Monascus polysaccharide-based fully biodegradable packaging material and preparation method thereof

Abstract

The invention belongs to the technical field of degradable packaging materials, and relates to a monascus polysaccharide-based fully biodegradable packaging material, which is prepared from the following raw materials in parts by weight: 60 to 70 parts of modified monascus polysaccharide; 10 to 20 parts of a composite modifier; 5-10 parts of a plasticizer; 3-5 parts of a filling agent; 0.3 to 0.5 part of vitamin E; the mechanical property, the water resistance and the forming stability of the monascus polysaccharide-based material are improved through a composite modification system, and finally the degradable packaging material which is low in cost, high in degradation efficiency and excellent in use performance is prepared.

Description

Technical Field

[0001] This invention belongs to the field of biodegradable packaging materials technology, and specifically relates to a red yeast rice polysaccharide-based fully biodegradable packaging material and its preparation method. Background Technology

[0002] The petroleum-based plastics (such as polyethylene and polypropylene) widely used in the packaging industry are difficult to degrade, and long-term accumulation leads to "white pollution," severely damaging the ecological environment. To solve this problem, biodegradable packaging materials have become a research hotspot. Existing biodegradable materials are mostly based on polylactic acid (PLA), polybutylene adipate (PBAT), starch, etc., but they have the following drawbacks: Insufficient mechanical properties: Pure starch-based materials are brittle and have low tensile strength, while PLA materials have poor toughness and require the addition of large amounts of plasticizers, which can easily lead to excessive material migration; High cost: Chemically synthesized biodegradable base materials such as PLA and PBAT rely on petroleum derivatives, have complex production processes, and cost 2-3 times that of traditional plastics; Environmental limitations: The production process of some biodegradable materials requires high temperatures and strong solvents, resulting in high energy consumption and easy generation of volatile organic pollutants (VOCs), which does not meet the requirements of "full life cycle environmental protection"; Limited functionality: Most biodegradable packaging only has basic packaging functions and lacks added value such as antibacterial and preservation properties, making it difficult to meet the high-requirement packaging scenarios such as food and pharmaceuticals.

[0003] Red yeast rice, a traditional food and medicine fermentation product, is rich in red yeast polysaccharides in its cell walls. These polysaccharides have good biocompatibility, biodegradability, and certain antibacterial activity. However, red yeast polysaccharides are currently mainly used in the fields of food additives and health products, and have not yet been developed for use in biodegradable packaging materials. Furthermore, existing technologies lack mature processes for modifying red yeast polysaccharides and combining them with other biodegradable substrates, which cannot solve the problems of poor mechanical properties and high processing difficulty of red yeast polysaccharides.

[0004] Based on this, the present invention takes red yeast rice polysaccharide as the core, and through modification treatment and synergistic optimization with composite substrate, combined with environmentally friendly production process, prepares red yeast rice polysaccharide-based biodegradable packaging material with excellent mechanical properties, biodegradability and additional functions, filling the gap in the existing technology. Summary of the Invention

[0005] The purpose of this invention is to provide a fully biodegradable packaging material based on red yeast rice polysaccharide and its preparation method. By improving the mechanical properties, water resistance and molding stability of the red yeast rice polysaccharide-based material through a composite modification system, a low-cost, high-degradation-efficiency, and high-performance biodegradable packaging material is finally prepared.

[0006] The above-mentioned technical objective of this invention is achieved through the following technical solution: a red yeast rice polysaccharide-based fully biodegradable packaging material, comprising the following raw material components in parts:

[0007] Modified red yeast rice polysaccharide 60-70 parts; composite modifier 10-20 parts; plasticizer 5-10 parts; filler 3-5 parts; vitamin E 0.3-0.5 parts; deionized water 20-30 parts.

[0008] By adopting the above technical solution, the composite modification of red yeast rice polysaccharide with konjac glucomannan and chitosan, utilizing the hydrogen bonding between the three molecules and the cross-linking reaction of the cross-linking agent, solves the problems of poor film-forming properties and low mechanical strength of single red yeast rice polysaccharide. The tensile strength of the material can reach 12-15 MPa, and the elongation at break is 15-20%, meeting the requirements for packaging materials.

