Method for degrading kitchen waste protein through mechanochemical enzyme coupling

Abstract

The invention discloses a method for degrading kitchen waste protein through mechanochemical enzyme coupling, which comprises the following steps: mixing a kitchen waste stock solution with a solid-phase reagent, putting the mixture into a polytetrafluoroethylene ball mill, adding stainless steel beads, setting the rotating speed of the ball mill to be 100-500rpm, carrying out a grinding reaction for 6-12 cycles, and filtering to remove residues after the ball-milling reaction is finished, the kitchen waste protein degradation liquid is obtained. The method has the advantages of short process route, less reagent dosage, simplicity in operation, low cost, less pollution, high protein degradation rate, large amount of obtained amino acid, good degradation efficiency and the like, can be used as a fertilizer to better promote plant growth, and is a technology with relatively good popularization and application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of protein degradation, and in particular to a method for degrading kitchen waste protein by mechanical chemical enzyme coupling. Background Art

[0002] As a byproduct of the food industry and catering industry, kitchen waste protein has huge economic and environmental potential, but its degradation and high-value utilization face many challenges. Compared with the mature applications of hemicellulose and cellulose, the utilization rate of kitchen waste protein is low, mainly limited by its complex molecular structure and difficulty in degradation. The stability of the peptide bond and tertiary structure of proteins, as well as certain natural antibacterial activities, increase the complexity of the degradation process and require specific enzymes or chemical methods. At present, protein degradation technology is gradually developing, including enzymatic degradation and chemical catalytic degradation. Enzymatic degradation is favored for its environmental friendliness and high efficiency. Through the use of specific proteases, such as trypsin and papain, proteins can be effectively degraded to generate amino acids and small peptides. Chemical catalytic degradation achieves peptide bond cleavage under mild conditions by using metal-based catalysts, such as catalysts derived from metal-organic frameworks (MOFs), to generate high-value-added amino acids and peptides. However, cost control, product selectivity and large-scale production are still bottlenecks for the degradation and resource utilization of kitchen waste protein. Future research will focus on developing more efficient and economical degradation technologies, combining the advantages of enzyme engineering, chemical catalysis and biotechnology to achieve high-value utilization of kitchen waste protein and promote its sustainability and economic value. Through these efforts, kitchen waste protein will be transformed from waste into a valuable resource, bringing new development opportunities to the fields of food, medicine, and chemical industry.

[0003] The study revealed that although there are many types of proteins in kitchen waste, their complex structures are rich in a large number of peptide bonds. They constitute the protein skeleton structure and are also the key to protein chemical degradation. Therefore, it is crucial to use appropriate methods to achieve sufficient hydrolysis and even targeted cleavage of peptide bonds for the full conversion of kitchen waste into amino acids. At present, many biological or chemical methods have been used in protein degradation. For example, Khan et al. used papain as a catalyst to achieve side chain oxidation and peptide bond cleavage of proteins through hydrolysis. Studies have found that under suitable pH and temperature conditions, the side chains of proteins undergo oxidative cleavage under the action of enzymes and are directly degraded into amino acids and small peptides. Li et al. used hydrogen peroxide as an oxidant to achieve side chain oxidation and structural cleavage of proteins through chemical oxidation. The experimental results show that the side chains of proteins undergo oxidative cleavage under the action of oxidants and are degraded into a series of oxygen-containing derivatives, such as the oxidation products of amino acids and the oxidative cleavage products of peptides; Zhang et al. used copper ions as a catalyst to achieve side chain oxidation and peptide bond cleavage of proteins through air oxidation. The study found that the side chains of proteins undergo oxidative cleavage under metal catalysis and directly degrade into amino acids and their derivatives, as well as oxidative cleavage products of some peptides; Wang et al. used photocatalytic technology, using titanium dioxide as a photocatalyst, and achieved protein side chain oxidation and peptide bond cleavage through ultraviolet light irradiation. The experimental results showed that the side chains of proteins undergo oxidative cleavage under photocatalysis and degrade into amino acids, peptides and a series of oxidation products; Liu et al. used specific microbial strains to achieve protein side chain oxidation and peptide bond cleavage through biodegradation. The study found that the side chains of proteins undergo oxidative cleavage under the action of microorganisms and degrade into amino acids, small peptides and some microbial metabolites, demonstrating the potential of biodegradation in protein degradation.

