Preparation method and device of tea polyphenol-chitosan film

Abstract

The invention relates to the technical field of biological product processing and utilization, and particularly discloses a preparation method and device of a tea polyphenol-chitosan film, and the preparation method comprises the following steps: (S01) dissolving chitosan in an acetic acid aqueous solution, and stirring; (S02) dissolving sodium alginate in distilled water, and standing for defoaming; (S03) mixing the chitosan solution with the sodium alginate solution, adding a proper amount of glycerol, and mixing to obtain a composite solution alpha; (S04) homogenizing the composite solution alpha, adding a proper amount of cinnamyl aldehyde and Tween into the homogenized composite solution alpha, and mixing to obtain a mixed solution beta; (S05) fully stirring the mixed solution beta, adding a proper amount of tea polyphenol, dissolving and uniformly mixing to obtain a tea polyphenol-chitosan membrane solution; (S06) carrying out ultrasonic bubble removal treatment on the tea polyphenol-chitosan membrane solution; (S07) drying and forming the treated tea polyphenol-chitosan membrane liquid, so as to obtain the tea polyphenol-chitosan membrane. The composite material has the characteristics of high tensile strength, high toughness and high antioxidant activity.

Description

Technical Field

[0001] The invention relates to the technical field of biological product processing and utilization, and in particular to a method and device for preparing a tea polyphenol-chitosan film. Background Art

[0002] In recent years, people have conducted a series of studies on chitosan as a food preservation material. Food cling film or coating made of chitosan has the advantages of being degradable and edible. It can not only prevent food from contacting the outside world and prevent changes in the water content of food, but also inhibit the growth of certain microorganisms, effectively extending the shelf life of food. Many natural Chinese herbs and spices can be used as excellent sources of plant-based preservatives, with the advantages of strong antibacterial properties, non-toxicity, good solubility and wide sources. For example, cloves, licorice, honeysuckle, etc. have been proven to have good antibacterial and preservation effects on food. The cling film made by combining these natural plant-based preservatives with chitosan not only improves the antibacterial properties of chitosan itself, but also gives it antioxidant function.

[0003] The patent document with the publication number of "CN105924659A" discloses a method for preparing chitosan film for health food, which uses chitosan as the main material, plasticizer, adhesive, film former and natural plant-based preservative as auxiliary materials, characterized in that chitosan is dissolved in acetic acid solution, mixed with dilute solutions of film former, plasticizer and adhesive to obtain chitosan solution, and then the chitosan solution is mixed with natural plant-based preservative solution, and finally an edible chitosan film is made by an appropriate film-forming method, or the chitosan composite solution is applied to the surface of health food to obtain a chitosan composite film solution coating. The chitosan prepared by this method has good biocompatibility and antibacterial properties, but its own mechanical strength is low, especially the performance of balanced tensile strength and toughness comprehensive performance is insufficient, which limits the application in the process of bearing large external forces or long-term use; at the same time, the antibacterial spectrum of a single chitosan film is narrow, and it cannot effectively inhibit the growth of a variety of food spoilage bacteria.

[0004] Therefore, the chitosan film for food prepared by the existing method has the problems of insufficient tensile strength and toughness and poor antioxidant performance. Summary of the invention

[0005] In order to solve the above technical problems existing in the existing chitosan film preparation process, the present invention provides a method and device for preparing a tea polyphenol-chitosan film, which has the characteristics of being able to take into account tensile strength and toughness as well as high antioxidant activity.

[0006] The first technical solution of the present invention: a method for preparing a tea polyphenol-chitosan film, comprising the following steps:

[0007] (S01) dissolving chitosan in an acetic acid aqueous solution and stirring;

[0008] (S02) dissolving sodium alginate in distilled water and allowing to stand to defoam;

[0009] (S03) mixing the chitosan solution in step (S01) with the sodium alginate solution in step (S02), and adding an appropriate amount of glycerol to mix, to obtain a composite solution α;

[0010] (S04) homogenizing the composite solution α in step (S03), and adding appropriate amounts of cinnamaldehyde and Tween to the homogenized composite solution α to obtain a mixed solution β;

[0011] (S05) fully stirring the mixed solution β in step (S04), and adding an appropriate amount of tea polyphenol to dissolve and mix well, thereby obtaining a tea polyphenol-chitosan film solution;

[0012] (S06) performing ultrasonic degassing treatment on the tea polyphenol-chitosan membrane solution in step (S05);

[0013] (S07) Drying and shaping the tea polyphenol-chitosan film liquid treated in step (S06) to obtain a tea polyphenol-chitosan film. The invention uses acetic acid aqueous solution to dissolve chitosan, so as to ensure that chitosan is evenly distributed in the solution, thereby improving the subsequent composite film-forming performance of the chitosan solution; sodium alginate, as an easily soluble salt, can be well dissolved in distilled water, and bubbles therein can be eliminated after standing, so as to facilitate the introduction of more and more stable ionic bonds and hydrogen bond action points after subsequent mixing and compounding with the chitosan solution, thereby better enhancing the network structure and tensile strength of the composite film; the chitosan solution prepared in advance is mixed with the sodium alginate solution to form a new mixed solution, which can well enhance the tensile strength of the chitosan solution after final film formation; the added glycerol can better promote the dissolution and diffusion between the molecules of the chitosan solution and the sodium alginate solution, enhance the mixing effect, and also increase the flexibility and plasticity of the chitosan solution after final film formation; the invention homogenizes the composite solution α, so that the added substances can be mixed more evenly, and the quality and performance of the final composite film can be better improved; wherein the addition of cinnamaldehyde can enhance the antibacterial and antiseptic properties of the final composite film, can well remove oxidative free radicals in food, so that the final composite film has good thermal stability and storage stability; wherein an appropriate amount of Tween The addition can better promote the dissolution between the water phase and the oil phase substances, and can also ensure the uniformity and stability of the final composite film during use; the present invention continues to fully stir the mixed solution β, so that the various components therein are more fully dissolved and acted; tea polyphenols are a powerful natural antioxidant, and the addition of an appropriate amount of tea polyphenols can significantly improve the antioxidant capacity of the final composite film, and the DPPH free radical scavenging rate and ABTS free radical scavenging rate of the composite film are significantly improved, thereby extending the shelf life of the composite film; the composite film after adding tea polyphenols also has a good elongation at break , so that the composite film has better toughness; the water solubility of the composite film formed after adding tea polyphenols is low, the composite film is least likely to dissolve in water, and can effectively inhibit chemical changes in food and the growth and reproduction of microorganisms after use; the present invention performs ultrasonic degassing treatment on the tea polyphenol-chitosan membrane liquid to prevent holes or unevenness after film formation, thereby ensuring the quality of the membrane; the treated tea polyphenol-chitosan membrane liquid is dried and formed to obtain a tea polyphenol-chitosan membrane, which has the characteristics of good tensile strength, good toughness, low water solubility, low transparency and good antioxidant performance.

[0014] Preferably, the mass concentration of the acetic acid aqueous solution in step (S01) is 1% to 3%. More preferably, the mass concentration of the acetic acid aqueous solution in step (S01) is 2%. Limiting the mass concentration of the acetic acid aqueous solution to a suitable range can more effectively promote the dissolution of chitosan and ensure that chitosan is evenly distributed in the solution, thereby improving the film-forming performance of the chitosan solution.

[0015] Preferably, the mass concentration of the chitosan solution in step (S01) is 1.5% to 2.5%. More preferably, the mass concentration of the chitosan solution in step (S01) is 2%. The chitosan solution with a limited mass concentration has good viscosity and fluidity, making the subsequent dissolution and film-forming process with other substances more stable and controllable.

[0016] Preferably, the temperature of the distilled water in step (S02) is 45° C. to 55° C. More preferably, the temperature of the distilled water in step (S02) is 50° C. The limited distilled water temperature can achieve rapid dissolution of sodium alginate.

[0017] Preferably, the mass concentration of sodium alginate in step (S02) is 0.4% to 0.6%. More preferably, the mass concentration of sodium alginate in step (S02) is 0.5%. The limited concentration of sodium alginate can introduce more and more stable ionic bonds and hydrogen bonding points after mixing with the chitosan solution, thereby better enhancing the network structure and tensile strength of the composite membrane.

[0018] Preferably, the defoaming in step (S02) is performed at room temperature, so that the foam generated during the dissolution of sodium alginate is naturally eliminated at room temperature, and the foam can be better mixed with the chitosan solution to play a stabilizing role.

[0019] Preferably, the volume ratio of the chitosan solution to the sodium alginate solution in the step (S03) is 1-3:1-3. More preferably, the volume ratio of the chitosan solution to the sodium alginate solution in the step (S03) is 1:1. The defined volume ratio allows the properties of chitosan and sodium alginate to be better balanced, ensuring that the two solutions are fully contacted and reacted during the mixing process to form a uniform composite system, thereby avoiding solution stratification or unevenness caused by improper proportions and improving the uniformity and stability of film formation.

[0020] Preferably, the mass concentration of glycerol in the composite solution α of step (S03) is 0.5% to 0.7%. More preferably, the mass concentration of glycerol in the composite solution α of step (S03) is 0.6%. The limited glycerol concentration can better promote the dissolution and diffusion between the molecules of the chitosan solution and the sodium alginate solution, enhance the mixing effect, and better increase the flexibility and plasticity of the chitosan solution after the final film is formed.

[0021] Preferably, the homogenization of the composite solution α in the step (S04) comprises the following steps:

[0022] (S04-1) transferring the composite solution α to a homogenizer (204);

[0023] (S04-2) The homogenizing pressure of the homogenizer (204) in step (S04-1) is adjusted to 500 bar to 1000 bar, the homogenizing speed is set to 12000 rpm to 18000 rpm, and the homogenizing is circulated for 2 to 5 times, and the homogenizing time for each time is 3 minutes to 7 minutes. Homogenizing within a limited pressure range can effectively destroy large particles and agglomerates in the solution, making the composite solution more delicate and uniform; the limited speed range, homogenization times and homogenization time can ensure the full mixing of the components in the solution, avoid stratification or precipitation, and improve the stability of the solution.

[0024] Preferably, in the step (S04-2), the homogenizing pressure of the homogenizer (204) is adjusted to 700 bar to 900 bar, the homogenizing speed is set to 14000 rpm to 16000 rpm, the homogenizing is circulated for 3 to 4 times, and the homogenizing time for each time is 4 min to 6 min. More preferably, in the step (S04-2), the homogenizing pressure of the homogenizer (204) is adjusted to 800 bar, the homogenizing speed is set to 15000 rpm, the homogenizing is circulated for 4 times, and the homogenizing time for each time is 5 min.

[0025] Preferably, the mass concentration of cinnamaldehyde in the mixed solution β of step (S04) is 0.1% to 0.3%. More preferably, the mass concentration of cinnamaldehyde in the mixed solution β of step (S04) is 0.2%. The limited cinnamaldehyde concentration can better improve the antibacterial and antiseptic properties of the final composite film, can better remove oxidative free radicals in food, and make the final composite film have better thermal stability and storage stability.

[0026] Preferably, the mass concentration of Tween in the mixed solution β in step (S04) is 0.1% to 0.3%. More preferably, the mass concentration of Tween in the mixed solution β in step (S04) is 0.2%. The limited Tween concentration can better promote the dissolution between the aqueous phase and the oil phase substances, and can also ensure that the final composite film has better uniformity and stability during use;

[0027] Preferably, the mixing time in step (S04) is 20 min to 40 min. More preferably, the mixing time in step (S04) is 25 min to 35 min. More preferably, the mixing time in step (S04) is 30 min. Limiting the mixing time can ensure that the surfactant Tween is evenly dispersed in the solution to form a stable emulsified system.

[0028] Preferably, the mass concentration of tea polyphenols in the tea polyphenol-chitosan film solution in step (S05) is 0.03% to 0.07%; the mass concentration of tea polyphenols in the tea polyphenol-chitosan film solution in step (S05) is 0.04% to 0.06%. The limited concentration of tea polyphenols can better exert its antioxidant and antibacterial effects.

