A food preservation film material and its application in meat preservation

Abstract

This invention belongs to the field of meat preservation films in food packaging materials, specifically relating to a preservation film material. The invention employs a chemical precipitation method to deposit the metallic antibacterial agent silver oxide onto plant fibers, and adds tannic acid, a polyphenolic compound with excellent antioxidant properties, mixed with a polymer matrix and solvent to prepare a spinning precursor solution. Then, an antibacterial and antioxidant film is prepared by electrospinning. When applied to meat preservation, it can extend the shelf life of chilled meat by more than 6 days. This invention utilizes the reduction of silver ions released from silver oxide to nano-silver under the action of tannic acid, achieving a synergistic effect of antibacterial and antioxidant properties with tannic acid. It also possesses good mechanical properties and hydrophobicity, showing broad application prospects in the meat and fruit / vegetable preservation industries.

Description

Technical Field

[0001] This invention belongs to the field of food preservation materials, specifically relating to a preservation film material and its application in meat preservation. Background Technology

[0002] Improper storage is one of the leading causes of food waste. Beef contains high-quality protein, minerals, vitamins, fats, and carbohydrates, but it is highly susceptible to spoilage due to physical, chemical, and microbiological changes that can occur during storage, including protein and lipid oxidation and an increase in methemoglobin. Currently, 20% of the world's beef is wasted due to improper storage. In recent years, significant progress has been made in preservation technologies to address some of the problems in beef storage, such as the use of modified atmosphere packaging and active packaging materials.

[0003] Electrospinning technology endows food preservation films with high surface area, high porosity, and high encapsulation efficiency, significantly expanding the contact area between active substances and meat molecules. Its micro / nanofiber structure facilitates the efficient encapsulation and sustained release of preservatives and antibacterial agents, thereby extending the shelf life of food. Furthermore, the interfaces between fibers promote gas exchange, providing favorable conditions for the respiration of food. In addition, electrospinning technology can utilize various natural polymers (such as cellulose, proteins, and polysaccharides) to produce micro / nanofibers for developing biodegradable and biocompatible preservation films, thus significantly improving the sustainability and renewability of food packaging systems. For example, Chinese patent (CN201911203528.8) discloses a multifunctional meat preservation film with a nanofiber membrane as the matrix and an acidic polysaccharide-based ovalbumin membrane loaded on the surface; this film can be used for meat preservation.

[0004] Polylactic acid (PLA) is a polymer material with good mechanical properties, biocompatibility, and biodegradability, which can be used to prepare environmentally friendly electrospun films. For example, Chinese patent (CN202310384907.1) discloses a method for preparing a PLA / citral electrospun nanofiber membrane. PLA is used as the shell material to encapsulate the quorum sensing inhibitor citral, thus preparing a PLA / citral coaxial spun fiber membrane, which is then used for the preservation of turbot. However, this membrane only has a single component as an antibacterial and antioxidant agent, and citral is chemically reactive and lacks long-lasting antibacterial and antioxidant functions. To extend the antibacterial and antioxidant effects of the preservation film, Chinese patent (CN202211006094.4) prepared an electrospun fiber preservation film and used it for the preservation of chilled beef. The preservation film is made by injecting a cinnamaldehyde-chitosan nanoparticle core spinning solution with a concentration of 10-30% and a polycaprolactone shell spinning solution with a concentration of 9-11% into two syringes, respectively, and then spinning to form an electrospun fiber preservation film. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention explores the physical, chemical, and microbial changes during meat preservation, using beef as a typical case study. This invention employs a chemical precipitation method to deposit silver oxide on plant fibers, and uses tannic acid, which possesses excellent antioxidant properties, to prepare a spinning precursor solution, followed by electrospinning to form a film. This invention reduces the silver ions released from silver oxide into silver nanoparticles under the action of tannic acid, thereby achieving a synergistic effect of antibacterial and antioxidant properties. Furthermore, it exhibits good mechanical properties and hydrophobicity, showing broad application prospects in the meat preservation industry.

[0006] A method for preparing a food preservation film material includes the following steps:

[0007] (1) Add plant fiber to an appropriate amount of water and ultrasonically break it up (500-600W) for 40-80 min. Then add the treated plant fiber to an appropriate amount of AgNO3 aqueous solution with a concentration of 2-10wt% and disperse it evenly (stir for 30-120 min). Then add NaOH aqueous solution with a concentration of 2-10wt% and react to obtain silver oxide deposited plant fiber.

