the stirring time is 5-10 minutes; in step 4.3, dilute hydrochloric acid or sodium hydroxide solution is used to adjust the pH.

7. A high-activity feather hydrolyzed amino acid water-soluble fertilizer prepared by the method for preparing the high-activity feather hydrolyzed amino acid water-soluble fertilizer according to any one of claims 1 to 6.

8. The water-soluble fertilizer according to claim 7, characterized in that The content of small molecule peptides with a molecular weight of less than 500 Da in the fertilizer accounts for more than 85% of the total protein content, and the content of free amino acids is not less than 30%.

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