Antibacterial and antioxidant composite film applied to food preservation and production method of antibacterial and antioxidant composite film

Abstract

According to the antibacterial and antioxidant composite film applied to food preservation and the production method of the antibacterial and antioxidant composite film, the chlorogenic acid, the catechin, the montmorillonite and the zeolite are introduced, and a drying process is optimized, so that the antibacterial performance, the antioxidant performance and the mechanical performance of the preservative film are remarkably improved, and meanwhile, the water vapor permeability and the oxygen permeability are reduced. The method comprises the specific steps of raw material preparation, polyphenol compound and mineral substance preparation, membrane liquid preparation and treatment, drying process optimization and finished product membrane uncovering. According to the preparation method disclosed by the invention, components such as chlorogenic acid, catechin, montmorillonite and zeolite are introduced, and a drying process is optimized, so that the food preservative film with synergistic antibacterial and antioxidant properties is prepared.

Description

Technical Field

[0001] The invention relates to the technical field of composite film layers, in particular to an antibacterial and antioxidant composite film used for food preservation and a production method thereof. Background Art

[0002] Traditional plastic packaging materials have become one of the important factors restricting sustainable development due to their shortcomings such as high resource consumption in the production process and difficulty in natural degradation after use. Therefore, exploring and developing new environmentally friendly and biodegradable food packaging materials has become a hot area of ​​current research.

[0003] In recent years, edible films based on natural polymer materials have gradually become an important direction of food packaging technology innovation due to their advantages of abundant raw materials, edible and pollution-free. Such films are mainly composed of natural ingredients such as lipids, proteins, and polysaccharides. However, these natural materials face two major challenges in practical applications: on the one hand, they are prone to become a hotbed for microbial growth; on the other hand, oxidation reactions are prone to occur during processing, affecting the safety and shelf life of food. In view of the above problems, it is particularly important to develop food packaging materials with high-efficiency antibacterial and antioxidant properties.

[0004] Currently, most of the popular antimicrobial agents and antioxidants on the market are chemically synthesized products. Although these chemicals can effectively inhibit bacterial growth and slow down the oxidation process of food, they can no longer fully meet the high standards of food safety in modern society due to potential safety hazards. In contrast, plant-based antimicrobial agents and antioxidants are favored because of their natural, harmless, safe and reliable characteristics. In particular, antimicrobial agents and antioxidants extracted from agricultural and forestry wastes (such as polyphenols and tea saponins extracted from camellia seed residues) can not only achieve the recycling of resources, but also provide more environmentally friendly antimicrobial and antioxidant solutions.

[0005] However, the existing food cling film still has deficiencies in antibacterial and antioxidant properties, especially when using natural ingredients. How to achieve synergistic effects between ingredients to improve performance is an important research direction. The present invention aims to prepare a food cling film with synergistic antibacterial and antioxidant properties by introducing ingredients such as chlorogenic acid, catechins, montmorillonite and zeolite and optimizing the drying process.

[0006] In view of this, the inventors specially designed an antibacterial and antioxidant composite film for food preservation and a production method thereof, which resulted in the present case. Summary of the invention

[0007] In order to solve the above problems, one of the technical solutions of the present invention is as follows: The production method of the antibacterial and antioxidant composite film used for food preservation comprises the following steps: Step 1: Extracting tea seed meal extract: Extracting the tea-seed meal with an ethanol solution at 80-95°C, filtering, and obtaining an extract; Decolorizing the extract, evaporating the solvent to concentrate the extract, and obtaining a camellia meal extract; Step 2: Prepare membrane solution: Dissolving edible gelatin, chlorogenic acid, catechin, montmorillonite and zeolite in water to obtain an aqueous solution; dissolving pullulan in lactic acid to obtain a lactic acid solution; The aqueous solution was mixed with the lactic acid solution and emulsified for 30 minutes to obtain a membrane solution; The concentrations of the components in the membrane solution are: 10-20 wt% of camellia meal extract, 0.3-0.8 wt% of edible gelatin, 10 wt% of chlorogenic acid, 10 wt% of catechins, 10 wt% of montmorillonite, 10 wt% of zeolite, 10 wt% of lactic acid, and 1-2 wt% of pullulan; Step 3: Processing the membrane solution: Homogenize and refine the membrane liquid with a homogenization pressure of 450 kgf / cm²; The membrane liquid was placed in a vacuum degasser for 6 times to remove the gas in the membrane liquid; Pour the degassed membrane solution into a membrane former (homemade glass plate, 20 cm × 20 cm), pour 100 mL of membrane solution into each glass plate, and cast it into shape; Step 4: Drying and peeling off the film: The cast glass plate was first dried at 60°C for 2 hours to quickly remove most of the moisture; The glass plate was then moved to 40 °C for 40 h to dry the remaining water slowly to ensure the uniformity and mechanical properties of the film; Alternatively, the cast glass plate is placed in a microwave drying device and microwave-dried at 50°C for 30 minutes to ensure that the water in the film liquid is removed evenly and quickly; The dried film is peeled off from the glass plate to obtain a food preservative film with synergistic antibacterial and antioxidant properties.