[0004] Through the comparison and analysis of the above studies, it can be found that both chemical methods and biological degradation face certain problems. First of all, chemical degradation is efficient and fast, but it usually requires a large amount of inorganic reagents and produces a large amount of saline waste liquid. For agricultural reuse, inorganic salts have a great impact on crop growth, which makes the product difficult to use. Compared with chemical explanations, enzyme degradation and bacterial degradation of protein have less pollution, but the price of efficient enzyme catalysts is too high, and the use of bacterial degradation is difficult to avoid the consumption of amino acids by bacteria, and the biodegradation reaction time is very long, which seriously affects production. In short, the core of the current degradation and reuse of kitchen waste protein is to introduce an efficient, convenient and low-cost reaction intensification technology that combines the advantages of biodegradation and chemical degradation technologies.

[0005] In recent years, mechanochemistry, as a reaction optimization technology, has been favored by the industrial field due to its unique reaction mechanism, higher yield and selectivity, and the convenience of solvent-free and micro-solvent reactions. Many metal-catalyzed reactions that originally required long-term high temperature and a large amount of high-boiling organic solvents can be carried out efficiently at room temperature, and the yield and selectivity of the reaction are even higher, and even raw materials that cannot be used in solution reactions can be used. Especially for chemical reactions between insoluble macromolecules, mechanochemistry can ignore the choice of solvent and directly promote various reactions such as complexation, neutralization, degradation, and grafting of macromolecules in the solid phase. At present, it has been widely used in the processing of polymers such as cellulose, pectin, lignin, cyclodextrin and cucurbituril. However, the use of mechanochemistry in protein degradation is still blank. Therefore, the mechanism of mechanochemistry to promote solid-phase reactions between polymers, strengthen the protein decomposition process, reduce wastewater pressure and ensure sufficient protein degradation can more fully realize the efficient degradation and resource utilization of kitchen waste protein. Summary of the invention

[0006] In view of the above problems, the purpose of the present invention is to overcome the problems existing in the existing protein degradation process, such as large amount of chemical reagents, high reaction temperature, long reaction time, complicated process, etc., and to provide a simple, efficient and environmentally friendly method for degrading kitchen waste protein by mechanochemical enzyme coupling. Based on the advantage of mechanochemistry in promoting polymer reactions, protein peptide bonds are activated through mechanochemical treatment, protein hydrolysis is promoted while preventing secondary damage to the produced amino acids, thereby overcoming the problem of poor degradation ability of kitchen waste protein.

[0007] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions: A method for degrading kitchen waste protein by mechanical chemical enzyme coupling comprises the following steps: taking a kitchen waste stock solution and mixing it with a solid phase reagent and placing it in a polytetrafluoroethylene ball mill, adding stainless steel beads, setting the ball mill speed to 100-500 rpm, performing a grinding reaction, and the grinding cycle is 6-12 cycles. After the ball milling reaction is completed, filtering to remove the residue, so as to obtain a kitchen waste protein degradation liquid.

[0008] In some of the embodiments, the mass ratio of the kitchen waste liquid to the solid phase reagent is 100:(5-12).

[0009] In some embodiments, the solid phase reagent includes an alkaline reagent and an enzyme reagent, wherein the alkaline reagent includes at least one of sodium bicarbonate, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, and urea; and the enzyme reagent includes at least one of alkaline protease, neutral protease, and papain. The alkaline protease is derived from Bacillus subtilis, Uniprot ID: P00782; the neutral protease is derived from Bacillus subtilis, Uniprot ID: P39899; and the papain is derived from papaya, Uniprot ID: P00784.

[0010] In some embodiments, the mass ratio of the alkaline reagent to the enzyme reagent is 10:(0.1-3).

[0011] In some embodiments, the diameter of the stainless steel bead is 14 mm.

