A household flower cow apple fresh-keeping kit and a post-ripening interruption control method thereof

Abstract

The present application relates to the technical field of fruit preservation, and particularly relates to a household flower and ox apple preservation kit and a post-ripening interruption control method. The preservation kit comprises, from outside to inside, a polyethylene film layer, a modified polyvinyl alcohol nanofiber film layer and a preservation patch layer. The modified polyvinyl alcohol nanofiber film is made of polyvinyl alcohol modified by three steps through electrospinning. The preservation patch layer contains microcapsules with 1-methylcyclopropene as the core material adsorbed by mesoporous silica. The present application realizes accurate control of the post-ripening process of flower and ox apple and synergistic regulation of the low-temperature storage microenvironment by using a three-layer composite kit containing a gas adsorption film layer and a slow-release preservation patch, and combining a standardized post-ripening interruption process based on color, luster and aroma judgment. The present application effectively prolongs the maintenance time of the best edible state of the fruit and maintains the taste and flavor of the fruit.

Description

Technical Field

[0001] This invention relates to the field of fruit preservation technology, and in particular to a household Huaniu apple preservation kit and its method for controlling the interruption of ripening. Background Technology

[0002] Huaniu apples, a distinctive and high-quality apple variety in my country, have delicate flesh and a crisp, juicy texture. However, they are typical climacteric fruits, meaning they ripen rapidly and are highly sensitive to environmental changes. Currently, commercial fruit preservation technologies include mature solutions such as low-temperature storage, modified atmosphere packaging, ethylene adsorbents, and 1-methylcyclopropene (1-MCP) treatment. However, preservation technologies specifically designed for home use still have significant shortcomings.

[0003] Existing research shows that traditional home preservation methods rely on low-temperature storage in refrigerators or packaging in ordinary polyethylene plastic bags. These methods can only delay some physiological metabolism and cannot precisely control the ripening process of fruits. On the one hand, ordinary packaging materials (such as low-density polyethylene film) have limited moisture and air permeability, making it difficult to maintain the humidity environment required by the fruit. This can easily lead to fruit skin wrinkling or condensation accumulation inside the bag, causing mold. On the other hand, they lack the ability to specifically adsorb key gases such as ethylene and carbon dioxide. Fruits are prone to softening due to accelerated ripening caused by ethylene accumulation, or producing off-odors due to anaerobic respiration caused by abnormal carbon dioxide concentration.

[0004] The core problems in existing technologies are concentrated in three aspects: First, insufficient gas regulation function. Most commercially available preservation materials treat ethylene through physical interception, lacking specific adsorption sites, resulting in low adsorption efficiency and easy saturation. Simultaneously, the adsorption of carbon dioxide relies on the physical effects of the material's pores, without introducing chemical adsorption functional groups, making it difficult to achieve precise gas concentration balance. Second, uncontrolled release of active ingredients. 1-MCP, as a highly efficient ethylene receptor inhibitor, is prone to problems such as excessively high initial dosage or later ineffectiveness in home applications due to the lack of corresponding sustained-release systems, leading to inconsistent ripening inhibition. Third, lack of quantitative standards for post-ripening interruption. Home users find it difficult to comprehensively judge the optimal eating state based on appearance, color, and aroma characteristics, and lack suitable preservation kits during transfer and storage. The crude control of humidity and gas environment under low-temperature conditions often leads to deterioration in fruit taste or accelerated spoilage. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a household Huaniu apple preservation kit and a method for controlling the interruption of ripening, so as to solve the existing problem of preserving Huaniu apples in the home.

[0006] Based on the above objectives, the present invention provides a household Huaniu apple preservation kit, which comprises, from the outside to the inside, a polyethylene-based film layer, a modified polyvinyl alcohol nanofiber film layer, and a preservation patch layer. The polyethylene-based film layer is a low-density polyethylene film; The modified polyvinyl alcohol nanofiber membrane is made of modified polyvinyl alcohol by electrospinning, and the preparation method of the modified polyvinyl alcohol is as follows: (1) Add polyvinyl alcohol to deionized water, heat to 80-90℃, stir until completely dissolved, cool to 45-55℃, add sodium hydroxide solution to adjust pH to 8-10, then add glycidaldehyde, stir for 8-12 hours, cool to room temperature, pour into ethanol to precipitate, centrifuge, wash the precipitate, and dry to obtain aldehyde-modified polyvinyl alcohol. The chemical reaction diagram is as follows: Equation (1), In an alkaline environment, the hydroxyl groups on the polyvinyl alcohol molecular chain first undergo deprotonation, generating alkoxy anions with strong nucleophilicity. The epoxy group has high ring strain and is easily attacked by nucleophiles. As a nucleophile, the alkoxy anion preferentially attacks the carbon atom with fewer substituents in the epoxy group, causing the epoxy ring to open and forming an oxonium intermediate. The oxonium in the intermediate rapidly abstracts a proton from the reaction medium to generate a stable ether bond product. The condensation of aldehyde and hydroxyl groups usually requires acidic catalysis or stronger alkaline conditions to form enol anions. For example, the crosslinking reaction of polyvinyl alcohol and glutaraldehyde generally needs to be carried out under acidic conditions at 60-90°C. Under the alkaline and temperature conditions of this reaction, the electrophilicity of the aldehyde group is insufficient to effectively initiate the condensation reaction, resulting in its kinetic disadvantage. (2) Add the aldehyde-modified polyvinyl alcohol obtained in (1) to an ethanol / water mixed solution, add glacial acetic acid to adjust the pH to 5-6, heat to 50-60℃ with stirring, then add 2-aminoimidazole, react for 2-4 hours, cool to room temperature, add acetone to precipitate, centrifuge, collect the solid, wash the solid and dry it to obtain imidazole-modified polyvinyl alcohol. The chemical reaction diagram is as follows: Equation (2); This reaction is a typical Schiff base reaction. Under weakly acidic conditions, the carbonyl group (C=O) of the aldehyde is first protonated, forming an intermediate (C=OH) that is more susceptible to nucleophilic attack. + The amino nitrogen atom of the primary amine (R-NH2) acts as a nucleophile, attacking the carbonyl carbon to form an amino alcohol intermediate with a hydroxyl group. The hydroxyl group (-OH) in the intermediate is protonated under acidic conditions and converted into easily leaving water. At the same time, the hydrogen (α-H) on the adjacent nitrogen atom is removed to form an imine double bond (C=N). (3) Under nitrogen protection, the imidazole-modified polyvinyl alcohol obtained in (2) was added to sodium hydroxide solution, heated to 30-40℃ with stirring, and then acrylamide was added. The reaction was carried out for 60-80 min. After cooling to room temperature, it was added to ethanol to precipitate. After centrifugation, the precipitate was washed and dried to obtain modified polyvinyl alcohol. The chemical reaction diagram is as follows: Equation (3), In a broad sense, the Michael addition reaction utilizes nucleophilic compound molecules containing active hydrogen groups such as (-NH2, -SH, -OH) as donors in the Michael addition reaction. In this step of the preparation of the present invention, specifically, the hydroxyl groups on the polyvinyl alcohol chain attack the α and β unsaturated bonds of acrylamide under the activation of sodium hydroxide, and a Michael addition reaction occurs to generate carbon-oxygen bonds. The preservation patch layer is made of functionalized microcapsules, polyurethane film, UV resin, and medical-grade acrylic pressure-sensitive adhesive. The preparation method of the functionalized microcapsules is as follows: (a) Mix sodium alginate solution and chitosan solution, cool to 0-5℃ to obtain wall material solution, calcine mesoporous silica at 200-300℃ for 40-60min, cool to room temperature and place in low temperature drying oven, cool to -5-0℃, then add 1-methylcyclopropene in an environment of -5-0℃, stir for 1-3h, then add to wall material solution, stir at 5000-7000rpm for 10-20min to obtain suspension; (b) Add calcium chloride solution at 0-5℃ to the suspension obtained in (a), stir, crosslink for 10-20 min, filter, wash with deionized water at 0-5℃, freeze dry to obtain functionalized microcapsules.

[0007] Preferably, in (1), polyvinyl alcohol, glycidaldehyde, deionized water and ethanol are in a weight ratio of 1:0.15-0.25:3-5:5-7. The purpose of the aldehyde modification is to introduce imidazole groups through Schiff base reaction to enhance the affinity for ethylene.

[0008] Preferably, in (2), the aldehyde-modified polyvinyl alcohol, 2-aminoimidazole, ethanol / water mixture and acetone are in a weight ratio of 1:0.15-0.25:3-5:5-7, and the ethanol / water mixture refers to ethanol and water mixed in a weight ratio of 1:1.