[0008] Preferably, the concentration of the edible gelatin is 0.5 wt %.

[0009] Preferably, the concentration of the lactic acid is 1.5 wt %.

[0010] Preferably, the drying conditions are: drying at 60° C. for 2 hours and then drying at 40° C. for 40 hours, or microwave drying at 50° C. for 30 minutes.

[0011] Preferably, in step 1, the volume fraction of ethanol in the ethanol solution is 60-80%.

[0012] Preferably, in step three, the emulsification time is 30 min.

[0013] The second technical solution of the present invention is as follows: An antibacterial and antioxidant composite film, comprising: Camellia oleifera meal extract: 100g.

[0014] Chlorogenic acid: purity ≥95%, 10 g; Catechins: purity ≥95%, 10 g; Montmorillonite: purity ≥95%, 10 g; Zeolite: purity ≥95%, 10 g; Edible gelatin: 5 g; Pullulan: 10 g; Lactic acid: 100 mL; Deionized water: 500 mL.

[0015] The beneficial effects of the present invention are as follows: First, chlorogenic acid and catechins form a synergistic effect with polyphenols in the tea seed meal extract, significantly enhancing the antibacterial effect of the plastic wrap. Montmorillonite and zeolite form complexes with polyphenols, further enhancing the antibacterial effect.

[0016] Secondly, the synergistic effect of polyphenols improves the antioxidant properties of the cling film and extends the shelf life of food. The slow-release properties of zeolite can prolong the release time of antibacterial and antioxidant ingredients and improve the long-term effectiveness of the cling film.

[0017] In addition, the addition of polyphenolic compounds and minerals improves the mechanical strength and transparency of the film. The optimized drying process reduces the stress concentration of the film and improves the uniformity and mechanical properties of the film.

[0018] In particular, the addition of functional minerals and polyphenolic compounds improves the stability of the membrane solution and prevents stratification and precipitation. The optimized drying process ensures the uniformity and mechanical properties of the membrane and improves the overall quality of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0020] in: Figure 1 It is the overall flow chart of the present invention; Figure 2 This is the preparation process of the tea oil meal extract in the present invention; Figure 3It is a flowchart of the preparation process of the membrane solution in the present invention; Figure 4 It is a flowchart of the treatment process of the membrane liquid in the present invention; Figure 5 It is a flowchart of the drying and film peeling process in the present invention. DETAILED DESCRIPTION

[0021] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] Production method of antibacterial and antioxidant composite film for food preservation, combined with Figure 1-5 , including the following steps: Step 1, extracting the tea seed cake with an ethanol solution at 80-95° C., filtering, and obtaining an extract; Step 2, decolorizing the extract, evaporating the solvent to concentrate the extract, and obtaining a camellia meal extract; Step three, dissolving edible gelatin, chlorogenic acid, catechins, montmorillonite and zeolite in water to obtain an aqueous solution; dissolving pullulan in lactic acid to obtain a lactic acid solution; then mixing and emulsifying the aqueous solution and the lactic acid solution to obtain a membrane liquid; in the membrane liquid, the concentration of camellia oleifera meal extract is 10-20 wt%, the concentration of edible gelatin is 0.3-0.8 wt%, the concentration of chlorogenic acid is 10 wt%, the concentration of catechins is 10 wt%, the concentration of montmorillonite is 10 wt%, the concentration of zeolite is 10 wt%, the concentration of lactic acid is 1-2 wt%, and the concentration of pullulan is 1-2 wt%.

[0023] Preferably, the concentration of the edible gelatin is 0.5 wt %.

[0024] Preferably, the concentration of the lactic acid is 1.5 wt %.