[0008] The molar ratio between AgNO3 and NaOH is (1-2):(1-4); the preferred mass ratio of the treated plant fiber to the AgNO3 aqueous solution is 1:(40-80).

[0009] (2) The silver oxide deposited plant fiber, hydrophobic polymer, tannic acid and solvent are mixed in a certain proportion and reacted fully at a certain temperature (by shaking) to reduce free silver ions into nano-silver particles, thus preparing an electrospinning precursor solution in which tannic acid and silver oxide / nano-silver particle deposited plant fiber coexist.

[0010] The mass ratio of the silver oxide deposited plant fiber, tannic acid, hydrophobic polymer and solvent is (2-20):(1-2):(15-50):(150-450).

[0011] (3) Electrospinning is performed using the electrospinning precursor solution to obtain a plastic wrap material.

[0012] Preferably, the plant fiber is at least one of coconut shell fiber, palm fiber, and pineapple leaf fiber, and the diameter of the plant fiber is 0.1 to 10 μm. More preferably, the diameter of the plant fiber is 0.5 to 6 μm.

[0013] Preferably, the tannic acid has a molecular weight of 1701 and an acidity coefficient (pKa) of 6.00 ± 0.50.

[0014] Preferably, the hydrophobic polymer is at least one of polylactic acid, polycaprolactone, and polyhydroxybutyrate.

[0015] Preferably, the solvent is at least one selected from N,N-dimethylformamide, acetone, dichloromethane, and chloroform.

[0016] Preferably, the electrospinning parameters are: voltage 13-21kV, roller speed 30-60rpm / s, flow rate 0.5-6mL / h, needle size 15-22; receiving distance 10-25cm, spinning amount 5-30mL, spinning time 1-12h, and relative humidity 5-80%.

[0017] Applying the above-mentioned plastic wrap material to food preservation, especially meat preservation, includes the following steps: wrapping the meat with plastic wrap material, placing it in a sealed plastic box, and storing it at 4±1℃.

[0018] The present invention has the following positive and beneficial effects:

[0019] (1) The preparation method of this invention does not require heating or other conditions, thus ensuring the efficient and stable capture of active substances in the nanostructure, which is beneficial for encapsulating antibacterial and antioxidant components. Depending on actual needs, a film can be prepared using electrospinning technology with good air permeability for preservation.

[0020] (2) The tannic acid added in this invention reduces the silver ions released from silver oxide into silver nanoparticles, thereby achieving a synergistic antibacterial and antioxidant effect. Furthermore, the selected matrix materials are all biodegradable, resulting in an environmentally friendly fiber membrane.

[0021] (3) The maximum migration of silver in the preservation film material prepared by this invention is less than the allowable migration limit of food components recognized by current regulations (10 mg / dm²). Furthermore, it can effectively maintain the freshness of beef and extend the storage period of meat by at least 6 days compared to PE preservation film. Attached Figure Description

[0022] To further illustrate the advantages and objectives of the technical solution of the present invention, the relevant figures in the embodiments will be briefly introduced below.

[0023] Figure 1 The images show the microstructure and elemental distribution of silver oxide, coconut shell fiber, broken coconut shell fiber, silver oxide deposited coconut shell fiber, and chilled beef preservation film in the embodiments of the present invention.

[0024] Figure 2 This is an XRD pattern of the plastic wrap in an embodiment of the present invention;

[0025] Figure 3 This is a diagram illustrating the antibacterial properties of the plastic wrap in an embodiment of the present invention;

[0026] Figure 4 This is a diagram illustrating the antioxidant properties of the plastic wrap in an embodiment of the present invention.

[0027] Figure 5 This is a diagram showing the changes in the apparent color of beef in different experimental groups in this invention.

[0028] Figure 6 The graph shows the changes in pH, total bacterial count (TVC), volatile basic nitrogen (TVB-N), and thiobarbituric acid reactants (TBARS) in beef from different experimental groups in this invention. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0030] Example 1

[0031] The preparation method of the plastic wrap material in this embodiment includes the following steps:

[0032] (1) First, coconut shell fiber is added to water at a mass ratio of 1:50 and subjected to ultrasonic cell disruption at 500W for 80 minutes to obtain micro-nano structured coconut shell fiber.