[0009] Preferably, the mechanism of imidazole affinity adsorption of ethylene mainly includes the following two points: 1. Imidazole is a five-membered heterocyclic compound containing two nitrogen atoms. Its molecular structure contains a delocalized π electron cloud. Ethylene molecules contain carbon-carbon double bonds and also have π electron clouds. When the imidazole group and the ethylene molecule are close to each other, an interaction will occur between their π electron clouds, namely π-π interaction. This interaction is a weak non-covalent interaction, similar to the π-π stacking effect between benzene rings. Through the π-π interaction, the imidazole group can have a certain adsorption effect on the ethylene molecule, making the ethylene molecule closer to the imidazole group. 2. The nitrogen atom on the imidazole ring has a lone pair of electrons, exhibiting a certain electron-donating ability, while the carbon-carbon double bond in the ethylene molecule has a certain electron-accepting ability. Therefore, the nitrogen atom on the imidazole ring can donate electrons to the antibonding π orbitals of the ethylene molecule, forming an electron-donating-accepting interaction. This interaction further enhances the attraction of the imidazole group to the ethylene molecule.

[0010] Preferably, in (3), the imidazole-modified polyvinyl alcohol, acrylamide, sodium hydroxide solution and ethanol are in a weight ratio of 1:0.2-0.4:5-7:10-14, and the concentration of sodium hydroxide solution is 10%.

[0011] Preferably, the mechanism of amino affinity adsorption of carbon dioxide is as follows: -NH2 in the amide group acts as a hydrogen bond donor and forms a hydrogen bond with the oxygen atom of CO2 (such as HN···O=C). This adsorption depends not only on physical adsorption but also on the chemical adsorption of hydrogen bonds, enabling the material to affinity adsorb a certain amount of carbon dioxide.

[0012] Preferably, in (a), the sodium alginate solution, chitosan solution, mesoporous silica and 1-methylcyclopropene are in a weight ratio of 1:1:3-5:9-15, the concentration of sodium alginate solution is 5%, and the concentration of chitosan solution is 2%.

[0013] Preferably, in step (b), the calcium chloride solution and the suspension are in a weight ratio of 1:3-5, and the concentration of the calcium chloride solution is 2%.

[0014] Furthermore, the present invention also provides a method for preparing the above-mentioned household Huaniu apple preservation kit, specifically including the following steps: S1. Add modified polyvinyl alcohol to deionized water, heat to 70-90℃, stir for 2-4 hours to obtain spinning solution, set spinning parameters: spinning voltage 15-30kV, receiving distance 10-20cm, spinneret diameter 0.4-0.8mm, and electrospin to produce modified polyvinyl alcohol nanofibers. The obtained modified polyvinyl alcohol nanofibers are cross-linked with a cross-linking agent to obtain modified polyvinyl alcohol nanofiber membrane; S2. Coat one side of the low-density polyethylene film with an adhesive with a thickness of 2-5 μm. After drying, laminate the modified polyvinyl alcohol nanofiber membrane obtained in S1 onto the side of the low-density polyethylene film coated with adhesive. Then, put it into a laminator and laminate it at 80-120℃ and 0.5-1 MPa. After holding the pressure for 10-20 seconds, use a heat sealer to prepare a food storage bag with a size that fits the size of a Huaniu apple. S3. After corona treatment of the polyurethane film, a layer of medical acrylic pressure-sensitive adhesive with a thickness of 2-5 μm is uniformly coated. After UV curing, release paper is applied. UV resin and ethanol are mixed and stirred for 10-20 minutes, then uniformly coated on the other side of the polyurethane film with a thickness of 5-15 μm to form a UV resin layer. UV pre-curing is performed for 3-5 seconds. Finally, functionalized microcapsules are uniformly dispersed on the UV resin layer at 0-5℃ using an electrostatic powder disperser, with a dispersion density of 5-10 g / m³. 2 After UV curing, it is dried to obtain a food preservation patch layer; S4. Cut the preservation patch layer into 5×5cm pieces, peel off the release paper and stick it on the side of the preservation bag obtained in S2 that is in contact with the Huaniu apple to obtain a household Huaniu apple preservation kit.

[0015] Preferably, in S1, the modified polyvinyl alcohol and deionized water are in a weight ratio of 1:5-9, and the crosslinking agent refers to glutaraldehyde.

[0016] Preferably, the crosslinking reaction in S1 refers to immersing the modified polyvinyl alcohol nanofibers in a 5% glutaraldehyde solution, adjusting the pH to 4-5, maintaining the temperature at 60-70℃, reacting for 2-4 hours, and then washing the product with deionized water until neutral before drying.

[0017] Preferably, in S3, the UV resin and ethanol are in a weight ratio of 1:0.08-0.12.

[0018] Furthermore, the present invention also provides a method for controlling the interruption of ripening of Huaniu apples for home use. The home-use Huaniu apple preservation kit obtained by the above preparation method is characterized by including the following steps: Ⅰ. Place Huaniu apples in the post-ripening stage in a normal temperature environment maintained at 20-25℃. Under this environment, the post-ripening flavor development will take place, providing suitable conditions for the formation of the fruit's flavor. II. By monitoring the appearance and color of the fruit and judging its aroma characteristics, and combining this with the consumer's taste, we can comprehensively determine whether Huaniu apples have reached their optimal eating condition. The specific criteria are: the red area of ​​the peel accounts for no less than 85%, and the yellow-green base color turns into light yellow-white. At the same time, the fruit emits a pleasant aroma. At this point, the fruit is considered to have reached its optimal eating condition. III. Once the fruit has reached its optimal taste, it should be transferred to the refrigerator compartment of a household refrigerator within 24 hours. The temperature of the refrigerator compartment should be controlled at 4±1℃. Use a household Huaniu apple preservation kit to wrap the fruit to ensure that the fruit enters a suitable low-temperature storage environment and slow down subsequent physiological changes. IV. The relative humidity inside the preservation bag is controlled by the humidity adjustment function of the bag body, and is maintained in a suitable range of 80-85%. In order to maintain the air circulation inside the bag, the bag should be opened for ventilation for 10 minutes every 5 days to prevent the gas environment inside the bag from deteriorating and affecting the quality of the fruit.

[0019] The beneficial effects of this invention are: 1. This invention utilizes a three-step chemical modification of polyvinyl alcohol to introduce imidazole and amide groups into the nanofiber membrane, constructing a dual ripening inhibition mechanism of "specific adsorption + sustained release of active ingredients." The imidazole group, leveraging the lone pair electrons and delocalized π-electron cloud of the nitrogen atom in the molecule, forms π-π interactions and electron donor-acceptor effects with ethylene molecules, efficiently capturing ethylene gas within the bag and blocking the transmission of ripening signals at the source. The amide group selectively adsorbs carbon dioxide through hydrogen bonding, preventing anaerobic respiration and off-odors caused by abnormal carbon dioxide concentrations. Simultaneously, the mesoporous silica microcapsules in the preservation patch layer are loaded with 1-methylcyclopropene. Utilizing the high specific surface area of ​​the mesoporous material and the network structure formed by cross-linking with the wall material, the active ingredients are continuously and stably released, inhibiting ethylene receptor activity for a prolonged period. This synergistic effect of gas adsorption and receptor inhibition effectively delays the arrival of the respiratory climacteric peak in Huaniu apples, significantly extending the time the fruit retains its crisp texture and rich aroma.

[0020] 2. The preservation kit prepared in this invention adopts a three-layer composite structure design from the outside to the inside. Each layer of material, through functional division and performance complementarity, forms a highly efficient preservation system integrating mechanical protection, humidity regulation, and slow-release of components. The outer layer, low-density polyethylene film, provides a tough physical barrier, resistant to handling and compression during home storage, preventing packaging bag breakage and fruit contamination. The middle layer, modified polyvinyl alcohol nanofiber film, forms a nanoscale porous network through electrospinning, precisely controlling the humidity inside the bag. This prevents fruit peel from wrinkling due to moisture loss and avoids condensation buildup leading to mold growth. The inner layer, preservation patch, comes into contact with the fruit surface, and its loaded functionalized microcapsules gradually release preservation components, forming a synergistic effect of "contact slow release + environmental regulation" with the gas adsorption function of the middle film layer. This three-layer structure not only achieves precise control of gas and humidity at the microscopic level through material modification but also constructs a stable microenvironment at the macroscopic level, comprehensively delaying the physiological metabolism and quality deterioration of the fruit. Compared with traditional single-material packaging, the preservation effect is significantly improved.