[0025] Preferably, the drying conditions are: drying at 60° C. for 2 hours and then drying at 40° C. for 40 hours, or microwave drying at 50° C. for 30 minutes.

[0026] Preferably, in step 1, the volume fraction of ethanol in the ethanol solution is 60-80%.

[0027] Preferably, in step three, the emulsification time is 30 min.

[0028] The second technical solution of the present invention is as follows: An antibacterial and antioxidant composite film, comprising: Camellia oleifera meal extract: 100g.

[0029] Chlorogenic acid: purity ≥95%, 10 g; Catechins: purity ≥95%, 10 g; Montmorillonite: purity ≥95%, 10 g; Zeolite: purity ≥95%, 10 g; Edible gelatin: 5 g; Pullulan: 10 g; Lactic acid: 100 mL; Deionized water: 500 mL. Example

[0030] (1) Raw material preparation: Camellia oleifera meal extract: 100 g; Edible gelatin: 5 g; Pullulan: 10 g; Lactic acid: 100 mL; Deionized water: 500 mL; (2) Membrane solution preparation: 100 g of camellia oleifera meal extract was dissolved in 500 mL of deionized water, heated to 80 °C and stirred for 30 min.

[0031] Add 5 g of edible gelatin and continue stirring for 30 minutes to ensure complete dissolution.

[0032] Add 10 g of pullulan to 100 mL of lactic acid and stir until completely dissolved.

[0033] The two solutions were mixed and emulsified for 30 minutes to obtain a membrane solution.

[0034] (3) Membrane liquid treatment: The membrane liquid is homogenized and refined (homogenizing pressure is 450 kgf / cm²) to fully mix the components in the mixed liquid.

[0035] The membrane liquid was placed in a vacuum degasser for degassing 6 times to remove the gas in the membrane liquid.

[0036] The degassed membrane liquid was poured into a membrane former (homemade glass plate, 20 cm × 20 cm), 100 mL of membrane liquid was poured into each glass plate, and cast into shape.

[0037] The cast glass plate was placed in a constant temperature drying oven, dried at 50° C. for 40 hours, and then the film was peeled off. Example

[0038] On the basis of the control group, 10 g chlorogenic acid and 10 g catechins were added: (1) Raw material preparation: Camellia oleifera meal extract: 100 g Edible gelatin: 5 g Pullulan: 10 g Lactic acid: 100 mL Deionized water: 500 mL Chlorogenic acid: 10 g Catechins: 10 g (2) Preparation of membrane solution: 100 g of camellia oleifera meal extract was dissolved in 500 mL of deionized water, heated to 80 °C and stirred for 30 min.

[0039] Add 10 g chlorogenic acid and 10 g catechins and continue stirring for 30 min to ensure complete dissolution.

[0040] Add 5 g of edible gelatin and continue stirring for 30 minutes to ensure complete dissolution.

[0041] Add 10 g of pullulan to 100 mL of lactic acid and stir until completely dissolved.

[0042] The two solutions were mixed and emulsified for 30 minutes to obtain a membrane solution.

[0043] (3) Treatment of membrane liquid: The membrane liquid is homogenized and refined (homogenizing pressure is 450 kgf / cm²) to fully mix the components in the mixed liquid.

[0044] The membrane liquid was placed in a vacuum degasser for degassing 6 times to remove the gas in the membrane liquid.

[0045] The degassed membrane liquid was poured into a membrane former (homemade glass plate, 20 cm × 20 cm), 100 mL of membrane liquid was poured into each glass plate, and cast into shape.

[0046] The cast glass plate was placed in a constant temperature drying oven, dried at 50° C. for 40 hours, and then the film was peeled off. Example

[0047] On the basis of the control group, 10 g of montmorillonite and 10 g of zeolite were added.

[0048] (1) Raw material preparation: Camellia oleifera meal extract: 100 g Edible gelatin: 5 g Pullulan: 10 g Lactic acid: 100 mL Deionized water: 500 mL Montmorillonite: 10 g Zeolite: 10 g (2) Preparation of membrane solution: 100 g of camellia oleifera meal extract was dissolved in 500 mL of deionized water, heated to 80 °C and stirred for 30 min.

[0049] Add 5 g of edible gelatin and continue stirring for 30 minutes to ensure complete dissolution.

[0050] Add 10 g of pullulan to 100 mL of lactic acid and stir until completely dissolved.