[0033] (2) Micro-nano structured coconut shell fibers were added to a 3wt% AgNO3 aqueous solution at a mass ratio of 1:50, stirred at room temperature for 30 min, and then reacted with a 2wt% NaOH aqueous solution to obtain silver oxide deposited coconut shell fibers. The molar ratio between AgNO3 and NaOH was 1:1.

[0034] (3) 2g of polylactic acid (PLA) was dissolved in a mixed solution of 13.3mL dichloromethane (DCM) and 6.7mL N,N-dimethylformamide (DMF). The mixture was heated and stirred at 50°C until completely dissolved. Subsequently, 0.2g of silver oxide deposited coconut shell fiber was added to the mixture, along with 0.05g of tannic acid. The mixture was placed on a shaker for 30min to reduce the free silver ions to silver, thus preparing an electrospinning precursor solution in which tannic acid and silver oxide / nano-silver particles coexist in the deposited coconut shell fiber.

[0035] (4) Micro-nanofiber films were prepared by electrospinning. The specific parameters are as follows: voltage: 19kV; roller speed: 50rpm / s; syringe advance speed: 3mL / h; needle type: No. 17 needle; receiving distance: 15cm.

[0036] Example 2

[0037] The preparation method of the plastic wrap material in this embodiment includes the following steps:

[0038] (1) First, add palm fiber to water at a mass ratio of 1:50 and treat it with ultrasonic disruption at 500W for 80 minutes to obtain palm fiber with micro-nano structure.

[0039] (2) Micro-nano structured palm fibers were added to a 3wt% AgNO3 aqueous solution at a mass ratio of 1:50, stirred at room temperature for 30 min, and then reacted with a 2wt% NaOH aqueous solution to obtain silver oxide deposited coconut shell fibers. The molar ratio between AgNO3 and NaOH was 1:1.

[0040] (3) 2 g of polylactic acid (PLA) was dissolved in a mixed solution of 13.3 mL of dichloromethane (DCM) and 6.7 mL of N,N-dimethylformamide (DMF). The mixture was heated and stirred at 50 °C until completely dissolved. Subsequently, 0.2 g of silver oxide deposited palm fiber was added to the mixture, along with 0.05 g of tannic acid. The mixture was placed on a shaker for 30 min to reduce the free silver ions to silver, thus preparing an electrospinning precursor solution in which tannic acid and silver oxide / nano-silver particles coexist in the deposited palm fiber.

[0041] (4) Micro-nanofiber films were prepared by electrospinning. The specific parameters are as follows: voltage: 19kV; roller speed: 50rpm / s; syringe advance speed: 3mL / h; needle type: No. 17 needle; receiving distance: 15cm.

[0042] Example 3

[0043] The preparation method of the plastic wrap material in this embodiment includes the following steps:

[0044] (1) First, pineapple leaf fiber was added to water at a mass ratio of 1:50 and subjected to ultrasonic cell disruption at 500W for 80 minutes to obtain pineapple leaf fiber with micro-nano structure.

[0045] (2) Micro-nano pineapple leaf fibers were added to a 3wt% AgNO3 aqueous solution at a mass ratio of 1:50, stirred at room temperature for 30 min, and then reacted with a 2wt% NaOH aqueous solution to obtain silver oxide deposited pineapple leaf fibers. The molar ratio between AgNO3 and NaOH was 1:1.

[0046] (3) 2g of polylactic acid (PLA) was dissolved in a mixed solution of 13.3mL dichloromethane (DCM) and 6.7mL N,N-dimethylformamide (DMF). The mixture was heated and stirred at 50°C until completely dissolved. Subsequently, 0.2g of silver oxide deposited pineapple leaf fibers were added to the mixture, along with 0.05g of tannic acid. The mixture was placed on a shaker for 30min to reduce the free silver ions to silver, thus preparing an electrospinning precursor solution in which tannic acid and silver oxide / silver nanoparticles deposited pineapple leaf fibers coexist.

[0047] (4) Micro-nanofiber films were prepared by electrospinning. The specific parameters are as follows: voltage: 19kV; roller speed: 50rpm / s; syringe advance speed: 3mL / h; needle type: No. 17 needle; receiving distance: 15cm.