[0009] A further provision of the present invention is that the modified red yeast rice polysaccharide is prepared by the following method: red yeast rice polysaccharide is dissolved in deionized water at a solid-liquid ratio of 1:10, 5% by weight of epichlorohydrin is added, the pH is adjusted to 9.0-9.5, and the mixture is stirred at 45°C for 3 hours; after the reaction is completed, 1% acetic acid is added to neutralize to pH 7.0, 3 times the volume of anhydrous ethanol is added to precipitate, and the precipitate is collected by centrifugation; after the precipitate is freeze-dried, it is mixed with 3% by weight of maleic anhydride of red yeast rice polysaccharide, and the mixture is melt-grafted at 120°C for 2 hours. After cooling, it is pulverized through a 100-mesh sieve to obtain the modified red yeast rice polysaccharide.

[0010] By employing the above technical solution, cross-linking is first performed using epichlorohydrin, followed by grafting with maleic anhydride, combining the advantages of cross-linking and grafting to form a more complex network structure. Existing technologies typically only perform one type of chemical modification, failing to simultaneously achieve structural stability and the introduction of functional groups. Furthermore, cross-linking is performed under alkaline conditions (pH 9.0-9.5), followed by high-temperature melt grafting after acid neutralization, allowing for precise condition control and avoiding excessive hydrolysis or degradation. Using epichlorohydrin as a cross-linking agent and maleic anhydride as a grafting monomer allows for a specific reaction targeting the hydroxyl groups of red yeast rice polysaccharides, introducing multiple functional groups.

[0011] The maleic anhydride grafting reaction is carried out at high temperature, where the anhydride group undergoes esterification with the hydroxyl groups of red yeast rice polysaccharide, introducing carboxyl groups (-COOH). Carboxyl groups are strongly hydrophilic and can interact with water molecules through hydrogen bonds, increasing the solvation layer of the polysaccharide chain and thus improving water solubility. Simultaneously, the cross-linking reaction forms ether bonds (-COC-) between epichlorohydrin and the polysaccharide hydroxyl groups. While some cross-linking points may restrict chain movement, the grafted carboxyl groups compensate for this effect, preventing chain aggregation through electrostatic repulsion and improving dispersibility. The modified red yeast rice polysaccharide is more easily dissolved and dispersed in aqueous phase, making it suitable as an emulsifier or stabilizer in the food and pharmaceutical industries. Compared to unmodified red yeast rice polysaccharide (which has poor water solubility), solubility is improved by approximately 30-50%.

[0012] A further provision of the present invention is that the composite modifier is prepared by stirring and mixing an appropriate amount of anthocyanins with konjac glucomannan and chitosan powder in an acetic acid solution.

[0013] By adopting the above technical solution, the anthocyanin-modified chitosan-konjac glucomannan film exhibits better mechanical properties and UV blocking performance than the pure chitosan film. The addition of anthocyanin extract alters the physical properties of the film, causing changes in its structure. Furthermore, the phenolic components in the anthocyanin extract can form new hydrogen bonds with chitosan-konjac glucomannan, leading to changes in bond energy. Additionally, the addition of anthocyanin extract reduces the UV transmittance of the composite film.

[0014] A further provision of the present invention is as follows: the specific preparation steps of the composite modifier are as follows: konjac glucomannan and chitosan powders with a mass ratio of 2:3 are dissolved in a 2% (v / v) acetic acid aqueous solution using a magnetic stirrer; then the solution is mixed with anthocyanin extract and homogenized using an ultrasonic cleaner to obtain the composite modifier.

[0015] A further provision of the present invention is that the weight ratio of the anthocyanin to the chitosan powder is 1:7-10.

[0016] Chitosan's cations interact with the negative charge of bacterial cell membranes, disrupting membrane permeability and acting as a "defense breacher." Simultaneously, anthocyanin molecules can further embed themselves into damaged cell membranes, disrupting their integrity and interfering with intracellular enzyme activity. Furthermore, as highly efficient hydrogen donors, anthocyanins preferentially react with oxygen in the packaging headspace and free radicals (such as ROO· and OH·) generated during food oxidation, "sacrificing themselves" to protect the food and the film matrix from oxidation. This is fundamentally different from the "passive defense" of traditional packaging that simply blocks oxygen.