[0029] Preferably, in step (S05), an appropriate amount of surfactant is added and then stirred to mix. The addition of a single surfactant can further optimize the uniformity of the mixed solution, change the microstructure of the membrane surface, and further enhance the hydrophilicity or hydrophobicity of the membrane; the additional addition of a surfactant can form a protective layer on the membrane surface, reduce the adsorption of macromolecules such as proteins on the membrane surface, thereby improving the anti-pollution ability of the membrane, adjusting the pore size and distribution of the membrane, and achieving selective separation of specific substances.

[0030] Preferably, the surfactant is sodium dodecyl sulfate or polyethylene glycol. Sodium dodecyl sulfate, as an anionic surfactant, has excellent emulsification, dispersing and wetting properties. After being added, it can effectively reduce the surface tension of the mixed solution, promote the interaction between the components, and improve the homogeneity of the solution; polyethylene glycol, as a nonionic surfactant, has good solubility and stability. After being added, it can improve the homogeneity of the mixed solution through the steric hindrance effect without introducing additional charges.

[0031] Preferably, the mass concentration of sodium dodecyl sulfate in the tea polyphenol-chitosan film solution in step (S05) is 0.1% to 0.3%. More preferably, the mass concentration of sodium dodecyl sulfate in the tea polyphenol-chitosan film solution in step (S05) is 0.2%. Sodium dodecyl sulfate with a limited mass concentration can more effectively reduce the surface tension of the mixed solution, promote the interaction between the components, and improve the homogeneity of the solution.

[0032] Preferably, the mass concentration of polyethylene glycol in the tea polyphenol-chitosan film solution in step (S05) is 0.2% to 0.4%, and more preferably, the mass concentration of polyethylene glycol in the tea polyphenol-chitosan film solution in step (S05) is 0.3%. Polyethylene glycol with a limited mass concentration can better improve the uniformity of the mixed solution through steric hindrance effect without introducing additional charges.

[0033] Preferably, in step (S05), an appropriate amount of vitamin E and silver nanoparticles are added. The addition of vitamin E can improve the antioxidant properties of the tea polyphenol-chitosan film; the addition of silver nanoparticles can improve the antibacterial properties of the tea polyphenol-chitosan film.

[0034] Preferably, the mass concentration of vitamin E in the tea polyphenol-chitosan film liquid in step (S05) is 0.4% to 0.9%. More preferably, the mass concentration of vitamin E in the tea polyphenol-chitosan film liquid in step (S05) is 0.5% to 0.8%. More preferably, the mass concentration of vitamin E in the tea polyphenol-chitosan film liquid in step (S05) is 0.6% to 0.7%. The limited mass concentration of vitamin E can better improve the antioxidant properties of the tea polyphenol-chitosan film, and play an auxiliary role in improving the antioxidant properties of tea polyphenols.

[0035] Preferably, the mass concentration of silver nanoparticles in the tea polyphenol-chitosan film solution in step (S05) is 0.02% to 0.05%. More preferably, the mass concentration of vitamin E and silver nanoparticles in the tea polyphenol-chitosan film solution in step (S05) is 0.03% to 0.04%. Silver nanoparticles with a limited mass concentration can help improve the antibacterial properties of the tea polyphenol-chitosan film, taking into account both antibacterial and safety in food.

[0036] Preferably, the ultrasonic defoaming time of step (S06) is 15 min to 30 min. More preferably, the ultrasonic defoaming time of step (S06) is 20 min to 25 min. The limited ultrasonic defoaming time can fully remove the foam in the tea polyphenol-chitosan membrane liquid, and better prevent the occurrence of holes or unevenness after the membrane is formed.

[0037] Preferably, the drying and forming step of the tea polyphenol-chitosan film liquid in step (S07) is:

[0038] (S07-1) placing the substrate coated with the tea polyphenol-chitosan film solution into a constant temperature drying oven for preheating;

[0039] (S07-2) drying the substrate placed in the constant temperature drying oven in step (S07-1) by a gradient temperature increase method;

[0040] (S07-3) After drying, turn off the heating source, let the film cool naturally to room temperature in the drying oven, and then remove the substrate to obtain the tea polyphenol-chitosan film. Put the substrate coated with the tea polyphenol-chitosan film liquid into a constant temperature drying oven for preheating treatment to reduce the problems of uneven film layer, blistering or cracking caused by the rapid water loss of the film liquid at high temperature, improve the flatness and structural stability of the film, and lay the foundation for the subsequent gradient heating drying; using the gradient heating method to dry the substrate can more gently remove the remaining water in the film liquid, avoid the stress concentration and physical property degradation of the film layer caused by sudden temperature changes, ensure the microstructure and chemical stability of the film, and ensure that the tea polyphenol-chitosan film finally formed has good mechanical strength, antibacterial and biocompatibility; let the film cool naturally to room temperature in the drying oven to relieve the thermal stress inside the film and prevent cracks or deformation caused by rapid cooling.

[0041] Preferably, the preheating temperature in the step (S07-1) is 40°C to 60°C. More preferably, the preheating temperature in the step (S07-1) is 45°C to 55°C. More preferably, the preheating temperature in the step (S07-1) is 50°C. The defined preheating temperature can more gently remove part of the water in the membrane liquid, ensure that the active ingredients of tea polyphenols and chitosan are better retained, and improve the flatness and initial curing degree of the membrane.

[0042] Preferably, the preheating time in the step (S07-1) is 30 min to 60 min. More preferably, the preheating time in the step (S07-1) is 35 min to 55 min. More preferably, the preheating time in the step (S07-1) is 40 min to 50 min. More preferably, the preheating time in the step (S07-1) is 45 min. The limited preheating time can not only ensure the effective evaporation of water so that the film liquid on the substrate is fully and evenly heated, but also prevent the film layer from aging or other adverse reactions that may be caused by long-term high temperature exposure.

[0043] Preferably, the gradient heating method in step (S07-2) is:

[0044] First, dry at an initial temperature of 60°C for 2h to 4h to gradually remove most of the moisture; then gradually increase the temperature to 80°C and continue drying for 2h to 3h to reduce the residual solvent content in the film. By performing a preliminary drying treatment at an initial temperature of 60°C for 2h to 4h, uneven film layer or blistering caused by rapid evaporation can be avoided, and the active ingredients of tea polyphenols and chitosan can be protected from being destroyed by high temperature; the temperature is gradually increased to 80°C and then the temperature is increased to dry to ensure that the film layer gradually adapts to higher temperatures, reducing the internal stress caused by temperature differences, thereby reducing the risk of cracking of the film layer.

[0045] Preferably, after the drying treatment (S07-2), the substrate coated with the tea polyphenol-chitosan film liquid is placed in a vacuum drying oven for vacuum drying. Vacuum drying can further remove residual solvent and moisture in the film, improve the purity and performance of the film; in a vacuum environment, the boiling point of the solvent is reduced, which helps to remove the residue more gently and avoid potential damage to the film structure and active ingredients by high temperature; vacuum drying can reduce the presence of oxygen and prevent the occurrence of oxidation reactions, thereby better maintaining the biological activity of tea polyphenols and chitosan.

[0046] Preferably, the vacuum drying treatment temperature is 50°C to 70°C. More preferably, the vacuum drying treatment temperature is 55°C to 65°C. More preferably, the vacuum drying treatment temperature is 60°C. The limited vacuum drying temperature can effectively promote the volatilization of residual solvents while avoiding potential damage to the active ingredients of tea polyphenols and chitosan caused by high temperature.

[0047] Preferably, the vacuum degree of the vacuum drying process is 0.08 MPa to 0.1 MPa. Drying under a limited vacuum degree can accelerate the evaporation process of the solvent, reduce the drying time, and improve the drying efficiency.

[0048] Preferably, the vacuum drying treatment time is 4 hours to 8 hours. More preferably, the vacuum drying treatment time is 5 hours to 7 hours. More preferably, the vacuum drying treatment time is 6 hours. The limited vacuum drying time can ensure that the solvent and water in the film are fully removed, so that the final tea polyphenol-chitosan film has better stability and performance.

[0049] Preferably, the natural cooling time in step (S07-3) is 1 hour to 2 hours. More preferably, the natural cooling time in step (S07-3) is 1.5 hours. The limited natural cooling time can ensure that the equipment or material can fully dissipate heat, thereby avoiding performance degradation caused by excessive temperature.

[0050] Preferably, the chitosan is prepared by deacetylation of chitin. Chitin has a wide range of sources, and deacetylation can ensure a sufficient source of chitosan, and continuously obtain chitosan with good solubility.

[0051] Preferably, the deacetylation degree is 70% to 85%. More preferably, the deacetylation degree is 75% to 80%. The deacetylation degree within the limited range can ensure the excellent performance of chitosan and good solubility.

[0052] Preferably, the molecular weight of the chitosan is 100 kDa to 300 kDa. More preferably, the molecular weight of the chitosan is 150 kDa to 250 kDa. Chitosan with a limited molecular weight can fully ensure the protective performance of the final tea polyphenol-chitosan film when used in food.

[0053] Preferably, the pore size of the tea polyphenol-chitosan membrane is 0.005 μm to 5 μm. More preferably, the pore size of the tea polyphenol-chitosan membrane is 0.01 μm to 4 μm. More preferably, the pore size of the tea polyphenol-chitosan membrane is 0.05 μm to 3 μm. More preferably, the pore size of the tea polyphenol-chitosan membrane is 0.08 μm to 2 μm. More preferably, the pore size of the tea polyphenol-chitosan membrane is 0.1 μm to 1 μm. More preferably, the pore size of the tea polyphenol-chitosan membrane is 0.3 μm to 0.8 μm. More preferably, the pore size of the tea polyphenol-chitosan membrane is 0.5 μm to 0.7 μm. The tea polyphenol-chitosan membrane with limited membrane pore size has good filtration performance and can effectively intercept microorganisms, bacteria and other tiny particles while maintaining sufficient air permeability and water permeability; smaller pore size helps to improve the selectivity of the membrane, making it more suitable for occasions requiring high-precision filtration, while larger pore size is conducive to improving the flux of the membrane.

[0054] Preferably, the film thickness of the tea polyphenol-chitosan film is 10 μm to 50 μm. More preferably, the film thickness of the tea polyphenol-chitosan film is 15 μm to 45 μm. More preferably, the film thickness of the tea polyphenol-chitosan film is 20 μm to 40 μm. More preferably, the film thickness of the tea polyphenol-chitosan film is 25 μm to 35 μm. Limiting the film thickness of the tea polyphenol-chitosan film can ensure the mechanical strength and durability of the film, and also ensure that it has good flexibility and plasticity.

