A postharvest preservation card for pineapples and a method of preparing the same

Abstract

The application relates to the field of postharvest preservation technology of fruits and vegetables, and particularly discloses a postharvest preservation card for pineapples and a preparation method thereof. The postharvest preservation card takes food-grade breathable non-woven fabric as a carrier, and the loaded preservation components include natural antibacterial agents, anti-oxidation and anti-browning agents, moisture absorption and water retention agents, sustained-release agents and compound solvents, and an ethylene inhibitor can be selectively added, wherein the natural antibacterial agents are compounded from lavender essential oil and cell-free supernatant of lactic acid bacteria. The preparation method sequentially comprises component preparation, step-by-step preparation of a preservation solution, carrier immersion and loading, temperature control drying and forming and degradable film sealing and packaging. The postharvest preservation card is specially used for postharvest storage and preservation of pineapples, can realize the effects of antibacterial, anti-browning, water retention and moisture control and sustained release and long-acting in a synchronous manner by virtue of the synergistic effect of multiple components, is free of chemical residues and hidden dangers in the whole process, has strong adaptability of the carrier to the process, is flexible in use scenarios, and effectively improves the defects of single function and poor sustained release of existing pineapple preservation products.

Description

Technical Field

[0001] This application relates to the field of postharvest preservation technology for fruits and vegetables, and more specifically, it relates to a pineapple postharvest preservation card and its preparation method. Background Technology

[0002] Pineapple is a specialty economic fruit of tropical and subtropical regions. Its flesh is rich in nutrients and has a unique flavor, enjoying high recognition in domestic and international consumer markets. However, pineapples undergo vigorous physiological metabolism after harvest, and their skin is easily damaged by mechanical forces, leading to a series of quality deteriorations such as enzymatic browning, microbial infection and rotting, and softening and dehydration of the flesh. Under conventional storage conditions, its shelf life is relatively short, severely restricting its cross-regional circulation and hindering the improvement of the industry's economic benefits.

[0003] Preservation cards have become one of the mainstream technologies for post-harvest preservation of pineapples due to their convenience and low cost. However, existing pineapple-specific preservation cards have failed to solve the core technical problem of balancing safety and long-term comprehensive preservation effects. Products using chemical preservatives pose certain residue risks, while natural ingredient preservation cards generally suffer from limitations such as single function, poor slow-release performance, and complex preparation processes. This not only leads to a large number of high-quality pineapples being sold at low prices near the production area, resulting in high post-harvest loss rates, but also exacerbates consumer concerns about food safety and hinders the high-quality development of the pineapple industry. Existing technologies mostly address single problems with partial improvements and have not yet formed a systematic solution that balances safety, effectiveness, and cost, making it difficult to meet the current market demand for green, safe, and long-lasting stable preservation products. Summary of the Invention

[0004] To address the problem that existing pineapple postharvest preservation cards cannot simultaneously achieve both safety and long-term comprehensive preservation effects, this application provides a pineapple postharvest preservation card and its preparation method.

[0005] Firstly, this application provides a post-harvest preservation card for pineapples, employing the following technical solution:

[0006] A postharvest preservation card for pineapples comprises a carrier and preservation components loaded on the carrier. The preservation components, by weight, include: 0.5-2.0 parts of natural antibacterial agent, 0.3-1.0 parts of antioxidant and anti-browning agent, 1.0-3.0 parts of moisture-absorbing and water-retaining agent, 0.2-0.8 parts of slow-release agent, and 85.0-95.0 parts of solvent. The carrier is a food-grade breathable non-woven fabric, and the mass ratio of the carrier to the preservation components is 1:(2.5-4.0).

[0007] By adopting the above technical solution and using food-grade breathable non-woven fabric as a carrier, its breathability allows for the slow release of preservative components. The specific mass ratio of carrier to preservative components ensures that the carrier adsorbs sufficient and appropriate amounts of preservative components, guaranteeing subsequent preservation effects while avoiding excessive adsorption that would lead to component waste. It also prevents excessive adsorption from causing premature initial release of preservative components followed by insufficient supply later. The various functional components in the preservative composition work synergistically: natural antibacterial agents inhibit microbial growth, antioxidants and anti-browning agents delay fruit browning, moisture-absorbing and water-retaining agents reduce fruit moisture loss, slow-release agents control the release rate of each functional component, and solvents ensure complete dissolution and uniform dispersion of each component. Through the synergistic effect of these components, comprehensive protection of the pineapple's post-harvest quality is achieved, solving the problem of balancing safety and long-term preservation in existing technologies.

[0008] Preferably, the natural antibacterial agent is a compound of lavender essential oil and cell-free supernatant of lactic acid bacteria, wherein the mass ratio of lavender essential oil to cell-free supernatant of lactic acid bacteria is 1:(2-4); the purity of the lavender essential oil is not less than 99%, and the concentration is not less than 700 μl / ml; the cell-free supernatant of lactic acid bacteria is prepared by fermentation culture of Lactobacillus plantarum CNTA600 or Pediococcus pentosaceus CNTA1059 strains, followed by centrifugation and filtration to remove bacterial cells.

[0009] By employing the above technical solutions, lavender essential oil possesses natural antibacterial properties, capable of disrupting microbial cell membrane structures and inhibiting microbial metabolism. Its high purity and concentration ensure antibacterial efficacy without producing any off-odors. The cell-free supernatant of lactic acid bacteria contains active substances such as antimicrobial peptides and organic acids produced during fermentation, further enhancing the antibacterial effect. Furthermore, both *Lactobacillus plantarum* CNTA600 and *Pediococcus pentosaceus* CNTA1059 are food-grade safe strains, non-pathogenic, and do not carry transferable antibiotic resistance genes, resulting in higher safety. The specific ratio of these two compounds achieves a broad-spectrum synergistic antibacterial effect, covering the main pathogenic bacteria and spoilage microorganisms in pineapple after harvest, avoiding the limited antibacterial range of single antibacterial components. Moreover, both are natural ingredients, preventing chemical residues in the fruit.

[0010] Preferably, the antioxidant and anti-browning agent is a compound of vitamin C and citric acid in a mass ratio of 1:(1-1.5); the moisture-absorbing and water-retaining agent is a compound of montmorillonite and starch in a mass ratio of 1:(1-3); the slow-release agent is a compound of dextrin and sodium carboxymethyl cellulose in a mass ratio of 2:(1-3); the solvent is a compound of deionized water and edible ethanol in a mass ratio of 8:(1-2); and the preservation component also contains 0.1 to 0.3 parts of ethylene inhibitor 1-methylcyclopropene.

[0011] By employing the above technical solutions, vitamin C, as a reducing agent, can reduce quinones produced by oxidation in pineapple pulp to phenols. Citric acid can lower the pH value of the system, further inhibiting the activity of polyphenol oxidase. The specific ratio of these two compounds maximizes the anti-browning effect and maintains the original color of the pulp. Montmorillonite, with its layered structure and excellent hygroscopic properties, can absorb excess moisture within the packaging. Starch can form a thin film on the fruit surface, locking in internal moisture. The combination of these two compounds reduces moisture loss from the fruit, keeping the pulp crisp and tender. The combination of dextrin and sodium carboxymethyl cellulose forms a stable gel system, encapsulating each functional component and enabling slow release, avoiding excessively high concentrations initially and insufficient concentrations later. The specific ratio of deionized water and edible ethanol ensures the dissolution of both water-soluble and fat-soluble components, guaranteeing a uniform and stable preservative solution. Simultaneously, edible ethanol aids in the dispersion of lavender essential oil and evaporates naturally during the subsequent drying process, leaving no residue. Ethylene inhibitors can suppress postharvest ethylene synthesis in pineapples, delay the respiratory climacteric, further delay flesh softening and quality deterioration, and adapt to different storage requirements.

