Food antioxidant preservative film and preparation method thereof

Abstract

The application discloses a food antioxidant fresh-keeping film and a preparation method thereof, relates to the technical field of food fresh-keeping, and comprises 50-70 parts of linear polyethylene resin, 6-15 parts of a plasticizer, 10-15 parts of an antioxidant ethylene composite resin and 0.1-0.6 parts of an additive in terms of weight parts; wherein the antioxidant ethylene composite resin is obtained by free radical polymerization of 70-80% ethylene monomers, 10-15% chitosan composite materials, 5-10% tea polyphenols and 1-5% initiators in terms of mass percentage. The application has the effect of effectively preventing oxidation and fresh-keeping while avoiding affecting the taste of food.

Description

Technical Field

[0001] This application relates to the field of food preservation technology, and in particular to a food antioxidant preservation film and its preparation method. Background Technology

[0002] Antioxidant food preservation film is a packaging material that adds antioxidants to traditional food preservation film, giving it the ability to delay food oxidation and spoilage. By adding antioxidants, it captures oxygen in the food packaging environment and free radicals generated during the food's own oxidation process, thereby slowing down the oxidation rate and preventing problems such as discoloration, off-flavors, nutrient loss, and microbial growth, thus extending the shelf life and freshness of the food.

[0003] Chinese patent application CN113150574A discloses a food-grade antioxidant preservation film, which comprises the following raw material components in parts by weight: 100-300 parts coconut shell, 50-80 parts soybean residue, 40-80 parts film-forming agent, 5-15 parts antioxidant, 3-10 parts coupling agent, 2-10 parts plasticizer, and 1-8 parts emulsifier.

[0004] However, this food-grade antioxidant preservation film only prevents the oxidation and deterioration of oils in aquatic products through the mixture of tea polyphenols and other ingredients. During use, the tea polyphenols have poor stability and, as a flavor modifier, can affect the taste of food and cause astringency, which needs to be improved. Summary of the Invention

[0005] In view of this, the first objective of this application is to provide a food antioxidant preservation film that effectively preserves food while avoiding affecting its taste. The specific solution is as follows:

[0006] An antioxidant food preservation film comprises 50-70 parts by weight of linear polyethylene resin, 6-15 parts of plasticizer, 10-15 parts of antioxidant ethylene composite resin, and 0.1-0.6 parts of additives; wherein:

[0007] The antioxidant ethylene composite resin is obtained by free radical polymerization of 70-80% ethylene monomer, 10-15% chitosan composite material, 5-10% tea polyphenols and 1-5% initiator by mass percentage.

[0008] Preferably, the linear polyethylene resin has a molecular weight of 100,000 to 500,000 and is purchased from Tianjin Sanzhi Petrochemical Co., Ltd.

[0009] Preferably, the plasticizer is epoxidized fatty acid methyl ester, epoxidized soybean oil ESO, acetylated tributyl citrate (ATBC), or tributyl citrate (TBC).

[0010] Preferably, the additives include at least one of a mildew inhibitor, an antistatic agent, and an opening agent; the mildew inhibitor is a nano-silver ion antibacterial agent; the antistatic agent is a fatty acid polyol ester or a polyethylene glycol fatty acid ester; and the opening agent is silica or talc.

[0011] Preferably, the preparation method of the chitosan composite material includes: Step ① adding chitosan to a 1% acetic acid solution, stirring and dissolving it completely, then adding 10% sodium hydroxide solution to adjust the pH to 8, and finally washing and drying the precipitated precipitate with deionized water to obtain activated chitosan; Step ② dissolving the activated chitosan in DMF, controlling the temperature of DMF at 60℃ to obtain a chitosan solution; Step ③ adding β-hydroxyethyl methacrylate to the chitosan solution, stirring until the addition is complete to obtain a mixed solution; Step ④ adding a catalyst to the mixed solution, and stirring continuously for 6-12 hours to obtain a reactant solution; Step ⑤ obtaining the chitosan composite material after cooling, precipitation and washing.

[0012] Preferably, in step ③, the mass ratio of β-hydroxyethyl methacrylate to chitosan added is 3:1.