[0021] 3. The accompanying post-ripening interruption control method uses the fruit's appearance, color, and aroma characteristics as the core judgment criteria. It guides users to accurately determine the optimal eating state of Huaniu apples through visual indicators such as the proportion of red area on the peel, changes in base color, and aroma characteristics, avoiding problems like overly soft or hard textures caused by improper control during the post-ripening stage. Once the criteria are met, the fruit can be transferred to a household refrigerator's crisper compartment within 24 hours using the preservation kit. The 4±1℃ low-temperature environment slows down physiological changes, while the humidity control window in the bag and regular ventilation maintain suitable humidity and air circulation. This method requires no professional equipment, and the operation process is simple and easy to understand, meeting the needs of home users for "understandable and easy-to-operate" preservation technology. It effectively solves the problems of difficult-to-track post-ripening processes and unstable fruit quality caused by rough storage conditions in traditional home preservation. It provides a standardized solution to improve the efficiency of daily fruit preservation and the eating experience, combining practicality and economy. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0023] The reagent raw materials used in the embodiments of the present invention are sourced from the following sources: Low-density polyethylene film, 0.2 mm thick, was purchased from Foshan Chili Technology Co., Ltd.; polyvinyl alcohol, 87.0-89.0%, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. mol%; glycidaldehyde was purchased from Shanghai Baoyang Baoxin Biotechnology Co., Ltd., purity 99%; 2-aminoimidazole was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., purity 97%; acrylamide was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., purity 99%; polyurethane film was purchased from Guangzhou Shanfu Chemical Co., Ltd., thickness 0.1mm; UV resin was purchased from Zhongshan Ketian Electronic Materials Co., Ltd.; medical acrylic pressure-sensitive adhesive was purchased from Shanghai Su'ao Chemical Co., Ltd.; sodium alginate was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., viscosity 850-1000 mPa·s; chitosan was purchased from Shanghai Haohong Biomedical Technology Co., Ltd., purity 98%; mesoporous silica was purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., particle size 80nm; 1-methylcyclopropene was purchased from Wuhan Senwell Century Chemical Co., Ltd., purity 99%; calcium chloride was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., purity 99%; glutaraldehyde was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., 25% in H2O; adhesive was purchased from Shanghai Chenxiang Adhesive Co., Ltd.

[0024] Example 1: A method for preparing a household Huaniu apple preservation kit, comprising the following steps: (1) Add 10 kg of polyvinyl alcohol to 30 kg of deionized water, heat to 80 °C, stir until completely dissolved, cool to 45 °C, add sodium hydroxide solution to adjust pH to 8, add 1.5 kg of glycidaldehyde, stir for 8 h, cool to room temperature, pour into 50 kg of ethanol to precipitate, centrifuge, wash the precipitate and dry to obtain aldehyde-modified polyvinyl alcohol; (2) Add 10 kg of aldehyde-modified polyvinyl alcohol obtained in (1) to 30 kg of ethanol / water mixed solution (ethanol and water are mixed in a weight ratio of 1:1), add glacial acetic acid to adjust the pH to 5, heat to 50 °C with stirring, add 1.5 kg of 2-aminoimidazole, react for 2 h, cool to room temperature, add 50 kg of acetone to precipitate, centrifuge, collect the solid, wash the solid and dry it to obtain imidazole-modified polyvinyl alcohol; (3) Under nitrogen protection, 10 kg of imidazole modified polyvinyl alcohol obtained in (2) was added to 50 kg of 10% sodium hydroxide solution, heated to 30°C with stirring, and then 2 kg of acrylamide was added. After reacting for 60 min and cooling to room temperature, 100 kg of ethanol was added to precipitate the product. After centrifugation, the precipitate was washed and dried to obtain modified polyvinyl alcohol. (4) Prepare a 5% solution of 200g sodium alginate and a 2% solution of 200g chitosan. Mix the two and cool to 0°C to obtain a wall material solution. Calcinate 600g mesoporous silica at 200°C for 40min. After cooling to room temperature, place it in a low-temperature drying oven and cool to -5°C. Then, add 1.8Kg 1-methylcyclopropene in an environment of -5°C and stir for 1h. Then add it to the wall material solution and stir at 5000rpm for 10min to obtain a suspension. (5) Add the 2% calcium chloride solution made from 109g of calcium chloride at 0℃ to the suspension obtained in (4), stir, crosslink for 10min, filter, wash with deionized water at 0℃, freeze dry to obtain functionalized microcapsules. (6) Add 10 kg of modified polyvinyl alcohol obtained in (3) to 50 kg of deionized water, heat to 70 °C, stir for 2 h to obtain spinning solution, set spinning parameters: spinning voltage 15 kV, receiving distance 10 cm, spinneret diameter 0.4 mm, and make modified polyvinyl alcohol nanofibers by electrospinning. The obtained modified polyvinyl alcohol nanofibers are cross-linked by glutaraldehyde to obtain modified polyvinyl alcohol nanofiber membrane; (7) Coat one side of the low-density polyethylene film with adhesive with a thickness of 2μm. After drying, attach the modified polyvinyl alcohol nanofiber film obtained in (6) to the side of the low-density polyethylene film coated with adhesive. Then, put it into a laminator and laminate it at 80℃ and 0.5MPa. After holding the pressure for 10s, use a heat sealer to prepare a food storage bag with a size that fits the size of a Huaniu apple. (8) The polyurethane film was corona treated, and a layer of medical acrylic pressure-sensitive adhesive with a thickness of 2 μm was uniformly coated. After UV curing, release paper was covered. UV resin and ethanol were mixed at a weight ratio of 1:0.08 and stirred for 10 min. Then, the mixture was uniformly coated on the other side of the polyurethane film with a thickness of 5 μm to form a UV resin layer. UV pre-curing was performed for 3 s. Finally, the functionalized microcapsules obtained in (5) were uniformly dispersed on the UV resin layer at 0 °C using an electrostatic powder dispersing machine with a dispersion density of 5 g / m³. 2 After UV curing, it is dried to obtain a food preservation patch layer; (9) Cut the preservation patch layer into 5×5cm pieces, tear off the release paper and stick it on the side of the preservation bag obtained in (7) that is in contact with the Huaniu apple to obtain a household Huaniu apple preservation kit.

[0025] Example 2: A method for preparing a household Huaniu apple preservation kit, comprising the following steps: (1) Add 10 kg of polyvinyl alcohol to 40 kg of deionized water, heat to 85 °C, stir until completely dissolved, cool to 50 °C, add sodium hydroxide solution to adjust pH to 9, add 2 kg of glycidaldehyde, stir and react for 10 h, cool to room temperature and pour into 60 kg of ethanol to precipitate, centrifuge and wash the precipitate and dry to obtain aldehyde-modified polyvinyl alcohol; (2) Add 10 kg of aldehyde-modified polyvinyl alcohol obtained in (1) to 40 kg of ethanol / water mixed solution (ethanol and water are mixed in a weight ratio of 1:1), add glacial acetic acid to adjust the pH to 5.5, heat to 55°C with stirring, add 2 kg of 2-aminoimidazole, react for 3 h, cool to room temperature, add 60 kg of acetone to precipitate, centrifuge, collect the solid, wash the solid and dry it to obtain imidazole-modified polyvinyl alcohol; (3) Under nitrogen protection, 10 kg of imidazole modified polyvinyl alcohol obtained in (2) was added to 60 kg of 10% sodium hydroxide solution, heated to 35°C with stirring, and then 3 kg of acrylamide was added. After reacting for 70 min, the mixture was cooled to room temperature and then added to 120 kg of ethanol to precipitate. After centrifugation, the precipitate was washed and dried to obtain modified polyvinyl alcohol. (4) Prepare a 5% solution of 200g sodium alginate and a 2% solution of 200g chitosan. Mix the two and cool to 3°C to obtain a wall material solution. Calcinate 800g mesoporous silica at 250°C for 50min. After cooling to room temperature, place it in a low-temperature drying oven and cool to -3°C. Then, add 2.4Kg 1-methylcyclopropene in an environment of -3°C and stir for 2h. Then add it to the wall material solution and stir at 6000rpm for 15min to obtain a suspension. (5) Add a 2% calcium chloride solution made from 86g of calcium chloride at 3℃ to the suspension obtained in (4), stir, crosslink for 15 min, filter, wash with deionized water at 3℃, freeze dry to obtain functionalized microcapsules. (6) Add 10 kg of modified polyvinyl alcohol obtained in (3) to 70 kg of deionized water, heat to 80 °C, stir for 3 h to obtain spinning solution, set spinning parameters: spinning voltage 25 kV, receiving distance 15 cm, spinneret diameter 0.6 mm, and make modified polyvinyl alcohol nanofibers by electrospinning. The obtained modified polyvinyl alcohol nanofibers are cross-linked by glutaraldehyde to obtain modified polyvinyl alcohol nanofiber membrane; (7) Coat one side of the low-density polyethylene film with adhesive with a thickness of 3 μm. After drying, attach the modified polyvinyl alcohol nanofiber film obtained in (6) to the side of the low-density polyethylene film coated with adhesive. Then, put it into a laminator and laminate it at 100°C and 0.8 MPa. After holding the pressure for 15 seconds, use a heat sealer to prepare a food storage bag with a size that fits the size of a Huaniu apple. (8) The polyurethane film was corona treated, and a layer of medical acrylic pressure-sensitive adhesive with a thickness of 3 μm was uniformly coated. After UV curing, release paper was covered. UV resin and ethanol were mixed at a weight ratio of 1:0.1 and stirred for 15 min. Then, the mixture was uniformly coated on the other side of the polyurethane film with a thickness of 10 μm to form a UV resin layer. UV pre-curing was performed for 4 s. Finally, the functionalized microcapsules obtained in (5) were uniformly dispersed on the UV resin layer at 3°C ​​using an electrostatic powder dispersing machine with a dispersion density of 8 g / m³. 2 After UV curing, it is dried to obtain a food preservation patch layer; (9) Cut the preservation patch layer into 5×5cm pieces, tear off the release paper and stick it on the side of the preservation bag obtained in (7) that is in contact with the Huaniu apple to obtain a household Huaniu apple preservation kit.