[0055] The second technical solution of the present invention: a preparation device of tea polyphenol-chitosan film, comprising a solution mixing mechanism and a solution homogenizing mechanism; the solution mixing mechanism comprises a chitosan mixing tank and a sodium alginate mixing tank, and the chitosan mixing tank and the sodium alginate mixing tank have the same structure; the solution homogenizing mechanism is respectively connected to the chitosan mixing tank and the sodium alginate mixing tank through a three-way connecting pipe, a liquid outlet pipe protrudes below the solution homogenizing mechanism, and a mixed solution stirring drum is arranged below the liquid outlet pipe;

[0056] The chitosan mixing tank comprises a mixing tank body, a mixing tank mounting seat is arranged outside the mixing tank body, a chitosan storage box is installed above the mixing tank mounting seat, the bottom of the chitosan storage box is higher than the top of the mixing tank body, and the bottom of the chitosan storage box is connected to the mixing tank body through an inclined chitosan delivery pipe;

[0057] A mixing chamber is provided inside the mixed solution mixing drum, a mixing and stirring motor is provided on the top of the mixing chamber, a mixing and stirring rod is provided at the driving end of the mixing and stirring motor, the mixing and stirring rod is located in the mixing chamber, a reaction part body is provided inside the mixed solution mixing drum, the reaction part body is located below the mixing and stirring rod, a chamber partition plate is provided between the reaction part body and the mixing and stirring rod, a liquid leakage hole is provided on the chamber partition plate, and a solenoid valve is provided at the liquid leakage hole; an ultrasonic generator is provided in the reaction part body; and a plurality of heating elements are circumferentially provided on the inner wall of the reaction part body. The present invention can ensure that chitosan and sodium alginate are evenly dispersed during the mixing process through the coordinated use of a solution mixing mechanism and a solution homogenizing mechanism, thereby avoiding the problem of uneven membrane performance caused by excessively high or low local concentrations; by providing an independent chitosan storage box and a sodium alginate storage box, and a delivery pipe respectively connected to the respective mixing tank bodies, it is ensured that the two raw materials are accurately mixed in a predetermined ratio, thereby ensuring the quality and performance of the final product; the three-way connecting pipe directly connects the chitosan storage box and the sodium alginate storage box, thereby ensuring that the two raw materials can be fully mixed to obtain a mixed solution during the delivery process, thereby avoiding the occurrence of stratification or unevenness, and also optimizing the solution mixing and homogenization process, reducing unnecessary steps and waiting time, and improving the overall production efficiency; the mixing stirring rod in the present invention effectively stirs the mixed solution β in the mixed solution stirring drum, thereby ensuring that the mixed solution β in the above process and the tea polyphenols added subsequently are fully dissolved and mixed, thereby improving the mixing efficiency; the provision of the chamber partition plate can separate the mixing chamber into The tea polyphenol-chitosan membrane liquid mixing chamber and the tea polyphenol-chitosan membrane liquid drying chamber are separated to increase the flexibility of the equipment, and different processes can be operated in the equipment at the same time, avoiding cross contamination between different processes and realizing effective isolation of different processes; in the tea polyphenol-chitosan membrane liquid mixing chamber, the tea polyphenol added later can fully contact and react with the mixed solution β to generate the desired product; due to the presence of the chamber partition plate, the tea polyphenol-chitosan membrane liquid mixing chamber and the tea polyphenol-chitosan membrane liquid drying chamber are independent of each other, avoiding mutual interference between different processes; the tea polyphenol-chitosan membrane liquid drying chamber ensures that the membrane liquid is dried and solidified under the best conditions through the setting of the reaction part body; the electromagnetic valve enables the user to easily control the state of the membrane liquid entering the reaction part body, so that the substrate plate can be attached with a suitable membrane liquid, and the tea polyphenol-chitosan membrane of the required thickness is obtained after drying and removing the substrate; the vibration wave generated by the ultrasonic generator can effectively remove the foam in the tea polyphenol-chitosan membrane liquid.

[0058] Preferably, a feeding port is protruded above the solution homogenizing mechanism, and the feeding port is arranged in parallel with the three-way connecting pipe. The feeding port is convenient for adding other materials.

[0059] Preferably, a conical guide structure is provided below the chitosan storage box, which allows the chitosan to naturally gather at the inlet of the delivery pipe under the action of gravity, thereby improving the fluidity of the chitosan during the delivery process, reducing blockage and residue, and ensuring that the raw materials can smoothly enter the delivery pipe.

[0060] Preferably, a solution stirring member is rotatably provided inside the mixing tank body; the solution stirring member comprises a stirring member body, a rotating motor is provided on the top of the mixing tank body, a driving end of the rotating motor is connected to the top of the stirring member body, a conical extension portion is axially extended from the bottom of the stirring member body, a positioning sleeve is obliquely provided on the outer curved surface of the conical extension portion, and a stirring shaft rod is provided in the positioning sleeve. By arranging a solution stirring piece inside the mixing tank body, the mixing uniformity of chitosan and sodium alginate solutions is improved, and it is ensured that the two raw materials are fully contacted and reacted during the mixing process; the stirring piece body is driven by a rotary motor and can rotate in all directions in the mixing tank, thereby driving the conical extension part and the stirring shaft to stir the solution; the obliquely arranged positioning sleeve cooperates with the outer curved surface of the conical extension part, and then during the rotation of the stirring piece, the inclination angle and curved surface of the conical extension part guide the fluid to flow along its surface, so that complex vortices and refluxes are formed in the flow process of the fluid; the positioning sleeve obliquely arranged on the outer curved surface of the conical extension part can enable the stirring shaft to generate an inclined torque during the rotation process, break the agglomeration or agglomeration in the fluid, and at the same time, combined with the above-formed vortex, a complex three-dimensional flow pattern is formed together, which increases the mixing uniformity of the fluid, improves the stirring efficiency, and ensures that chitosan and sodium alginate can be fully contacted and reacted during the mixing process.

[0061] Preferably, the stirring element body, the conical extension and the positioning sleeve are arranged in an integrally formed structure. By adopting the stirring element body, the conical extension and the positioning sleeve arranged in an integrally formed structure, the structural strength and stability of the entire device are enhanced, the leakage risk caused by the connection of multiple components is reduced, the sealing and cooperative working performance between the components during high pressure or high speed rotation are ensured, the durability and reliability of the equipment are improved, and it is also easy to process and manufacture.

[0062] Preferably, the solution stirring member also includes a mounting plate, which is fixedly arranged inside the mixing tank body, and a first positioning shaft plate, a second positioning shaft plate and a third positioning shaft plate protrude from one side of the mounting plate toward the stirring member body, the first positioning shaft plate, the second positioning shaft plate and the third positioning shaft plate are arranged in parallel up and down, a positioning ear plate is provided on the first positioning shaft plate, the stirring member body is arranged on the positioning ear plate, and a connecting ear plate is provided on the side of the second positioning shaft plate and the third positioning shaft plate close to the stirring member body, one end of the stirring shaft rod is coaxially connected to the positioning shaft sleeve, and the other opposite end of the stirring shaft rod obliquely passes through two connecting ear plates, a rolling bearing is provided in the middle of the stirring shaft rod, and the rolling bearing is rotatably matched with the two connecting ear plates; a tail stock is provided at the tail end of the stirring shaft rod, and a plurality of stirring plates are circumferentially arranged on the outer periphery of the tail stock. The three positioning shaft plates arranged in parallel in the mounting plate ensure that the stirring shaft can always be stably maintained in the predetermined position during the rotation process; the positioning ear plate of the first positioning shaft plate ensures that the shaft column on the upper part of the stirring element body can maintain a coaxial structure with the stirring shaft, thereby improving the stability and efficiency of the stirring process; the connecting ear plates of the second positioning shaft plate and the third positioning shaft plate further fix the position of the stirring shaft to prevent it from shifting or shaking during high-speed rotation; the setting of the rolling bearing reduces the friction resistance, and through the contact between its upper and lower arc surfaces and the first and second conical guide surfaces, the smooth rotation of the stirring shaft is achieved, the heat and wear caused by friction are avoided, and the service life of the equipment is extended; the oblique setting of the first conical guide surface and the second conical guide surface enables the rolling bearing to generate additional torque during movement, further breaking up the agglomeration or caking in the fluid, enhancing the mixing effect and improving the stirring efficiency, thereby ensuring that chitosan and sodium alginate can fully contact and react during the mixing process.

[0063] Preferably, the rolling bearing includes an upper arc portion, the upper arc portion is connected to a lower arc portion through a connecting shaft column, and the surfaces of the upper arc portion and the lower arc portion are both rotatably provided with a plurality of rotating balls; the lower end of the second positioning shaft plate connected to the ear plate is provided with a first conical guide surface, and the upper end of the third positioning shaft plate connected to the ear plate is provided with a second conical guide surface, and the first conical guide surface and the second conical guide surface are both provided with arc grooves, and the rotating balls are rotatably arranged in the arc grooves. The upper arc portion can roll well with the first conical guide surface through the rotating balls, and the lower arc portion can roll well with the second conical guide surface through the rotating balls, so as to ensure that the conical surface of the stirring shaft rod rotates continuously as a whole.

[0064] Preferably, a side mounting ear plate is provided on one side of the connecting ear plate in the second positioning shaft plate and the third positioning shaft plate, a rotating shaft seat is rotatably provided between the two side mounting ear plates, a rotating gear is provided on the rotating shaft seat, rotating teeth are provided on the outer periphery of the connecting shaft column, and the rotating teeth are meshed with the rotating gear; a transmission pulley is connected to the upper part of the rotating shaft seat through a connecting shaft rod, a pulley groove is provided between the stirring member body and the conical extension part, and the pulley groove is rotatably connected to the transmission pulley through a transmission belt; a stirring screw is provided below the rotating shaft seat. The rotating gear and the rotating teeth are meshed and rotated relative to each other, and together with the cooperation between the transmission pulley, the pulley groove and the transmission belt, the stirring screw can play a role in stabilizing auxiliary stirring, and together with the main stirring function of the stirring shaft rod, a more uniform dissolution of chitosan and sodium alginate solution can be achieved during the preparation process.

[0065] Preferably, the rotation path of the rotating tooth and the rotation path of the rotating gear are arranged at an angle of 15°, so as to achieve a stable matching transmission effect.

[0066] Preferably, a filtering mechanism is arranged in the mixing tank body; the filtering mechanism comprises a hydraulic layer plate and a filtering layer plate, the hydraulic layer plate is installed above the filtering layer plate by means of a lifting cylinder, the hydraulic layer plate is slidably fitted with the inner wall of the mixing tank body, a through slot hole for avoiding the solution stirring member is provided at the axial position of the hydraulic layer plate, the filtering layer plate is arranged at the bottom of the mixing tank body, and a plurality of filtering holes are arranged on the surface of the filtering layer plate. Under the action of the hydraulic layer plate, the solution in the mixing tank body can pass through the filtering layer plate to prevent large particles of impurities from passing through; the filtering layer plate arranged inside the mixing tank body realizes the filtering and purification of the material; the through slot hole provided in the hydraulic layer plate above the stirring plate can avoid the installation position of the stirring shaft; the filtering holes in the filtering layer plate below the stirring plate play a good filtering role, ensuring that only materials meeting the specific particle size requirements can pass through.

[0067] Preferably, the surface of the filter layer is coated with a hydrophobic coating. The hydrophobic coating prevents the material from adhering to the filter layer due to excessive humidity or viscosity during the filtration process, thereby keeping the filter holes unobstructed and improving the filtration efficiency; effectively reducing the contact angle between the material and the surface of the filter layer, reducing the adhesion of the material, and making it easier for the material to pass through the filter holes.

[0068] Preferably, the solution homogenizing mechanism includes a mechanism body, the mechanism body is connected to a three-way connecting pipe through a feed port at the top, a fixed mounting seat is arranged on a side wall of one side of the mechanism body, a homogenizer is fixedly mounted on the fixed mounting seat, and the rotor and stator in the homogenizer axially extend into the solution homogenizing cavity in the mechanism body. By connecting the feed port at the top of the homogenizing body with the three-way connecting pipe, the input of the material is facilitated, and it is also ensured that the material can smoothly enter the homogenizer for processing; the rotor and stator of the homogenizer are arranged inside the solution homogenizing cavity, and when the homogenizer is started, the rotor can rotate at a high speed to generate a strong shear force and impact force, so that the solution passing through is subjected to a strong mechanical action, thereby achieving uniform dispersion and refinement of the solution.

[0069] Preferably, the mixing and stirring rod comprises a stirring rod body, the stirring rod body is rotatably connected to the driving end of the mixing and stirring motor, and a cage-shaped auxiliary stirring rod is arranged on the outer periphery of the stirring rod body. The cage-shaped auxiliary stirring rod has a better stirring effect.

[0070] Preferably, a tea polyphenols feeding port is protruding from the outer wall of the mixed solution stirring barrel.

[0071] Preferably, the reaction part comprises a substrate plate, wherein the substrate plate is located in the reaction part body. The desired tea polyphenol-chitosan membrane product can be obtained through the substrate plate, and the tea polyphenol-chitosan membrane of the desired thickness can be obtained by controlling the thickness of the membrane liquid on the substrate plate, and the desired tea polyphenol-chitosan membrane can be obtained by removing the substrate plate after drying.