[0012] In some embodiments, the grinding cycle is 6-12 cycles, specifically: grinding for 30 minutes as one cycle, resting for 5 minutes, and grinding for a total of 6-12 cycles.

[0013] In some embodiments, the ball mill rotates at 400 rpm.

[0014] In some embodiments, the grinding cycle is 10 cycles.

[0015] Compared with the prior art, the method of mechanochemical enzyme coupling for degrading kitchen waste protein of the present invention has the following beneficial effects: (1) The use of mechanical ball milling reaction and enzyme combination to degrade kitchen waste has simple operation, short process route and short degradation time.

[0016] (2) Compared with traditional methods, mechanical ball milling to assist in the degradation of kitchen waste protein can greatly reduce the use of chemical reagents, lower production costs, and alleviate environmental pollution.

[0017] (3) The degradation process takes place at room temperature, the conditions are mild and the rate is much higher than that of simple enzymatic hydrolysis.

[0018] (4) The loss of amino acids obtained is low, and the product is highly effective as a fertilizer.

[0019] In summary, the present invention has the advantages of short process route, small amount of reagents, simple operation, low cost, less pollution, high protein degradation rate, large amount of amino acids, good degradation efficiency, etc. It is an efficient protein degradation technology. It can also be used as a fertilizer to better promote plant growth, and is a technology with good promotion and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1Effect of the amount of solid phase reagent added on the degradation rate of kitchen waste protein.

[0021] Figure 2 It is the effect of ball mill speed on the degradation rate of kitchen waste protein.

[0022] Figure 3 It is the effect of ball milling cycle on the degradation rate of kitchen waste protein.

[0023] Figure 4 This is the free amino acid analysis chart of kitchen waste protein degradation products.

[0024] Figure 5 These are TEM images of food waste before and after degradation.

[0025] Figure 6 It is the effect of the degradation solution on the plant height and biological quality of Arabidopsis thaliana. DETAILED DESCRIPTION

[0026] The present invention is described in detail below in conjunction with specific embodiments.

[0027] Method for determining the protein content of kitchen waste stock solution: The protein content of the solution was determined by the BCA method using a kit. Bovine serum albumin was used as the standard. 2g of bovine serum albumin was accurately weighed and diluted to 100mL as a 20g / L protein standard stock solution. 10, 6, 4, 2, and 1ml of the standard solution were measured and diluted to 100mL to obtain a series of standard solutions. 50 parts of BCA reagent A were mixed with 1 part of BCA reagent B (the ratio of reagent A to reagent B = 50:1) to obtain a green clear working solution. Take 25uL of each diluted protein standard, add it to the microplate, and add 200uL of working solution to each well, and shake it on an oscillator for 30 seconds to mix it thoroughly. Incubate at 37℃ for 30 minutes. Cool to room temperature. Measure the absorbance of the sample at 562nm. Repeat the measurement three times for the same sample. Plot the average absorbance of the standard at 562nm after blank correction against its concentration (g / L) to obtain a standard curve for protein content. Take 10 mL of the sample to be tested, make up to 100 mL, measure according to the above method, and calculate the protein concentration of the sample according to the absorbance.

[0028] Determination of free amino acid content in degradation solution: The method and principle of amino acid analyzer for determining free amino acids are as follows: First, the treated sample is centrifuged (8000g, 10min), and then the sample is filtered through a 0.22μm filter membrane. The sample is then separated using a cation exchange column (Na+ type cation exchange column). This process uses the structural differences, acidity, polarity and molecular size of amino acids to separate them on the cation exchange column. Next, the separated individual amino acid components react with ninhydrin reagent to generate purple or yellow compounds. Derivatizing agents include o-phthalaldehyde (OPA), dinitrofluorobenzene (FDNB), 9-fluorenylmethyl chloroformate (FMOC) and phenyl isothiocyanate (PITC). The generated compounds are then photometrically determined at a specific wavelength. Proline is detected at a wavelength of 440nm, and other amino acids are detected at a wavelength of 570nm. The content of each amino acid is calculated using the internal standard method, and the sum is used to obtain the total free amino acid content. The final results are usually analyzed and processed by the amino acid analyzer's built-in software (EZChrom Elite).