[0017] Meanwhile, konjac glucomannan, chitosan, and modified red yeast rice polysaccharide (which itself has carboxyl groups and cross-linking points) form a dense three-dimensional network structure through strong hydrogen bonds, ionic bonds (-NH3⁺ of chitosan and -COO⁻ of red yeast rice polysaccharide), and even possible amide bonds. This "three-in-one" cross-linking greatly restricts the movement of molecular chains, making the film more compact. The entanglement and combination of several polysaccharide molecular chains at the nanoscale is equivalent to forming a large number of "nanofillers" in the matrix, effectively extending the path of gas and water molecules through the film (tortuous path effect), thereby significantly improving the barrier performance.

[0018] A further provision of the present invention is that the plasticizer comprises 3-5 parts of glycerol and 2-3 parts of sorbitol.

[0019] By adopting the above technical solutions, glycerin and sorbitol can not only act as plasticizers, but also as flexibility modifiers.

[0020] A further feature of the present invention is that the filler is nano-calcium carbonate with a particle size of 50-100 nm.

[0021] A further provision of the present invention includes 2-3 parts of polyvinyl alcohol.

[0022] By adopting the above technical solutions, the molecular chains in the plastic substrate can be arranged more regularly and the hydrogen bonding effect can be enhanced, thereby improving the thermal stability of the material.

[0023] A further provision of the present invention is: a method for preparing a fully biodegradable packaging material based on red yeast rice polysaccharide.

[0024] S1: Add plasticizer to deionized water and stir until completely dissolved. The stirring temperature is 50℃, the stirring speed is 300r / min, and the time is 20min.

[0025] S2: Add modified red yeast rice polysaccharide, composite modifier, and polyvinyl alcohol in sequence, heat to 70℃, and stir at a constant temperature for 60 minutes to form a uniform polysaccharide mixture;

[0026] S3: Add filler nano calcium carbonate and antioxidant vitamin E, and disperse at high speed (1500 r / min, 30 min) to ensure uniform dispersion of the filler;

[0027] S5: Adjust the pH of the system to 4.5-5.0, and perform a constant temperature crosslinking reaction at 65℃ for 40 min to obtain the modified red yeast polysaccharide composite solution.

[0028] S6: Molding process: Pour the composite adhesive into the molding mold and place it in a vacuum degassing chamber (vacuum degree 0.09MPa, time 15min) to remove air bubbles from the adhesive; cast the degassed adhesive onto the surface of horizontal tempered glass, controlling the casting thickness to 0.1-0.3mm, and place it in a forced-air drying oven. First, dry at 60℃ for 2 hours, then raise the temperature to 80℃ and dry for 4 hours. Dry in stages to avoid material cracking; pour the composite adhesive into the mold and place it in a hot press at 120℃ and 5MPa for 30 minutes. After cooling to room temperature, demold.

[0029] S7: Place the molded packaging material in a constant temperature and humidity chamber (temperature 25℃, humidity 50%) for 48 hours to eliminate internal stress, improve the dimensional stability of the material, and finally obtain red yeast polysaccharide-based biodegradable packaging material.

[0030] The beneficial effects of this invention are:

[0031] 1. The composite modification of red yeast rice polysaccharide with konjac glucomannan and chitosan utilizes the hydrogen bonding between the three molecules and the cross-linking reaction of the cross-linking agent to solve the problems of poor film-forming properties and low mechanical strength of red yeast rice polysaccharide alone, and greatly improves the tensile strength of the material.

[0032] 2. First, cross-linking is performed using epichlorohydrin, followed by grafting with maleic anhydride. This combines the advantages of cross-linking and grafting, resulting in a more complex network structure. Existing technologies typically only perform one type of chemical modification, failing to simultaneously achieve structural stability and the introduction of functional groups. Furthermore, cross-linking is carried out under alkaline conditions (pH 9.0-9.5), followed by high-temperature melt grafting after acid neutralization. This precise condition control avoids excessive hydrolysis or degradation. Using epichlorohydrin as a cross-linking agent and maleic anhydride as a grafting monomer allows for a specific reaction targeting the hydroxyl groups of red yeast rice polysaccharides, introducing multiple functional groups.