[0012] Secondly, this application provides a method for preparing a pineapple postharvest preservation card, which adopts the following technical solution:

[0013] A method for preparing a pineapple postharvest preservation card includes the following steps:

[0014] S1. Component preparation: Weigh each raw material component and carrier according to the weight proportions, and pre-treat the natural antibacterial agent for later use;

[0015] S2. Preparation of preservation liquid: Add the solvent to the mixing tank and stir at room temperature. Add the functional components in the preset order and stir until a uniform and stable preservation liquid is formed.

[0016] S3, Carrier Loading: After cutting the food-grade breathable non-woven fabric into the preset size, it is completely immersed in the preservation liquid. The immersion conditions are controlled to ensure that the carrier fully and evenly absorbs the preservation liquid.

[0017] S4. Drying and shaping: Take out the impregnated carrier and put it in an oven to dry in a ventilated place, controlling the moisture content of the carrier after drying;

[0018] S5. Composite Packaging: The dried carrier is cut into preservation cards of a preset size and individually sealed with a biodegradable composite film to obtain the finished pineapple post-harvest preservation card.

[0019] By adopting the above technical solution, the entire process—component preparation, preservative solution formulation, carrier loading, drying and molding, and composite packaging—is completed step-by-step. The process is simple and orderly, requiring no complex equipment or special techniques, and enabling large-scale production. Pretreatment ensures the activity and purity of the natural antibacterial agents, preventing impurities from affecting the preservation effect; the pre-defined order of component addition avoids interactions between components that could affect their function, ensuring a uniform and stable preservative solution. Carrier loading allows the preservative components to be fully adsorbed onto the carrier; drying and molding control the carrier's moisture content, preventing excessive moisture from causing component loss or mold growth; and composite packaging prevents the volatilization of preservative components, extending the product's shelf life. Simultaneously, the biodegradable packaging meets environmental protection requirements and aligns with the trend of green development.

[0020] Preferably, in step S1, the pretreatment method of the natural antibacterial agent is as follows: inoculate *Lactobacillus plantarum* or *Pediococcus pentosaceus* into MRS medium, incubate at 37°C for 24 to 48 hours, then centrifuge at 5000 to 8000 r / min for 10 to 15 minutes, take the supernatant and filter it through a 0.20-0.24 μm filter membrane to remove bacterial cells, and obtain cell-free supernatant of lactic acid bacteria, which is then refrigerated for later use; dilute lavender essential oil with a small amount of edible ethanol for later use.

[0021] By employing the above technical solutions, constant temperature culture provides suitable conditions for the growth and fermentation of the bacterial strains. The MRS medium provides sufficient nutrients for the growth and reproduction of *Lactobacillus plantarum* or *Pediococcus pentosaceus*, ensuring the strains fully multiply and produce sufficient antimicrobial active substances. Controlling the culture time avoids insufficient culture leading to low antimicrobial content or over-culture resulting in contamination by other microorganisms. Centrifugation at specific speeds and times thoroughly separates the bacterial cells from the supernatant. Filtering further removes residual bacterial cells and impurities, ensuring the purity of the cell-free supernatant from the lactic acid bacteria and preventing bacterial residue from affecting product safety. Refrigeration maintains the antimicrobial activity of the supernatant and prevents the loss of active ingredients. Diluting lavender essential oil with edible ethanol solves the problem of its high lipid solubility and difficulty in dispersion, ensuring uniform mixing with other components, avoiding stratification, and guaranteeing the stability of the preservative solution.

[0022] Preferably, in step S2, the stirring speed is 200 r / min to 300 r / min; after adding the antioxidant and anti-browning agent and the slow-release agent, stir for 10 min to 15 min until completely dissolved; after adding the natural antibacterial agent, continue stirring for 15 min to 20 min until no stratification occurs; after adding the moisture-absorbing and water-retaining agent, stir for 20 min to 30 min.

[0023] By employing the above technical solutions, controlling the stirring speed ensures thorough mixing of all components, while preventing excessively high speeds from causing the loss of volatile components or excessively low speeds from causing uneven mixing. Antioxidants and slow-release agents are readily soluble in solvents; controlling the stirring time ensures complete dissolution and uniform dispersion in the solvent, maximizing their functionality. The natural antibacterial agent contains fat-soluble lavender essential oil; therefore, the stirring time needs to be extended to 15-20 minutes to ensure complete dispersion and prevent stratification, guaranteeing the uniformity of the preservative solution. The hygroscopic and water-retaining agent is a solid component; extending the stirring time to 20-30 minutes ensures thorough dispersion in the preservative solution, preventing clumping and ensuring uniform adsorption by the subsequent carrier, maximizing its hygroscopic and water-retaining effects.

[0024] Preferably, in step S2, when the preservation component contains the ethylene inhibitor 1-methylcyclopropene, the ethylene inhibitor is added after the moisture-absorbing and water-retaining agent is added and stirring is completed, and stirring is continued for 8 to 12 minutes to ensure uniform mixing.

[0025] By adopting the above technical solution, adding the ethylene inhibitor after the hygroscopic and water-retaining agent has been stirred can avoid interaction between them, preventing any impact on the functionality of both and preventing the hygroscopic and water-retaining agent from adsorbing the ethylene inhibitor and thus preventing its abnormal release. Stirring for 8 to 12 minutes ensures that the ethylene inhibitor is evenly dispersed in the preservative solution, avoiding excessively high or low local concentrations. This ensures that after subsequent carrier loading, the ethylene inhibitor can be slowly and evenly released, effectively inhibiting ethylene synthesis, delaying the deterioration of pineapple quality, and guaranteeing the stability of the preservation effect.

[0026] Preferably, in step S3, the immersion temperature is 25°C to 35°C, the immersion time is 20 min to 30 min, the mixture is stirred once every 8 min to 12 min during the immersion process, and the amount of the carrier adsorbed by the preservative liquid is controlled to be 2.5 to 4.0 times the mass of the carrier itself.

[0027] By adopting the above technical solution, an immersion temperature of 25℃ to 35℃ ensures the stability of the preservative solution, preventing excessively high temperatures from causing the loss of natural active ingredients or excessively low temperatures from resulting in slow or insufficient adsorption. An immersion time of 20 to 30 minutes ensures that the carrier fully adsorbs the preservative solution, avoiding insufficient adsorption leading to poor preservation or excessive adsorption leading to component waste. Stirring every 8 to 12 minutes during the immersion process prevents the carrier from tangling and knotting, ensuring uniform adsorption across all parts of the carrier and promoting the penetration of the preservative solution into the carrier, thus enhancing the adsorption effect. Controlling the adsorption amount allows it to be matched with the mass ratio of the carrier and the preservative components, ensuring a stable release rate of the subsequent preservative components and achieving long-lasting preservation.