[0029] Protein content determination and degradation rate determination method: Degradation rate (%g / g) = (protein content of degradation solution - total amount of amino acids in degradation solution) / (protein before degradation - total amount of amino acids before degradation) Example 1

[0030] A method for degrading kitchen waste protein by mechanical chemical enzyme coupling, comprising the following steps: adding 100 mL of kitchen waste stock solution, 10 g of sodium carbonate, 1 g of alkaline protease, and 6 stainless steel beads with a diameter of 14 mm to a 250 mL polytetrafluoroethylene ball mill, grinding and reacting in the ball mill at 400 rpm, 30 minutes as a cycle, 5 minutes of rest, and 10 cycles of grinding. After ball milling, the ball mill is centrifuged and separated, and the protein content and amino acid content of the degradation liquid are determined. The degradation rate of kitchen waste protein after degradation in this embodiment is 94.32%, and the amino acid content reaches 9.82 g / L. Example 2

[0031] A method for degrading kitchen waste protein by mechanical chemical enzyme coupling, comprising the following steps: adding 100 mL of kitchen waste stock solution, 10 g of sodium bicarbonate, 1 g of alkaline protease, and 6 stainless steel beads with a diameter of 14 mm to a 250 mL polytetrafluoroethylene ball mill, grinding and reacting in the ball mill at 400 rpm, 30 minutes as a cycle, 5 minutes of rest, and 10 cycles of grinding. After ball milling, the ball mill is centrifuged and separated, and the protein content and amino acid content of the degradation liquid are determined. The degradation rate of kitchen waste protein after degradation in this embodiment is 85.51%, and the amino acid content reaches 8.36 g / L. Example 3

[0032] A method for degrading kitchen waste protein by mechanical chemical enzyme coupling, comprising the following steps: adding 100 mL of kitchen waste stock solution, 10 g of sodium hydroxide, 1 g of alkaline protease, and 6 stainless steel beads with a diameter of 14 mm to a 250 mL polytetrafluoroethylene ball mill, grinding the reaction in the ball mill at 400 rpm, 30 minutes as a cycle, 5 minutes of rest, and 10 cycles of grinding. After ball milling, the ball mill is centrifuged and separated, and the protein content and amino acid content of the degradation liquid are determined. The degradation rate of kitchen waste protein after degradation in this embodiment is 88.31%, and the amino acid content reaches 7.99 g / L. Example 4

[0033] A method for degrading kitchen waste protein by mechanical chemical enzyme coupling, comprising the following steps: adding 100 mL of kitchen waste stock solution, 10 g of potassium carbonate, 1 g of alkaline protease, and 6 stainless steel beads with a diameter of 14 mm to a 250 mL polytetrafluoroethylene ball mill, grinding and reacting in the ball mill at 400 rpm, 30 minutes as a cycle, 5 minutes of rest, and 10 cycles of grinding. After ball milling, the ball mill is centrifuged and separated, and the protein content and amino acid content of the degradation liquid are determined. The degradation rate of kitchen waste protein after degradation in this embodiment is 95.53%, and the amino acid content reaches 11.34 g / L. Example 5

[0034] A method for degrading kitchen waste protein by mechanical chemical enzyme coupling, comprising the following steps: adding 100 mL of kitchen waste stock solution, 10 g of potassium hydroxide, 1 g of alkaline protease, and 6 stainless steel beads with a diameter of 14 mm to a 250 mL polytetrafluoroethylene ball mill, grinding and reacting in the ball mill at 400 rpm, 30 minutes as a cycle, 5 minutes of rest, and 10 cycles of grinding. After ball milling, the ball mill is centrifuged and separated, and the protein content and amino acid content of the degradation liquid are determined. The degradation rate of kitchen waste protein after degradation in this embodiment is 74.19%, and the amino acid content reaches 7.30 g / L. Example 6