[0013] Preferably, in step ④, the catalyst is p-toluenesulfonic acid or ammonium persulfate, and the mass ratio of the catalyst to chitosan is 1:50.

[0014] Preferably, in step ⑤, after cooling to room temperature, ethanol is added as a precipitant to precipitate the material, and after surface cleaning with ethanol, the material is dried in a vacuum desiccant to obtain the chitosan composite material.

[0015] The second objective of this invention is to provide a method for preparing a food antioxidant preservation film, comprising the following steps:

[0016] Step 1: Add 50-70 parts by weight of linear polyethylene resin, 6-15 parts by weight of plasticizer, 10-15 parts by weight of antioxidant ethylene composite resin and 0.1-0.6 parts by weight of additives into a high-speed mixer and mix to obtain a premix.

[0017] Step 2: The premixed material is fed into the extruder and extruded into sheets, which are then cast onto the cooling rollers and cooled to form a film.

[0018] Step 3: Cut the plastic wrap into the desired size.

[0019] Preferably, the preparation of the antioxidant ethylene composite resin includes step ① adding tea polyphenols to phosphate buffer to obtain a tea polyphenol solution; step ② adding glutaraldehyde to the tea polyphenol solution and controlling the mass ratio of glutaraldehyde to tea polyphenols to be 1:30, and stirring to obtain a buffer solution; step ③ making chitosan composite material into particles and adding them to the buffer solution, allowing them to stand at 25-35℃ for 2-4 hours, and then washing them with deionized water to obtain a tea polyphenol / chitosan crosslinked material; step ④ adding the tea polyphenol / chitosan crosslinked material, ethylene monomer and initiator to a solvent, controlling the temperature at 60℃ and stirring for 4-8 hours to obtain the antioxidant ethylene composite resin.

[0020] As can be seen from the above solutions, this application provides a food antioxidant preservation film and its preparation method, which has the following beneficial effects:

[0021] 1. Effectively prevents oxidation and preserves freshness while avoiding affecting the taste of food;

[0022] 2. Long-chain structures are obtained through the polymerization of vinyl monomers, thereby achieving the effects of flexibility, high strength and barrier properties;

[0023] 3. By grafting β-hydroxyethyl methacrylate with vinyl groups onto chitosan, the chitosan composite material is polymerized with ethylene monomers to form a network structure, thereby improving flexibility and strength. It also effectively prevents the penetration of oxygen, moisture and microorganisms by forming a denser membrane structure, thus extending the shelf life of food.

[0024] 4. By leveraging the antibacterial properties of chitosan, the antibacterial properties of the chitosan composite material in the antioxidant ethylene composite resin are enhanced;

[0025] 5. By using chitosan composite materials to form strong chemical bonds with tea polyphenols, the binding stability between tea polyphenols and chitosan is improved, enabling tea polyphenols to exert their antioxidant function for a longer period of time.

[0026] 6. An antioxidant ethylene composite resin is prepared by combining ethylene monomer, chitosan composite material, tea polyphenols, and an initiator, and then added to linear polyethylene resin. This significantly improves the dispersion effect of each component in the food antioxidant preservation film, resulting in a food antioxidant preservation film with improved structural strength, antioxidant performance, and the ability to effectively prevent the rapid deterioration of tea polyphenols and their impact on the taste of food. Detailed Implementation

[0027] The technical solutions described below in conjunction with the embodiments of this application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0028] It should be mentioned that in the preparation of the antioxidant ethylene composite resin, either commercially available azobisisobutyronitrile (AIBN) or ammonium persulfate can be used as the initiator, which will not be elaborated here. The linear polyethylene resin has a molecular weight of 100,000-500,000 and was purchased from Tianjin Sanzhi Petrochemical Co., Ltd.

[0029] The following will provide a detailed description of a food antioxidant preservation film and its preparation method, as described in this application.

[0030] An antioxidant food preservation film comprises 50-70 parts by weight of linear polyethylene resin, 6-15 parts by weight of plasticizer, 10-15 parts by weight of antioxidant ethylene composite resin, and 0.1-0.6 parts by weight of additives. The antioxidant ethylene composite resin is obtained by free radical polymerization of 70-80% by weight of ethylene monomer, 10-15% by weight of chitosan composite material, 5-10% by weight of tea polyphenols, and 1-5% by weight of initiator.