[0051] The above two solutions were mixed, 10 g of montmorillonite and 10 g of zeolite were added, and stirring was continued for 30 minutes to ensure that all ingredients were thoroughly mixed.

[0052] Emulsification was performed for 30 minutes to obtain a membrane solution.

[0053] (3) Treatment of membrane liquid: The membrane liquid is homogenized and refined (homogenizing pressure is 450 kgf / cm²) to fully mix the components in the mixed liquid.

[0054] The membrane liquid was placed in a vacuum degasser for degassing 6 times to remove the gas in the membrane liquid.

[0055] The degassed membrane liquid was poured into a membrane former (homemade glass plate, 20 cm × 20 cm), 100 mL of membrane liquid was poured into each glass plate, and cast into shape.

[0056] The cast glass plate was placed in a constant temperature drying oven, dried at 50° C. for 40 hours, and then the film was peeled off. Example

[0057] On the basis of the control group, 10 g chlorogenic acid, 10 g catechin, 10 g montmorillonite and 10 g zeolite were added.

[0058] (1) Raw material preparation: Camellia oleifera meal extract: 100 g Edible gelatin: 5 g Pullulan: 10 g Lactic acid: 100 mL Deionized water: 500 mL Chlorogenic acid: 10 g Catechins: 10 g Montmorillonite: 10 g Zeolite: 10 g (2) Preparation of membrane solution: 100 g of camellia oleifera meal extract was dissolved in 500 mL of deionized water, heated to 80 °C and stirred for 30 min.

[0059] Add 10 g chlorogenic acid and 10 g catechins and continue stirring for 30 min to ensure complete dissolution.

[0060] Add 5 g of edible gelatin and continue stirring for 30 minutes to ensure complete dissolution.

[0061] Add 10 g of pullulan to 100 mL of lactic acid and stir until completely dissolved.

[0062] The above two solutions were mixed, 10 g of montmorillonite and 10 g of zeolite were added, and stirring was continued for 30 minutes to ensure that all ingredients were thoroughly mixed.

[0063] Emulsification was performed for 30 minutes to obtain a membrane solution.

[0064] (3) Treatment of membrane liquid: The membrane liquid is homogenized and refined (homogenizing pressure is 450 kgf / cm²) to fully mix the components in the mixed liquid.

[0065] The membrane liquid was placed in a vacuum degasser for degassing 6 times to remove the gas in the membrane liquid.

[0066] The degassed membrane liquid was poured into a membrane former (homemade glass plate, 20 cm × 20 cm), 100 mL of membrane liquid was poured into each glass plate, and cast into shape.

[0067] The cast glass plate was placed in a constant temperature drying oven, dried at 50° C. for 40 hours, and then the film was peeled off. Example

[0068] On the basis of improvement group 3, an optimized drying process was adopted.

[0069] Gradient drying: first drying at 60 °C for 2 h, then drying at 40 °C for 40 h.

[0070] Microwave drying: Microwave drying at 50 °C for 30 min.

[0071] (1) Raw material preparation: Camellia oleifera meal extract: 100 g Edible gelatin: 5 g Pullulan: 10 g Lactic acid: 100 mL Deionized water: 500 mL Chlorogenic acid: 10 g Catechins: 10 g Montmorillonite: 10 g Zeolite: 10 g (2) Preparation of membrane solution: 100 g of camellia oleifera meal extract was dissolved in 500 mL of deionized water, heated to 80 °C and stirred for 30 min.

[0072] Add 10 g chlorogenic acid and 10 g catechins and continue stirring for 30 min to ensure complete dissolution.

[0073] Add 5 g of edible gelatin and continue stirring for 30 minutes to ensure complete dissolution.

[0074] Add 10 g of pullulan to 100 mL of lactic acid and stir until completely dissolved.

[0075] The above two solutions were mixed, 10 g of montmorillonite and 10 g of zeolite were added, and stirring was continued for 30 minutes to ensure that all ingredients were thoroughly mixed.

[0076] Emulsification was performed for 30 minutes to obtain a membrane solution.

[0077] (3) Treatment of membrane liquid: The membrane liquid is homogenized and refined (homogenizing pressure is 450 kgf / cm²) to fully mix the components in the mixed liquid.

[0078] The membrane liquid was placed in a vacuum degasser for degassing 6 times to remove the gas in the membrane liquid.

[0079] The degassed membrane liquid was poured into a membrane former (homemade glass plate, 20 cm × 20 cm), 100 mL of membrane liquid was poured into each glass plate, and cast into shape.