[0035] A method for degrading kitchen waste protein by mechanical chemical enzyme coupling, comprising the following steps: adding 100 mL of kitchen waste stock solution, 10 g of potassium carbonate, 1 g of neutral protease, and 6 stainless steel beads with a diameter of 14 mm to a 250 mL polytetrafluoroethylene ball mill, grinding and reacting in the ball mill at 400 rpm, 30 minutes as a cycle, 5 minutes of rest, and 10 cycles of grinding. After ball milling, the ball mill is centrifuged and separated, and the protein content and amino acid content of the degradation liquid are determined. The degradation rate of kitchen waste protein after degradation in this embodiment is 72.37%, and the amino acid content reaches 7.38 g / L. Example 7

[0036] A method for mechanochemical enzyme coupling degradation of kitchen waste protein, comprising the following steps: adding 100 mL of kitchen waste stock solution, 10 g of potassium carbonate, 1 g of papain, and 6 stainless steel beads with a diameter of 14 mm to a 250 mL polytetrafluoroethylene ball mill, grinding and reacting in the ball mill at 400 rpm, 30 minutes as a cycle, 5 minutes of rest, and 10 cycles of grinding. After ball milling, the ball mill is centrifuged and separated, and the protein content and amino acid content of the degradation liquid are determined. The degradation rate of kitchen waste protein after degradation in this embodiment is 73.52%, and the amino acid content reaches 7.79 g / L. Example 8

[0037] A method for degrading kitchen waste protein by mechanical chemical enzyme coupling, comprising the following steps: adding 100 mL of kitchen waste stock solution, 10 g of potassium carbonate, 0.5 g of alkaline protease, and 6 stainless steel beads with a diameter of 14 mm to a 250 mL polytetrafluoroethylene ball mill, grinding and reacting at 300 rpm, 30 minutes as a cycle, 5 minutes of rest, and 10 cycles of grinding. After ball milling, the ball mill is centrifuged and separated, and the protein content and amino acid content of the degradation liquid are determined. The degradation rate of kitchen waste protein after degradation in this embodiment is 91.72%, and the amino acid content reaches 9.56 g / L. Example 9

[0038] A method for degrading kitchen waste protein by mechanical chemical enzyme coupling, comprising the following steps: adding 100 mL of kitchen waste stock solution, 10 g of potassium carbonate, 0.2 g of alkaline protease, and 6 stainless steel beads with a diameter of 14 mm to a 250 mL polytetrafluoroethylene ball mill, grinding and reacting at 200 rpm, 30 minutes as a cycle, 5 minutes of rest, and 10 cycles of grinding. After ball milling, the ball mill is centrifuged and separated, and the protein content and amino acid content of the degradation liquid are determined. The degradation rate of kitchen waste protein after degradation in this embodiment is 92.45%, and the amino acid content reaches 9.22 g / L. Example 10

[0039] A method for degrading kitchen waste protein by mechanical chemical enzyme coupling, comprising the following steps: adding 100 mL of kitchen waste stock solution, 10 g of potassium carbonate, 2 g of alkaline protease, and 6 stainless steel beads with a diameter of 14 mm to a 250 mL polytetrafluoroethylene ball mill, grinding and reacting at 500 rpm, 30 minutes as a cycle, 5 minutes of rest, and 10 cycles of grinding. After ball milling, the ball mill is centrifuged and separated, and the protein content and amino acid content of the degradation liquid are determined. The degradation rate of kitchen waste protein after degradation in this embodiment is 93.09%, and the amino acid content reaches 10.08 g / L.

[0040] Example 11 Optimal mass ratio of solid phase reagent to kitchen waste stock solution A method for mechanochemical enzyme coupling degradation of kitchen waste protein, comprising the following steps: adding 100 mL of kitchen waste stock solution to a 250 mL polytetrafluoroethylene ball mill, controlling the addition amount of solid phase reagent (potassium carbonate: alkaline protease = 10:1) to 5, 6, 7, 8, 9, 10, 11, and 12 g respectively, and 6 stainless steel beads with a diameter of 14 mm, grinding the reaction at 400 rpm, 30 minutes as a cycle, 5 minutes of rest, and grinding for 10 cycles. After ball milling, the ball mill is centrifuged and separated, and the protein content and amino acid content of the degradation liquid are determined. Figure 1 As shown, the test results show that if the amount of solid phase reagent added is too little, the protein cannot be fully oxidized and degraded, and the degradation effect is poor; if the amount of solid phase reagent added is too much, the system will be too alkaline, which will further destroy the activity of the enzyme and also cause the loss of amino acids. Therefore, the preferred mass ratio of solid phase reagent to kitchen waste stock solution is 1:10.