[0028] Preferably, in step S3, the food-grade breathable nonwoven fabric has a thickness of 0.1 mm to 0.2 mm, a pore size of 50 μm to 100 μm, and an air permeability of 100 ml / (cm²). 2 •min) to 150ml / (cm 2 •min); The preset size is 5cm×8cm or 6cm×10cm.

[0029] By adopting the above technical solution, a thickness of 0.1mm to 0.2mm can balance the mechanical strength and air permeability of the carrier. Too thin a thickness makes it prone to breakage, while too thick a thickness hinders the release of preservative components. A pore size of 50μm to 100μm and an air permeability of 100ml / (cm²・min) to 150ml / (cm²・min) ensure that the preservative components are released slowly and evenly, avoiding excessively rapid release that shortens the preservation period or excessively slow release that fails to provide timely preservation. The two preset sizes of 5cm×8cm and 6cm×10cm can be adapted to small packaging, fresh-cut pineapple, and whole-fruit packaging, respectively, ensuring that the preservation card in each bag fully covers the fruit to achieve its preservation effect, while avoiding waste due to excessively large sizes or insufficient preservation effect due to excessively small sizes.

[0030] Preferably, in step S4, the drying temperature is 45°C to 55°C, and the drying time is 10 min to 15 min; the moisture content of the carrier after drying is controlled to be 8% to 12%; the biodegradable composite film is a composite film of PVA and potato starch; the entire preparation process is carried out at room temperature and pressure, with an ambient relative humidity of 40% to 60%, avoiding direct sunlight and keeping the ambient temperature below 60°C.

[0031] By adopting the above technical solutions, low-temperature drying at 45℃ to 55℃ avoids high-temperature damage to active ingredients such as natural antibacterial agents and antioxidants, ensuring that the functions of each component are not affected. A drying time of 10 to 15 minutes allows for precise control of the carrier's moisture content, maintaining it between 8% and 12%. This prevents excessive moisture from causing mold growth and loss of preservative components, while also preventing excessively low moisture content from making the carrier brittle and easily damaged, affecting its usability. The biodegradable film composed of PVA and potato starch has excellent sealing and biodegradability, effectively preventing the volatilization of preservative components and extending the product's shelf life. It is also biodegradable and will not cause environmental pollution. Normal temperature and pressure preparation conditions reduce production difficulty and cost. Controlling the relative humidity at 40% to 60%, avoiding direct sunlight, and ensuring the ambient temperature does not exceed 60℃ prevents environmental factors from causing inactivation of preservative components and carrier deterioration during preparation, ensuring the stability and consistency of the finished product.

[0032] In summary, this application has the following beneficial effects:

[0033] 1. This application uses lavender essential oil and cell-free supernatant of Lactobacillus plantarum CNTA600 or Pediococcus pentosaceus CNTA1059 as a natural antibacterial agent, combined with food-grade antioxidants and moisture-absorbing agents. No harmful chemical preservatives are added throughout the process, resulting in a chemical-free, food-safe product that does not introduce off-odors and meets the requirements of green food production.

[0034] 2. This application preferably adopts a multifunctional compound system with natural antibacterial, antioxidant and anti-browning, moisture absorption and water retention, slow release and controlled release and selective respiration. The components are scientifically matched and work together to achieve the effect of simultaneously solving multiple quality deterioration problems of pineapple after harvest, effectively maintaining the fruit's inherent taste and nutrition.

[0035] 3. Because this application uses a slow-release agent composed of dextrin and sodium carboxymethyl cellulose, combined with a food-grade breathable non-woven fabric carrier with specific thickness, pore size and air permeability, it achieves a stable and slow release of the preservation components, avoiding the problem of excessively high concentration in the early stage and insufficient concentration in the later stage, and is suitable for long-distance transportation needs.

[0036] 4. The method of this application, through the steps of component preparation, preservation liquid preparation, carrier loading, low-temperature drying and composite packaging at room temperature and pressure, does not require complex processes and professional equipment. All raw materials used are readily available food-grade raw materials, thus achieving the effects of simple preparation, low cost and suitability for large-scale production.

[0037] 5. Since this application adopts a gas-phase release mechanism, it is compatible with common packaging materials such as OPP or PE. Depending on storage requirements, it can choose whether to add ethylene inhibitors, thus achieving the effect of being suitable for both whole pineapples and fresh-cut pineapples, expanding the product's applicable scenarios. Attached Figure Description

[0038] Figure 1 This is a flowchart of a method for preparing a pineapple postharvest preservation card provided in this application. Detailed Implementation

[0039] The present application will be further described in detail below with reference to embodiments and comparative examples. Unless otherwise specified, the experimental methods used below are conventional methods. Unless otherwise specified, the materials, reagents, methods and instruments used are all conventional materials, reagents, methods and instruments in the art, which can be obtained by those skilled in the art through commercial channels or prepared according to literature methods.

[0040] Technical Concept: Current pineapple post-harvest preservation products generally suffer from the problem of balancing safety and overall preservation performance. Preservation cards using chemical preservatives are prone to residue risks, while natural preservation cards mostly adopt a single-component design, which has the defects of narrow antibacterial spectrum and single function. They cannot simultaneously solve multiple quality deterioration problems such as browning, rotting, dehydration, and softening of the flesh. At the same time, most products lack a reasonable slow-release structure design, and the preservation ingredients are prone to rapid volatilization and loss. In addition, the carrier selection and preparation process are poorly matched, making it difficult to achieve stable and long-lasting preservation effects, and they cannot be adapted to the diverse usage scenarios of whole pineapples and fresh-cut fruits.

[0041] This technical solution uses a natural antibacterial system composed of lavender essential oil and cell-free supernatant of lactic acid bacteria, combined with an antioxidant and anti-browning component composed of vitamin C and citric acid, a moisture-absorbing and water-retaining component composed of montmorillonite and starch, and a slow-release component composed of dextrin and sodium carboxymethyl cellulose. Ethylene inhibitors can be selectively added. Using food-grade breathable non-woven fabric with specific parameters as a carrier, and through standardized pretreatment, step-by-step stirring and preparation, temperature-controlled impregnation, and low-temperature drying processes, the functional components are uniformly loaded onto the carrier and achieve stable slow release. This simultaneously improves the preservation effect from multiple aspects, including component synergy, carrier compatibility, and process optimization, and achieves comprehensive protection of the post-harvest quality of pineapples without chemical residues.

[0042] Example 1: This example provides a pineapple postharvest preservation card, which consists of a carrier and preservation components loaded on the carrier;

[0043] The preservation components, by weight, include: 1.25 parts of natural antibacterial agent, 0.65 parts of antioxidant and anti-browning agent, 2.0 parts of moisture-absorbing and water-retaining agent, 0.5 parts of slow-release agent, and 90.0 parts of solvent; the carrier is food-grade breathable non-woven fabric, and the mass ratio of the carrier to the preservation components is 1:3.25.