[0026] Example 3: A method for preparing a household Huaniu apple preservation kit, comprising the following steps: (1) Add 10 kg of polyvinyl alcohol to 50 kg of deionized water, heat to 90 °C, stir until completely dissolved, cool to 55 °C, add sodium hydroxide solution to adjust pH to 10, add glycidaldehyde, stir and react for 12 h, cool to room temperature and pour into 70 kg of ethanol to precipitate, centrifuge and wash the precipitate and dry to obtain aldehyde-modified polyvinyl alcohol. (2) Add 10 kg of aldehyde-modified polyvinyl alcohol obtained in (1) to 50 kg of ethanol / water mixed solution (ethanol and water are mixed in a weight ratio of 1:1), add glacial acetic acid to adjust the pH to 6, heat to 60 °C with stirring, add 2.5 kg of 2-aminoimidazole, react for 4 h, cool to room temperature, add acetone to precipitate, centrifuge, collect the solid, wash the solid and dry it to obtain imidazole-modified polyvinyl alcohol; (3) Under nitrogen protection, 10 kg of imidazole modified polyvinyl alcohol obtained in (2) was added to 70 kg of 10% sodium hydroxide solution, heated to 40 °C with stirring, and then 4 kg of acrylamide was added. After reacting for 80 min, the mixture was cooled to room temperature and then added to 140 kg of ethanol to precipitate the product. After centrifugation, the precipitate was washed and dried to obtain modified polyvinyl alcohol. (4) Prepare a 5% solution of 200g sodium alginate and a 2% solution of 200g chitosan. Mix the two and cool to 5°C to obtain a wall material solution. Calcinate 1Kg mesoporous silica at 300°C for 60min. After cooling to room temperature, place it in a low-temperature drying oven and cool to 0°C. Then add 3Kg 1-methylcyclopropene in an environment of 0°C and stir for 3h. Then add it to the wall material solution and stir at 7000rpm for 20min to obtain a suspension. (5) Add a 2% calcium chloride solution made from 72g of calcium chloride at 5℃ to the suspension obtained in (4), stir, crosslink for 20min, filter, wash with deionized water at 5℃, freeze dry to obtain functionalized microcapsules; (6) Add 10 kg of modified polyvinyl alcohol obtained in (3) to 90 kg of deionized water, heat to 90 °C, stir for 4 h to obtain spinning solution, set spinning parameters: spinning voltage 30 kV, receiving distance 20 cm, spinneret diameter 0.8 mm, and make modified polyvinyl alcohol nanofibers by electrospinning. Crosslink the obtained modified polyvinyl alcohol nanofibers with glutaraldehyde to obtain modified polyvinyl alcohol nanofiber membrane; (7) Coat one side of the low-density polyethylene film with adhesive with a thickness of 5 μm. After drying, attach the modified polyvinyl alcohol nanofiber film obtained in (6) to the side of the low-density polyethylene film coated with adhesive. Then, put it into a laminator and laminate it at 120°C and 1 MPa. After holding the pressure for 20 seconds, use a heat sealer to prepare a food storage bag with a size that fits the size of a Huaniu apple. (8) The polyurethane film was corona treated, and a layer of medical acrylic pressure-sensitive adhesive with a thickness of 5 μm was uniformly coated. After UV curing, release paper was covered. UV resin and ethanol were mixed at a weight ratio of 1:0.12 and stirred for 20 min. Then, the mixture was uniformly coated on the other side of the polyurethane film with a thickness of 15 μm to form a UV resin layer. UV pre-curing was performed for 5 s. Finally, the functionalized microcapsules obtained in (5) were uniformly dispersed on the UV resin layer at 5 °C using an electrostatic powder disperser with a dispersion density of 10 g / m³. 2 After UV curing, it is dried to obtain a food preservation patch layer; (9) Cut the preservation patch layer into 5×5cm pieces, tear off the release paper and stick it on the side of the preservation bag obtained in (7) that is in contact with the Huaniu apple to obtain a household Huaniu apple preservation kit.

[0027] Comparative Example 1: The difference between Comparative Example 1 and Example 2 is that the polyvinyl alcohol is not grafted with 2-aminoimidazole. The specific preparation process is as follows: A method for preparing a household Huaniu apple preservation kit includes the following steps: (1) Under nitrogen protection, 10 kg of polyvinyl alcohol was added to 60 kg of 10% sodium hydroxide solution, and the temperature was raised to 35°C with stirring. Then 3 kg of acrylamide was added and reacted for 70 min. After cooling to room temperature, 120 kg of ethanol was added to precipitate the product. After centrifugation, the precipitate was washed and dried to obtain modified polyvinyl alcohol. (2) Prepare a 5% solution of 200g sodium alginate and a 2% solution of 200g chitosan. Mix the two and cool to 3°C to obtain a wall material solution. Calcinate 800g mesoporous silica at 250°C for 50min. After cooling to room temperature, place it in a low-temperature drying oven and cool to -3°C. Then, add 2.4Kg 1-methylcyclopropene in an environment of -3°C and stir for 2h. Then add it to the wall material solution and stir at 6000rpm for 15min to obtain a suspension. (3) Add a 2% calcium chloride solution made from 86g of calcium chloride at 3℃ to the suspension obtained in (2), stir, crosslink for 15 min, filter, wash with deionized water at 3℃, freeze dry to obtain functionalized microcapsules. (4) Add 10 kg of modified polyvinyl alcohol obtained in (1) to 70 kg of deionized water, heat to 80 °C, stir for 3 h to obtain spinning solution, set spinning parameters: spinning voltage 25 kV, receiving distance 15 cm, spinneret diameter 0.6 mm, and make modified polyvinyl alcohol nanofibers by electrospinning. The obtained modified polyvinyl alcohol nanofibers are cross-linked by glutaraldehyde to obtain modified polyvinyl alcohol nanofiber membrane; (5) Coat one side of the low-density polyethylene film with adhesive with a thickness of 3μm. After drying, attach the modified polyvinyl alcohol nanofiber film obtained in (4) to the side of the low-density polyethylene film coated with adhesive. Then, put it into a laminator and laminate it at 100℃ and 0.8MPa. After holding the pressure for 15s, use a heat sealer to prepare a food storage bag with a size that fits the size of a Huaniu apple. (6) The polyurethane film was corona treated, and a layer of medical acrylic pressure-sensitive adhesive with a thickness of 3 μm was uniformly coated. After UV curing, release paper was covered. UV resin and ethanol were mixed at a weight ratio of 1:0.1 and stirred for 15 min. Then, the mixture was uniformly coated on the other side of the polyurethane film with a thickness of 10 μm to form a UV resin layer. UV pre-curing was performed for 4 s. Finally, the functionalized microcapsules obtained in (3) were uniformly dispersed on the UV resin layer at 3°C ​​using an electrostatic powder dispersing machine with a dispersion density of 8 g / m³. 2 After UV curing, it is dried to obtain a food preservation patch layer; (7) Cut the preservation patch layer into 5×5cm pieces, tear off the release paper and stick it on the side of the preservation bag obtained in (5) that is in contact with the Huaniu apple to obtain a household Huaniu apple preservation kit.