[0041] Example 12 Optimal rotation speed of ball mill A method for degrading kitchen waste protein by mechanical chemical enzyme coupling, comprising the following steps: adding 100 mL of kitchen waste stock solution, 10 g of potassium carbonate, 1 g of alkaline protease, and 6 stainless steel beads with a diameter of 14 mm to a 250 mL polytetrafluoroethylene ball mill, mixing the ball mill evenly, and then placing the ball mill in a planetary ball mill, controlling the speed of the ball mill to be 100, 150, 200, 250, 300, 350, 400, 450, and 500 rpm, respectively, for 10 cycles, centrifuging the milled material after ball milling, and determining the protein content and amino acid content of the degradation liquid. Figure 2 As shown, the test results show that if the rotation speed is too low, the grinding and dispersion are not sufficient, resulting in poor degradation effect; while if the grinding rate is too high, the heat release of the system increases, causing partial inactivation of the enzyme and reduced degradation efficiency, so the preferred rotation speed is 400 rpm.

[0042] Example 13 Optimization of ball milling cycle A method for degrading kitchen waste protein by mechanical chemical enzyme coupling, comprising the following steps: adding 100 mL of kitchen waste stock solution, 10 g of potassium carbonate, 1 g of alkaline protease, and 6 stainless steel beads with a diameter of 14 mm to a 250 mL polytetrafluoroethylene ball mill, mixing evenly, placing the ball mill into a planetary ball mill, controlling the speed of the ball mill to 400 rpm, and performing 6, 7, 8, 9, 10, 11, and 12 cycles respectively, centrifuging the ball mill after ball milling, and determining the protein content and amino acid content of the degradation liquid. Figure 3 As shown, the test results show that when the ball milling time is short, the materials are not fully mixed and reacted in the ball mill, and the degradation rate is low; while when the ball milling time is too long, the degradation rate of the product does not increase, so the preferred ball milling time is 10 cycles.

[0043] Example 14 Liquid Phase Enzymatic Hydrolysis of Kitchen Waste A method for degrading kitchen waste protein by mechanochemical enzyme coupling comprises the following steps: adding 100 mL of kitchen waste stock solution, 10 g of potassium carbonate, and 1 g of alkaline protease to a 250 mL beaker, controlling the enzymatic hydrolysis temperature at 35°C, performing enzymatic hydrolysis for 5 hours, centrifuging after the enzymatic hydrolysis, and determining the protein content and amino acid content of the degraded liquid. The results show that the degradation rate of kitchen waste protein after degradation is 42.15%, and the amino acid content reaches 4.59 g / L. The test results show that the enzymatic hydrolysis effect cannot be well exerted without mechanochemical assistance.

[0044] Example 15 Analysis of amino acid types in protein degradation from kitchen waste A method for degrading kitchen waste protein by mechanical chemical enzyme coupling comprises the following steps: adding 100 mL of kitchen waste stock solution, 10 g of potassium carbonate, 1 g of alkaline protease, and 6 stainless steel beads with a diameter of 14 mm into a 250 mL polytetrafluoroethylene ball mill, mixing evenly, placing the ball mill into a planetary ball mill, controlling the speed of the ball mill to be 400 rpm, and the time to be 10 cycles. After ball milling, the ball mill is centrifuged and separated, and the amino acid content is obtained using an amino acid analyzer. The amino acid content of the protein degradation solution prepared under the optimal conditions is 11.34 g / L. The composition and distribution thereof are shown in Tables 1 and 2. Figure 4 .

[0045] The results in Table 1 show that the free amino acid components of the degradation liquid are complete, containing 18 natural amino acids, among which the content distribution of various amino acids is relatively balanced, which is in line with the characteristics of kitchen waste food sources and can more comprehensively supplement amino acid nutrition for plants.