[0072] Preferably, a liquid level sensor is provided on the inner wall of the reaction part body.

[0073] Preferably, a shaking mechanism is provided at the bottom of the mixed solution stirring drum, and the shaking end of the shaking mechanism is connected to the reaction part body. The shaking mechanism can shake the reaction part body as needed to help the membrane solution adhere better to the substrate plate.

[0074] Preferably, the shaking mechanism includes at least three electric telescopic rods 7162), the fixed ends of the electric telescopic rods are connected to the bottom of the mixed solution mixing drum, and the telescopic ends of the electric telescopic rods are movably connected to the reaction part body; a top rod is fixedly provided at the bottom of the mixed solution mixing drum, and the top of the top rod is movably connected to the reaction part body. The shaking mechanism can achieve appropriate shaking of the reaction part body through the synergistic effect of the top rod and the electric telescopic rod, ensuring that the tea polyphenol-chitosan film solution in the reaction part body is evenly coated on the substrate plate.

[0075] Preferably, the reaction part body has an inclination angle of 3 to 8 degrees relative to the plane where the top of the push rod is located. More preferably, the reaction part body has an inclination angle of 5 to 7 degrees relative to the plane where the top of the push rod is located. The limited inclination angle can prevent the membrane liquid from being shaken out of the reaction part body due to excessive shaking.

[0076] Preferably, the heating element is an electric heating tube and / or a heating lamp, which can achieve good drying of the film liquid on the substrate plate by stably controlling the temperature.

[0077] The present invention has the following beneficial effects:

[0078] (1) using acetic acid aqueous solution to dissolve chitosan, ensuring that chitosan is evenly distributed in the solution, thereby improving the subsequent composite film-forming performance of the chitosan solution; sodium alginate, as a readily soluble salt, can be well dissolved in distilled water, and the bubbles therein are eliminated after standing, so that it is convenient to introduce more and more stable ionic bonds and hydrogen bond action points after subsequent mixing and compounding with the chitosan solution, thereby better enhancing the network structure and tensile strength of the composite film; mixing the chitosan solution prepared in advance with the sodium alginate solution to form a new mixed solution, which can well enhance the tensile strength of the chitosan solution after the final film is formed; the added glycerol can better promote the dissolution and diffusion between the molecules of the chitosan solution and the sodium alginate solution, enhance the mixing effect, and also increase the flexibility and plasticity of the chitosan solution after the final film is formed;

[0079] (2) The composite solution α is homogenized to make the added substances mixed more evenly, thereby improving the quality and performance of the composite film formed in the end; the addition of cinnamaldehyde can improve the antibacterial and antiseptic properties of the composite film in the end, and can effectively remove oxidative free radicals in food, so that the composite film in the end has good thermal stability and storage stability; the addition of an appropriate amount of Tween can better promote the dissolution between the aqueous phase and the oil phase substances, and can also ensure the uniformity and stability of the composite film in the use process;

[0080] (3) Continue to fully stir the mixed solution β so that the components therein are more fully dissolved and acted; tea polyphenols are a powerful natural antioxidant. The addition of an appropriate amount of tea polyphenols can significantly improve the antioxidant capacity of the final composite film, and the DPPH free radical scavenging rate and ABTS free radical scavenging rate of the composite film are significantly improved, thereby extending the shelf life of the composite film; the composite film after adding tea polyphenols also has a good elongation at break, making the composite film have better toughness; the composite film formed after adding tea polyphenols has a low water solubility, and the composite film is least likely to dissolve in water. After use, it can effectively inhibit the chemical changes of food and the growth and reproduction of microorganisms;

[0081] (4) subjecting the tea polyphenol-chitosan membrane liquid to ultrasonic degassing treatment to prevent the formation of holes or unevenness after membrane formation, thereby ensuring the quality of the membrane; drying and forming the treated tea polyphenol-chitosan membrane liquid to obtain a tea polyphenol-chitosan membrane having the characteristics of good tensile strength, good toughness, low water solubility, low transparency and good antioxidant performance;

[0082] (5) By using the solution mixing mechanism and the solution homogenizing mechanism in coordination, it is possible to ensure that chitosan and sodium alginate are evenly dispersed during the mixing process, thereby avoiding the problem of uneven membrane performance caused by excessively high or low local concentrations; by providing independent chitosan storage boxes and sodium alginate storage boxes, and conveying pipes respectively connected to the respective mixing tank bodies, it is ensured that the two raw materials are accurately mixed in a predetermined ratio, thereby ensuring the quality and performance of the final product; the three-way connecting pipe directly connects the chitosan storage box and the sodium alginate storage box, thereby ensuring that the two raw materials can be fully mixed to obtain a mixed solution during the conveying process, thereby avoiding the occurrence of stratification or unevenness, and optimizing the solution mixing and homogenizing process, reducing unnecessary steps and waiting time, and improving the overall production efficiency;

[0083] (6) The mixing stirring rod effectively stirs the mixed solution β in the mixed solution stirring drum to ensure that the mixed solution β in the above process and the tea polyphenols added subsequently are fully dissolved and mixed, thereby improving the mixing efficiency; the arrangement of the chamber partition plate can separate the mixing chamber into a tea polyphenol-chitosan membrane liquid mixing chamber and a tea polyphenol-chitosan membrane liquid drying chamber, thereby increasing the flexibility of the equipment and being able to perform different processes in the equipment at the same time, thereby avoiding cross contamination between different processes and achieving effective isolation of different processes; in the tea polyphenol-chitosan membrane liquid mixing chamber, the tea polyphenols added subsequently can be fully dissolved and mixed with the mixed solution β. The contact and reaction of the parts are separated to generate the desired product; due to the presence of the chamber partition, the tea polyphenol-chitosan membrane liquid mixing chamber and the tea polyphenol-chitosan membrane liquid drying chamber are independent of each other, avoiding mutual interference between different processes; the tea polyphenol-chitosan membrane liquid drying chamber is set up by the reaction part body to ensure that the membrane liquid is dried and solidified under the best conditions; the solenoid valve allows the user to easily control the state of the membrane liquid entering the reaction part body, so that the substrate plate can be attached with a suitable membrane liquid, and the tea polyphenol-chitosan membrane of the required thickness can be obtained after drying and removing the substrate; the vibration wave generated by the ultrasonic generator can effectively remove the foam in the tea polyphenol-chitosan membrane liquid. . BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 is a performance comparison diagram of elongation at break between the existing single chitosan CS film and the tea polyphenol-chitosan composite film of the present invention in the experimental example;

[0085] Figure 2It is a comparison chart of the moisture content performance of the existing single chitosan CS membrane and the tea polyphenol-chitosan composite membrane of the present invention in the experimental example;

[0086] Figure 3 It is a comparison chart of the water solubility performance of the existing single chitosan CS film and the tea polyphenol-chitosan composite film of the present invention in the experimental example;

[0087] Figure 4 It is a comparison chart of the transmittance performance of the existing single chitosan CS membrane and the tea polyphenol-chitosan composite membrane of the present invention in the experimental example;

[0088] Figure 5 It is a comparison chart of the color difference performance between the existing single chitosan CS film in the experimental example and the tea polyphenol-chitosan composite film of the present invention;

[0089] Figure 6 It is a comparison diagram of the DPPH performance of the existing single chitosan CS membrane and the tea polyphenol-chitosan composite membrane of the present invention in the experimental example;

[0090] Figure 7 It is a comparison chart of the ABTS performance of the existing single chitosan CS membrane and the tea polyphenol-chitosan composite membrane of the present invention in the experimental example;

[0091] Figure 8 It is the overall structural diagram of the device of the present invention;

[0092] Fig. 9 It is a structural diagram of the chitosan mixing tank of the present invention;

[0093] Fig.10 It is the internal structure diagram of the chitosan mixing tank of the present invention;

[0094] Fig.11 It is a structural diagram of the solution stirring member of the present invention;

[0095] Fig.12 It is a structural diagram of the rolling bearing of the present invention;

[0096] Fig.13 It is a structural diagram of the stirring blade of the present invention;

[0097] Fig.14 yes Fig.13 The enlarged view of point B in the figure;

[0098] Fig.15 It is a structural diagram of the solution homogenizing mechanism of the present invention;

[0099] Fig.16 It is an internal structure diagram of the solution homogenizing mechanism of the present invention;

[0100] Fig.17 This is an internal structure diagram of the mixed solution stirring drum of the present invention;

[0101] Fig.18 It is the first structural diagram of the shaking mechanism of the present invention;

[0102] Fig.19 It is the second structural diagram of the shaking mechanism of the present invention.

[0103] The markings in the accompanying drawings are: 100-solution mixing mechanism; 200-solution homogenizing mechanism; 201-mechanism body; 202-feeding port; 203-fixed mounting seat; 204-homogenizer; 300-chitosan mixing tank; 301-mixing tank body; 302-mixing tank mounting seat; 303-chitosan storage box; 304-chitosan delivery pipe; 310-solution stirring member; 3101-stirring member body; 3102-rotating motor; 3103-conical extension; 3104-fixed 3105-stirring shaft; 3106-mounting plate; 3107a-first positioning shaft plate; 3107b-second positioning shaft plate; 3107c-third positioning shaft plate; 3108-connecting ear plate; 3109-rolling bearing; 31091-upper arc portion; 31092-lower arc portion; 31093-connecting shaft column; 31094-rotating ball; 31095-arc groove; 3110a-first conical guide surface; 3110b-second conical guide surface; 3110c-third conical guide surface; 3111-first conical guide surface; 3110c-third conical guide surface; 3110c-third conical guide surface; 3110d ... 10-tailstock; 3111-side mounting ear plate; 3112-rotating gear; 3113-rotating tooth; 3114-drive pulley; 3115-pulley groove; 3116-drive belt; 3117-stirring screw; 3118-rotating shaft seat; 3119-positioning ear plate; 3120-stirring blade; 3121-connecting shaft; 311-filtering layer plate; 312-through slot hole; 314-filtering hole; 315-hydraulic layer plate; 316-lifting cylinder; 400-sodium alginate mixing Combined tank; 500- three-way connecting pipe; 600- liquid outlet pipe; 700- mixed solution stirring drum; 701- mixing chamber; 702- mixing stirring rod; 7021- stirring rod body; 7022- auxiliary stirring rod; 703- reaction part body; 704- chamber partition plate; 713- ultrasonic generator; 714- substrate plate; 716- shaking mechanism; 7161- push rod; 7162- electric telescopic rod; 717- mixing stirring motor; 718- solenoid valve; 800- feeding port. DETAILED DESCRIPTION

[0104] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0105] The method for preparing tea polyphenol-chitosan film comprises the following steps:

[0106] (S01) dissolving chitosan in an acetic acid aqueous solution and stirring; the mass concentration of the acetic acid aqueous solution in step (S01) is 1% to 3%; the mass concentration of the acetic acid aqueous solution in step (S01) is 2%; the mass concentration of the chitosan solution in step (S01) is 1.5% to 2.5%; the mass concentration of the chitosan solution in step (S01) is 2%; chitosan is prepared by deacetylation of chitin; the degree of deacetylation is 70% to 85%; the degree of deacetylation is 75% to 80%; the molecular weight of chitosan is 100 kDa to 300 kDa; the molecular weight of chitosan is 150 kDa to 250 kDa;

[0107] (S02) dissolving sodium alginate in distilled water and standing to defoam; the temperature of the distilled water in step (S02) is 45°C to 55°C; the temperature of the distilled water in step (S02) is 50°C; the mass concentration of sodium alginate in step (S02) is 0.4% to 0.6%; the mass concentration of sodium alginate in step (S02) is 0.5%; the defoaming in step (S02) is carried out at room temperature;

[0108] (S03) mixing the chitosan solution in step (S01) with the sodium alginate solution in step (S02), and adding an appropriate amount of glycerol to mix, to obtain a composite solution α; the volume ratio of the chitosan solution to the sodium alginate solution in step (S03) is 1-3:1-3; the volume ratio of the chitosan solution to the sodium alginate solution in step (S03) is 1:1; the mass concentration of glycerol in the composite solution α of step (S03) is 0.5%-0.7%; the mass concentration of glycerol in the composite solution α of step (S03) is 0.6%;