[0080] The cast glass plate was first dried at 60° C. for 2 hours to quickly remove most of the moisture.

[0081] The glass plate was then moved to 40 °C for 40 h to dry the remaining moisture slowly to ensure the uniformity and mechanical properties of the film.

[0082] Alternatively, the cast glass plate is placed in a microwave drying device and microwave dried at 50°C for 30 minutes to ensure that the moisture in the film liquid is evenly and quickly removed.

[0083] The dried film is peeled off from the glass plate to obtain a food preservative film with synergistic antibacterial and antioxidant properties.

[0084] standard: GB / T 21510-2008 Test methods for antimicrobial properties of plastic products ISO 22196:2007 "Determination of antimicrobial properties of plastic products"

[0085] (1) Sample preparation: The prepared food cling film was cut into circular samples with a diameter of 20 mm.

[0086] (2) Selection of strains: Escherichia coli and Staphylococcus aureus were selected as test bacteria.

[0087] (3) Vaccination method: The bacterial suspension was evenly spread on the surface of the plastic wrap sample. The inoculation amount of each bacterial species was 10 6 CFU / mL.

[0088] (4) Culture conditions: The inoculated samples were placed in an incubator at 37°C for 24 hours.

[0089] (5) Result detection: After the incubation, the bacteria on the surface of the sample were washed with sterile saline, and the plate counts were performed to calculate the inhibition rate.

[0090]

[0091] standard: GB / T 8946-2013 Test method for oxidation resistance of plastics ISO 4892-2:2013 "Plastics laboratory light source exposure test method Part 2: Xenon arc lamp"

[0092] (1) Sample preparation: Cut the prepared food wrap into samples of appropriate size.

[0093] (2) Test instruments: Use DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical scavenging rate tester.

[0094] (3) Test steps: The samples were immersed in DPPH solution and placed in the dark at room temperature for 30 minutes.

[0095] The absorbance was measured at 517 nm using a UV-visible spectrophotometer.

[0096] (4) Calculation of results: The DPPH free radical scavenging rate was calculated.

[0097]

[0098] standard: GB / T 1040.3-2006 "Determination of tensile properties of plastics Part 3: Test conditions for films and sheets" ISO 527-3:1995 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets"

[0099] (1) Sample preparation: The prepared food cling film was cut into long strip samples with a size of 150 mm × 10 mm.

[0100] (2) Test instruments: Use an electronic universal testing machine.

[0101] (3) Test steps: The sample was clamped in the fixture of the testing machine and the tensile speed was set to 100 mm / min.

[0102] Perform a tensile test and record the maximum load and elongation at break.

[0103] (4) Calculation of results: Calculate the tensile strength and elongation at break.

[0104]

[0105]

[0106] standard: GB / T 1037-1988 Test method for water vapor permeability of plastic films and sheets ASTM E96-16 "Standard Test Method for Determination of Water Vapor Transmission Rate"

[0107] (1) Sample preparation: The prepared food cling film was cut into circular samples with a diameter of 75 mm.

[0108] (2) Test instruments: Use a water vapor permeability tester.

[0109] (3) Test steps: Secure the sample to the permeable cup, ensuring a good seal.

[0110] The moisture permeable cup was placed in a constant temperature and humidity chamber, and the set temperature was 38°C and the relative humidity was 90%.

[0111] Weigh the moisture permeable cup regularly and record the weight change.

[0112] (4) Calculation of results: Calculate the water vapor transmission rate.

[0113]

[0114]

[0115] standard: GB / T 1038-2000 "Test method for gas permeability of plastic film and sheeting" ASTM D3985-16 "Standard Test Method for Oxygen Transmission Rate of Plastic Film and Sheeting"

[0116] (1) Sample preparation: The prepared food cling film was cut into circular samples with a diameter of 75 mm.

[0117] (2) Test instruments: Use an oxygen transmission rate tester.

[0118] (3) Test steps: Secure the sample in the test cavity, ensuring a good seal.

[0119] The test chamber is filled with high purity nitrogen on one side and high purity oxygen on the other side.

[0120] The oxygen permeation was recorded.

[0121] (4) Calculation of results: Calculate the oxygen transmission rate.

[0122]

[0123] Where V is the volume of oxygen permeated (mL), P is the test pressure (atm), AA is the sample area (m²), and t is the test time (days).