[0028] Comparative Example 2: The difference between Comparative Example 2 and Example 2 is that the polyvinyl alcohol is not grafted with acrylamide. The specific preparation process is as follows: A method for preparing a household Huaniu apple preservation kit includes the following steps: (1) Add 10 kg of polyvinyl alcohol to 40 kg of deionized water, heat to 85 °C, stir until completely dissolved, cool to 50 °C, add sodium hydroxide solution to adjust pH to 9, add 2 kg of glycidaldehyde, stir and react for 10 h, cool to room temperature and pour into 60 kg of ethanol to precipitate, centrifuge and wash the precipitate and dry to obtain aldehyde-modified polyvinyl alcohol; (2) Add 10 kg of aldehyde-modified polyvinyl alcohol obtained in (1) to 40 kg of ethanol / water mixed solution (ethanol and water are mixed in a weight ratio of 1:1), add glacial acetic acid to adjust the pH to 5.5, heat to 55°C with stirring, add 2 kg of 2-aminoimidazole, react for 3 h, cool to room temperature, add 60 kg of acetone to precipitate, centrifuge, collect the solid, wash the solid and dry it to obtain modified polyvinyl alcohol; (3) Prepare a 5% solution of 200g sodium alginate and a 2% solution of 200g chitosan. Mix the two and cool to 3°C to obtain a wall material solution. Calcinate 800g mesoporous silica at 250°C for 50min. After cooling to room temperature, place it in a low-temperature drying oven and cool to -3°C. Then, add 2.4Kg 1-methylcyclopropene in an environment of -3°C and stir for 2h. Then add it to the wall material solution and stir at 6000rpm for 15min to obtain a suspension. (4) Add a 2% calcium chloride solution made from 86g of calcium chloride at 3°C ​​to the suspension obtained in (3), stir, crosslink for 15 min, filter, wash with deionized water at 3°C, freeze dry to obtain functionalized microcapsules. (5) Add 10 kg of modified polyvinyl alcohol obtained in (2) to 70 kg of deionized water, heat to 80 °C, stir for 3 h to obtain spinning solution, set spinning parameters: spinning voltage 25 kV, receiving distance 15 cm, spinneret diameter 0.6 mm, and make modified polyvinyl alcohol nanofibers by electrospinning. Crosslink the obtained modified polyvinyl alcohol nanofibers with glutaraldehyde to obtain modified polyvinyl alcohol nanofiber membrane; (6) Coat one side of the low-density polyethylene film with adhesive with a thickness of 3μm. After drying, attach the modified polyvinyl alcohol nanofiber film obtained in (5) to the side of the low-density polyethylene film coated with adhesive. Then, put it into a laminator and laminate it at 100℃ and 0.8MPa. After holding the pressure for 15s, use a heat sealer to prepare a food storage bag with a size that fits the size of a Huaniu apple. (7) The polyurethane film was corona treated, and a layer of medical acrylic pressure-sensitive adhesive with a thickness of 3 μm was uniformly coated. After UV curing, release paper was covered. UV resin and ethanol were mixed at a weight ratio of 1:0.1 and stirred for 15 min. Then, the mixture was uniformly coated on the other side of the polyurethane film with a thickness of 10 μm to form a UV resin layer. UV pre-curing was performed for 4 s. Finally, the functionalized microcapsules obtained in (4) were uniformly dispersed on the UV resin layer at 3 °C using an electrostatic powder dispersing machine with a dispersion density of 8 g / m³. 2 After UV curing, it is dried to obtain a food preservation patch layer; (8) Cut the preservation patch layer into 5×5cm pieces, tear off the release paper and stick it on the side of the preservation bag obtained in (6) that is in contact with the Huaniu apple to obtain a household Huaniu apple preservation kit.

[0029] Comparative Example 3: The difference between Comparative Example 3 and Example 2 is that the modified polyvinyl alcohol is not made into a film by electrospinning. The specific preparation process is as follows: A method for preparing a household Huaniu apple preservation kit includes the following steps: (1) Add 10 kg of polyvinyl alcohol to 40 kg of deionized water, heat to 85 °C, stir until completely dissolved, cool to 50 °C, add sodium hydroxide solution to adjust pH to 9, add 2 kg of glycidaldehyde, stir and react for 10 h, cool to room temperature and pour into 60 kg of ethanol to precipitate, centrifuge and wash the precipitate and dry to obtain aldehyde-modified polyvinyl alcohol; (2) Add 10 kg of aldehyde-modified polyvinyl alcohol obtained in (1) to 40 kg of ethanol / water mixed solution (ethanol and water are mixed in a weight ratio of 1:1), add glacial acetic acid to adjust the pH to 5.5, heat to 55°C with stirring, add 2 kg of 2-aminoimidazole, react for 3 h, cool to room temperature, add 60 kg of acetone to precipitate, centrifuge, collect the solid, wash the solid and dry it to obtain imidazole-modified polyvinyl alcohol; (3) Under nitrogen protection, 10 kg of imidazole modified polyvinyl alcohol obtained in (2) was added to 60 kg of 10% sodium hydroxide solution, heated to 35°C with stirring, and then 3 kg of acrylamide was added. After reacting for 70 min, the mixture was cooled to room temperature and then added to 120 kg of ethanol to precipitate. After centrifugation, the precipitate was washed and dried to obtain modified polyvinyl alcohol. (4) Prepare a 5% solution of 200g sodium alginate and a 2% solution of 200g chitosan. Mix the two and cool to 3°C to obtain a wall material solution. Calcinate 800g mesoporous silica at 250°C for 50min. After cooling to room temperature, place it in a low-temperature drying oven and cool to -3°C. Then, add 2.4Kg 1-methylcyclopropene in an environment of -3°C and stir for 2h. Then add it to the wall material solution and stir at 6000rpm for 15min to obtain a suspension. (5) Add a 2% calcium chloride solution made from 86g of calcium chloride at 3℃ to the suspension obtained in (4), stir, crosslink for 15 min, filter, wash with deionized water at 3℃, freeze dry to obtain functionalized microcapsules. (6) Add 10 kg of modified polyvinyl alcohol obtained in (3) to 70 kg of deionized water, heat to 80 °C, stir for 3 h, and then let stand for 2 h. Use a stainless steel casting machine, set the casting thickness to 1 mm and the casting speed to 1 m / min, and use hot air drying to make a film. Then crosslink the film with glutaraldehyde to obtain a modified polyvinyl alcohol film. (7) Coat one side of the low-density polyethylene film with adhesive with a thickness of 3μm. After drying, attach the modified polyethylene film obtained in (6) to the side of the low-density polyethylene film coated with adhesive. Then, put it into a laminator and laminate it at 100℃ and 0.8MPa. After holding the pressure for 15s, use a heat sealer to prepare a food storage bag with a size that fits the size of a Huaniu apple. (8) The polyurethane film was corona treated, and a layer of medical acrylic pressure-sensitive adhesive with a thickness of 3 μm was uniformly coated. After UV curing, release paper was covered. UV resin and ethanol were mixed at a weight ratio of 1:0.1 and stirred for 15 min. Then, the mixture was uniformly coated on the other side of the polyurethane film with a thickness of 10 μm to form a UV resin layer. UV pre-curing was performed for 4 s. Finally, the functionalized microcapsules obtained in (5) were uniformly dispersed on the UV resin layer at 3°C ​​using an electrostatic powder dispersing machine with a dispersion density of 8 g / m³. 2 After UV curing, it is dried to obtain a food preservation patch layer; (9) Cut the preservation patch layer into 5×5cm pieces, tear off the release paper and stick it on the side of the preservation bag obtained in (7) that is in contact with the Huaniu apple to obtain a household Huaniu apple preservation kit.

[0030] Comparative Example 4: The difference between Comparative Example 4 and Example 2 is that: Polyvinyl alcohol was used to prepare a polyvinyl alcohol nanofiber membrane by electrospinning, which was then combined with a low-density polyethylene film to make a food preservation bag. The specific preparation process is as follows: A method for preparing a household Huaniu apple preservation kit includes the following steps: (1) Prepare a 5% solution of 200g sodium alginate and a 2% solution of 200g chitosan. Mix the two and cool to 3°C to obtain a wall material solution. Calcinate 800g mesoporous silica at 250°C for 50min. After cooling to room temperature, place it in a low-temperature drying oven and cool to -3°C. Then, add 2.4Kg 1-methylcyclopropene in an environment of -3°C and stir for 2h. Then add it to the wall material solution and stir at 6000rpm for 15min to obtain a suspension. (2) Add a 2% calcium chloride solution made from 86g of calcium chloride at 3℃ to the suspension obtained in (1), stir, crosslink for 15 min, filter, wash with deionized water at 3℃, freeze dry to obtain functionalized microcapsules. (3) Add 10 kg of polyvinyl alcohol to 70 kg of deionized water, heat to 80 °C, stir for 3 h to obtain spinning solution, set spinning parameters: spinning voltage 25 kV, receiving distance 15 cm, spinneret diameter 0.6 mm, and make polyvinyl alcohol nanofibers by electrospinning. The obtained polyvinyl alcohol nanofibers are cross-linked by glutaraldehyde to obtain polyvinyl alcohol nanofiber membrane. (4) Coat one side of the low-density polyethylene film with adhesive with a thickness of 3 μm. After drying, attach the polyvinyl alcohol nanofiber membrane obtained in (3) to the side of the low-density polyethylene film coated with adhesive. Then, put it into a laminator and laminate it at 100°C and 0.8 MPa. After holding the pressure for 15 seconds, use a heat sealer to prepare a food storage bag that fits the size of a Huaniu apple. (5) The polyurethane film was corona treated, and a layer of medical acrylic pressure-sensitive adhesive with a thickness of 3 μm was uniformly coated. After UV curing, release paper was covered. UV resin and ethanol were mixed at a weight ratio of 1:0.1 and stirred for 15 min. Then, the mixture was uniformly coated on the other side of the polyurethane film with a thickness of 10 μm to form a UV resin layer. UV pre-curing was performed for 4 s. Finally, the functionalized microcapsules obtained in (2) were uniformly dispersed on the UV resin layer at 3°C ​​using an electrostatic powder dispersing machine with a dispersion density of 8 g / m³. 2 After UV curing, it is dried to obtain a food preservation patch layer; (6) Cut the preservation patch layer into 5×5cm pieces, tear off the release paper and stick it on the side of the preservation bag obtained in (4) that is in contact with the Huaniu apple to obtain a household Huaniu apple preservation kit.