[0048] Example 4

[0049] The preparation method of the plastic wrap material in this embodiment includes the following steps:

[0050] (1) First, coconut shell fiber is added to water at a mass ratio of 1:50 and subjected to ultrasonic cell disruption at 500W for 80 minutes to obtain micro-nano structured coconut shell fiber.

[0051] (2) Micro-nano structured coconut shell fibers were added to a 3wt% AgNO3 aqueous solution at a mass ratio of 1:50, stirred at room temperature for 30 min, and then reacted with a 2wt% NaOH aqueous solution to obtain silver oxide deposited coconut shell fibers. The molar ratio between AgNO3 and NaOH was 1:1.

[0052] (3) 2g of polycaprolactone (PCL) was dissolved in a mixture of 12mL dichloromethane (DCM) and 8mL acetone. The mixture was heated and stirred at 50°C until completely dissolved. Subsequently, 0.2g of silver oxide deposited coconut shell fiber was added to the mixture, along with 0.05g of tannic acid. The mixture was placed on a shaker for 30min to reduce the free silver ions to silver, thus preparing an electrospinning precursor solution in which tannic acid and silver oxide / nano-silver particles coexist in the deposited coconut shell fiber.

[0053] (4) Micro-nanofiber films were prepared by electrospinning. The specific parameters are as follows: voltage: 16kV; roller speed: 50rpm / s; syringe push speed: 3mL / h; needle type: No. 17 needle; receiving distance: 15cm.

[0054] Example 5

[0055] The preparation method of the plastic wrap material in this embodiment includes the following steps:

[0056] (1) First, coconut shell fiber is added to water at a mass ratio of 1:50 and subjected to ultrasonic cell disruption at 500W for 80 minutes to obtain micro-nano structured coconut shell fiber.

[0057] (2) Micro-nano structured coconut shell fibers were added to a 3wt% AgNO3 aqueous solution at a mass ratio of 1:50, stirred at room temperature for 30 min, and then reacted with a 2wt% NaOH aqueous solution to obtain silver oxide deposited coconut shell fibers. The molar ratio between AgNO3 and NaOH was 1:1.

[0058] (3) 2g of polyhydroxybutyrate (PHB) was dissolved in a mixed solution of 16mL chloroform and 4mL N,N-dimethylformamide (DMF). The mixture was heated and stirred at 50°C until completely dissolved. Subsequently, 0.2g of silver oxide deposited coconut shell fiber was added to the mixture, along with 0.05g of tannic acid. The mixture was placed on a shaker for 30min to reduce the free silver ions to silver, thus preparing an electrospinning precursor solution in which tannic acid and silver oxide / nano-silver particles coexist in the deposited coconut shell fiber.

[0059] (4) Micro-nanofiber films were prepared by electrospinning. The specific parameters are as follows: voltage: 13kV; roller speed: 50rpm / s; syringe push speed: 3mL / h; needle type: No. 17 needle; receiving distance: 15cm.

[0060] Example 6

[0061] The preparation method of the plastic wrap material in this embodiment includes the following steps:

[0062] (1) First, coconut shell fiber is added to water at a mass ratio of 1:50 and subjected to ultrasonic cell disruption at 500W for 80 minutes to obtain micro-nano structured coconut shell fiber.

[0063] (2) Micro-nano structured coconut shell fibers were added to a 3wt% AgNO3 aqueous solution at a mass ratio of 1:50, stirred at room temperature for 30 min, and then reacted with a 2wt% NaOH aqueous solution to obtain silver oxide deposited coconut shell fibers. The molar ratio between AgNO3 and NaOH was 1:1.

[0064] (3) 2g of polylactic acid (PLA) was dissolved in a mixed solution of 13.3mL dichloromethane (DCM) and 6.7mL N,N-dimethylformamide (DMF). The mixture was heated and stirred at 50°C until completely dissolved. Subsequently, 0.1g of silver oxide deposited coconut shell fiber was added to the mixture, along with 0.05g of tannic acid. The mixture was placed on a shaker for 30min to reduce the free silver ions to silver, thus preparing an electrospinning precursor solution in which tannic acid and silver oxide / nano-silver particles coexist in the deposited coconut shell fiber.