[0031] In the embodiments of this application, the plasticizer is epoxidized fatty acid methyl ester, epoxidized soybean oil ESO, acetylated tributyl citrate (ATBC), or tributyl citrate (TBC). The additives include at least one of a fungicide, an antistatic agent, and an opening agent. The fungicide is a nano-silver ion antibacterial agent. The antistatic agent is a fatty acid polyol ester or polyethylene glycol fatty acid ester; the opening agent is silica or talc. All of the above materials are commercially available and will not be described in detail here.

[0032] It should be noted that the preparation method of chitosan composite material includes the following steps: Step ① Chitosan is added to a 1% acetic acid solution and stirred until fully dissolved. Then, a 10% sodium hydroxide solution is added dropwise to adjust the pH to 8. Finally, the precipitated precipitate is washed with deionized water and dried to obtain activated chitosan. Step ② Activated chitosan is added to DMF and dissolved, and the temperature of DMF is controlled at 60℃ to obtain a chitosan solution. Step ③ β-hydroxyethyl methacrylate is added dropwise to the chitosan solution, and the mass ratio of β-hydroxyethyl methacrylate to chitosan is controlled at 3:1. Stirring is maintained until the addition is completed to obtain a mixed solution. Step ④ A catalyst is added to the mixed solution. The catalyst is p-toluenesulfonic acid or ammonium persulfate, and the mass ratio with chitosan is 1:50. After continuous stirring for 6-12 hours, a reactant solution is obtained. Step ⑤ After cooling to room temperature, ethanol is added as a precipitant to precipitate the product. The surface is then cleaned with ethanol and dried in a vacuum desiccant to obtain the chitosan composite material.

[0033] A method for preparing a food antioxidant preservation film includes the following steps:

[0034] Step 1: Add 50-70 parts by weight of linear polyethylene resin, 6-15 parts by weight of plasticizer, 10-15 parts by weight of antioxidant ethylene composite resin and 0.1-0.6 parts by weight of additives into a high-speed mixer and mix to obtain a premix.

[0035] Step 2: The premixed material is fed into the extruder and extruded into sheets, which are then cast onto the cooling rollers and cooled to form a film.

[0036] Step 3: Cut the plastic wrap into the desired size.

[0037] The preparation of the antioxidant ethylene composite resin includes the following steps: Step ①: Adding tea polyphenols to phosphate buffer to obtain a tea polyphenol solution; Step ②: Adding glutaraldehyde to the tea polyphenol solution and controlling the mass ratio of glutaraldehyde to tea polyphenols to be 1:30, and stirring to obtain a buffer solution; Step ③: Making chitosan composite material into particles and adding them to the buffer solution, allowing them to stand at 25-35℃ for 2-4 hours, and then washing them with deionized water to obtain a tea polyphenol / chitosan crosslinked material; Step ④: Adding the tea polyphenol / chitosan crosslinked material, ethylene monomer and initiator to a solvent, controlling the temperature at 60℃ and stirring for 4-8 hours to obtain the antioxidant ethylene composite resin.

[0038] Example 1

[0039] An antioxidant food preservation film comprises 50 parts by weight of linear polyethylene resin, 6 parts by weight of plasticizer, 10 parts by weight of antioxidant ethylene composite resin, and 0.1 parts by weight of additives. The antioxidant ethylene composite resin is obtained by free radical polymerization of 70% ethylene monomer, 15% chitosan composite material, 10% tea polyphenols, and 5% initiator by weight.

[0040] In the embodiments of this application, the plasticizer is epoxy fatty acid methyl ester. The additive is silicon dioxide.