[0044] The natural antibacterial agent is a compound of lavender essential oil and cell-free supernatant of lactic acid bacteria, with a mass ratio of lavender essential oil to cell-free supernatant of lactic acid bacteria of 1:3; the purity of lavender essential oil is not less than 99%, and the concentration is not less than 700 μl / ml; the cell-free supernatant of lactic acid bacteria is prepared by fermenting and culturing Lactobacillus plantarum strain CNTA600, followed by centrifugation and filtration to remove bacterial cells;

[0045] Among them, the antioxidant and anti-browning agent is a compound of vitamin C and citric acid with a mass ratio of 1:1.25; the moisture-absorbing and water-retaining agent is a compound of montmorillonite and starch with a mass ratio of 1:2; the slow-release agent is a compound of dextrin and sodium carboxymethyl cellulose with a mass ratio of 1:1; and the solvent is a compound of deionized water and edible ethanol with a mass ratio of 8:1.5.

[0046] The preparation method of the above-mentioned pineapple postharvest preservation card includes the following steps:

[0047] S1. Component preparation: Weigh each raw material component and carrier according to the weight proportions, and pre-treat the natural antibacterial agent for later use;

[0048] The pretreatment method for the natural antibacterial agent is as follows: Lactobacillus plantarum CNTA600 is inoculated into MRS medium and cultured at 37℃ for 36h. Then, it is centrifuged at 6500r / min for 12.5min. The supernatant is filtered through a 0.22μm filter membrane to remove the bacterial cells, and the cell-free supernatant of lactic acid bacteria is obtained and stored at 4℃ for later use. Lavender essential oil is diluted with a small amount of edible ethanol. The dilution ratio is controlled at 1:5 to ensure that the essential oil is evenly dispersed in ethanol and to avoid subsequent stratification.

[0049] S2. Preparation of preservation liquid: Add the solvent to the mixing tank and stir at room temperature. Add the functional components in the preset order and stir until a uniform and stable preservation liquid is formed.

[0050] The stirring speed was 250 r / min; after adding the antioxidant and anti-browning agent and the slow-release agent, the mixture was stirred for 12.5 min until completely dissolved; after adding the natural antibacterial agent, the mixture was stirred for 17.5 min until no stratification occurred; after adding the moisture-absorbing and water-retaining agent, the mixture was stirred for 25 min. During the stirring process, the vessel was kept sealed to reduce the loss of volatile components.

[0051] S3, Carrier Loading: After cutting the food-grade breathable non-woven fabric into the preset size, it is completely immersed in the preservation liquid. The immersion conditions are controlled to ensure that the carrier fully and evenly absorbs the preservation liquid.

[0052] The soaking temperature was 30℃ and the soaking time was 25 minutes. During the soaking process, the mixture was stirred every 10 minutes, and the stirring direction was kept the same as before to avoid the carrier from tangling and knotting. The amount of preservative liquid adsorbed by the carrier was controlled to reach 3.25 times the mass of the carrier itself.

[0053] The food-grade breathable nonwoven fabric has a thickness of 0.15 mm, a pore size of 75 μm, and an air permeability of 125 ml / (cm²). 2 •min); The preset size is 6cm×10cm. The cut edges must be flat and free of burrs to prevent fibers from falling off and contaminating the fruit during use.

[0054] S4. Drying and shaping: Take out the impregnated carrier and put it in an oven to dry in a ventilated place, controlling the moisture content of the carrier after drying;

[0055] The drying temperature was 50℃, and the drying time was 12.5 min; the moisture content of the carrier after drying was controlled to be 10%; the oven was kept continuously ventilated during the drying process, and the ventilation volume was controlled to be 2 m³ / min. 3 / min ensures uniform temperature inside the oven and avoids localized overheating that could damage the natural active ingredients.

[0056] S5. Composite Packaging: The dried carrier is cut into preservation cards of a preset size and individually sealed with a biodegradable composite film to obtain the finished pineapple post-harvest preservation card.

[0057] The biodegradable composite film is a composite film of PVA and potato starch. The entire preparation process is carried out at room temperature and pressure, with a relative humidity of 50%, avoiding direct sunlight and an ambient temperature not exceeding 60°C. After packaging, the product name, production date, expiration date and usage method are labeled, and the finished product is stored in a cool and dry place.

[0058] Example 2: This example provides a pineapple postharvest preservation card, which consists of a carrier and preservation components loaded on the carrier;

[0059] The preservation components, by weight, include: 1.25 parts of natural antibacterial agent, 0.65 parts of antioxidant and anti-browning agent, 2.0 parts of moisture-absorbing and water-retaining agent, 0.5 parts of slow-release agent, 90.0 parts of solvent, and 0.2 parts of ethylene inhibitor 1-methylcyclopropene; the carrier is food-grade breathable non-woven fabric, and the mass ratio of the carrier to the preservation components is 1:3.25.

[0060] The natural antibacterial agent is a compound of lavender essential oil and cell-free supernatant of lactic acid bacteria, with a mass ratio of lavender essential oil to cell-free supernatant of lactic acid bacteria of 1:3; the purity of lavender essential oil is not less than 99%, and the concentration is not less than 700 μl / ml; the cell-free supernatant of lactic acid bacteria is prepared by fermenting and culturing Lactobacillus plantarum strain CNTA600, followed by centrifugation and filtration to remove bacterial cells;

[0061] Among them, the antioxidant and anti-browning agent is a compound of vitamin C and citric acid with a mass ratio of 1:1.25; the moisture-absorbing and water-retaining agent is a compound of montmorillonite and starch with a mass ratio of 1:2; the slow-release agent is a compound of dextrin and sodium carboxymethyl cellulose with a mass ratio of 1:1; and the solvent is a compound of deionized water and edible ethanol with a mass ratio of 8:1.5.

[0062] The preparation method of the above-mentioned pineapple postharvest preservation card includes the following steps:

[0063] S1. Component preparation: Weigh each raw material component and carrier according to the weight proportions, and pre-treat the natural antibacterial agent for later use;

[0064] The pretreatment method for the natural antibacterial agent is as follows: Lactobacillus plantarum CNTA600 is inoculated into MRS medium and cultured at 37℃ for 36h. Then, it is centrifuged at 6500r / min for 12.5min. The supernatant is filtered through a 0.22μm filter membrane to remove the bacterial cells, and the cell-free supernatant of lactic acid bacteria is obtained and stored at 4℃ for later use. Lavender essential oil is diluted with a small amount of edible ethanol. The dilution ratio is controlled at 1:5 to ensure that the essential oil is evenly dispersed in ethanol and to avoid subsequent stratification.

[0065] S2. Preparation of preservation liquid: Add the solvent to the mixing tank and stir at room temperature. Add the functional components in the preset order and stir until a uniform and stable preservation liquid is formed.

[0066] The stirring speed was 250 r / min; after adding the antioxidant and anti-browning agent and the slow-release agent, the mixture was stirred for 12.5 min until completely dissolved; after adding the natural antibacterial agent, the mixture was stirred for 17.5 min until no stratification occurred; after adding the moisture-absorbing and water-retaining agent, the mixture was stirred for 25 min. During the stirring process, the vessel was kept sealed to reduce the loss of volatile components.

[0067] When the preservation component contains the ethylene inhibitor 1-methylcyclopropene, the ethylene inhibitor is added after the moisture-absorbing and water-retaining agent is added and the mixture is stirred. Stirring is continued for 10 minutes to ensure uniform mixing. The addition process should be slow and uniform to avoid excessive local concentrations that could affect the sustained-release effect.

[0068] S3, Carrier Loading: After cutting the food-grade breathable non-woven fabric into the preset size, it is completely immersed in the preservation liquid. The immersion conditions are controlled to ensure that the carrier fully and evenly absorbs the preservation liquid.