[0065] (4) Micro-nanofiber films were prepared by electrospinning. The specific parameters are as follows: voltage: 19kV; roller speed: 50rpm / s; syringe advance speed: 3mL / h; needle type: No. 17 needle; receiving distance: 15cm.

[0066] Example 7

[0067] The preparation method of the plastic wrap material in this embodiment includes the following steps:

[0068] (1) First, coconut shell fiber is added to water at a mass ratio of 1:50 and subjected to ultrasonic cell disruption at 500W for 80 minutes to obtain micro-nano structured coconut shell fiber.

[0069] (2) Micro-nano structured coconut shell fibers were added to a 3wt% AgNO3 aqueous solution at a mass ratio of 1:50, stirred at room temperature for 30 min, and then reacted with a 2wt% NaOH aqueous solution to obtain silver oxide deposited coconut shell fibers. The molar ratio between AgNO3 and NaOH was 1:1.

[0070] (3) 2g of polylactic acid (PLA) was dissolved in a mixed solution of 13.3mL dichloromethane (DCM) and 6.7mL N,N-dimethylformamide (DMF). The mixture was heated and stirred at 50°C until completely dissolved. Subsequently, 0.3g of silver oxide deposited coconut shell fiber was added to the mixture, along with 0.05g of tannic acid. The mixture was placed on a shaker for 30min to reduce the free silver ions to silver, thus preparing an electrospinning precursor solution in which tannic acid and silver oxide / nano-silver particles coexist in the deposited coconut shell fiber.

[0071] (4) Micro-nanofiber films were prepared by electrospinning. The specific parameters are as follows: voltage: 19kV; roller speed: 50rpm / s; syringe advance speed: 3mL / h; needle type: No. 17 needle; receiving distance: 15cm.

[0072] Example 8

[0073] The preparation method of the plastic wrap material in this embodiment includes the following steps:

[0074] (1) First, coconut shell fiber is added to water at a mass ratio of 1:50 and subjected to ultrasonic cell disruption at 500W for 80 minutes to obtain micro-nano structured coconut shell fiber.

[0075] (2) Micro-nano structured coconut shell fibers were added to a 3wt% AgNO3 aqueous solution at a mass ratio of 1:50, stirred at room temperature for 30 min, and then reacted with a 2wt% NaOH aqueous solution to obtain silver oxide deposited coconut shell fibers. The molar ratio between AgNO3 and NaOH was 1:1.

[0076] (3) 2g of polylactic acid (PLA) was dissolved in a mixed solution of 13.3mL dichloromethane (DCM) and 6.7mL N,N-dimethylformamide (DMF). The mixture was heated and stirred at 50°C until completely dissolved. Subsequently, 0.4g of silver oxide deposited coconut shell fiber was added to the mixture, along with 0.05g of tannic acid. The mixture was placed on a shaker for 30min to reduce the free silver ions to silver, thus preparing an electrospinning precursor solution in which tannic acid and silver oxide / nano-silver particles coexist in the deposited coconut shell fiber.

[0077] (4) Micro-nanofiber films were prepared by electrospinning. The specific parameters are as follows: voltage: 19kV; roller speed: 50rpm / s; syringe advance speed: 3mL / h; needle type: No. 17 needle; receiving distance: 15cm.

[0078] Comparative Example 1

[0079] (1) Dissolve 2g of polylactic acid (PLA) in a mixed solution of 13.3mL dichloromethane (DCM) and 6.7mL N,N-dimethylformamide (DMF). Heat and stir the mixture at 50°C until it is completely dissolved to obtain a spinning precursor solution.

[0080] (2) Nanofiber films were prepared by electrospinning. The specific parameters are as follows: voltage: 19kV; roller speed: 50rpm / s; syringe advance speed: 3mL / h; needle type: No. 17 needle; receiving distance: 15cm.

[0081] Comparative Example 2

[0082] (1) First, coconut shell fiber was added to an aqueous solution at a ratio of 1:50 and subjected to ultrasonic disruption at 500W for 80 minutes to obtain micro-nano structured coconut shell fiber.

[0083] (2) Dissolve 2g of polylactic acid (PLA) in a mixed solution of 13.3mL dichloromethane (DCM) and 6.7mL N,N-dimethylformamide (DMF). Heat and stir the mixture at 50°C until completely dissolved. Then, add 0.2g of coconut shell fiber and 0.05g of tannic acid to the mixture, and place it on a shaker for 30min to obtain the spinning precursor solution.