[0109] (S04) homogenizing the composite solution α in step (S03), and adding appropriate amounts of cinnamaldehyde and Tween to the homogenized composite solution α to obtain a mixed solution β;

[0110] The homogenization of the composite solution α in step (S04) includes the following steps:

[0111] (S04-1) transferring the composite solution α to a homogenizer (204);

[0112] (S04-2) adjusting the homogenizing pressure of the homogenizer (204) in step (S04-1) to 500 bar to 1000 bar, setting the homogenizing speed to 12000 rpm to 18000 rpm, and circulating the homogenization for 2 to 5 times, with each homogenization time being 3 min to 7 min; adjusting the homogenizing pressure of the homogenizer (204) in step (S04-2) to 700 bar to 900 bar, setting the homogenizing speed to 14000 rpm to 16000 rpm, and circulating the homogenization for 3 to 4 times, with each homogenization time being 4 min to 6 min; adjusting the homogenizing pressure of the homogenizer (204) in step (S04-2) to 800 bar , the homogenization speed is set to 15000rpm, the homogenization is circulated for 4 times, and the homogenization time is 5min each time; the mass concentration of cinnamaldehyde in the mixed solution β of step (S04) is 0.1% to 0.3%; the mass concentration of cinnamaldehyde in the mixed solution β of step (S04) is 0.2%; the mass concentration of Tween in the mixed solution β of step (S04) is 0.1% to 0.3%; the mass concentration of Tween in the mixed solution β of step (S04) is 0.2%; the mixing time in step (S04) is 20min to 40min; the mixing time in step (S04) is 25min to 35min; the mixing time in step (S04) is 30min;

[0113] (S05) fully stirring the mixed solution β in step (S04), and adding an appropriate amount of tea polyphenols to dissolve and mix well, thereby obtaining a tea polyphenol-chitosan film liquid; the mass concentration of tea polyphenols in the tea polyphenol-chitosan film liquid in step (S05) is 0.03% to 0.07%; the mass concentration of tea polyphenols in the tea polyphenol-chitosan film liquid in step (S05) is 0.04% to 0.06%; to ensure that it exists in the solution at an appropriate concentration, so as to effectively exert its antioxidant and antibacterial effects;

[0114] In step (S05), a proper amount of surfactant is added and stirred to mix; the surfactant is sodium dodecyl sulfate or polyethylene glycol; the mass concentration of sodium dodecyl sulfate in the tea polyphenol-chitosan film liquid in step (S05) is 0.1% to 0.3%; the mass concentration of sodium dodecyl sulfate in the tea polyphenol-chitosan film liquid in step (S05) is 0.2%; the mass concentration of polyethylene glycol in the tea polyphenol-chitosan film liquid in step (S05) is 0.2% to 0.4%; the mass concentration of polyethylene glycol in the tea polyphenol-chitosan film liquid in step (S05) is 0.3%;

[0115] In step (S05), an appropriate amount of vitamin E and silver nanoparticles are added; the mass concentration of vitamin E in the tea polyphenol-chitosan film liquid in step (S05) is 0.4% to 0.9%; the mass concentration of vitamin E in the tea polyphenol-chitosan film liquid in step (S05) is 0.5% to 0.8%; the mass concentration of vitamin E in the tea polyphenol-chitosan film liquid in step (S05) is 0.6% to 0.7%; the mass concentration of silver nanoparticles in the tea polyphenol-chitosan film liquid in step (S05) is 0.02% to 0.05%; the mass concentration of silver nanoparticles in the tea polyphenol-chitosan film liquid in step (S05) is 0.03% to 0.04%;

[0116] (S06) performing ultrasonic debubbling treatment on the tea polyphenol-chitosan membrane liquid in step (S05); the ultrasonic debubbling time in step (S06) is 15 min to 30 min; the ultrasonic debubbling time in step (S06) is 20 min to 25 min;

[0117] (S07) drying and molding the tea polyphenol-chitosan film liquid treated in step (S06) to obtain a tea polyphenol-chitosan film;

[0118] In step (S07), the drying and forming step of the tea polyphenol-chitosan film liquid is as follows:

[0119] (S07-1) placing the substrate coated with tea polyphenol-chitosan film liquid in a constant temperature drying oven for preheating treatment; the preheating temperature in step (S07-1) is 40°C to 60°C; the preheating temperature in step (S07-1) is 45°C to 55°C; the preheating temperature in step (S07-1) is 50°C; the preheating time in step (S07-1) is 30min to 60min; the preheating time in step (S07-1) is 35min to 55min; the preheating time in step (S07-1) is 40min to 50min; the preheating time in step (S07-1) is 45min;

[0120] (S07-2) drying the substrate placed in the constant temperature drying oven in step (S07-1) by a gradient temperature increase method;

[0121] The gradient heating method in step (S07-2) is:

[0122] First, dry at an initial temperature of 60°C for 2h to 4h to gradually remove most of the moisture; then gradually increase the temperature to 80°C and continue drying for 2h to 3h to reduce the residual solvent content in the film;

[0123] After the drying treatment (S07-2), the substrate coated with the tea polyphenol-chitosan film liquid is placed in a vacuum drying oven for vacuum drying treatment; the vacuum drying treatment temperature is 50°C to 70°C; the vacuum drying treatment temperature is 55°C to 65°C; the vacuum drying treatment temperature is 60°C; the vacuum degree of the vacuum drying treatment is 0.08MPa to 0.1MPa; the vacuum drying treatment time is 4h to 8h; the vacuum drying treatment time is 5h to 7h; the vacuum drying treatment time is 6h;

[0124] (S07-3) After drying, turn off the heating source, let the film cool naturally to room temperature in the drying oven, and then remove the substrate to obtain the tea polyphenol-chitosan film; the natural cooling time in step (S07-3) is 1h to 2h; the natural cooling time in step (S07-3) is 1.5h;

[0125] The pore size of tea polyphenol-chitosan membrane is 0.005μm~5μm; the pore size of tea polyphenol-chitosan membrane is 0.01μm~4μm; the pore size of tea polyphenol-chitosan membrane is 0.05μm~3μm; the pore size of tea polyphenol-chitosan membrane is 0.08μm~2μm; the pore size of tea polyphenol-chitosan membrane is 0.1μm~1μm; the pore size of tea polyphenol-chitosan membrane is The diameter is 0.3μm~0.8μm; the pore diameter of tea polyphenol-chitosan membrane is 0.5μm~0.7μm; the membrane thickness of tea polyphenol-chitosan membrane is 10μm~50μm; the membrane thickness of tea polyphenol-chitosan membrane is 15μm~45μm; the membrane thickness of tea polyphenol-chitosan membrane is 20μm~40μm; the membrane thickness of tea polyphenol-chitosan membrane is 25μm~35μm.

[0126] Embodiment 1:

[0127] The method for preparing tea polyphenol-chitosan film comprises the following steps:

[0128] (S01) dissolving chitosan in an acetic acid aqueous solution and stirring; the mass concentration of the acetic acid aqueous solution in step (S01) is 1%; the mass concentration of the chitosan solution in step (S01) is 1.5%; chitosan is prepared by deacetylation of chitin; the degree of deacetylation is 70%; the molecular weight of chitosan is 100 kDa to 300 kDa;

[0129] (S02) dissolving sodium alginate in distilled water and standing to defoam; the temperature of the distilled water in step (S02) is 45° C.; the mass concentration of sodium alginate in step (S02) is 0.4%; the defoaming in step (S02) is carried out at room temperature;

[0130] (S03) mixing the chitosan solution in step (S01) with the sodium alginate solution in step (S02), and adding an appropriate amount of glycerol to mix, to obtain a composite solution α; the volume ratio of the chitosan solution to the sodium alginate solution in step (S03) is 2:1; the mass concentration of glycerol in the composite solution α in step (S03) is 0.5%;

[0131] (S04) homogenizing the composite solution α in step (S03), and adding appropriate amounts of cinnamaldehyde and Tween to the homogenized composite solution α to obtain a mixed solution β;

[0132] The homogenization of the composite solution α in step (S04) includes the following steps:

[0133] (S04-1) transferring the composite solution α to a homogenizer (204);

[0134] (S04-2) adjusting the homogenization pressure of the homogenizer (204) in step (S04-1) to 500 bar, setting the homogenization speed to 12000 rpm, and performing cyclic homogenization for 2 times, each homogenization time being 3 min; the mass concentration of cinnamaldehyde in the mixed solution β of step (S04) is 0.1%; the mass concentration of Tween in the mixed solution β of step (S04) is 0.1%; the mixing time in step (S04) is 20 min;

[0135] (S05) fully stirring the mixed solution β in step (S04), and adding an appropriate amount of tea polyphenol to dissolve and mix well, thereby obtaining a tea polyphenol-chitosan film solution; the mass concentration of tea polyphenol in the tea polyphenol-chitosan film solution in step (S05) is 0.03%;

[0136] In step (S05), an appropriate amount of surfactant is added and stirred to mix; the surfactant is sodium dodecyl sulfate; the mass concentration of sodium dodecyl sulfate in the tea polyphenol-chitosan film liquid in step (S05) is 0.1%;

[0137] In step (S05), an appropriate amount of vitamin E and silver nanoparticles are added; the mass concentration of vitamin E in the tea polyphenol-chitosan film liquid in step (S05) is 0.4%; the mass concentration of silver nanoparticles in the tea polyphenol-chitosan film liquid in step (S05) is 0.02%;

[0138] (S06) performing ultrasonic debubbling treatment on the tea polyphenol-chitosan membrane liquid in step (S05); the ultrasonic debubbling time in step (S06) is 15 minutes;

[0139] (S07) drying and molding the tea polyphenol-chitosan film liquid treated in step (S06) to obtain a tea polyphenol-chitosan film;

[0140] In step (S07), the drying and forming step of the tea polyphenol-chitosan film liquid is as follows:

[0141] (S07-1) placing the substrate coated with the tea polyphenol-chitosan film liquid in a constant temperature drying oven for preheating; the preheating temperature in step (S07-1) is 40° C.; the preheating time in step (S07-1) is 30 minutes;

[0142] (S07-2) drying the substrate placed in the constant temperature drying oven in step (S07-1) by a gradient temperature increase method;

[0143] The gradient heating method in step (S07-2) is:

[0144] First, the film was dried at an initial temperature of 60°C for 2 h to gradually remove most of the water; then the temperature was gradually increased to 80°C and the film was dried for another 2 h to reduce the residual solvent content in the film;

[0145] After the drying treatment (S07-2), the substrate coated with the tea polyphenol-chitosan film liquid is placed in a vacuum drying oven for vacuum drying treatment; the vacuum drying treatment temperature is 50° C.; the vacuum degree of the vacuum drying treatment is 0.08 MPa; and the vacuum drying treatment time is 4 hours;

[0146] (S07-3) After drying, turn off the heating source, let the film cool naturally to room temperature in the drying oven, and then remove the substrate to obtain the tea polyphenol-chitosan film; the natural cooling time in step (S07-3) is 1 hour;

[0147] The membrane pore size of the tea polyphenol-chitosan membrane is 0.005 μm to 5 μm; the membrane thickness of the tea polyphenol-chitosan membrane is 10 μm to 50 μm.