[0069] The soaking temperature was 30℃ and the soaking time was 25 minutes. During the soaking process, the mixture was stirred every 10 minutes, and the stirring direction was kept the same as before to avoid the carrier from tangling and knotting. The amount of preservative liquid adsorbed by the carrier was controlled to reach 3.25 times the mass of the carrier itself.

[0070] The food-grade breathable nonwoven fabric has a thickness of 0.15 mm, a pore size of 75 μm, and an air permeability of 125 ml / (cm²). 2 •min); The preset size is 6cm×10cm. The cut edges must be flat and free of burrs to prevent fibers from falling off and contaminating the fruit during use.

[0071] S4. Drying and shaping: Take out the impregnated carrier and put it in an oven to dry in a ventilated place, controlling the moisture content of the carrier after drying;

[0072] The drying temperature was 50℃, and the drying time was 12.5 min; the moisture content of the carrier after drying was controlled to be 10%; the oven was kept continuously ventilated during the drying process, and the ventilation volume was controlled to be 2 m³ / min. 3 / min ensures uniform temperature inside the oven and avoids localized overheating that could damage the natural active ingredients.

[0073] S5. Composite Packaging: The dried carrier is cut into preservation cards of a preset size and individually sealed with a biodegradable composite film to obtain the finished pineapple post-harvest preservation card.

[0074] The biodegradable composite film is a composite film of PVA and potato starch. The entire preparation process is carried out at room temperature and pressure, with a relative humidity of 50%, avoiding direct sunlight and an ambient temperature not exceeding 60°C. After packaging, the product name, production date, expiration date and usage method are labeled, and the finished product is stored in a cool and dry place.

[0075] Example 3: This example provides a pineapple postharvest preservation card, which consists of a carrier and preservation components loaded on the carrier;

[0076] The preservation components, by weight, include: 0.5 parts of natural antibacterial agent, 0.3 parts of antioxidant and anti-browning agent, 1.0 part of moisture-absorbing and water-retaining agent, 0.2 parts of slow-release agent, and 85.0 parts of solvent; the carrier is food-grade breathable non-woven fabric, and the mass ratio of the carrier to the preservation components is 1:2.5.

[0077] The natural antibacterial agent is a compound of lavender essential oil and cell-free supernatant of lactic acid bacteria, with a mass ratio of lavender essential oil to cell-free supernatant of lactic acid bacteria of 1:2; the purity of lavender essential oil is not less than 99%, and the concentration is not less than 700 μl / ml; the cell-free supernatant of lactic acid bacteria is prepared by fermentation culture of Pediococcus pentosaceus strain CNTA1059, followed by centrifugation and filtration to remove bacterial cells;

[0078] Among them, the antioxidant and anti-browning agent is a compound of vitamin C and citric acid in a mass ratio of 1:1; the moisture-absorbing and water-retaining agent is a compound of montmorillonite and starch in a mass ratio of 1:1; the slow-release agent is a compound of dextrin and sodium carboxymethyl cellulose in a mass ratio of 2:1; and the solvent is a compound of deionized water and edible ethanol in a mass ratio of 8:1.

[0079] The preparation method of the above-mentioned pineapple postharvest preservation card includes the following steps:

[0080] S1. Component preparation: Weigh each raw material component and carrier according to the weight proportions, and pre-treat the natural antibacterial agent for later use;

[0081] The pretreatment method for the natural antibacterial agent is as follows: Pediococcus pentosaceus CNTA1059 is inoculated into MRS medium and cultured at 37℃ for 24h. Then, it is centrifuged at 5000r / min for 10min. The supernatant is filtered through a 0.20μm filter membrane to remove the bacterial cells, and the cell-free supernatant of lactic acid bacteria is obtained and stored at 4℃ for later use. Lavender essential oil is diluted with a small amount of edible ethanol. The dilution ratio is controlled at 1:4 to ensure that the essential oil is evenly dispersed in ethanol and to avoid subsequent stratification.

[0082] S2. Preparation of preservation liquid: Add the solvent to the mixing tank and stir at room temperature. Add the functional components in the preset order and stir until a uniform and stable preservation liquid is formed.

[0083] The stirring speed was 200 r / min; after adding the antioxidant and anti-browning agent and the slow-release agent, the mixture was stirred for 10 minutes until completely dissolved; after adding the natural antibacterial agent, the mixture was stirred for 15 minutes until no stratification occurred; after adding the moisture-absorbing and water-retaining agent, the mixture was stirred for 20 minutes. During the stirring process, the vessel was kept sealed to reduce the loss of volatile components.

[0084] S3, Carrier Loading: After cutting the food-grade breathable non-woven fabric into the preset size, it is completely immersed in the preservation liquid. The immersion conditions are controlled to ensure that the carrier fully and evenly absorbs the preservation liquid.

[0085] The soaking temperature was 25℃, and the soaking time was 20 minutes. During the soaking process, the mixture was stirred every 8 minutes, and the stirring direction was kept the same as before to avoid the carrier from tangling and knotting. The amount of preservative liquid adsorbed by the carrier was controlled to reach 2.5 times the mass of the carrier itself.

[0086] The food-grade breathable nonwoven fabric has a thickness of 0.1 mm, a pore size of 50 μm, and an air permeability of 100 ml / (cm²). 2 •min); The preset size is 5cm×8cm. The cut edges must be flat and free of burrs to prevent fibers from falling off and contaminating the fruit during use.

[0087] S4. Drying and shaping: Take out the impregnated carrier and put it in an oven to dry in a ventilated place, controlling the moisture content of the carrier after drying;

[0088] The drying temperature was 45℃, and the drying time was 10 minutes; the moisture content of the carrier after drying was controlled to be 8%; the oven was kept continuously ventilated during the drying process, and the ventilation volume was controlled to be 1.5m³. 3 / min ensures uniform temperature inside the oven and avoids localized overheating that could damage the natural active ingredients.

[0089] S5. Composite Packaging: The dried carrier is cut into preservation cards of a preset size and individually sealed with a biodegradable composite film to obtain the finished pineapple post-harvest preservation card.

[0090] The biodegradable composite film is a composite film of PVA and potato starch. The entire preparation process is carried out at room temperature and pressure, with a relative humidity of 40%, avoiding direct sunlight and an ambient temperature not exceeding 60°C. After packaging, the product name, production date, expiration date and usage method are labeled, and the finished product is stored in a cool and dry place.

[0091] Example 4: This example provides a pineapple postharvest preservation card, which consists of a carrier and preservation components loaded on the carrier;

[0092] The preservation components, by weight, include: 2.0 parts of natural antibacterial agent, 1.0 part of antioxidant and anti-browning agent, 3.0 parts of moisture-absorbing and water-retaining agent, 0.8 parts of slow-release agent, 95.0 parts of solvent, and 0.3 parts of ethylene inhibitor 1-methylcyclopropene; the carrier is food-grade breathable non-woven fabric, and the mass ratio of the carrier to the preservation components is 1:4.0.