[0041] It should be noted that the preparation method of chitosan composite material includes the following steps: Step ① Chitosan is added to a 1% acetic acid solution and stirred until fully dissolved. Then, 10% sodium hydroxide solution is added dropwise to adjust the pH to 8. Finally, the precipitated precipitate is washed with deionized water and dried to obtain activated chitosan; Step ② Activated chitosan is added to DMF and dissolved, and the temperature of DMF is controlled at 60℃ to obtain chitosan solution; Step ③ β-hydroxyethyl methacrylate is added dropwise to chitosan solution, and the mass ratio of β-hydroxyethyl methacrylate to chitosan is controlled at 3:1. Stirring is maintained until the addition is completed to obtain a mixed solution; Step ④ A catalyst is added to the mixed solution. The catalyst is p-toluenesulfonic acid or ammonium persulfate, and the mass ratio with chitosan is 1:50. After continuous stirring for 6 hours, a reactant solution is obtained; Step ⑤ After cooling to room temperature, ethanol is added as a precipitant to precipitate the product. After surface cleaning with ethanol, the product is dried in a vacuum desiccant to obtain chitosan composite material.

[0042] A method for preparing a food antioxidant preservation film includes the following steps:

[0043] Step 1: Add 50 parts by weight of linear polyethylene resin, 6 parts by weight of plasticizer, 10 parts by weight of antioxidant ethylene composite resin and 0.1 parts by weight of silica into a high-speed mixer and mix to obtain a premix.

[0044] Step 2: The premixed material is fed into the extruder and extruded into sheets, which are then cast onto the cooling rollers and cooled to form a film.

[0045] Step 3: Cut the plastic wrap into the desired size.

[0046] The preparation of the antioxidant ethylene composite resin includes the following steps: Step ①: Adding tea polyphenols to phosphate buffer to obtain a tea polyphenol solution; Step ②: Adding glutaraldehyde to the tea polyphenol solution and controlling the mass ratio of glutaraldehyde to tea polyphenols to be 1:30, and stirring to obtain a buffer solution; Step ③: Making chitosan composite material into particles and adding them to the buffer solution, allowing them to stand at 25°C for 4 hours, and then washing them with deionized water to obtain a tea polyphenol / chitosan crosslinked material; Step ④: Adding the tea polyphenol / chitosan crosslinked material, ethylene monomer, and initiator to a solvent, controlling the temperature at 60°C and stirring for 4 hours to obtain the antioxidant ethylene composite resin.

[0047] Example 2

[0048] An antioxidant food preservation film comprises 60 parts by weight of linear polyethylene resin, 10 parts of plasticizer, 14 parts of antioxidant ethylene composite resin, and 0.3 parts of additives. The antioxidant ethylene composite resin is obtained by free radical polymerization of 75% ethylene monomer, 13% chitosan composite material, 9% tea polyphenols, and 3% initiator by weight.

[0049] In the embodiments of this application, the plasticizer is epoxidized soybean oil (ESO). The additive is a nano-silver ion antibacterial agent.

[0050] It should be noted that the preparation method of chitosan composite material includes the following steps: Step ① Chitosan is added to a 1% acetic acid solution and stirred until fully dissolved. Then, 10% sodium hydroxide solution is added dropwise to adjust the pH to 8. Finally, the precipitated precipitate is washed with deionized water and dried to obtain activated chitosan; Step ② Activated chitosan is added to DMF and dissolved, and the temperature of DMF is controlled at 60℃ to obtain chitosan solution; Step ③ β-hydroxyethyl methacrylate is added dropwise to chitosan solution, and the mass ratio of β-hydroxyethyl methacrylate to chitosan is controlled at 3:1. Stirring is maintained until the addition is completed to obtain a mixed solution; Step ④ A catalyst is added to the mixed solution. The catalyst is p-toluenesulfonic acid or ammonium persulfate, and the mass ratio with chitosan is 1:50. After continuous stirring for 8 hours, a reactant solution is obtained; Step ⑤ After cooling to room temperature, ethanol is added as a precipitant to precipitate the product. After surface cleaning with ethanol, the product is dried in a vacuum desiccant to obtain chitosan composite material.

[0051] A method for preparing a food antioxidant preservation film includes the following steps:

[0052] Step 1: Add 60 parts by weight of linear polyethylene resin, 10 parts by weight of plasticizer, 14 parts by weight of antioxidant ethylene composite resin and 0.3 parts by weight of additives into a high-speed mixer and mix to obtain a premix.