[0148] Embodiment 2:

[0149] The method for preparing tea polyphenol-chitosan film comprises the following steps:

[0150] (S01) dissolving chitosan in an acetic acid aqueous solution and stirring; the mass concentration of the acetic acid aqueous solution in step (S01) is 3%; the mass concentration of the chitosan solution in step (S01) is 2.5%; chitosan is prepared by deacetylation of chitin; the degree of deacetylation is 85%; the molecular weight of chitosan is 150 kDa to 250 kDa;

[0151] (S02) dissolving sodium alginate in distilled water and standing to defoam; the temperature of the distilled water in step (S02) is 55° C.; the mass concentration of sodium alginate in step (S02) is 0.6%; the defoaming in step (S02) is carried out at room temperature;

[0152] (S03) mixing the chitosan solution in step (S01) with the sodium alginate solution in step (S02), and adding an appropriate amount of glycerol to mix, to obtain a composite solution α; the volume ratio of the chitosan solution to the sodium alginate solution in step (S03) is 3:2; the mass concentration of glycerol in the composite solution α in step (S03) is 0.7%;

[0153] (S04) homogenizing the composite solution α in step (S03), and adding appropriate amounts of cinnamaldehyde and Tween to the homogenized composite solution α to obtain a mixed solution β;

[0154] The homogenization of the composite solution α in step (S04) includes the following steps:

[0155] (S04-1) transferring the composite solution α to a homogenizer (204);

[0156] (S04-2) adjusting the homogenization pressure of the homogenizer (204) in step (S04-1) to 1000 bar, setting the homogenization speed to 18000 rpm, and performing homogenization for 5 times, each homogenization time being 7 minutes; the mass concentration of cinnamaldehyde in the mixed solution β of step (S04) is 0.3%; the mass concentration of Tween in the mixed solution β of step (S04) is 0.3%; the mixing time in step (S04) is 40 minutes;

[0157] (S05) fully stirring the mixed solution β in step (S04), and adding an appropriate amount of tea polyphenols to dissolve and mix well, thereby obtaining a tea polyphenol-chitosan film solution; the mass concentration of tea polyphenols in the tea polyphenol-chitosan film solution in step (S05) is 0.07%; this is used to ensure that the tea polyphenols exist in the solution at an appropriate concentration, thereby effectively exerting their antioxidant and antibacterial effects;

[0158] In step (S05), an appropriate amount of surfactant is added and stirred to mix; the surfactant is polyethylene glycol; the mass concentration of polyethylene glycol in the tea polyphenol-chitosan film solution in step (S05) is 0.4%;

[0159] In step (S05), an appropriate amount of vitamin E and silver nanoparticles are added; the mass concentration of vitamin E in the tea polyphenol-chitosan film liquid in step (S05) is 0.9%; the mass concentration of silver nanoparticles in the tea polyphenol-chitosan film liquid in step (S05) is 0.05%;

[0160] (S06) performing ultrasonic debubbling treatment on the tea polyphenol-chitosan membrane liquid in step (S05); the ultrasonic debubbling time in step (S06) is 30 minutes;

[0161] (S07) drying and molding the tea polyphenol-chitosan film liquid treated in step (S06) to obtain a tea polyphenol-chitosan film;

[0162] In step (S07), the drying and forming step of the tea polyphenol-chitosan film liquid is as follows:

[0163] (S07-1) placing the substrate coated with the tea polyphenol-chitosan film liquid in a constant temperature drying oven for preheating; the preheating temperature in step (S07-1) is 60° C.; the preheating time in step (S07-1) is 60 minutes;

[0164] (S07-2) drying the substrate placed in the constant temperature drying oven in step (S07-1) by a gradient temperature increase method;

[0165] The gradient heating method in step (S07-2) is:

[0166] First, the film was dried at an initial temperature of 60°C for 4 h to gradually remove most of the water; then the temperature was gradually increased to 80°C and the film was dried for another 3 h to reduce the residual solvent content in the film;

[0167] After the drying treatment (S07-2), the substrate coated with the tea polyphenol-chitosan film solution is placed in a vacuum drying oven for vacuum drying treatment; the vacuum drying treatment temperature is 70°C; the vacuum degree of the vacuum drying treatment is 0.1MPa; and the vacuum drying treatment time is 8h;

[0168] (S07-3) After drying, turn off the heating source, let the film cool naturally to room temperature in the drying oven, and then remove the substrate to obtain the tea polyphenol-chitosan film; the natural cooling time in step (S07-3) is 2h;

[0169] The pore size of the tea polyphenol-chitosan membrane is 0.01 μm to 4 μm; the thickness of the tea polyphenol-chitosan membrane is 15 μm to 45 μm.

[0170] Embodiment 3:

[0171] The method for preparing tea polyphenol-chitosan film comprises the following steps:

[0172] (S01) dissolving chitosan in an acetic acid aqueous solution and stirring; the mass concentration of the acetic acid aqueous solution in step (S01) is 1%; the mass concentration of the chitosan solution in step (S01) is 2%; chitosan is prepared by deacetylation of chitin; the degree of deacetylation is 70% to 85%; the molecular weight of chitosan is 100 kDa to 300 kDa;

[0173] (S02) dissolving sodium alginate in distilled water and standing to defoam; the temperature of the distilled water in step (S02) is 50° C.; the mass concentration of sodium alginate in step (S02) is 0.5%; the defoaming in step (S02) is carried out at room temperature;

[0174] (S03) mixing the chitosan solution in step (S01) with the sodium alginate solution in step (S02), and adding an appropriate amount of glycerol to mix, to obtain a composite solution α; the volume ratio of the chitosan solution to the sodium alginate solution in step (S03) is 1:1; the mass concentration of glycerol in the composite solution α in step (S03) is 0.6%;

[0175] (S04) homogenizing the composite solution α in step (S03), and adding appropriate amounts of cinnamaldehyde and Tween to the homogenized composite solution α to obtain a mixed solution β;

[0176] The homogenization of the composite solution α in step (S04) includes the following steps:

[0177] (S04-1) transferring the composite solution α to a homogenizer (204);

[0178] (S04-2) adjusting the homogenization pressure of the homogenizer (204) in step (S04-1) to 800 bar, setting the homogenization speed to 15000 rpm, and performing homogenization for 3 times, each homogenization time being 5 min; the mass concentration of cinnamaldehyde in the mixed solution β of step (S04) is 0.2%; the mass concentration of Tween in the mixed solution β of step (S04) is 0.2%; the mixing time in step (S04) is 30 min;

[0179] (S05) fully stirring the mixed solution β in step (S04), and adding an appropriate amount of tea polyphenols to dissolve and mix well, thereby obtaining a tea polyphenol-chitosan film solution; the mass concentration of tea polyphenols in the tea polyphenol-chitosan film solution in step (S05) is 0.05%; this is used to ensure that the tea polyphenols exist in the solution at an appropriate concentration, thereby effectively exerting their antioxidant and antibacterial effects;

[0180] In step (S05), an appropriate amount of surfactant is added and stirred to mix; the surfactant is sodium dodecyl sulfate; the mass concentration of sodium dodecyl sulfate in the tea polyphenol-chitosan film liquid in step (S05) is 0.2%;

[0181] In step (S05), an appropriate amount of vitamin E and silver nanoparticles are added; the mass concentration of vitamin E in the tea polyphenol-chitosan film liquid in step (S05) is 0.6%; the mass concentration of silver nanoparticles in the tea polyphenol-chitosan film liquid in step (S05) is 0.03%;

[0182] (S06) performing ultrasonic debubbling treatment on the tea polyphenol-chitosan membrane liquid in step (S05); the ultrasonic debubbling time in step (S06) is 20 minutes;

[0183] (S07) drying and molding the tea polyphenol-chitosan film liquid treated in step (S06) to obtain a tea polyphenol-chitosan film;

[0184] In step (S07), the drying and forming step of the tea polyphenol-chitosan film liquid is as follows:

[0185] (S07-1) placing the substrate coated with the tea polyphenol-chitosan film liquid in a constant temperature drying oven for preheating; the preheating temperature in step (S07-1) is 50° C.; the preheating time in step (S07-1) is 45 minutes;

[0186] (S07-2) drying the substrate placed in the constant temperature drying oven in step (S07-1) by a gradient temperature increase method;

[0187] The gradient heating method in step (S07-2) is:

[0188] First, the film was dried at an initial temperature of 60°C for 3 h to gradually remove most of the water; then the temperature was gradually increased to 80°C and the film was dried for another 2.5 h to reduce the residual solvent content in the film;

[0189] After the drying treatment (S07-2), the substrate coated with the tea polyphenol-chitosan film solution is placed in a vacuum drying oven for vacuum drying treatment; the vacuum drying treatment temperature is 60°C; the vacuum degree of the vacuum drying treatment is 0.09MPa; and the vacuum drying treatment time is 6h;

[0190] (S07-3) After drying, turn off the heating source, let the film cool naturally to room temperature in the drying oven, and then remove the substrate to obtain the tea polyphenol-chitosan film; the natural cooling time in step (S07-3) is 1.5h;

[0191] The pore size of the tea polyphenol-chitosan membrane is 0.05 μm to 3 μm; the thickness of the tea polyphenol-chitosan membrane is 20 μm to 40 μm.

[0192] Experimental example:

[0193] The method for preparing tea polyphenol-chitosan film comprises the following steps:

[0194] (S01) dissolving chitosan in an acetic acid aqueous solution, and stirring at room temperature overnight on a magnetic stirrer; the mass concentration of the acetic acid aqueous solution is 1%; the mass concentration of the chitosan solution in step (S01) is 2%; chitosan is prepared by deacetylation of chitin; the degree of deacetylation is 70% to 85%; the molecular weight of chitosan is 100 kDa to 300 kDa;

[0195] (S02) dissolving sodium alginate in 50° C. distilled water and standing at room temperature to defoam; the mass concentration of sodium alginate is 0.5%;

[0196] (S03) mixing the chitosan solution in step (S01) and the sodium alginate solution in step (S02) in a volume ratio of 1:1, and adding an appropriate amount of glycerol to mix, to obtain a composite solution α; the mass concentration of glycerol in the composite solution α is 0.6%;

[0197] (S04) cyclically homogenizing the composite solution α in step (S03) at a pressure of 800 bar and a rotation speed of 15000 rpm for 3 times, each homogenization time being 5 minutes; and adding appropriate amounts of cinnamaldehyde and Tween to the homogenized composite solution α and magnetically mixing and stirring for 30 minutes to obtain a mixed solution β; the mass concentration of cinnamaldehyde in the mixed solution β is 0.2%; the mass concentration of Tween in the mixed solution β is 0.2%;

[0198] (S05) fully stirring the mixed solution β in step (S04), adding an appropriate amount of tea polyphenols and magnetically stirring for 20 minutes to dissolve and mix, thereby obtaining a tea polyphenol-chitosan film liquid; the mass concentration of tea polyphenols in the tea polyphenol-chitosan film liquid is 0.05%;

[0199] In step (S05), an appropriate amount of sodium dodecyl sulfate is added and then magnetically stirred for 20 minutes to mix; the mass concentration of sodium dodecyl sulfate in the tea polyphenol-chitosan film liquid is 0.2%;

[0200] In step (S05), an appropriate amount of vitamin E and silver nanoparticles are added; the mass concentration of vitamin E in the tea polyphenol-chitosan film liquid is 0.6%; the mass concentration of silver nanoparticles in the tea polyphenol-chitosan film liquid is 0.03%;

[0201] (S06) subjecting the tea polyphenol-chitosan membrane solution in step (S05) to an ultrasonic treatment for 20 minutes to remove bubbles;

[0202] (S07) taking 20 ml of the membrane solution and drying it in a 9 cm culture dish to obtain a tea polyphenol-chitosan membrane;

[0203] In step (S07), the drying and forming step of the tea polyphenol-chitosan film liquid is as follows:

[0204] (S07-1) placing the substrate coated with the tea polyphenol-chitosan film solution in a constant temperature drying oven at 50° C. for preheating for 45 minutes;

[0205] (S07-2) drying the substrate placed in the constant temperature drying oven in step (S07-1) by a gradient temperature increase method;

[0206] The gradient heating method in step (S07-2) is:

[0207] First, the film was dried at an initial temperature of 60°C for 3 h to gradually remove most of the water; then the temperature was gradually increased to 80°C and the film was dried for another 2.5 h to reduce the residual solvent content in the film;

[0208] After the drying treatment (S07-2), the substrate coated with the tea polyphenol-chitosan film solution is placed in a vacuum drying oven with a vacuum degree of 0.09 MPa and a vacuum drying treatment temperature of 60° C. for 6 hours;

[0209] (S07-3) After drying, the heating source is turned off, and the membrane is allowed to cool naturally in a drying oven for 1.5 hours to room temperature before removing the substrate to obtain a tea polyphenol-chitosan membrane.