[0093] The natural antibacterial agent is a compound of lavender essential oil and cell-free supernatant of lactic acid bacteria, with a mass ratio of lavender essential oil to cell-free supernatant of lactic acid bacteria of 1:4; the purity of lavender essential oil is not less than 99%, and the concentration is not less than 700 μl / ml; the cell-free supernatant of lactic acid bacteria is prepared by fermenting and culturing Lactobacillus plantarum strain CNTA600, followed by centrifugation and filtration to remove bacterial cells;

[0094] Among them, the antioxidant and anti-browning agent is a compound of vitamin C and citric acid with a mass ratio of 1:1.5; the moisture-absorbing and water-retaining agent is a compound of montmorillonite and starch with a mass ratio of 1:3; the slow-release agent is a compound of dextrin and sodium carboxymethyl cellulose with a mass ratio of 2:3; and the solvent is a compound of deionized water and edible ethanol with a mass ratio of 8:2.

[0095] The preparation method of the above-mentioned pineapple postharvest preservation card includes the following steps:

[0096] S1. Component preparation: Weigh each raw material component and carrier according to the weight proportions, and pre-treat the natural antibacterial agent for later use;

[0097] The pretreatment method for the natural antibacterial agent is as follows: Lactobacillus plantarum CNTA600 is inoculated into MRS medium and cultured at 37℃ for 48h. Then, it is centrifuged at 8000r / min for 15min. The supernatant is filtered through a 0.24μm filter membrane to remove the bacterial cells, and the cell-free supernatant of lactic acid bacteria is prepared and stored at 4℃ for later use. Lavender essential oil is diluted with a small amount of edible ethanol. The dilution ratio is controlled at 1:6 to ensure that the essential oil is evenly dispersed in ethanol and to avoid subsequent stratification.

[0098] S2. Preparation of preservation liquid: Add the solvent to the mixing tank and stir at room temperature. Add the functional components in the preset order and stir until a uniform and stable preservation liquid is formed.

[0099] The stirring speed was 300 r / min; after adding the antioxidant and anti-browning agent and the slow-release agent, the mixture was stirred for 15 min until completely dissolved; after adding the natural antibacterial agent, the mixture was stirred for 20 min until no stratification occurred; after adding the moisture-absorbing and water-retaining agent, the mixture was stirred for 30 min. During the stirring process, the vessel was kept sealed to reduce the loss of volatile components.

[0100] When the preservation component contains the ethylene inhibitor 1-methylcyclopropene, the ethylene inhibitor is added after the moisture-absorbing and water-retaining agent is added and the mixture is stirred. Stirring is continued for 12 minutes to ensure uniform mixing. The addition process should be slow and uniform to avoid excessive local concentrations that could affect the sustained-release effect.

[0101] S3, Carrier Loading: After cutting the food-grade breathable non-woven fabric into the preset size, it is completely immersed in the preservation liquid. The immersion conditions are controlled to ensure that the carrier fully and evenly absorbs the preservation liquid.

[0102] The immersion temperature was 35℃, and the immersion time was 30 minutes. During the immersion process, the mixture was stirred every 12 minutes, and the stirring direction was kept consistent with the previous stirring to avoid the carrier from tangling and knotting. The amount of preservative liquid adsorbed by the carrier was controlled to reach 4.0 times the mass of the carrier itself.

[0103] The food-grade breathable nonwoven fabric has a thickness of 0.2 mm, a pore size of 100 μm, and an air permeability of 150 ml / (cm²). 2 •min); The preset size is 6cm×10cm. The cut edges must be flat and free of burrs to prevent fibers from falling off and contaminating the fruit during use.

[0104] S4. Drying and shaping: Take out the impregnated carrier and put it in an oven to dry in a ventilated place, controlling the moisture content of the carrier after drying;

[0105] The drying temperature was 55℃, and the drying time was 15 minutes; the moisture content of the carrier after drying was controlled at 12%; continuous ventilation was maintained in the oven during the drying process, and the ventilation volume was controlled at 2.5m³. 3 / min ensures uniform temperature inside the oven and avoids localized overheating that could damage the natural active ingredients.

[0106] S5. Composite Packaging: The dried carrier is cut into preservation cards of a preset size and individually sealed with a biodegradable composite film to obtain the finished pineapple post-harvest preservation card.

[0107] The biodegradable composite film is a composite film of PVA and potato starch. The entire preparation process is carried out at room temperature and pressure, with a relative humidity of 60%, avoiding direct sunlight and an ambient temperature not exceeding 60°C. After packaging, the product name, production date, expiration date and usage method are labeled, and the finished product is stored in a cool and dry place.

[0108] Comparative Example 1: The only difference between this comparative example and Example 1 is that a commercially available mainstream chemical preservation card for pineapples is used instead of the preservation card prepared in this invention, and its core effective component is sodium metabisulfite.

[0109] Comparative Example 2: The only difference between this comparative example and Example 1 is that the cell-free supernatant of lactic acid bacteria in the natural antibacterial agent was removed and replaced with an equal amount of lavender essential oil, that is, the natural antibacterial agent is only lavender essential oil.

[0110] Comparative Example 3: The only difference between this comparative example and Example 1 is that lavender essential oil in the natural antibacterial agent is removed and replaced with an equal amount of Lactobacillus plantarum CNTA600 cell-free supernatant. That is, the natural antibacterial agent is only a single lactic acid bacteria cell-free supernatant. The other components and preparation process are exactly the same as in Example 1.

[0111] Comparative Example 4: The only difference between this comparative example and Example 1 is that all the sustained-release agents were removed, and the dextrin and sodium carboxymethyl cellulose compound was replaced with an equal amount of solvent. The remaining components and preparation process are exactly the same as in Example 1.

[0112] I. Determination of shelf life under ambient temperature storage: Referring to GB / T23351-2009 "Guidelines for the Storage of Fresh Fruits and Vegetables", whole Tainong No. 17 pineapples with uniform maturity, no mechanical damage, and no pests or diseases were selected and randomly divided into 8 groups, with 30 fruits in each group. Three parallel replicates were set up. The fruits were placed in OPP bags of the same size, and one preservation card corresponding to the group was placed in each bag. After sealing, they were stored in a constant temperature and humidity chamber at a temperature of 25±2℃ and a relative humidity of 60±5%. The appearance, color, texture, and odor changes of the fruits were observed and recorded at regular intervals every day. The qualified standard was that the fruits had no obvious browning, no rotten spots, crisp and tender flesh, and no off-odor. The longest qualified storage time of each group of fruits in Examples 1-4 and Comparative Examples 1-4 was counted, which was the ambient temperature shelf life of the corresponding preservation card.

[0113] II. Determination of pulp browning rate: Referring to GB / T30768-2014 "Technical Specifications for Packaging and Preservation of Fresh-Cut Fruits and Vegetables", on the 7th and 12th days of the above-mentioned room temperature storage test, 10 fruits were randomly selected from each group of Examples 1-4 and Comparative Examples 1-4, respectively. The fruits were cut evenly along the longitudinal axis, and the area grid method was used to count the proportion of browned area of ​​each fruit to the total flesh area. The average value of the proportion of browned area of ​​all fruits in each group of Examples 1-4 and Comparative Examples 1-4 was calculated, which is the pulp browning rate of that group at the corresponding time point. The difference in browning prevention effect between Examples 1-4 and Comparative Examples 1-4 at different storage times was compared.