[0084] (3) Nanofiber films were prepared by electrospinning. The specific parameters are as follows: voltage: 19kV; roller speed: 50rpm / s; syringe push speed: 3mL / h; needle type: No. 17 needle; receiving distance: 15cm.

[0085] Comparative Example 3

[0086] (1) First, coconut shell fiber was added to an aqueous solution at a ratio of 1:50 and subjected to ultrasonic disruption at 500W for 80 minutes to obtain micro-nano structured coconut shell fiber.

[0087] (2) The coconut shell fiber was added to a 3% AgNO3 aqueous solution at a ratio of 1:50, stirred at room temperature for 30 min, and then reacted with a 2% NaOH aqueous solution to obtain silver oxide deposited coconut shell fiber. The molar ratio between AgNO3 and NaOH was 1:1.

[0088] (3) Dissolve 2g of polylactic acid (PLA) in a mixed solution of 13.3mL dichloromethane (DCM) and 6.7mL N,N-dimethylformamide (DMF). Heat and stir the mixture at 50°C until completely dissolved. Then, add 0.2g of silver oxide deposited coconut shell fiber to the mixture and place it on a shaker for 30min to obtain a spinning precursor solution.

[0089] (4) Nanofiber films were prepared by electrospinning. The specific parameters are as follows: voltage: 19kV; roller speed: 50rpm / s; syringe push speed: 3mL / h; needle type: No. 17 needle; receiving distance: 15cm.

[0090] Performance testing:

[0091] The preservation films prepared in Examples 1-8 and Comparative Examples 1-3 were tested according to GB / T 1040.1-2018 for mechanical properties, GB / T 30693-2014 for water contact angle, GB / T 1037-2021 for water vapor transmission rate, WS / T 650-2019 for antibacterial properties, GB / T 39100-2020 for antioxidant properties, GB 31604.1-2023 for silver migration, GB 5009.237-2016 for pH of chilled beef, GB 4789.2-2022 for total bacterial count (TVC), GB 5009.228-2016 for volatile basic nitrogen (TVB-N), and GB 5009.181-2016 for thiobarbituric acid reactants (TBARS). The test results are shown in Table 1 and Figures 1-6 .

[0092] Table 1. Test results of the preservation film samples of chilled fresh beef in the examples and comparative examples.

[0093]

[0094]

[0095] Test results:

[0096] Based on the test results of Examples 1-8 and Comparative Example 1, it can be seen that adding different proportions of silver oxide deposited plant fibers affects the mechanical properties of the film. When the addition amount is 0.2g, the tensile strength and elongation at break reach their maximum. As the silver oxide deposited plant fibers adhere to the matrix material, they act as reinforcing particles filling the spaces between the fibers. The reason for this reinforcement is that the addition of an appropriate amount of silver oxide deposited plant fibers can increase the crystallinity of the blend, thereby improving the mechanical properties. Furthermore, the test results show that the film exhibits excellent hydrophobicity. Based on the test results of Examples 1 and Comparative Example 3, it can be seen that the addition of tannic acid reduces the mechanical properties of the film but imparts better antibacterial properties. Moreover, in the presence of tannic acid, the DPPH scavenging rate of the film can reach approximately 95%, achieving excellent antioxidant properties. Examples 1-8 simulated the migration of the film in lipophilic foods in 50% ethanol, and the results showed that the maximum migration of silver was far less than the allowable migration amount of food components recognized by current regulations (10 mg / dm²).

[0097] The microstructure and elemental distribution diagram of the tannic acid-silver oxide / silver film obtained in Example 1 of this invention are shown below. Figure 1 As shown, Figure 1 It can be seen that silver oxide deposited on coconut shell fibers was successfully and uniformly attached to PLA fibers. The tannic acid-silver oxide / silver film has a small pore size, high specific surface area and porosity, a smooth surface, and no other defects such as beading, and has good hydrophobicity and mechanical properties.