[0124] Test results: Analysis shows that: In terms of antibacterial properties, after adding chlorogenic acid and catechins, the inhibition rate of improved group 1 increased from 50% to 65%, indicating that polyphenol compounds significantly enhanced the antibacterial properties.

[0125] After adding montmorillonite and zeolite, the inhibition rate of improved group 2 increased from 50% to 60%, indicating that minerals also have a positive effect on antibacterial properties.

[0126] After adding chlorogenic acid, catechins, montmorillonite and zeolite at the same time, the antibacterial rate of improved group 3 was further increased to 70%, indicating that there is a synergistic effect between polyphenols and minerals.

[0127] After optimizing the drying process on the basis of improved group 3, the antibacterial rate of improved group 4 was further increased to 75%, indicating that the optimized drying process helps to improve the antibacterial effect.

[0128] In terms of antioxidant properties, after adding chlorogenic acid and catechins, the DPPH radical scavenging rate of improved group 1 increased from 70% to 80%, indicating that polyphenol compounds significantly enhanced the antioxidant properties.

[0129] After adding montmorillonite and zeolite, the DPPH radical scavenging rate of improved group 2 increased from 70% to 75%, indicating that the antioxidant properties of minerals were also improved to a certain extent.

[0130] After adding chlorogenic acid, catechins, montmorillonite and zeolite at the same time, the DPPH radical scavenging rate of improved group 3 was further increased to 85%, indicating that there is a synergistic effect between polyphenols and minerals.

[0131] After optimizing the drying process based on improved group 3, the DPPH radical scavenging rate of improved group 4 was further increased to 90%, indicating that the optimized drying process helps to improve the antioxidant effect.

[0132] In terms of mechanical properties, after adding chlorogenic acid and catechins, the tensile strength of improved group 1 increased from 97.21 MPa to 105.43 MPa, and the elongation at break increased from 13.48% to 15.23%, indicating that polyphenolic compounds improved the mechanical properties.

[0133] After adding montmorillonite and zeolite, the tensile strength of improved group 2 increased from 97.21 MPa to 103.67 MPa, and the elongation at break increased from 13.48% to 14.85%, indicating that minerals also have a positive effect on the mechanical properties.

[0134] After adding chlorogenic acid, catechins, montmorillonite and zeolite at the same time, the tensile strength of improved group 3 was further increased to 112.89 MPa, and the elongation at break was increased to 16.54%, indicating that there is a synergistic effect between polyphenols and minerals.

[0135] After optimizing the drying process on the basis of improved group 3, the tensile strength of improved group 4 was further improved to 118.21 MPa, and the elongation at break was improved to 17.12%, indicating that the optimized drying process helps to improve the mechanical properties.

[0136] In terms of barrier properties, after adding chlorogenic acid and catechins, the water vapor transmission rate of improved group 1 decreased from 109.08 g / m²·day to 102.56 g / m²·day, indicating that polyphenol compounds help to reduce the water vapor transmission rate.

[0137] After adding montmorillonite and zeolite, the water vapor transmission rate of improved group 2 decreased from 109.08 g / m²·day to 101.23 g / m²·day, indicating that minerals also help to reduce the water vapor transmission rate.

[0138] After adding chlorogenic acid, catechins, montmorillonite and zeolite at the same time, the water vapor transmission rate of improved group 3 was further reduced to 98.75 g / m²·day, indicating that there is a synergistic effect between polyphenols and minerals.

[0139] After optimizing the drying process on the basis of improved group 3, the water vapor transmission rate of improved group 4 was further reduced to 95.34 g / m²·day, indicating that the optimized drying process is helpful to reduce the water vapor transmission rate.

[0140] In terms of oxygen permeability, after adding chlorogenic acid and catechins, the oxygen permeability of improved group 1 decreased from 0.15 mL / m²·day·atm to 0.13 mL / m²·day·atm, indicating that polyphenol compounds help to reduce the oxygen permeability.

[0141] After adding montmorillonite and zeolite, the oxygen transmission rate of improved group 2 decreased from 0.15 mL / m²·day·atm to 0.14 mL / m²·day·atm, indicating that minerals also help to reduce the oxygen transmission rate.

[0142] After adding chlorogenic acid, catechins, montmorillonite and zeolite at the same time, the oxygen permeability of improved group 3 was further reduced to 0.12 mL / m²·day·atm, indicating that there is a synergistic effect between polyphenols and minerals.