[0053] Step 2: The premixed material is fed into the extruder and extruded into sheets, which are then cast onto the cooling rollers and cooled to form a film.

[0054] Step 3: Cut the plastic wrap into the desired size.

[0055] The preparation of the antioxidant ethylene composite resin includes the following steps: Step ①: Adding tea polyphenols to phosphate buffer to obtain a tea polyphenol solution; Step ②: Adding glutaraldehyde to the tea polyphenol solution and controlling the mass ratio of glutaraldehyde to tea polyphenols to be 1:30, and stirring to obtain a buffer solution; Step ③: Making chitosan composite material into particles and adding them to the buffer solution, allowing them to stand at 30°C for 3 hours, and then washing them with deionized water to obtain a tea polyphenol / chitosan crosslinked material; Step ④: Adding the tea polyphenol / chitosan crosslinked material, ethylene monomer, and initiator to a solvent, controlling the temperature at 60°C and stirring for 6 hours to obtain the antioxidant ethylene composite resin.

[0056] Example 3

[0057] An antioxidant food preservation film comprises 70 parts by weight of linear polyethylene resin, 15 parts of plasticizer, 15 parts of antioxidant ethylene composite resin, and 0.6 parts of additives. The antioxidant ethylene composite resin is obtained by free radical polymerization of 80% ethylene monomer, 13% chitosan composite material, 6% tea polyphenols, and 1% initiator by weight.

[0058] In this embodiment, the plasticizer is epoxidized soybean oil (ESO). The additives are 0.2 parts of fatty acid polyol ester and 0.4 parts of silicon dioxide.

[0059] It should be noted that the preparation method of chitosan composite material includes the following steps: Step ① Chitosan is added to a 1% acetic acid solution and stirred until fully dissolved. Then, a 10% sodium hydroxide solution is added dropwise to adjust the pH to 8. Finally, the precipitated precipitate is washed with deionized water and dried to obtain activated chitosan. Step ② Activated chitosan is added to DMF and dissolved, and the temperature of DMF is controlled at 60℃ to obtain a chitosan solution. Step ③ β-hydroxyethyl methacrylate is added dropwise to the chitosan solution, and the mass ratio of β-hydroxyethyl methacrylate to chitosan is controlled at 3:1. Stirring is maintained until the addition is completed to obtain a mixed solution. Step ④ A catalyst is added to the mixed solution. The catalyst is p-toluenesulfonic acid or ammonium persulfate, and the mass ratio with chitosan is 1:50. After continuous stirring for 12 hours, a reactant solution is obtained. Step ⑤ After cooling to room temperature, ethanol is added as a precipitant to precipitate the product. The surface is then cleaned with ethanol and dried in a vacuum desiccant to obtain the chitosan composite material.

[0060] A method for preparing a food antioxidant preservation film includes the following steps:

[0061] Step 1: Add 70 parts by weight of linear polyethylene resin, 15 parts by weight of plasticizer, 15 parts by weight of antioxidant ethylene composite resin and 0.6 parts by weight of additives into a high-speed mixer and mix to obtain a premix.

[0062] Step 2: The premixed material is fed into the extruder and extruded into sheets, which are then cast onto the cooling rollers and cooled to form a film.

[0063] Step 3: Cut the plastic wrap into the desired size.

[0064] The preparation of the antioxidant ethylene composite resin includes the following steps: Step ①: Adding tea polyphenols to phosphate buffer to obtain a tea polyphenol solution; Step ②: Adding glutaraldehyde to the tea polyphenol solution and controlling the mass ratio of glutaraldehyde to tea polyphenols to be 1:30, and stirring to obtain a buffer solution; Step ③: Making chitosan composite material into particles and adding them to the buffer solution, allowing them to stand at 35°C for 2 hours, and then washing them with deionized water to obtain a tea polyphenol / chitosan crosslinked material; Step ④: Adding the tea polyphenol / chitosan crosslinked material, ethylene monomer, and initiator to a solvent, controlling the temperature at 60°C and stirring for 8 hours to obtain the antioxidant ethylene composite resin.

[0065] Comparative Example 1

[0066] The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, activated chitosan was used instead of chitosan composite material and mixed with tea polyphenols and stirred with an acidic solution to form a complex.