[0114] III. Fruit rot rate determination: Referring to GB / T23351-2009 "Guidelines for the Storage of Fresh Fruits and Vegetables", on the 7th and 12th days of the above-mentioned room temperature storage test, the number of fruits with obvious rot spots, soft flesh, or rotten odor in each group of Examples 1-4 and Comparative Examples 1-4 was counted. The rot rate was calculated according to the following formula: Rot rate = Number of rotten fruits / Total number of fruits in the group × 100%. The average value of 3 parallel replicates was taken to obtain the fruit rot rate of each group of Examples 1-4 and Comparative Examples 1-4 at the corresponding time points, and to evaluate the inhibitory effect of different preservation cards in Examples 1-4 and Comparative Examples 1-4 on the main pathogenic bacteria and spoilage microorganisms of pineapple after harvest.

[0115] IV. Fruit weight loss rate determination: Referring to GB / T8855-2008 "Sampling Methods for Fresh Fruits and Vegetables", before the start of the room temperature storage test, the total mass of all fruits in each group of Examples 1-4 and Comparative Examples 1-4 was accurately weighed and recorded. On the 12th day of storage, the total mass of the remaining qualified fruits in each group of Examples 1-4 and Comparative Examples 1-4 was accurately weighed again. The weight loss rate was calculated according to the following formula: Weight loss rate = (Total mass before storage - Total mass after storage) / Total mass before storage × 100%. The average value of 3 parallel replicates was taken to obtain the average weight loss rate of fruits in each group of Examples 1-4 and Comparative Examples 1-4, reflecting the moisture absorption and water retention performance of different preservation cards in Examples 1-4 and Comparative Examples 1-4 and their inhibitory effect on fruit moisture loss.

[0116] V. Fruit firmness determination: Referring to the fruit firmness determination method in GB / T10651-2008 "Fresh Apples", on the 12th day of the room temperature storage test, 10 undamaged and rot-free fruits were randomly selected from each group of Examples 1-4 and Comparative Examples 1-4. Four test points were symmetrically selected at the equatorial region of each fruit. The firmness was determined by puncture using a texture analyzer with a P / 2 cylindrical probe. The probe diameter was set to 2 mm, the test speed to 1 mm / s, the compression depth to 5 mm, and the trigger force to 5 g. The maximum force value at each test point was recorded. The average firmness value of all test points in each group of Examples 1-4 and Comparative Examples 1-4 was calculated in N. The effect of different preservation cards in Examples 1-4 and Comparative Examples 1-4 on delaying the softening process of the fruit was evaluated.

[0117] VI. Determination of soluble solids content: Referring to GB / T12295-1990 "Determination of soluble solids content in fruit and vegetable products - refractometer method", on the 12th day of the room temperature storage test, 10 fruits were randomly selected from each group of Examples 1-4 and Comparative Examples 1-4. Equal amounts of pulp were mixed and homogenized using a tissue homogenizer. The mixture was filtered through four layers of gauze to obtain clear juice. The juice was dropped onto the prism of a calibrated handheld refractometer, and the soluble solids content was determined under constant temperature conditions of 20℃. Each sample was measured in parallel 3 times, and the average value was taken. The unit is %, which reflects the effect of different preservation cards in Examples 1-4 and Comparative Examples 1-4 on the retention of fruit nutrients.

[0118] VII. Determination of titratable acid content: Referring to GB / T12293-1990 "Determination of titratable acidity of fruit and vegetable products", on the 12th day of the room temperature storage test, take 10 mL of the clarified fruit juice prepared above in each of Examples 1-4 and Comparative Examples 1-4, add 50 mL of boiled and cooled deionized water, add 2 to 3 drops of phenolphthalein indicator, and titrate with 0.1 mol / L sodium hydroxide standard solution until the solution turns slightly red and does not fade within 30 seconds. Record the volume of sodium hydroxide standard solution consumed. At the same time, perform a blank test and calculate the titratable acid content, expressed as citric acid, in g / 100g. Evaluate the preservation effect of different preservation cards of Examples 1-4 and Comparative Examples 1-4 on the flavor quality of the fruit.

[0119] VIII. Microbiological index detection: Referring to GB4789.2-2022 "National Food Safety Standard - Microbiological Examination of Food - Determination of Total Colony Count" and GB4789.15-2016 "National Food Safety Standard - Microbiological Examination of Food - Count of Molds and Yeasts", on the 12th day of the room temperature storage test, 5 fruits were randomly selected from each group of Examples 1-4 and Comparative Examples 1-4. Under aseptic conditions, 25g of fruit pulp tissue was taken, and 225mL of sterile physiological saline was added. The mixture was homogenized at 8000r / min for 1min to prepare a 10-fold serial dilution. The bacterial solutions of appropriate dilutions were inoculated onto plate counting agar and potato dextrose agar, respectively. The total colony count was based on the incubation at 36℃ for 48h on plate counting agar, and the mold and yeast count was based on the incubation at 28℃ for 72h on potato dextrose agar. The results were expressed as CFU / g, and the broad-spectrum antibacterial effects of different preservation cards in Examples 1-4 and Comparative Examples 1-4 were compared.

[0120] IX. Chemical Residue Detection: Referring to GB5009.34-2016 "National Food Safety Standard - Determination of Sulfur Dioxide in Food", on the 12th day of the room temperature storage test, 200g of fruit pulp was randomly selected from each of the groups of Examples 1-4 and Comparative Examples 1-4. The residual amount of sodium metabisulfite in each sample was determined by the hydrochloric acid pararosaniline spectrophotometric method. Each sample was measured in triplicate, and the average value was taken. The unit is mg / kg.

[0121] Table 1: Summary of Test Results of Postharvest Preservation Card Performance of Pineapple

[0122] Testing items Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Shelf life at room temperature (d) 12 15 10 16 6 7 7 5 Browning rate on day 7 (%) 2.1 1.5 3.4 1.2 18.5 12.7 13.2 15.8 Browning rate on day 12 (%) 8.3 6.1 12.7 5.3 35.2 29.8 31.5 42.6 Decomposition rate on day 7 (%) 1.2 0.8 2.5 0.5 12.3 8.9 9.5 14.7 Decomposition rate on day 12 (%) 5.7 4.2 8.9 3.6 28.6 22.1 24.3 36.2 Weight loss rate on day 12 (%) 3.2 2.8 4.1 2.5 7.8 6.5 6.7 7.2 Hardness (N) on day 12 11.2 12.5 9.8 13.1 5.6 6.9 6.7 5.2 Soluble solids (%) on day 12 12.8 13.1 12.5 13.3 10.2 11.1 10.9 9.8 The acid (g / 100g) can be titrated on day 12. 0.62 0.65 0.59 0.67 0.38 0.45 0.43 0.35 Total bacterial count (CFU / g) on ​​day 12 <![CDATA[2.3×10 2 ]]> <![CDATA[1.8×10 2 ]]> <![CDATA[3.7×10 2 ]]> <![CDATA[1.5×10 2 ]]> <![CDATA[2.1×10 5 ]]> <![CDATA[1.7×10 4 ]]> <![CDATA[1.9×10 4 ]]> <![CDATA[3.2×10 5 ]]> Day 12 mold and yeast count (CFU / g) <![CDATA[1.5×10 1 ]]> <![CDATA[1.1×10 1 ]]> <![CDATA[2.3×10 1 ]]> <![CDATA[0.9×10 1 ]]> <![CDATA[1.3×10 4 ]]> <![CDATA[8.5×10 3 ]]> <![CDATA[7.8×10 3 ]]> <![CDATA[2.1×10 4 ]]> Sodium metabisulfite residue (mg / kg) Not detected Not detected Not detected Not detected 0.03 Not detected Not detected Not detected

[0123] As can be seen from Examples 1-3 and Comparative Example 1, and Table 1, although the preservation card using traditional chemical preservatives can inhibit the growth of microorganisms to a certain extent, its overall preservation effect is far inferior to the natural compound system of the present invention, and it will produce chemical residues in the fruit, which cannot meet the current consumer demand for clean labels.