[0143] After optimizing the drying process on the basis of improved group 3, the oxygen permeability of improved group 4 was further reduced to 0.11mL / m²·day·atm, indicating that the optimized drying process is helpful to reduce the oxygen permeability.

[0144] In summary, the present invention significantly improves the antibacterial, antioxidant and mechanical properties of food preservative film by introducing chlorogenic acid, catechins, montmorillonite and zeolite and optimizing the drying process, while reducing the water vapor permeability and oxygen permeability. Specifically, it is manifested in the following aspects: Antibacterial properties: The inhibition rate increased from 50% to 75%, indicating that there is a synergistic effect between polyphenols and minerals, which significantly enhances the antibacterial effect.

[0145] Antioxidant properties: The DPPH free radical scavenging rate increased from 70% to 90%, indicating that there was a synergistic effect between polyphenols and minerals, which significantly enhanced the antioxidant properties.

[0146] Mechanical properties: The tensile strength increased from 97.21 MPa to 118.21 MPa, and the elongation at break increased from 13.48% to 17.12%, indicating that there was a synergistic effect between polyphenols and minerals, which significantly improved the mechanical properties.

[0147] Water vapor transmission rate: decreased from 109.08 g / m²·day to 95.34 g / m²·day, indicating that there is a synergistic effect between polyphenols and minerals, which significantly reduces the water vapor transmission rate.

[0148] Oxygen permeability: decreased from 0.15 mL / m²·day·atm to 0.11 mL / m²·day·atm, indicating that there is a synergistic effect between polyphenols and minerals, which significantly reduces the oxygen permeability.

[0149] The principle of its synergistic effect is analyzed as follows: 1. Synergistic effects of polyphenols (chlorogenic acid and catechins)

[0150] Antimicrobial effects of polyphenols: Polyphenols (such as chlorogenic acid and catechins) can kill or inhibit bacterial growth by destroying the integrity of bacterial cell membranes, causing leakage of cell contents.

[0151] Synergistic effect: When two or more polyphenolic compounds work together, they can synergistically destroy different parts of the bacterial cell membrane and enhance the antibacterial effect. Chlorogenic acid mainly acts on the lipid part of the cell membrane, while catechins act on the protein part. The two work together to more effectively destroy the cell membrane and improve the antibacterial efficiency.

[0152] Free radical scavenging ability: Polyphenols have strong free radical scavenging ability and can neutralize free radicals by providing hydrogen atoms or electrons, thereby protecting cells from oxidative damage.

[0153] Synergistic effect: Different types of polyphenols have different free radical scavenging mechanisms. When they work together, they can cover a wider range of free radical types and improve the overall antioxidant capacity. For example, chlorogenic acid and catechins show complementarity in scavenging different types of free radicals (such as DPPH free radicals), and jointly improve the antioxidant effect.

[0154] 2. Synergistic effect of functional minerals (montmorillonite and zeolite)

[0155] Adsorption: Montmorillonite and zeolite have high adsorption capacity and can adsorb bacteria and viruses and reduce their number.

[0156] Synergistic effect: Montmorillonite and zeolite can adsorb polyphenolic compounds to form complexes, which can form a protective film on the surface of bacteria, further enhancing the antibacterial effect. For example, montmorillonite can adsorb chlorogenic acid and catechins to form stable complexes, which can more effectively attach to the surface of bacteria and destroy the cell membrane.

[0157] Sustained release effect: Montmorillonite and zeolite can be used as carriers to slowly release polyphenol compounds and prolong their antioxidant effect.

[0158] Synergistic effect: After being adsorbed on montmorillonite and zeolite, polyphenols can be gradually released to provide continuous antioxidant protection. This slow-release effect can prolong the antioxidant properties of food wrap and improve its long-term effectiveness.

[0159] 3. Optimizing the synergy of drying processes

[0160] Gradient drying: First, most of the moisture is quickly removed at a higher temperature (60°C), and then the remaining moisture is slowly dried at a lower temperature (40°C). This method can reduce stress concentration inside the membrane and improve the uniformity and mechanical properties of the membrane.

[0161] Microwave drying: Microwave drying can quickly and evenly remove moisture, reduce the pores inside the membrane, and improve the density and mechanical strength of the membrane.

[0162] Reduce internal stress: Gradient drying and microwave drying can effectively reduce the internal stress inside the membrane and improve the stability and durability of the membrane.