[0067] Comparative Example 2

[0068] The difference between Comparative Example 2 and Example 1 is that in Comparative Example 2, 1 part by weight of tea polyphenols was used instead of 15 parts by weight of antioxidant ethylene composite resin.

[0069] Comparative Example 3

[0070] The difference between Comparative Example 3 and Example 1 is that the antioxidant ethylene composite resin used in Comparative Example 3 is formed by combining ethylene monomers and tea polyphenols.

[0071] Performance testing:

[0072] 1. Food antioxidant preservation films prepared using Examples 1 to 3 and Comparative Examples 1 to 3, with the thickness of the food antioxidant preservation film controlled at 6±0.15μm;

[0073] 2. The scavenging activity of free radicals and hydroxyl radicals was tested using DPPH solution. The scavenging rate (%) was calculated as follows: n% = absorbance (original) / absorbance (added) 100%;

[0074] 3. The tensile strength and elongation at break were tested according to GB / T 1040.3-2006.

[0075] 4. In a refrigerated environment with a temperature of 4℃ and a humidity of 80-90%, cut fresh apples into pieces and wrap them in plastic wrap for 5 days and 10 days respectively, and observe the signs of spoilage.

[0076] The performance test results are shown in Table 1 below.

[0077] Table 1. Performance test results of the examples and comparative examples.

[0078]

[0079] As shown in Table 1 above, when tea polyphenols are directly compounded with ethylene monomers, the antioxidant properties of tea polyphenols will decrease, and the poor dispersion of tea polyphenols in linear polyethylene resin will affect the mechanical properties.

[0080] Analysis of the components of Examples 1 to 3 shows that the content of tea polyphenols in Examples 1 and 2 is the same and greater than that in Example 3. Therefore, it is expected that the scavenging rate of Example 3 is lower than that of Examples 1 and 2. The tea polyphenols in Comparative Examples 1 and 2 can still play an effective antioxidant role and achieve a high scavenging rate, but they cannot withstand long-term antioxidant effects. It can be seen that the tea polyphenols gradually lose their antioxidant ability over time.

[0081] Meanwhile, the food antioxidant preservation film described in this application exhibits significant antioxidant effects, thereby achieving the purpose of food preservation. Furthermore, the combination with chitosan significantly enhances the antibacterial effect, effectively preventing mold growth. When chitosan is used, it improves the structural strength of the food antioxidant preservation film and enhances its antioxidant and antibacterial capabilities.

[0082] In summary, this application provides a food antioxidant preservation film and its preparation method. The preparation method of this food antioxidant preservation film is simple, easy to implement, and suitable for large-scale production. Furthermore, the food antioxidant preservation film prepared by this method effectively prevents oxidation and preserves freshness while avoiding affecting the taste of the food. Specifically, the food antioxidant preservation film obtains a long-chain structure through the polymerization of vinyl monomers, thereby achieving flexibility, high strength, and barrier properties. Furthermore, by grafting β-hydroxyethyl methacrylate with vinyl groups onto chitosan, the chitosan composite material and ethylene monomers polymerize to form a network structure, further enhancing flexibility and strength. The formation of a denser film structure effectively prevents the penetration of oxygen, moisture, and microorganisms, thereby extending the shelf life of the food. Meanwhile, the antibacterial properties of chitosan enhance the antibacterial performance of the chitosan composite material in the antioxidant ethylene composite resin. Furthermore, based on the properties of chitosan, the formation of strong chemical bonds between the chitosan composite material and tea polyphenols improves the binding stability between the two, allowing the tea polyphenols to exert their antioxidant function for a longer period. Therefore, this food antioxidant preservation film is prepared by using ethylene monomers, chitosan composite materials, tea polyphenols, and an initiator to obtain an antioxidant ethylene composite resin, which is then added to linear polyethylene resin. This significantly improves the dispersion of the components in the food antioxidant preservation film, resulting in improved structural strength, antioxidant performance, and effective prevention of rapid efflorescence of tea polyphenols and their impact on food taste.