[0210] Two days later, the elongation at break, moisture content, water solubility, transmittance, color difference, DPPH and ABTS properties of the tea polyphenol-chitosan film were measured.

[0211] The addition of sodium alginate introduces more ionic and hydrogen bonding sites, enhances the network structure and tensile strength of the membrane, and the elongation at break of the composite membrane after adding tea polyphenols is improved. Figure 1 As shown, the tea polyphenol-chitosan film of the present invention can take into account both tensile strength and toughness.

[0212] The composite film has a certain water absorption capacity. When the moisture content of the composite film exceeds a certain moisture content, it is conducive to the growth and reproduction of microorganisms; low moisture content can inhibit the chemical changes of food and the growth and reproduction of microorganisms; moisture content below 40% is not conducive to the growth of most microorganisms; Figure 2 and Figure 3 As shown, the tea polyphenol-chitosan composite film of the present invention has low water solubility, is not easily dissolved in water, and has a good effect.

[0213] The transmittance of the film can indirectly reflect its transparency. The greater the transmittance, the greater the density of the film and the higher the transparency. The surface color difference can be used to measure the color change of the composite film surface. The transmittance of the single chitosan CS film is higher, and the transparency of the film is higher. The single chitosan CS film is transparent. After adding cinnamaldehyde, the color of the film has a light yellow color and the color difference increases. After adding sodium alginate, the film becomes milky white. Figure 4 and Figure 5 As shown, the transparency of the tea polyphenol-chitosan film of the present invention is relatively low.

[0214] like Figure 6 and Figure 7 As shown, the tea polyphenol-chitosan composite film of the present invention has high DPPH free radical scavenging rate and ABTS free radical scavenging rate, and has good antioxidant performance.

[0215] like Figure 8The tea polyphenol-chitosan film preparation device shown in the figure comprises a solution mixing mechanism 100 and a Fig.15 The solution homogenizing mechanism 200 shown; the solution mixing mechanism 100 includes Fig. 9 The chitosan mixing tank 300 and the sodium alginate mixing tank 400 shown in the figure have the same structure as the sodium alginate mixing tank 400; the solution homogenizing mechanism 200 is connected to the chitosan mixing tank 300 and the sodium alginate mixing tank 400 respectively through a three-way connecting pipe 500, and a liquid outlet pipe 600 is protruded below the solution homogenizing mechanism 200, and a liquid outlet pipe 600 is provided below the liquid outlet pipe 600. Fig.17 The mixed solution stirring drum 700 is shown;

[0216] The chitosan mixing tank 300 includes: Fig.10 The mixing tank body 301 shown in the figure has a mixing tank mounting seat 302 disposed outside the mixing tank body 301, a chitosan storage box 303 is mounted above the mixing tank mounting seat 302, the bottom of the chitosan storage box 303 is higher than the top of the mixing tank body 301, and the bottom of the chitosan storage box 303 is connected to the mixing tank body 301 through an inclined chitosan delivery pipe 304;

[0217] A mixing chamber 701 is provided inside the mixed solution stirring drum 700, a mixing and stirring motor 717 is provided on the top of the mixing chamber 701, a mixing and stirring rod 702 is provided at the driving end of the mixing and stirring motor, and the mixing and stirring rod 702 is located in the mixing chamber 701, a reaction unit body 703 is provided inside the mixed solution stirring drum 700, the reaction unit body 703 is located below the mixing and stirring rod 702, a chamber partition plate 704 is provided between the reaction unit body 703 and the mixing and stirring rod 702, a liquid leakage hole is provided on the chamber partition plate 704, and a solenoid valve 718 is provided at the liquid leakage hole; an ultrasonic generator 713 is provided inside the reaction unit body 703; and a plurality of heating elements are circumferentially provided on the inner wall of the reaction unit body 703.

[0218] A feeding port 800 is protruded above the solution homogenizing mechanism 200, and the feeding port 800 is arranged in parallel with the three-way connecting pipe 500. A solution stirring member 310 is rotatably arranged inside the mixing tank body 301; the solution stirring member 310 includes a stirring member body 3101, a rotating motor 3102 is arranged on the top of the mixing tank body 301, and the driving end of the rotating motor 3102 is connected to the top of the stirring member body 3101, and a conical extension portion 3103 is axially extended from the bottom of the stirring member body 3101, and a positioning sleeve 3104 is obliquely arranged on the outer curved surface of the conical extension portion 3103, and the positioning sleeve 3104 is provided with a Fig.11The stirring shaft 3105 is shown. The stirring member body 3101, the conical extension 3103 and the positioning sleeve 3104 are an integrally formed structure. The solution stirring member 310 also includes a mounting plate 3106, which is fixedly arranged inside the mixing tank body 301. The mounting plate 3106 has a first positioning shaft plate 3107a, a second positioning shaft plate 3107b and a third positioning shaft plate 3107c protruding from one side of the mounting plate 3106 toward the stirring member body 3101. The first positioning shaft plate 3107a, the second positioning shaft plate 3107b and the third positioning shaft plate 3107c are arranged in parallel up and down. The first positioning shaft plate 3107a is provided with a positioning ear plate 3119, and the stirring member body 3101 is arranged on the positioning ear plate 3119. 119, a connecting ear plate 3108 is provided on one side of the second positioning shaft plate 3107b and the third positioning shaft plate 3107c close to the stirring member body 3101, one end of the stirring shaft rod 3105 is coaxially connected to the positioning shaft sleeve 3104, and the other opposite end of the stirring shaft rod 3105 obliquely passes through the two connecting ear plates 3108, and a rolling bearing 3109 is provided in the middle of the stirring shaft rod 3105, and the rolling bearing 3109 is rotatably matched with the two connecting ear plates 3108; a tailstock 3110 is provided at the tail of the stirring shaft rod 3105, and the outer circumference of the tailstock 3110 is circumferentially arranged as shown in the figure. Fig.13 The rolling bearing 3109 includes an upper arc portion 31091, and the upper arc portion 31091 is formed by Fig.12 The connecting shaft column 31093 shown is connected to the lower arc portion 31092, and a plurality of rotating balls 31094 are rotatably provided on the surfaces of the upper arc portion 31091 and the lower arc portion 31092; a first conical guide surface 3110a is provided at the lower end of the ear plate 3108 connected to the second positioning shaft plate 3107b, and a second conical guide surface 3110b is provided at the upper end of the ear plate 3108 connected to the third positioning shaft plate 3107c, and an arc groove 31095 is provided on the first conical guide surface 3110a and the second conical guide surface 3110b, and the rotating balls 31094 are rotatably set in the arc groove 31095.

[0219] A side mounting ear plate 3111 is provided on one side of the connecting ear plate 3108 in the second positioning shaft plate 3107b and the third positioning shaft plate 3107c. A rotating shaft seat 3118 is provided between the two side mounting ear plates 3111. Fig.14The rotating gear 3112 shown in the figure has rotating teeth 3113 arranged on the outer periphery of the connecting shaft column 31093, and the rotating teeth 3113 mesh with the rotating gear 3112; a driving pulley 3114 is connected to the upper part of the rotating shaft seat 3118 through a connecting shaft rod 3121, a pulley groove 3115 is arranged between the stirring member body 3101 and the conical extension 3103, and the pulley groove 3115 is rotatably connected to the driving pulley 3114 through a driving belt 3116; a stirring screw 3117 is arranged below the rotating shaft seat 3118. The rotating path of the rotating teeth 3113 and the rotating path of the rotating gear 3112 are arranged at an angle of 15°.

[0220] A filtering mechanism is arranged in the mixing tank body 301; the filtering mechanism includes a hydraulic layer plate 315 and a filter layer plate 311. The hydraulic layer plate 315 is movably installed above the filter layer plate 311 through a lifting cylinder 316. The hydraulic layer plate 315 is slidably fitted with the inner wall of the mixing tank body 301. A through slot 312 for avoiding the solution stirring member 310 is provided at the axial position of the hydraulic layer plate 315. The filter layer plate 311 is arranged at the bottom of the mixing tank body 301. A plurality of filtering holes 314 are arranged on the surface of the filter layer plate 311. The surface of the filter layer plate 311 is coated with a hydrophobic coating. The solution homogenizing mechanism 200 includes a mechanism body 201. The mechanism body 201 is connected to the three-way connecting pipe 500 through the upper feed port 202. A fixed mounting seat 203 is arranged on the side wall of one side of the mechanism body 201. The fixed mounting seat 203 is fixedly installed with a Fig.16 In the homogenizer 204 shown, the rotor and the stator in the homogenizer 204 extend axially into the solution homogenizing chamber 205 in the mechanism body 201 .

[0221] The mixing and stirring rod 702 includes a stirring rod body 7021, which is rotatably connected to the driving end of the mixing and stirring motor, and a cage-shaped auxiliary stirring rod 7022 is arranged on the outer periphery of the stirring rod body 7021. A tea polyphenol feeding port is protruded from the outer wall of the mixed solution stirring barrel 700. The substrate plate 714 is included, and the substrate plate 714 is located in the reaction part body 703. A liquid level sensor is arranged on the inner wall of the reaction part body 703.

[0222] The bottom of the mixed solution stirring drum 700 is provided with Fig.18 and Fig.19The shaking mechanism 716 shown, the shaking end of the shaking mechanism 716 is connected to the reaction part body 703. The shaking mechanism 716 includes at least three electric telescopic rods 7162, the fixed end of the electric telescopic rod 7162 is connected to the bottom of the mixed solution mixing drum 700, and the telescopic end of the electric telescopic rod 7162 is movably connected to the reaction part body 703; the bottom of the mixed solution mixing drum 700 is fixed with a top rod 7161, and the top of the top rod 7161 is movably connected to the reaction part body 703. The inclination angle of the reaction part body 703 relative to the plane where the top of the top rod 7161 is located is 3 degrees to 8 degrees. The heating element is an electric heating tube and / or a heating lamp.

[0223] The working principle of the device of the present invention is:

[0224] Chitosan and sodium alginate are premixed in their respective mixing tank bodies 301 .

[0225] Then, the solution stirring parts 310 provided in the main body of the chitosan mixing tank 300 and the main body of the sodium alginate mixing tank 400 are used to stir the two raw materials sufficiently to ensure that the two raw materials are evenly dispersed in their respective mixing tanks.

[0226] Specifically, when chitosan enters the chitosan mixing tank 300 body from the chitosan storage box 303 through the chitosan delivery pipe 304, and sodium alginate enters the sodium alginate mixing tank 400 from the sodium alginate storage box body through the sodium alginate delivery pipe, the materials pass through the filter layer plate 311 inside the mixing tank body 301, and are filtered and purified before entering the filter layer plate 311, and larger impurities or incompletely mixed particles are intercepted to prevent them from directly entering the subsequent mixing process.

[0227] Then, the stirring element main body 3101 inside the mixing tank body 301 is driven by the rotating motor 3102 to rotate 360 ​​degrees in all directions in the mixing tank, driving the conical extension part 3103 and the stirring shaft 3105 to stir the solution; the obliquely arranged positioning sleeve 3104 cooperates with the outer curved surface of the conical extension part 3103, and during the rotation of the stirring element, the inclination angle and curved surface of the conical extension part 3103 guide the fluid to flow along its surface, so that complex vortices and refluxes are formed in the flow of the fluid; the positioning sleeve 3104 obliquely arranged on the outer curved surface of the conical extension part 3103 can enable the stirring shaft 3105 to generate an inclined torque during the rotation process, break up the agglomeration or agglomeration in the fluid, and at the same time combine with the vortex formed as mentioned above to form a complex three-dimensional flow pattern.