[0031] Comparative Example 5: The difference between Comparative Example 5 and Example 2 is that no mesoporous silica is added to the functionalized microcapsules. The specific preparation process is as follows: A method for preparing a household Huaniu apple preservation kit includes the following steps: (1) Add 10 kg of polyvinyl alcohol to 40 kg of deionized water, heat to 85 °C, stir until completely dissolved, cool to 50 °C, add sodium hydroxide solution to adjust pH to 9, add 2 kg of glycidaldehyde, stir and react for 10 h, cool to room temperature and pour into 60 kg of ethanol to precipitate, centrifuge and wash the precipitate and dry to obtain aldehyde-modified polyvinyl alcohol; (2) Add 10 kg of aldehyde-modified polyvinyl alcohol obtained in (1) to 40 kg of ethanol / water mixed solution (ethanol and water are mixed in a weight ratio of 1:1), add glacial acetic acid to adjust the pH to 5.5, heat to 55°C with stirring, add 2 kg of 2-aminoimidazole, react for 3 h, cool to room temperature, add 60 kg of acetone to precipitate, centrifuge, collect the solid, wash the solid and dry it to obtain imidazole-modified polyvinyl alcohol; (3) Under nitrogen protection, 10 kg of imidazole modified polyvinyl alcohol obtained in (2) was added to 60 kg of 10% sodium hydroxide solution, heated to 35°C with stirring, and then 3 kg of acrylamide was added. After reacting for 70 min, the mixture was cooled to room temperature and then added to 120 kg of ethanol to precipitate. After centrifugation, the precipitate was washed and dried to obtain modified polyvinyl alcohol. (4) Prepare a 5% solution of 200g sodium alginate and a 2% solution of 200g chitosan. Mix the two and cool to 3°C to obtain a wall material solution. Add 2.4Kg 1-methylcyclopropene and stir at 6000rpm for 15min to obtain a suspension. (5) Add a 2% calcium chloride solution made from 86g of calcium chloride at 3℃ to the suspension obtained in (4), stir, crosslink for 15 min, filter, wash with deionized water at 3℃, freeze dry to obtain functionalized microcapsules. (6) Add 10 kg of modified polyvinyl alcohol obtained in (3) to 70 kg of deionized water, heat to 80 °C, stir for 3 h to obtain spinning solution, set spinning parameters: spinning voltage 25 kV, receiving distance 15 cm, spinneret diameter 0.6 mm, and make modified polyvinyl alcohol nanofibers by electrospinning. The obtained modified polyvinyl alcohol nanofibers are cross-linked by glutaraldehyde to obtain modified polyvinyl alcohol nanofiber membrane; (7) Coat one side of the low-density polyethylene film with adhesive with a thickness of 3 μm. After drying, attach the modified polyvinyl alcohol nanofiber film obtained in (6) to the side of the low-density polyethylene film coated with adhesive. Then, put it into a laminator and laminate it at 100°C and 0.8 MPa. After holding the pressure for 15 seconds, use a heat sealer to prepare a food storage bag with a size that fits the size of a Huaniu apple. (8) The polyurethane film was corona treated, and a layer of medical acrylic pressure-sensitive adhesive with a thickness of 3 μm was uniformly coated. After UV curing, release paper was covered. UV resin and ethanol were mixed at a weight ratio of 1:0.1 and stirred for 15 min. Then, the mixture was uniformly coated on the other side of the polyurethane film with a thickness of 10 μm to form a UV resin layer. UV pre-curing was performed for 4 s. Finally, the functionalized microcapsules obtained in (5) were uniformly dispersed on the UV resin layer at 3°C ​​using an electrostatic powder dispersing machine with a dispersion density of 8 g / m³. 2 After UV curing, it is dried to obtain a food preservation patch layer; (9) Cut the preservation patch layer into 5×5cm pieces, tear off the release paper and stick it on the side of the preservation bag obtained in (7) that is in contact with the Huaniu apple to obtain a household Huaniu apple preservation kit.

[0032] Comparative Example 6: The difference between Comparative Example 6 and Example 2 is that the preservation bag is made by laminating polyvinyl alcohol film and low-density polyethylene film. The specific preparation process is as follows: A method for preparing a household Huaniu apple preservation kit includes the following steps: (1) Prepare a 5% solution of 200g sodium alginate and a 2% solution of 200g chitosan. Mix the two and cool to 3°C to obtain a wall material solution. Calcinate 800g mesoporous silica at 250°C for 50min. After cooling to room temperature, place it in a low-temperature drying oven and cool to -3°C. Then, add 2.4Kg 1-methylcyclopropene in an environment of -3°C and stir for 2h. Then add it to the wall material solution and stir at 6000rpm for 15min to obtain a suspension. (2) Add a 2% calcium chloride solution made from 86g of calcium chloride at 3℃ to the suspension obtained in (1), stir, crosslink for 15 min, filter, wash with deionized water at 3℃, freeze dry to obtain functionalized microcapsules. (3) Add 10 kg of polyvinyl alcohol to 70 kg of deionized water, heat to 80 °C, stir for 3 h, then let stand for 2 h, and use a stainless steel casting machine with a casting thickness of 1 mm and a casting speed of 1 m / min to dry the film with hot air. The film is then cross-linked with glutaraldehyde to obtain a polyvinyl alcohol film. (4) Coat one side of the low-density polyethylene film with adhesive with a thickness of 3μm. After drying, attach the polyvinyl alcohol film obtained in (3) to the side of the low-density polyethylene film coated with adhesive, and put it into a laminator. Laminate it at 100℃ and 0.8MPa. After holding the pressure for 15s, prepare a food storage bag with a size that fits the size of a Huaniu apple by heat sealing machine. (5) The polyurethane film was corona treated, and a layer of medical acrylic pressure-sensitive adhesive with a thickness of 3 μm was uniformly coated. After UV curing, release paper was covered. UV resin and ethanol were mixed at a weight ratio of 1:0.1 and stirred for 15 min. Then, the mixture was uniformly coated on the other side of the polyurethane film with a thickness of 10 μm to form a UV resin layer. UV pre-curing was performed for 4 s. Finally, the functionalized microcapsules obtained in (2) were uniformly dispersed on the UV resin layer at 3°C ​​using an electrostatic powder dispersing machine with a dispersion density of 8 g / m³. 2 After UV curing, it is dried to obtain a food preservation patch layer; (6) Cut the preservation patch layer into 5×5cm pieces, tear off the release paper and stick it on the side of the preservation bag obtained in (4) that is in contact with the Huaniu apple to obtain a household Huaniu apple preservation kit.

[0033] A method for controlling the interruption of ripening in household Huaniu apples, using the preservation kits prepared in Examples 1-3 and Comparative Examples 1-6, includes the following steps: Ⅰ. Place Huaniu apples in the post-ripening stage in a normal temperature environment maintained at 20-25℃. Under this environment, the post-ripening flavor development will take place, providing suitable conditions for the formation of the fruit's flavor. II. By monitoring the appearance and color of the fruit and judging its aroma characteristics, and combining this with the consumer's taste, we can comprehensively determine whether Huaniu apples have reached their optimal eating condition. The specific criteria are: the red area of ​​the peel accounts for no less than 85%, and the yellow-green base color turns into light yellow-white. At the same time, the fruit emits a pleasant aroma. At this point, the fruit is considered to have reached its optimal eating condition. III. Once the fruit has reached its optimal taste, it should be transferred to the refrigerator compartment of a household refrigerator within 24 hours. The temperature of the refrigerator compartment should be controlled at 4±1℃. Use a household Huaniu apple preservation kit to wrap the fruit to ensure that the fruit enters a suitable low-temperature storage environment and slow down subsequent physiological changes. IV. Control the relative humidity inside the preservation bag through the humidity adjustment window on the bag to maintain it within a suitable range of 80-85%. To maintain air circulation inside the bag, open the bag for ventilation for 10 minutes every 5 days to prevent the gas environment inside the bag from deteriorating and affecting the quality of the fruit.