[0046] Table 1: Degradation products of food waste proteins

[0047] Microscopic morphology of the solution before and after kitchen waste degradation The aggregation of protein microparticles in the solution before and after degradation was observed using a transmission electron microscope. The specific method was as follows: 1 mg of the sample to be tested was added with 3 mL of deionized water and mixed thoroughly. A small amount of the prepared liquid was dropped onto a copper sheet coated with a carbon film using a capillary tube, and then excess solution was wiped off with filter paper. After the sample solution was dried in the air, a transmission electron microscope was used to observe the morphology and take photos at a detection voltage of 100 kV. Figure 5 As shown in the figure, through morphological observation, it was found that there were a large number of protein particles in the kitchen waste solution before degradation, which were large and irregular in size. After degradation, the particles in the solution were significantly reduced, and the particles were reduced and rounded, indicating that mechanical force and enzymes synergized to convert most of the suspended insoluble proteins into soluble amino acids and proteins, which fully demonstrated the role of mechanical force.

[0048] Study on the effect of kitchen waste protein degradation liquid on promoting the growth of Arabidopsis Preparation of chemical degradation liquid of kitchen waste: According to the literature, take 100 ml of kitchen waste, add 20 g of sodium hydroxide to make the alkali content more than 20%, boil it under hot reflux for 12 hours, and then use acetic acid to neutralize it to pH~7. After filtering the solution, the protein degradation rate was determined to be 52.37%, and the amino acid content was only 5.92 g / L.

[0049] Arabidopsis thaliana at the same growth stage were divided into three groups: experimental group, control group and blank group, with 10 plants in each group. The experimental group was fertilized with the degradation solution of Example 10, diluted 1000 times, the control group was fertilized with the chemical degradation solution, diluted 1000 times, and the blank group was not fertilized. Fertilization was applied once a day for 3 consecutive months, and the average height and biomass were calculated after the end. Figure 6 As shown, the test results show that using this method to degrade fertilizer, the plant height of Arabidopsis thaliana is significantly higher than that of the control group and the blank group, and the biomass content is increased. The experimental results show that the protein degradation liquid prepared by this method, the organic nitrogen elements it contains, has a better effect in promoting plant growth.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for degrading kitchen waste protein by mechanical chemical enzyme coupling, characterized in that: The method comprises the following steps: mixing a kitchen waste stock solution with a solid phase reagent and placing the mixture in a polytetrafluoroethylene ball mill, adding stainless steel beads, setting the ball mill speed to 100-500 rpm, performing a grinding reaction, and the grinding cycle is 6-12 cycles. After the ball milling reaction is completed, filtering and removing the residue to obtain a kitchen waste protein degradation solution.

2. The method for degrading kitchen waste protein by mechanochemical enzyme coupling according to claim 1, characterized in that: The mass ratio of the kitchen waste stock solution to the solid phase reagent is 100:(5-12).

3. The method for degrading kitchen waste protein by mechanochemical enzyme coupling according to claim 1, characterized in that: The solid phase reagent includes an alkali reagent and an enzyme reagent, wherein the alkali reagent includes at least one of sodium bicarbonate, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide and urea; and the enzyme reagent includes at least one of alkaline protease and papain.

4. The method for degrading kitchen waste protein by mechanochemical enzyme coupling according to claim 3, characterized in that: The mass ratio of the alkaline reagent to the enzyme reagent is 10:(0.1-3).

5. The method for degrading kitchen waste protein by mechanochemical enzyme coupling according to claim 1, characterized in that: The diameter of the stainless steel beads was 14 mm.

6. The method for degrading kitchen waste protein by mechanochemical enzyme coupling according to claim 1, characterized in that: The grinding cycle is 6-12 cycles, specifically: grinding for 30 minutes as one cycle, resting for 5 minutes, and grinding for 6-12 cycles in total.

7. The method for degrading kitchen waste protein by mechanochemical enzyme coupling according to claim 1, characterized in that: The ball mill rotates at 400 rpm.

8. The method for degrading kitchen waste protein by mechanochemical enzyme coupling according to claim 1, characterized in that: The grinding cycle is 10 cycles.

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