[0124] Based on Examples 1-3 and Comparative Example 2, and in conjunction with Table 1, it can be seen that when lavender essential oil is used as the sole antibacterial component, it is impossible to comprehensively inhibit the growth of various spoilage microorganisms in pineapple after harvest, which leads to an increase in fruit rot rate and a significant shortening of shelf life. This indicates that the combination of lavender essential oil and cell-free supernatant of lactic acid bacteria can achieve a synergistic effect of broad-spectrum antibacterial activity.

[0125] Based on Examples 1-3 and Comparative Example 3, and in conjunction with Table 1, it can be seen that when only the cell-free supernatant of lactic acid bacteria is used as a single antibacterial component, the inhibitory effect on the main pathogenic bacteria of pineapple after harvest is limited, and the fruit is prone to rotting and spoilage. This further verifies the necessity and superiority of using two natural antibacterial components in combination.

[0126] As can be seen from Examples 1-3 and Comparative Example 4, and Table 1, when a slow-release system is lacking, the preservative components will rapidly evaporate and be lost in a short period of time, failing to maintain an effective concentration throughout the entire storage period. This results in a sharp decline in the preservation effect and a significant shortening of the shelf life, indicating that the compounded slow-release system is a key technical link in achieving long-term preservation of pineapples.

[0127] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A pineapple postharvest preservation card, comprising a carrier and preservation components loaded on the carrier, characterized in that: The preservation components, by weight, include: 0.5-2.0 parts of natural antibacterial agent, 0.3-1.0 parts of antioxidant and anti-browning agent, 1.0-3.0 parts of moisture-absorbing and water-retaining agent, 0.2-0.8 parts of slow-release agent, and 85.0-95.0 parts of solvent; the carrier is a food-grade breathable non-woven fabric, and the mass ratio of the carrier to the preservation components is 1:(2.5-4.0).

2. The pineapple post-harvest preservation card according to claim 1, characterized in that: The natural antibacterial agent is a compound of lavender essential oil and cell-free supernatant of lactic acid bacteria, wherein the mass ratio of lavender essential oil to cell-free supernatant of lactic acid bacteria is 1:(2-4); the purity of lavender essential oil is not less than 99%, and the concentration is not less than 700 μl / ml; the cell-free supernatant of lactic acid bacteria is prepared by fermentation culture of Lactobacillus plantarum CNTA600 or Pediococcus pentosaceus CNTA1059 strains, followed by centrifugation and filtration to remove bacterial cells.

3. The pineapple post-harvest preservation card according to claim 1, characterized in that: The antioxidant and anti-browning agent is a compound of vitamin C and citric acid in a mass ratio of 1:(1-1.5); the moisture-absorbing and water-retaining agent is a compound of montmorillonite and starch in a mass ratio of 1:(1-3); the slow-release agent is a compound of dextrin and sodium carboxymethyl cellulose in a mass ratio of 2:(1-3); the solvent is a compound of deionized water and edible ethanol in a mass ratio of 8:(1-2); and the preservation components also contain 0.1 to 0.3 parts of ethylene inhibitor 1-methylcyclopropene.

4. A method for preparing a pineapple post-harvest preservation card, characterized in that, A post-harvest preservation card for pineapples according to any one of claims 1-3 includes the following steps: S1. Component preparation: Weigh each raw material component and carrier according to the weight proportions, and pre-treat the natural antibacterial agent for later use; S2. Preparation of preservation liquid: Add the solvent to the mixing tank and stir at room temperature. Add the functional components in the preset order and stir until a uniform and stable preservation liquid is formed. S3, Carrier Loading: After cutting the food-grade breathable non-woven fabric into the preset size, it is completely immersed in the preservation liquid. The immersion conditions are controlled to ensure that the carrier fully and evenly absorbs the preservation liquid. S4. Drying and shaping: Take out the impregnated carrier and put it in an oven to dry in a ventilated place, controlling the moisture content of the carrier after drying; S5. Composite Packaging: The dried carrier is cut into preservation cards of a preset size and individually sealed with a biodegradable composite film to obtain the finished pineapple post-harvest preservation card.

5. The method for preparing a pineapple postharvest preservation card according to claim 4, characterized in that: In step S1, the pretreatment method for the natural antibacterial agent is as follows: inoculate *Lactobacillus plantarum* or *Pediococcus pentosaceus* into MRS medium and incubate at 37°C for 24 to 48 hours. Then, centrifuge at 5000 to 8000 r / min for 10 to 15 minutes, take the supernatant and filter it through a 0.20-0.24 μm filter membrane to remove the bacterial cells, and prepare a cell-free supernatant of lactic acid bacteria, which is then refrigerated for later use. Dilute lavender essential oil with a small amount of edible ethanol for later use.

6. The method for preparing a pineapple postharvest preservation card according to claim 4, characterized in that: In step S2, the stirring speed is 200 r / min to 300 r / min; after adding the antioxidant and anti-browning agent and the slow-release agent, stir for 10 min to 15 min until completely dissolved; after adding the natural antibacterial agent, continue stirring for 15 min to 20 min until no stratification occurs; After adding the moisture-absorbing and water-retaining agent, stir for 20 to 30 minutes.

7. The method for preparing a pineapple postharvest preservation card according to claim 4, characterized in that: In step S2, when the preservation component contains the ethylene inhibitor 1-methylcyclopropene, the ethylene inhibitor is added after the moisture-absorbing and water-retaining agent is added and the stirring is completed, and stirring is continued for 8 to 12 minutes to ensure uniform mixing.

8. The method for preparing a pineapple postharvest preservation card according to claim 4, characterized in that: In step S3, the immersion temperature is 25°C to 35°C, and the immersion time is 20 min to 30 min; the mixture is stirred every 8 min to 12 min during the immersion process; the amount of preservative adsorbed by the carrier is controlled to be 2.5 to 4.0 times the mass of the carrier itself.

9. The method for preparing a pineapple postharvest preservation card according to claim 4, characterized in that: In step S3, the food-grade breathable nonwoven fabric has a thickness of 0.1 mm to 0.2 mm, a pore size of 50 μm to 100 μm, and an air permeability of 100 ml / (cm²). 2 •min) to 150ml / (cm 2 •min); The preset size is 5cm×8cm or 6cm×10cm.

10. The method for preparing a pineapple postharvest preservation card according to claim 4, characterized in that: In step S4, the drying temperature is 45°C to 55°C, and the drying time is 10 min to 15 min; the moisture content of the carrier after drying is controlled to be 8% to 12%; the biodegradable composite film is a composite film of PVA and potato starch; the entire preparation process is carried out at room temperature and pressure, with an ambient relative humidity of 40% to 60%, avoiding direct sunlight and keeping the ambient temperature below 60°C.

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