[0034] Interruption control results: After storing Huaniu apples for 45 days using the above method, the freshness of the fruit pulp was evaluated, and the results are as follows: Example 1: The red areas of the flesh remain bright, the surface is oily and glossy, the texture of the fruit remains firm, and only slight elastic deformation occurs when pressed with a finger. After opening the bag, it emits a fresh fruity aroma, without any off-odors of alcoholic fermentation. The peel is not wrinkled, and the amount of juice seeping from the cut surface of the flesh is close to that of fresh fruit. After the cut surface of the flesh is exposed to air for 30 minutes, it only slightly oxidizes and turns yellow.

[0035] Example 2: The red areas of the flesh remain bright, the surface is oily and glossy, the texture of the fruit remains firm, and only slight elastic deformation occurs when pressed with a finger. After opening the bag, it emits a fresh fruity aroma, without any off-odors of alcoholic fermentation. The peel is not wrinkled, and the amount of juice seeping from the cut surface of the flesh is close to that of fresh fruit. After the cut surface of the flesh is exposed to air for 30 minutes, it only slightly oxidizes and turns yellow.

[0036] Example 3: The red areas of the flesh remain bright, the surface is oily and glossy, the texture of the fruit remains firm, and only slight elastic deformation occurs when pressed with a finger. After opening the bag, it emits a fresh fruity aroma, without any off-odors of alcoholic fermentation. The peel is not wrinkled, and the amount of juice seeping from the cut surface of the flesh is close to that of fresh fruit. After the cut surface of the flesh is exposed to air for 30 minutes, it only slightly oxidizes and turns yellow.

[0037] Comparative Example 1: The red area spreads to the shoulder of the fruit, but the color fades to light pink with a pale base color. The fruit softens evenly and leaves a lasting indentation after being pressed. The starch in the pulp undergoes rapid saccharification, increasing the sweetness, but this is accompanied by excessive degradation of pectin, leading to juice loss. Fine wrinkles appear on the peel, and translucent water stains are produced in some areas.

[0038] Comparative Example 2: The red area expanded to 95%, but the color was dull, presenting an unnatural purplish-red tone. Initially, the flesh remained firm, but later the flesh quickly became soft, eventually presenting a double-layer structure of "hard on the outside and rotten on the inside". A strong alcohol smell accumulated inside the bag. After cutting it open, transparent fermented juice seeped out from the core area. Radial brown lines appeared around the fruit stem, but there were no obvious mold spots on the skin.

[0039] Comparative Example 3: The surface is covered with a grayish-white hazy film, the red area is blurred, the flesh is generally soft but not naturally softened, it produces an off-odor, the peel has blue-green metallic patches, and black mold grows at the stem end, spreading in concentric circles.

[0040] Comparative Example 4: The overall browning was more severe, and the remaining red areas were a pathological bright red. It began to soften on the 7th day, and eventually the pulp became pasty, with mucus seeping from the surface, accompanied by a white bacterial film covering the entire fruit surface.

[0041] Comparative Example 5: The red color retention rate was relatively high in the first 15 days, but it quickly turned brown to coffee color from the 20th day onwards. On the 25th day, the flesh became soft and rotten, and the flesh showed a layered decay structure with alternating "sponge-liquefaction".

[0042] Comparative Example 6: The fruit showed complete browning with black star-shaped spots, the outer skin was dry and hard like leather, the internal pulp was completely liquefied, foul odor accumulated inside the bag, and the rotten pulp juice seeped into and contaminated the packaging bag.

[0043] Performance testing: 1. Mechanical property testing: In accordance with the testing standard GB / T 1040.3-2006, a universal testing machine was used with a tensile speed of 100 mm / min and a room temperature of 23±2℃ and a humidity of 50±5% to test the tensile strength and elongation at break of the food preservation kits prepared in Examples 1-3 and Comparative Examples 1-6. The experimental results are shown in Table 1.

[0044] 2. Moisture permeability and air permeability test: Uniformly ripe Huaniu apples were placed in the preservation kits prepared in Examples 1-3 and Comparative Examples 1-4 and stored in a refrigerator environment at 0-5℃. The bags were sealed, and the test lasted for 5 days. A humidity sensor probe and a portable gas analyzer probe were inserted into the bag through a micro-hole (the hole was sealed with silicone to prevent air leakage). Real-time humidity and gas concentration recording were initiated, recording the humidity value inside the bag and the concentrations of carbon dioxide, oxygen, and ethylene gas inside the bag. The following indicators were calculated: Humidity equilibrium time: The time (h) from the initial state to the first entry into the 80-85% humidity range; Target humidity maintenance rate: The percentage of time (%) during which the humidity is between 80-85% during the test period. Peak carbon dioxide concentration: The highest concentration of carbon dioxide gas (%) during the test period; Oxygen fluctuation range: The difference (%) between the highest and lowest oxygen concentration values ​​during the test period; Peak ethylene concentration: The highest concentration of ethylene gas (ppm) during the test period; the experimental results are shown in Table 1.

[0045] 3. Test on the sustained-release performance of the preservation patches: The preservation patches were removed from the preservation kits prepared in Examples 1-3 and Comparative Example 5 and placed in a 1dm³ volume container. 3 The sealed chamber contained a 1-methylcyclopropene gas concentration measurement probe, simulating a humidity of 80-85% and a pH environment of 5.5-6.5. It was placed in a refrigerator environment at 0-5℃ to measure the maximum concentration of 1-methylcyclopropene, the time T for the concentration to decay to half of the maximum concentration, and the time for the concentration to first decay to ≤0.5ppb, which is the failure time t. The experimental results are shown in Table 2.

[0046] 4. Actual preservation effect test: After preserving Huaniu apples for 45 days using the preservation kits prepared in Examples 1-3 and Comparative Examples 1-6 according to the above-mentioned post-ripening interruption control method, the freshness of the fruit pulp was evaluated, and the results are shown in Table 3.

[0047] Table 1 Mechanical properties and moisture permeability

[0048] Table 2. Sustained-release performance of food preservation patches

[0049] Table 3 Actual Preservation Effect

[0050] Performance Analysis: Based on the experimental data and phenomena in Tables 1, 2 and 3, it can be seen that the household Huaniu apple preservation kit prepared by the present invention in Examples 1-3 has good mechanical properties and excellent moisture permeability and air permeability. It can maintain the humidity requirements required for Huaniu apple storage for a longer period of time, effectively preserve Huaniu apples in the post-ripening stage, and extend the storage time. Among them, Example 2 has the best overall performance.

[0051] From a mechanical performance perspective, the preservation kit prepared in Example 2 exhibits good tensile strength and elongation at break, meeting the performance requirements for daily preservation of Huaniu apples. This may be because the outer low-density polyethylene film of Example 2 provides basic mechanical support, while the middle modified polyvinyl alcohol nanofiber membrane is prepared by electrospinning and cross-linked with glutaraldehyde to form an intermolecular covalent bond network, significantly improving the membrane's toughness and tensile strength. Compared to the dense polyethylene membranes (low porosity and brittleness) prepared by the casting method in Comparative Examples 3 and 6, the nanofiber membrane of Example 2, due to its high porosity and molecular cross-linking density, has superior tensile strength and elongation at break, and can withstand deformation during storage, preventing packaging bag breakage and contamination.

[0052] In terms of moisture and air permeability, the preservation kit prepared in Example 2 can maintain the environmental humidity required for the post-ripening preservation of Huaniu apples for a relatively long time. It can also synergistically suppress the negative effects of carbon dioxide and ethylene gas on the preservation of Huaniu apples through gas exchange and adsorption functions, as well as the slow-release of 1-methylcyclopropene from the preservation patch, thus extending the preservation time. This may be because the moisture and air permeability of the preservation kit prepared in Example 2 is due to the synergistic effect of the porous network structure and the hydrophilicity of the functional groups of the modified polyvinyl alcohol nanofiber membrane. The three-dimensional mesh fiber membrane formed by electrospinning has a high porosity, and the micropores between the fibers allow water vapor and gas to diffuse moderately, which not only meets the respiration needs of the fruit, but also avoids excessive water loss or condensation accumulation. At the same time, the polar functional groups of imidazole and amide groups enhance the hydrophilicity of the membrane layer, promote the balance of water vapor adsorption and release, and keep the humidity inside the bag stable at 80%-85%, which can be maintained within this range for a relatively long time. In contrast, the dense cast films in ratios 3 and 6, although able to reach the target humidity range in a shorter time, maintain it for a shorter time. The imbalance between moisture permeability and humidity can easily lead to mold growth, which in turn shortens the shelf life.