[0228] After filtering and all-round stirring, the solution has achieved a high degree of uniformity and purity before entering the solution homogenizing mechanism 200; the chitosan and sodium alginate solutions obtained above are mixed through a three-way connecting tube 500 to obtain a mixed solution, which is then introduced into the solution homogenizing mechanism 200, and glycerol as a plasticizer and cinnamaldehyde as a cross-linking agent are added into the solution homogenizing mechanism 200 in a certain proportion, and the mixed solution containing glycerol and cinnamaldehyde is fully stirred and mixed to obtain a mixed solution β, and then the mixed solution β obtained above is introduced into the mixed solution mixing drum 700 through a liquid outlet pipe 600 protruding from the outer wall of the solution homogenizing mechanism 200.

[0229] The mixing and stirring rod 702 effectively stirs the mixed solution β in the mixed solution stirring drum 700, ensuring that the mixed solution β in the above process and the tea polyphenols added subsequently are fully dissolved and mixed, thereby improving the mixing efficiency; the arrangement of the chamber partition plate 704 can separate the mixing chamber into a tea polyphenol-chitosan membrane liquid mixing chamber and a tea polyphenol-chitosan membrane liquid drying chamber, thereby increasing the flexibility of the equipment, being able to perform operations of different processes in the equipment at the same time, thereby avoiding cross contamination between different processes and achieving effective isolation of different processes; in the tea polyphenol-chitosan membrane liquid mixing chamber, the tea polyphenols added subsequently can fully contact and react with the mixed solution β to generate the desired product; due to the presence of the chamber partition plate 704, the tea polyphenol-chitosan membrane liquid mixing chamber and the tea polyphenol-chitosan membrane liquid drying chamber are independent of each other, thereby avoiding mutual interference between different processes; ... The polysaccharide film liquid drying chamber is set up by the reaction part body to ensure that the film liquid is dried and solidified under the best conditions; the electromagnetic valve 18 allows the user to easily control the state of the film liquid entering the reaction part body, so that the substrate plate 714 can be attached with a suitable film liquid, and the tea polyphenol-chitosan film of the required thickness is obtained after drying and removing the substrate; the vibration wave generated by the ultrasonic generator 713 can effectively remove the foam in the tea polyphenol-chitosan film liquid; the required tea polyphenol-chitosan film product can be obtained through the substrate plate 714, and the tea polyphenol-chitosan film of the required thickness can be obtained by controlling the thickness of the film liquid on the substrate plate. After drying, the substrate plate is removed to obtain the required tea polyphenol-chitosan film; the shaking mechanism 716 can realize the appropriate shaking of the reaction part body 703 through the synergistic effect of the top rod 7161 and the electric telescopic rod 7162, ensuring that the tea polyphenol-chitosan film liquid in the reaction part body is evenly coated on the substrate plate.

[0230] Finally, the tea polyphenol-chitosan membrane liquid is dried by a heating lamp group arranged on the circumference of the inner wall of the reaction part body 703 .

Claims

1. A method for preparing tea polyphenol-chitosan film, characterized in that: Includes the following step, (S01) dissolving chitosan in an acetic acid aqueous solution and stirring; (S02) dissolving sodium alginate in distilled water and allowing to stand to defoam; (S03) mixing the chitosan solution in step (S01) with the sodium alginate solution in step (S02), and adding an appropriate amount of glycerol to mix, to obtain a composite solution α; (S04) homogenizing the composite solution α in step (S03), and adding appropriate amounts of cinnamaldehyde and Tween to the homogenized composite solution α to obtain a mixed solution β; (S05) fully stirring the mixed solution β in step (S04), and adding an appropriate amount of tea polyphenol to dissolve and mix well, thereby obtaining a tea polyphenol-chitosan film solution; (S06) performing ultrasonic degassing treatment on the tea polyphenol-chitosan membrane solution in step (S05); (S07) drying and molding the tea polyphenol-chitosan film liquid treated in step (S06) to obtain a tea polyphenol-chitosan film; The mass concentration of the acetic acid aqueous solution in step (S01) is 1% to 3%; the mass concentration of the chitosan solution in step (S01) is 1.5% to 2.5%; the temperature of the distilled water in step (S02) is 45°C to 55°C; the mass concentration of sodium alginate in step (S02) is 0.4% to 0.6%; the volume ratio of the chitosan solution to the sodium alginate solution in step (S03) is 1 to 3:1 to 3; the mass concentration of glycerol in the composite solution α in step (S03) is 0.5% to 0.7%; The mass concentration of cinnamaldehyde in the mixed solution β of step (S04) is 0.1% to 0.3%; the mass concentration of Tween in the mixed solution β of step (S04) is 0.1% to 0.3%; the mixing time in step (S04) is 20min to 40min; the mass concentration of tea polyphenol in the tea polyphenol-chitosan membrane solution of step (S05) is 0.03% to 0.07%; the ultrasonic debubbling time in step (S06) is 15min to 30min.

2. The method for preparing the tea polyphenol-chitosan film according to claim 1, characterized in that: The homogenization of the composite solution α in the step (S04) includes the following steps: (S04-1) transferring the composite solution α to a homogenizer (204); (S04-2) Adjust the homogenization pressure of the homogenizer (204) in step (S04-1) to 500 bar to 1000 bar, set the homogenization speed to 12000 rpm to 18000 rpm, and cycle homogenization 2 to 5 times, with each homogenization time being 3 min to 7 min.

3. The method for preparing the tea polyphenol-chitosan film according to claim 1, characterized in that: In the step (S05), a proper amount of surfactant is added and then stirred to mix; the surfactant is sodium dodecyl sulfate or polyethylene glycol; the mass concentration of sodium dodecyl sulfate in the tea polyphenol-chitosan membrane liquid in the step (S05) is 0.1% to 0.3%, or the mass concentration of polyethylene glycol in the tea polyphenol-chitosan membrane liquid in the step (S05) is 0.2% to 0.4%.

4. The method for preparing the tea polyphenol-chitosan film according to claim 1, characterized in that: In the step (S05), appropriate amounts of vitamin E and silver nanoparticles are added; the mass concentration of vitamin E in the tea polyphenol-chitosan film liquid in the step (S05) is 0.4% to 0.9%; the mass concentration of silver nanoparticles in the tea polyphenol-chitosan film liquid in the step (S05) is 0.02% to 0.05%.

5. The method for preparing the tea polyphenol-chitosan film according to claim 1, characterized in that: The drying and forming step of the tea polyphenol-chitosan film liquid in step (S07) is: (S07-1) placing the substrate coated with the tea polyphenol-chitosan film solution into a constant temperature drying oven for preheating; (S07-2) drying the substrate placed in the constant temperature drying oven in step (S07-1) by a gradient temperature increase method; (S07-3) After drying, the heating source is turned off, and the film is allowed to cool naturally to room temperature in a drying oven, and then the substrate is removed to obtain a tea polyphenol-chitosan film.

6. The method for preparing the tea polyphenol-chitosan film according to claim 5, characterized in that: The preheating temperature in the step (S07-1) is 40°C to 60°C; the preheating time in the step (S07-1) is 30min to 60min; The gradient heating method in step (S07-2) is: First, dry at an initial temperature of 60°C for 2h to 4h to gradually remove most of the moisture; then gradually increase the temperature to 80°C and continue drying for 2h to 3h to reduce the residual solvent content in the film; After the drying treatment (S07-2), the substrate coated with the tea polyphenol-chitosan film liquid is placed in a vacuum drying oven for vacuum drying treatment.

7. The method for preparing the tea polyphenol-chitosan film according to claim 1, characterized in that: The chitosan is prepared by deacetylation of chitin; the deacetylation degree is 70% to 85%; the molecular weight of the chitosan is 100 kDa to 300 kDa; the pore size of the tea polyphenol-chitosan membrane is 0.005 μm to 5 μm; the thickness of the tea polyphenol-chitosan membrane is 10 μm to 50 μm; the thickness of the tea polyphenol-chitosan membrane is 15 μm to 45 μm; the thickness of the tea polyphenol-chitosan membrane is 20 μm to 40 μm; the thickness of the tea polyphenol-chitosan membrane is 25 μm to 35 μm.

8. A device for preparing tea polyphenol-chitosan film, characterized in that: The invention comprises a solution mixing mechanism (100) and a solution homogenizing mechanism (200); the solution mixing mechanism (100) comprises a chitosan mixing tank (300) and a sodium alginate mixing tank (400), and the chitosan mixing tank (300) and the sodium alginate mixing tank (400) have the same structure; the solution homogenizing mechanism (200) is respectively connected to the chitosan mixing tank (300) and the sodium alginate mixing tank (400) via a three-way connecting pipe (500); a liquid outlet pipe (600) protrudes from the bottom of the solution homogenizing mechanism (200), and a mixed solution stirring drum (700) is arranged below the liquid outlet pipe (600); The chitosan mixing tank (300) comprises a mixing tank body (301), a mixing tank mounting seat (302) is arranged outside the mixing tank body (301), a chitosan storage box (303) is installed above the mixing tank mounting seat (302), the bottom of the chitosan storage box (303) is higher than the top of the mixing tank body (301), and the bottom of the chitosan storage box (303) is connected to the mixing tank body (301) through an inclined chitosan delivery pipe (304); The mixed solution stirring drum (700) is provided with a mixing chamber (701) inside, a mixing and stirring motor (717) is provided at the top of the mixing chamber (701), a mixing and stirring rod (702) is provided at the driving end of the mixing and stirring motor, the mixing and stirring rod (702) is located in the mixing chamber (701), a reaction part body (703) is provided in the mixed solution stirring drum (700), the reaction part body (703) is located below the mixing and stirring rod (702), a chamber partition plate (704) is provided between the reaction part body (703) and the mixing and stirring rod (702), a liquid leakage hole is provided on the chamber partition plate (704), and a solenoid valve (718) is provided at the liquid leakage hole; an ultrasonic generator (713) is provided in the reaction part body (703); and a plurality of heating elements are circumferentially provided on the inner wall of the reaction part body (703).

9. The device for preparing tea polyphenol-chitosan film according to claim 8, characterized in that: A solution stirring member (310) is rotatably arranged inside the mixing tank body (301); the solution stirring member (310) comprises a stirring member main body (3101); a rotating motor (3102) is arranged on the top of the mixing tank body (301); a driving end of the rotating motor (3102) is connected to the top of the stirring member main body (3101); a conical extension portion (3103) is axially extended from the bottom of the stirring member main body (3101); a positioning sleeve (3104) is obliquely arranged on the outer curved surface of the conical extension portion (3103); a stirring shaft rod (3105) is arranged inside the positioning sleeve (3104).

10. The device for preparing tea polyphenol-chitosan film according to claim 9, characterized in that: The solution stirring member (310) further comprises a mounting plate (3106), wherein the mounting plate (3106) is fixedly arranged inside the mixing tank body (301), and a first positioning shaft plate (3107a), a second positioning shaft plate (3107b) and a third positioning shaft plate (3107c) are protruded from the mounting plate (3106) on one side facing the stirring member body (3101), wherein the first positioning shaft plate (3107a), the second positioning shaft plate (3107b) and the third positioning shaft plate (3107c) are arranged in parallel up and down, and a positioning ear plate (3119) is arranged on the first positioning shaft plate (3107a), and the stirring member body (3101) is arranged on the positioning ear plate (3119). A connecting ear plate (3108) is provided on one side of the second positioning shaft plate (3107b) and the third positioning shaft plate (3107c) close to the stirring element main body (3101); one end of the stirring shaft rod (3105) is coaxially connected to the positioning shaft sleeve (3104); the other opposite end of the stirring shaft rod (3105) obliquely passes through the two connecting ear plates (3108); a rolling bearing (3109) is provided in the middle of the stirring shaft rod (3105); the rolling bearing (3109) is rotatably matched with the two connecting ear plates (3108); a tail stock (3110) is provided at the tail of the stirring shaft rod (3105); and a plurality of stirring blades (3120) are circumferentially provided on the outer periphery of the tail stock (3110).

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