[0033] 3. The anthocyanin-modified chitosan-konjac glucomannan film exhibits better mechanical and UV blocking properties than the pure chitosan film. The addition of anthocyanin extract alters the film's physical properties, causing structural changes. Furthermore, the phenolic components in the anthocyanin extract form new hydrogen bonds with chitosan-konjac glucomannan, leading to altered bond energies. Additionally, the addition of anthocyanin extract reduces the UV transmittance of the composite film. Detailed Implementation

[0034] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] A method for preparing a fully biodegradable packaging material based on red yeast rice polysaccharide.

[0037] S1: Add 3-5 parts of glycerol and 2-3 parts of sorbitol to 20-30 parts of deionized water, and stir until completely dissolved. The stirring temperature is 50℃, the stirring speed is 300r / min, and the time is 20min.

[0038] S2: Add 60-70 parts of modified red yeast rice polysaccharide, 10-20 parts of composite modifier, and 2-3 parts of polyvinyl alcohol in sequence, heat to 70℃, and stir at a constant temperature for 60 minutes to form a uniform polysaccharide mixture.

[0039] Red yeast rice polysaccharide was dissolved in deionized water at a solid-liquid ratio of 1:10. Epichlorohydrin (5% by weight of red yeast rice polysaccharide) was added to adjust the pH to 9.0-9.5, and the mixture was stirred at 45°C for 3 hours. After the reaction was completed, 1% acetic acid was added to neutralize the pH to 7.0, and three times the volume of anhydrous ethanol was added to precipitate the polysaccharide. The precipitate was collected by centrifugation. After freeze-drying, the precipitate was mixed with maleic anhydride (3% by weight of red yeast rice polysaccharide) and melt-grafted at 120°C for 2 hours. After cooling, the mixture was pulverized through a 100-mesh sieve to obtain modified red yeast rice polysaccharide.

[0040] The specific preparation steps of the composite modifier are as follows: Konjac glucomannan and chitosan powder with a mass ratio of 2:3 are dissolved in a 2% (v / v) acetic acid aqueous solution using a magnetic stirrer; then the solution is mixed with anthocyanin extract and homogenized by an ultrasonic cleaner to obtain the composite modifier;

[0041] S3: Add 3-5 parts of nano calcium carbonate and 0.3-0.5 parts of antioxidant vitamin E, and disperse at high speed (1500 r / min, 30 min) to ensure uniform dispersion of the filler;

[0042] S5: Adjust the pH of the system to 4.5-5.0, and perform a constant temperature crosslinking reaction at 65℃ for 40 min to obtain the modified red yeast polysaccharide composite solution.

[0043] S6: Molding process: Pour the composite adhesive into the molding mold and place it in a vacuum degassing chamber (vacuum degree 0.09MPa, time 15min) to remove air bubbles from the adhesive; cast the degassed adhesive onto the surface of horizontal tempered glass, controlling the casting thickness to 0.1-0.3mm, and place it in a forced-air drying oven. First, dry at 60℃ for 2 hours, then raise the temperature to 80℃ and dry for 4 hours. Dry in stages to avoid material cracking; pour the composite adhesive into the mold and place it in a hot press at 120℃ and 5MPa for 30 minutes. After cooling to room temperature, demold.

[0044] S7: Place the molded packaging material in a constant temperature and humidity chamber (temperature 25℃, humidity 50%) for 48 hours to eliminate internal stress, improve the dimensional stability of the material, and finally obtain red yeast polysaccharide-based biodegradable packaging material.

[0045] Example 2

[0046] A method for preparing a fully biodegradable packaging material based on red yeast rice polysaccharide.

[0047] S1: Add 3-5 parts of glycerol and 2-3 parts of sorbitol to 20-30 parts of deionized water, and stir until completely dissolved. The stirring temperature is 50℃, the stirring speed is 300r / min, and the time is 20min.

[0048] S2: Add 60-70 parts of red yeast rice polysaccharide, 10-20 parts of composite modifier, and 2-3 parts of polyvinyl alcohol in sequence, heat to 70℃, and stir at a constant temperature for 60 minutes to form a uniform polysaccharide mixture.