[0053] From the perspective of the sustained-release effect of the preservation patch, the preservation patch prepared in Example 2 can stably and sustainably release 1-methylcyclopropene with a long half-life, and the action time can basically cover the needs of household food preservation. This may be because the core of the sustained-release performance of the preservation patch layer lies in the cross-linking design of the mesoporous carrier and wall material of the functionalized microcapsule. Example 2 uses mesoporous silica as the adsorption carrier for 1-methylcyclopropene. Its high specific surface area increases the content of the effective component of 1-methylcyclopropene in the core material, while the ordered pore structure delays the release through the physical confinement effect. Combined with the network gel structure formed by the cross-linking of sodium alginate-chitosan wall material with calcium chloride at low temperature, the release rate of active ingredients is further controlled. Table 2 shows that the maximum concentration of 1-methylcyclopropene in Example 2 was 14.8 ppb, and the failure time was 42 days, which was significantly better than that of Comparative Example 5. The high specific surface area of ​​the mesoporous carrier provided high adsorption content, the physical confinement effect provided by the ordered channels and the synergistic effect of the wall material crosslinking enabled the 1-methylcyclopropene in Example 2 to be continuously and slowly released in a simulated ripening and preservation process of Huaniu apples under an environment of 80-85% humidity and pH 5.5-6.5, which inhibited ethylene receptor activity for a long time and blocked the ripening signal transduction from the source.

[0054] Finally, the excellent preservation effect of Example 2 is the result of the combined effects of gas regulation, humidity maintenance, slow release function and mechanical stability. Table 1 shows that the peak ethylene concentration was only 38.7 ppm, thanks to the specific adsorption of ethylene by the imidazole group and the inhibition of ethylene acceptors by 1-methylcyclopropene. The peak carbon dioxide concentration was 1.05% and the oxygen fluctuation range was 2.2%, which was achieved through the hydrogen bonding of the amide group and the air-permeable structure of the nanofiber membrane, avoiding anaerobic respiration and metabolic disorders. The 42-day slow-release failure time in Table 2 ensures that 1-methylcyclopropene continues to inhibit ripening. Combined with the stable maintenance of 80%-85% humidity, it effectively delays the softening of the fruit flesh, color fading and mold growth. At the microscopic level, the π-π interaction and electron donor effect of the imidazole group, the CO adsorption of the amide group, the porous mass transfer of the nanofiber membrane and the slow release of the mesoporous microcapsules jointly construct a multi-level preservation mechanism from intermolecular forces to macroscopic structure, so that the fruit still maintains a firm texture, bright color and fresh aroma after 45 days, which is significantly better than the problems of spoilage and browning caused by single performance defects in the comparison.

[0055] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A household apple preservation kit, characterized in that, From the outside to the inside, it consists of a polyethylene-based film layer, a modified polyvinyl alcohol nanofiber film layer, and a food preservation patch layer; The polyethylene-based film layer is a low-density polyethylene film; The modified polyvinyl alcohol nanofiber membrane is made of modified polyvinyl alcohol by electrospinning, and the preparation method of the modified polyvinyl alcohol is as follows: (1) Add polyvinyl alcohol to deionized water, heat to 80-90℃, stir until completely dissolved, cool to 45-55℃, add sodium hydroxide solution to adjust pH to 8-10, add glycidaldehyde, stir for 8-12h, cool to room temperature and pour into ethanol to precipitate, centrifuge and wash the precipitate and dry to obtain aldehyde-modified polyvinyl alcohol. (2) Add the aldehyde-modified polyvinyl alcohol obtained in (1) to an ethanol / water mixed solution, add glacial acetic acid to adjust the pH to 5-6, heat to 50-60℃ with stirring, add 2-aminoimidazole, react for 2-4h, cool to room temperature, add acetone to precipitate, centrifuge, collect the solid, wash the solid and dry it to obtain imidazole-modified polyvinyl alcohol. (3) Under nitrogen protection, the imidazole-modified polyvinyl alcohol obtained in (2) was added to sodium hydroxide solution, heated to 30-40℃ with stirring, then acrylamide was added, reacted for 60-80 min, cooled to room temperature, added to ethanol to precipitate, centrifuged, the precipitate was washed and dried to obtain modified polyvinyl alcohol. The preservation patch layer is made of functionalized microcapsules, polyurethane film, UV resin, and medical-grade acrylic pressure-sensitive adhesive. The preparation method of the functionalized microcapsules is as follows: (a) Mix sodium alginate solution and chitosan solution, cool to 0-5℃ to obtain wall material solution, calcine mesoporous silica at 200-300℃ for 40-60min, cool to room temperature and place in low temperature drying oven, cool to -5-0℃, then add 1-methylcyclopropene in an environment of -5-0℃, stir for 1-3h, then add to wall material solution, stir at 5000-7000rpm for 10-20min to obtain suspension; (b) Add calcium chloride solution at 0-5℃ to the suspension obtained in (a), stir, crosslink for 10-20 min, filter, wash with deionized water at 0-5℃, freeze dry to obtain functionalized microcapsules.

2. The household Huaniu apple preservation kit according to claim 1, characterized in that, In (1), polyvinyl alcohol, glycidaldehyde, deionized water and ethanol are in a weight ratio of 1:0.15-0.25:3-5:5-7.

3. The household Huaniu apple preservation kit according to claim 1, characterized in that, In (2), the aldehyde-modified polyvinyl alcohol, 2-aminoimidazole, ethanol / water mixture and acetone are in a weight ratio of 1:0.15-0.25:3-5:5-7. The ethanol / water mixture refers to the mixture of ethanol and water in a weight ratio of 1:

1.

4. The household Huaniu apple preservation kit according to claim 1, characterized in that, In (3), the imidazole-modified polyvinyl alcohol, acrylamide, sodium hydroxide solution and ethanol are in a weight ratio of 1:0.2-0.4:5-7:10-14, and the concentration of sodium hydroxide solution is 10%.

5. The household Huaniu apple preservation kit according to claim 1, characterized in that, In (b), the calcium chloride solution and suspension are in a weight ratio of 1:3-5, and the concentration of the calcium chloride solution is 2%.

6. The method for preparing the household Huaniu apple preservation kit according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Add modified polyvinyl alcohol to deionized water, heat to 70-90℃, stir for 2-4 hours to obtain spinning solution, set spinning parameters: spinning voltage 15-30kV, receiving distance 10-20cm, spinneret diameter 0.4-0.8mm, and electrospin to produce modified polyvinyl alcohol nanofibers. The obtained modified polyvinyl alcohol nanofibers are cross-linked with a cross-linking agent to obtain modified polyvinyl alcohol nanofiber membrane; S2. Coat one side of the low-density polyethylene film with an adhesive with a thickness of 2-5 μm. After drying, laminate the modified polyvinyl alcohol nanofiber membrane obtained in S1 onto the side of the low-density polyethylene film coated with adhesive. Then, put it into a laminator and laminate it at 80-120℃ and 0.5-1 MPa. After holding the pressure for 10-20 seconds, use a heat sealer to prepare a food storage bag with a size that fits the size of a Huaniu apple. S3. After corona treatment of the polyurethane film, a layer of medical acrylic pressure-sensitive adhesive with a thickness of 2-5 μm is uniformly coated. After UV curing, release paper is applied. UV resin and ethanol are mixed and stirred for 10-20 minutes, then uniformly coated on the other side of the polyurethane film with a thickness of 5-15 μm to form a UV resin layer. UV pre-curing is performed for 3-5 seconds. Finally, functionalized microcapsules are uniformly dispersed on the UV resin layer at 0-5℃ using an electrostatic powder disperser, with a dispersion density of 5-10 g / m³. 2 After UV curing, it is dried to obtain a food preservation patch layer; S4. Cut the preservation patch layer into 5×5cm pieces, peel off the release paper and stick it on the side of the preservation bag obtained in S2 that is in contact with the Huaniu apple to obtain a household Huaniu apple preservation kit.

7. The preparation method of the household Huaniu apple preservation kit according to claim 6, characterized in that, In S1, the modified polyvinyl alcohol and deionized water are in a weight ratio of 1:5-9, and the crosslinking agent refers to glutaraldehyde.

8. The preparation method of the household Huaniu apple preservation kit according to claim 6, characterized in that, The weight ratio of UV resin to ethanol in S3 is 1:0.08-0.12.

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