[0098] like Figure 2 The image shown is the XRD pattern of a tannic acid-silver oxide / silver thin film, indicating the simultaneous presence of silver oxide and silver nanoparticles in the film, with free silver ions being reduced to silver nanoparticles. Figure 3 The image shows the antibacterial properties of a tannic acid-silver oxide / silver film. Example 1 demonstrates an antibacterial effect exceeding 99%, indicating that the tannic acid-silver oxide / silver film possesses excellent antibacterial properties. Figure 4 As shown, the DPPH scavenging rate of tannic acid-silver oxide / silver film is as follows. The DPPH scavenging rate eventually reaches equilibrium at around 95%, demonstrating good antioxidant properties.

[0099] like Figure 5 As shown, fresh beef was used as the test subject. Beef wrapped in the tannic acid-silver oxide / silver film of Example 1 of this invention was compared with beef wrapped in commercial PE cling film as a control group. One piece of beef was randomly selected from three pieces tested daily for photographing. The beef in the experimental group largely maintained its original shape after 18 days, although its color turned greener and darker. The beef in the control group, however, began to spoil, darkened in color, and developed an off-odor, even producing mucus.

[0100] like Figure 6As shown, during the preservation process, the pH changes in both groups exhibited the same trend, with the pH value first stabilizing and then increasing. The pH of the beef wrapped in the tannic acid-silver oxide / silver film group was lower than that of the PE film group on day 18, proving that the tannic acid-silver oxide / silver film can effectively delay the spoilage of beef.

[0101] The total bacterial counts in both groups showed significant changes. The tannic acid-silver oxide / silver film group reached a TVC value of 6.21±0.05log CFU / g on day 15, while the PE film group reached a TVC value of 6.13±0.01log CFU / g on day 9. This indicates that the tannic acid-silver oxide / silver film can effectively and continuously inhibit the growth of microorganisms in lean beef.

[0102] The overall trend of TVB-N changes is similar to that of TVC. In the first 6 days, TVB-N changes slowly, and then rises rapidly over time. On the 9th day, the TVB-N of beef covered with tannic acid-silver oxide / silver film is below 15 mg / 100g, indicating good freshness and significantly extending the shelf life of the beef.

[0103] After 6 days of treatment with two different membranes, the increase in thiobarbituric acid reactants (TBARS) in beef from the tannic acid-silver oxide / silver film group was significantly lower than that in the control group. The slowly released tannic acid, acting as an inhibitor of thiobarbituric acid reactants, indicates that the tannic acid-silver oxide / silver film can slow down lipid oxidation, maintain freshness, and thus extend shelf life.

[0104] In summary, the preservation film material provided by this invention can effectively maintain the freshness of beef and extend the storage period of meat.

[0105] The above embodiments merely illustrate several specific implementations of the present invention and are not intended to limit the scope of the patent. It should be understood that those skilled in the art can make different improvements and obtain other implementations without inventive effort, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A food preservation film material, characterized in that: An electrospinning precursor solution composed of silver oxide deposited plant fibers, tannic acid, hydrophobic polymer, solvent, etc., is prepared by electrospinning. The mass ratio of the silver oxide deposited plant fiber, tannic acid, and hydrophobic polymer is 4:1:

40. The hydrophobic polymer is polylactic acid; the plant fiber is coconut shell fiber. The solvent is a mixed solution of dichloromethane and N,N-dimethylformamide, with a volume ratio of 13.3:6.

7. The silver oxide deposited plant fiber is made by a method including the following steps: first, the plant fiber is treated by ultrasonic cell disruption technology to obtain micro-nano structured plant fiber, then the plant fiber is added to AgNO3 aqueous solution and dispersed evenly, and then NaOH is added to carry out the reaction; The molar ratio between AgNO3 and NaOH is 1:1; the concentration of the AgNO3 aqueous solution is 3wt%; and the mass ratio of the treated plant fiber to the AgNO3 aqueous solution is 1:

50.

2. The food preservation film material according to claim 1, characterized in that: The tannic acid has a molecular weight of 1701 and an acidity coefficient (pKa) of 6.00 ± 0.

50.

3. A food preservation film material according to claim 1, characterized in that: The electrospinning parameters are as follows: voltage 13~21 kV, roller speed 30~60 rpm / s, flow rate 0.5~6 mL / h, needle size 15~22; receiving distance 10~25cm, spinning amount 5~30 mL, spinning time 1~12 h, and relative humidity 5~80%.

4. The application of the preservation film material according to any one of claims 1-3 in meat preservation.

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