[0083] The terms “first,” “second,” “third,” “fourth,” etc., used in this application (if applicable) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, or apparatus that includes a series of steps or units is not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, or apparatus.

[0084] It should be noted that the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0085] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A food antioxidant preservation film, characterized in that: It includes 50-70 parts by weight of linear polyethylene resin, 6-15 parts by weight of plasticizer, 10-15 parts by weight of antioxidant ethylene composite resin, and 0.1-0.6 parts by weight of additives; wherein: The antioxidant ethylene composite resin is obtained by free radical polymerization of 70-80% ethylene monomer, 10-15% chitosan composite material, 5-10% tea polyphenols and 1-5% initiator by mass percentage. The preparation method of the chitosan composite material includes the following steps: Step ① Chitosan is added to a 1% acetic acid solution and stirred until fully dissolved. Then, a 10% sodium hydroxide solution is added dropwise to adjust the pH to 8. Finally, the precipitated precipitate is washed with deionized water and dried to obtain activated chitosan; Step ② Activated chitosan is added to DMF and dissolved, and the temperature of DMF is controlled at 60℃ to obtain a chitosan solution; Step ③ β-hydroxyethyl methacrylate is added dropwise to the chitosan solution, and stirring is maintained until the addition is completed to obtain a mixed solution; Step ④ A catalyst is added to the mixed solution, and the reactant solution is obtained after continuous stirring for 6-12 hours; Step ⑤ After cooling, precipitation, and washing, the chitosan composite material is obtained. The preparation of the antioxidant ethylene composite resin includes the following steps: Step ①: Adding tea polyphenols to phosphate buffer to obtain a tea polyphenol solution; Step ②: Adding glutaraldehyde to the tea polyphenol solution and controlling the mass ratio of glutaraldehyde to tea polyphenols to be 1:30, and stirring to obtain a buffer solution; Step ③: Making chitosan composite material into particles and adding them to the buffer solution, allowing them to stand at 25-35℃ for 2-4 hours, and then washing them with deionized water to obtain a tea polyphenol / chitosan crosslinked material; Step ④: Adding the tea polyphenol / chitosan crosslinked material, ethylene monomer and initiator to a solvent, controlling the temperature at 60℃ and stirring for 4-8 hours to obtain the antioxidant ethylene composite resin.

2. The food antioxidant preservation film according to claim 1, characterized in that: The linear polyethylene resin has a molecular weight of 100,000 to 500,000.

3. The food antioxidant preservation film according to claim 1, characterized in that: The plasticizer is epoxidized fatty acid methyl ester, epoxidized soybean oil ESO, acetylated tributyl citrate ATBC, or tributyl citrate TBC.

4. The food antioxidant preservation film according to claim 1, characterized in that: The additives include at least one of a mildew inhibitor, an antistatic agent, and an opening agent; the mildew inhibitor is a nano-silver ion antibacterial agent; the antistatic agent is a fatty acid polyol ester or a polyethylene glycol fatty acid ester; and the opening agent is silica or talc.

5. The food antioxidant preservation film according to claim 1, characterized in that: In step ③, the mass ratio of β-hydroxyethyl methacrylate to chitosan added is 3:

1.

6. The food antioxidant preservation film according to claim 1, characterized in that: In step ④, the catalyst is p-toluenesulfonic acid or ammonium persulfate, and the mass ratio of the catalyst to chitosan is 1:

50.

7. The food antioxidant preservation film according to claim 1, characterized in that: In step ⑤, after cooling to room temperature, ethanol is added as a precipitant to precipitate the material, and after surface cleaning with ethanol, the material is dried in a vacuum dryer to obtain the chitosan composite material.

8. A method for preparing a food antioxidant preservation film, characterized in that, Includes the following steps: Step 1: Add 50-70 parts by weight of linear polyethylene resin, 6-15 parts by weight of plasticizer, 10-15 parts by weight of antioxidant ethylene composite resin and 0.1-0.6 parts by weight of additives into a high-speed mixer and mix to obtain a premix. Step 2: The premixed material is fed into the extruder and extruded into sheets, which are then cast onto the cooling rollers and cooled to form a film. Step 3: Cut the plastic wrap into the desired size.

Images