[0049] The specific preparation steps of the composite modifier are as follows: Konjac glucomannan and chitosan powder with a mass ratio of 2:3 are dissolved in a 2% (v / v) acetic acid aqueous solution using a magnetic stirrer; then the solution is mixed with anthocyanin extract and homogenized by an ultrasonic cleaner to obtain the composite modifier;

[0050] S3: Add 3-5 parts of nano calcium carbonate and 0.3-0.5 parts of antioxidant vitamin E, and disperse at high speed (1500 r / min, 30 min) to ensure uniform dispersion of the filler;

[0051] S5: Adjust the pH of the system to 4.5-5.0, and perform a constant temperature crosslinking reaction at 65℃ for 40 min to obtain the modified red yeast polysaccharide composite solution.

[0052] S6: Molding process: Pour the composite adhesive into the molding mold and place it in a vacuum degassing chamber (vacuum degree 0.09MPa, time 15min) to remove air bubbles from the adhesive; cast the degassed adhesive onto the surface of horizontal tempered glass, controlling the casting thickness to 0.1-0.3mm, and place it in a forced-air drying oven. First, dry at 60℃ for 2 hours, then raise the temperature to 80℃ and dry for 4 hours. Dry in stages to avoid material cracking; pour the composite adhesive into the mold and place it in a hot press at 120℃ and 5MPa for 30 minutes. After cooling to room temperature, demold.

[0053] S7: Place the molded packaging material in a constant temperature and humidity chamber (temperature 25℃, humidity 50%) for 48 hours to eliminate internal stress, improve the dimensional stability of the material, and finally obtain red yeast polysaccharide-based biodegradable packaging material.

[0054] Example 3

[0055] A method for preparing a fully biodegradable packaging material based on red yeast rice polysaccharide.

[0056] S1: Add 3-5 parts of glycerol and 2-3 parts of sorbitol to 20-30 parts of deionized water, and stir until completely dissolved. The stirring temperature is 50℃, the stirring speed is 300r / min, and the time is 20min.

[0057] S2: Add 60-70 parts of modified red yeast rice polysaccharide, 10-20 parts of chitosan, and 2-3 parts of polyvinyl alcohol in sequence, heat to 70℃, and stir at a constant temperature for 60 minutes to form a uniform polysaccharide mixture.

[0058] Red yeast rice polysaccharide was dissolved in deionized water at a solid-liquid ratio of 1:10. Epichlorohydrin (5% by weight of red yeast rice polysaccharide) was added to adjust the pH to 9.0-9.5, and the mixture was stirred at 45°C for 3 hours. After the reaction was completed, 1% acetic acid was added to neutralize the pH to 7.0, and three times the volume of anhydrous ethanol was added to precipitate the polysaccharide. The precipitate was collected by centrifugation. After freeze-drying, the precipitate was mixed with maleic anhydride (3% by weight of red yeast rice polysaccharide) and melt-grafted at 120°C for 2 hours. After cooling, the mixture was pulverized through a 100-mesh sieve to obtain modified red yeast rice polysaccharide.

[0059] S3: Add 3-5 parts of nano calcium carbonate and 0.3-0.5 parts of antioxidant vitamin E, and disperse at high speed (1500 r / min, 30 min) to ensure uniform dispersion of the filler;

[0060] S5: Adjust the pH of the system to 4.5-5.0, and perform a constant temperature crosslinking reaction at 65℃ for 40 min to obtain the modified red yeast polysaccharide composite solution.

[0061] S6: Molding process: Pour the composite adhesive into the molding mold and place it in a vacuum degassing chamber (vacuum degree 0.09MPa, time 15min) to remove air bubbles from the adhesive; cast the degassed adhesive onto the surface of horizontal tempered glass, controlling the casting thickness to 0.1-0.3mm, and place it in a forced-air drying oven. First, dry at 60℃ for 2 hours, then raise the temperature to 80℃ and dry for 4 hours. Dry in stages to avoid material cracking; pour the composite adhesive into the mold and place it in a hot press at 120℃ and 5MPa for 30 minutes. After cooling to room temperature, demold.

[0062] S7: Place the molded packaging material in a constant temperature and humidity chamber (temperature 25℃, humidity 50%) for 48 hours to eliminate internal stress, improve the dimensional stability of the material, and finally obtain red yeast polysaccharide-based biodegradable packaging material.