[0163] Improved uniformity: An optimized drying process can ensure more uniform film thickness and density, improving the overall performance of the film.

[0164] Antibacterial properties: Polyphenol compounds destroy bacterial cell membranes, and functional minerals adsorb bacteria. The synergistic effect of the two significantly enhances the antibacterial effect.

[0165] Antioxidant properties: Polyphenols can scavenge free radicals, while functional minerals can slowly release polyphenols. The synergistic effect of the two significantly improves the antioxidant capacity.

[0166] Mechanical properties: Polyphenols and functional minerals improve the mechanical strength and toughness of the membrane, and the optimized drying process further improves the uniformity and stability of the membrane.

[0167] Water vapor permeability and oxygen permeability: Polyphenols and functional minerals reduce the permeability of water vapor and oxygen by forming a dense composite structure, and the optimized drying process further improves the density of the membrane.

[0168] Therefore, the food preservative film of the present invention shows significant improvement in antibacterial, antioxidative, mechanical properties, water vapor permeability and oxygen permeability, and has high practical value and market prospects.

[0169] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A method for producing an antibacterial and antioxidant composite film for food preservation, characterized in that: The steps include: Step 1: Extracting tea seed meal extract: Extracting the tea-seed meal with an ethanol solution at 80-95°C, filtering, and obtaining an extract; Decolorizing the extract, evaporating the solvent to concentrate the extract, and obtaining a camellia meal extract; Step 2: Prepare membrane solution: Dissolving edible gelatin, chlorogenic acid, catechin, montmorillonite and zeolite in water to obtain an aqueous solution; dissolving pullulan in lactic acid to obtain a lactic acid solution; The aqueous solution was mixed with the lactic acid solution and emulsified for 30 minutes to obtain a membrane solution; The concentrations of the components in the membrane solution are: 10-20 wt% of camellia oleifera meal extract, 0.3-0.8 wt% of edible gelatin, 10 wt% of chlorogenic acid, 10 wt% of catechins, 10 wt% of montmorillonite, 10 wt% of zeolite, 10 wt% of lactic acid, and 1-2 wt% of pullulan; Step 3: Processing the membrane solution: Homogenize and refine the membrane liquid with a homogenization pressure of 450 kgf / cm²; The membrane liquid was placed in a vacuum degasser for 6 times to remove the gas in the membrane liquid; Pour the degassed membrane solution into a membrane former (self-made glass plate, 20 cm × 20 cm), pour 100 mL of membrane solution into each glass plate, and cast into shape; Step 4: Drying and peeling off the film: The cast glass plate was first dried at 60°C for 2 hours to quickly remove most of the moisture; The glass plate was then moved to 40 °C for 40 h to dry the remaining water slowly to ensure the uniformity and mechanical properties of the film; Alternatively, the cast glass plate is placed in a microwave drying device and microwave-dried at 50°C for 30 minutes to ensure that the water in the film liquid is removed evenly and quickly; The dried film is peeled off from the glass plate to obtain a food preservative film with synergistic antibacterial and antioxidant properties.

2. The method for producing an antibacterial and antioxidant composite film for food preservation according to claim 1, characterized in that: The concentration of the edible gelatin is 0.5 wt %.

3. The method for producing an antibacterial and antioxidant composite film for food preservation according to claim 1, characterized in that: The concentration of the lactic acid is 1.5 wt %.

4. The method for producing an antibacterial and antioxidant composite film for food preservation according to claim 1, characterized in that: The drying conditions are: drying at 60° C. for 2 hours and then drying at 40° C. for 40 hours, or microwave drying at 50° C. for 30 minutes.

5. The method for producing an antibacterial and antioxidant composite film for food preservation according to claim 1, characterized in that: In step 1, the volume fraction of ethanol in the ethanol solution is 60-80%.

6. The method for producing an antibacterial and antioxidant composite film for food preservation according to claim 1, characterized in that: In step 3, the emulsification time is 30 min.

7. An antibacterial and antioxidant composite film prepared by the production method according to claim 1, characterized in that: include: Camellia oleifera meal extract: 100g; Chlorogenic acid: purity ≥95%, 10 g; Catechins: purity ≥95%, 10 g; Montmorillonite: purity ≥95%, 10 g; Zeolite: purity ≥95%, 10 g; Edible gelatin: 5 g; Pullulan: 10 g; Lactic acid: 100 mL; Deionized water: 500 mL.

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