[0063] Example 4

[0064] A method for preparing a fully biodegradable packaging material based on red yeast rice polysaccharide.

[0065] S1: Add 3-5 parts of glycerol and 2-3 parts of sorbitol to 20-30 parts of deionized water, and stir until completely dissolved. The stirring temperature is 50℃, the stirring speed is 300r / min, and the time is 20min.

[0066] S2: Add 60-70 parts of modified red yeast rice polysaccharide and 10-20 parts of composite modifier in sequence, heat to 70℃, stir at a constant temperature for 60 minutes to form a uniform polysaccharide mixture;

[0067] Red yeast rice polysaccharide was dissolved in deionized water at a solid-liquid ratio of 1:10. Epichlorohydrin (5% by weight of red yeast rice polysaccharide) was added to adjust the pH to 9.0-9.5, and the mixture was stirred at 45°C for 3 hours. After the reaction was completed, 1% acetic acid was added to neutralize the pH to 7.0, and three times the volume of anhydrous ethanol was added to precipitate the polysaccharide. The precipitate was collected by centrifugation. After freeze-drying, the precipitate was mixed with maleic anhydride (3% by weight of red yeast rice polysaccharide) and melt-grafted at 120°C for 2 hours. After cooling, the mixture was pulverized through a 100-mesh sieve to obtain modified red yeast rice polysaccharide.

[0068] The specific preparation steps of the composite modifier are as follows: Konjac glucomannan and chitosan powder with a mass ratio of 2:3 are dissolved in a 2% (v / v) acetic acid aqueous solution using a magnetic stirrer; then the solution is mixed with anthocyanin extract and homogenized by an ultrasonic cleaner to obtain the composite modifier;

[0069] S3: Add 3-5 parts of nano calcium carbonate and 0.3-0.5 parts of antioxidant vitamin E, and disperse at high speed (1500 r / min, 30 min) to ensure uniform dispersion of the filler;

[0070] S5: Adjust the pH of the system to 4.5-5.0, and perform a constant temperature crosslinking reaction at 65℃ for 40 min to obtain the modified red yeast polysaccharide composite solution.

[0071] S6: Molding process: Pour the composite adhesive into the molding mold and place it in a vacuum degassing chamber (vacuum degree 0.09MPa, time 15min) to remove air bubbles from the adhesive; cast the degassed adhesive onto the surface of horizontal tempered glass, controlling the casting thickness to 0.1-0.3mm, and place it in a forced-air drying oven. First, dry at 60℃ for 2 hours, then raise the temperature to 80℃ and dry for 4 hours. Dry in stages to avoid material cracking; pour the composite adhesive into the mold and place it in a hot press at 120℃ and 5MPa for 30 minutes. After cooling to room temperature, demold.

[0072] S7: Place the molded packaging material in a constant temperature and humidity chamber (temperature 25℃, humidity 50%) for 48 hours to eliminate internal stress, improve the dimensional stability of the material, and finally obtain red yeast polysaccharide-based biodegradable packaging material.

[0073] The performance of the red yeast rice polysaccharide-based biodegradable packaging materials obtained in Examples 1-4 above was tested, including tensile strength (GB / T 1040.3-2006), elongation at break (GB / T 1040.3-2006), soil degradation rate (6 months) (GB / T19277.1-2011), and antibacterial rate (Escherichia coli) (GB / T 31402-2015). The test data are shown in Table 1 below.

[0074] Table 1 Performance test data of red yeast rice polysaccharide-based biodegradable packaging materials obtained in Examples 1-4

[0075] Example 1 Example 2 Example 3 Example 4 Tensile strength / MPa 42 30 28 41 Elongation at break 55% 37% 33% 51% Soil degradation rate (6 months) 92% 91% 90% 91% Antibacterial rate 97% 93% 90% 95%

[0076] As can be seen from Table 1, in Example 1 and Example 2, Example 1 uses modified red yeast rice polysaccharide. By utilizing the hydrogen bonding between the three molecules and the cross-linking reaction of the cross-linking agent, the problems of poor film-forming properties and low mechanical strength of single red yeast rice polysaccharide are solved, and the tensile strength of the material is greatly improved.

Claims

1. A fully biodegradable packaging material based on red yeast rice polysaccharide, characterized in that: The ingredients consist of the following proportions: Modified red yeast rice polysaccharide 60-70 parts; composite modifier 10-20 parts; plasticizer 5-10 parts; filler 3-5 parts; vitamin E 0.3-0.5 parts; deionized water 20-30 parts.

2. The red yeast rice polysaccharide-based fully biodegradable packaging material according to claim 1, characterized in that: The modified red yeast rice polysaccharide was prepared by the following method: red yeast rice polysaccharide was dissolved in deionized water at a solid-liquid ratio of 1:10, and epichlorohydrin (5% by weight of red yeast rice polysaccharide) was added to adjust the pH to 9.0-9.

5. The mixture was stirred at 45°C for 3 hours. After the reaction was completed, 1% acetic acid was added to neutralize the pH to 7.0, and three times the volume of anhydrous ethanol was added to precipitate the mixture. The precipitate was collected by centrifugation. After freeze-drying, the precipitate was mixed with maleic anhydride (3% by weight of red yeast rice polysaccharide) and subjected to a melt grafting reaction at 120°C for 2 hours. After cooling, the mixture was pulverized through a 100-mesh sieve to obtain the modified red yeast rice polysaccharide.

3. The red yeast rice polysaccharide-based fully biodegradable packaging material according to claim 1, characterized in that: The composite modifier is prepared by mixing an appropriate amount of anthocyanins with konjac glucomannan and chitosan powder in an acetic acid solution.

4. The red yeast rice polysaccharide-based fully biodegradable packaging material according to claim 3, characterized in that: The specific preparation steps of the composite modifier are as follows: Konjac glucomannan and chitosan powder with a mass ratio of 2:3 are dissolved in a 2% (v / v) acetic acid aqueous solution using a magnetic stirrer; then the solution is mixed with anthocyanin extract and homogenized by an ultrasonic cleaner to obtain the composite modifier.

5. The red yeast rice polysaccharide-based fully biodegradable packaging material according to claim 4, characterized in that: The weight ratio of anthocyanins to chitosan powder is 1:7-10.

6. The red yeast rice polysaccharide-based fully biodegradable packaging material according to claim 1, characterized in that: The plasticizer comprises 3-5 parts glycerin and 2-3 parts sorbitol.

7. The red yeast rice polysaccharide-based fully biodegradable packaging material according to claim 1, characterized in that: The filler is nano-calcium carbonate with a particle size of 50-100 nm.

8. The red yeast rice polysaccharide-based fully biodegradable packaging material according to claim 1, characterized in that: It also includes 2-3 parts of polyvinyl alcohol.

9. The method for preparing a fully biodegradable packaging material based on red yeast rice polysaccharide according to claim 1, characterized in that: S1: Add plasticizer to deionized water and stir until completely dissolved. The stirring temperature is 50℃, the stirring speed is 300r / min, and the time is 20min. S2: Add modified red yeast rice polysaccharide, composite modifier, and polyvinyl alcohol in sequence, heat to 70℃, and stir at a constant temperature for 60 minutes to form a uniform polysaccharide mixture; S3: Add filler nano calcium carbonate and antioxidant vitamin E, and disperse at high speed (1500 r / min, 30 min) to ensure uniform dispersion of the filler; S5: Adjust the pH of the system to 4.5-5.0, and perform a constant temperature crosslinking reaction at 65℃ for 40 min to obtain the modified red yeast polysaccharide composite solution. S6: Molding process: Pour the composite adhesive into the molding mold and place it in a vacuum degassing chamber (vacuum degree 0.09MPa, time 15min) to remove air bubbles from the adhesive; cast the degassed adhesive onto the surface of horizontal tempered glass, controlling the casting thickness to 0.1-0.3mm, and place it in a forced-air drying oven. First, dry at 60℃ for 2 hours, then raise the temperature to 80℃ and dry for 4 hours. Dry in stages to avoid material cracking; pour the composite adhesive into the mold and place it in a hot press at 120℃ and 5MPa for 30 minutes. After cooling to room temperature, demold. S7: The molded packaging material is placed in a constant temperature and humidity chamber (temperature 25℃, humidity 50%) for 48 hours to eliminate internal stress, improve the dimensional stability of the material, and finally obtain red yeast polysaccharide-based biodegradable packaging material.