Regulation and control method for prolonging fresh-keeping period of prunes

Abstract

The invention provides a regulation and control method for prolonging the refreshing time of prunes, which comprises the following steps: disinfecting a phase-temperature fresh-keeping storehouse for 24 hours by using absolute ethyl alcohol, and ventilating for 8-10 hours to ensure a sterile environment. During harvesting, prunes which are free of plant diseases and insect pests, free of mechanical damage, complete in fruit cream and larger than or equal to 20% in sugar content are selected, and the temperature of the prunes is rapidly reduced to 2-2.2 DEG C within 10 hours by means of portable differential pressure precooling equipment. After precooling, a methyl jasmonate aqueous solution is adopted for electrostatic atomization spraying, and 1-methylcyclopropene is used for airtight fumigation for 18-20 hours to inhibit ethylene generation and respiration. And then, storing in a phase temperature warehouse at the temperature of-1.5 to-1.2 DEG C, controlling the relative humidity to be 85-87%, and carrying out intermittent nano-atomization sterilization by using a hydrogen peroxide aqueous solution once every 15-18 days. According to the method, the fresh-keeping effect of the prunes is comprehensively improved, the safety and the quality of the fruits are ensured, and the fresh-keeping period is remarkably prolonged.

Description

Technical Field

[0001] The present invention relates to the field of fruit preservation, and more specifically, to a method for regulating and controlling the extension of the shelf life of prunes. Background Art

[0002] As a fruit that is loved by consumers, the preservation of prunes has always been the focus of the industry. In the current market environment, how to effectively extend the shelf life of prunes and ensure that they maintain good quality during storage, transportation and sales is of great significance to meeting consumer demand and improving economic benefits.

[0003] At present, some prune preservation methods have been proposed, such as patent application No. 202210592807.3, which discloses a prune cold chain logistics storage and preservation method. This method has played a certain role in the cold chain transportation and storage of prunes, but it also has some shortcomings. For example, this method uses natamycin, an antibiotic, as an antibacterial and fresh-keeping ingredient. Although it can inhibit the growth of microorganisms to a certain extent, the use of antibiotics may cause consumers to worry about food safety, and there may also be a risk of inducing microbial resistance. In addition, this method is mainly used in cold chain transportation, and the control of the storage link is relatively simple, which may not fully meet the preservation needs of prunes at different stages.

[0004] The existing methods for preserving prunes generally have the following problems: incomplete disinfection of storage warehouses can easily lead to the residue of harmful microorganisms; lax harvesting standards affect the initial quality of the fruit; the pre-cooling method is not efficient enough, making it difficult to quickly lower the temperature of the prunes to inhibit physiological metabolism; the preservation treatment measures are single and cannot fully address the various problems faced by prunes during storage, such as microbial growth and fruit aging; the sterilization treatment during storage is not accurate and continuous enough, making it difficult to effectively control the number of microorganisms in the environment.

[0005] In view of this, in order to better meet the market demand for prune preservation and overcome the shortcomings of the existing technology, it is necessary to provide a new regulation method for extending the shelf life of prunes. Summary of the invention

[0006] The purpose of the present invention is to provide a control method for extending the shelf life of prunes. The method comprehensively controls multiple links from storage disinfection, strict harvesting requirements, efficient pre-cooling, multi-step preservation treatment and precise sterilization during storage, avoids the use of antibiotics, and provides a safer, more efficient and comprehensive solution for the preservation of prunes.

[0007] In order to achieve these purposes and other advantages of the present invention, a method for regulating and controlling to prolong the shelf life of prunes is provided, comprising: Disinfection: Before storing prunes, spray the temperature-keeping warehouse with 75% to 80% anhydrous ethanol. After 24 hours of disinfection, start the circulating ventilation for 8 to 10 hours. Harvesting requirements: Harvested prunes must be free of pests and diseases, mechanical damage, and the fruit frost must remain intact, with a sugar content of ≥20%; Precooling treatment: precool the harvested prunes to 2-2.2℃, and use portable differential pressure precooling to quickly cool them to the precooling temperature for ≤10h; Electrostatic atomization spraying: After precooling, methyl jasmonate aqueous solution is used to electrostatically spray the prunes; Fumigation treatment: After electrostatic atomization spraying, use 1-methylcyclopropene to fumigate the fruit in a closed temperature warehouse for 18 to 20 hours, and then start the machine for 2 to 3 hours to allow air circulation; Storage at near-freezing temperature: The fumigated prunes are stored at near-freezing temperature in a temperature warehouse; Intermittent nano-atomization sterilization: During the storage period, hydrogen peroxide aqueous solution is used to perform intermittent nano-atomization sterilization on the environment and prunes, with the interval between each sterilization being 15 to 18 days.

[0008] Preferably, in the control method for extending the shelf life of prunes, a piece of 18 cm×25 cm fresh-keeping paper is placed in the pre-cooled prune fruit for every two kilograms of prunes; The fresh-keeping paper is obtained by soaking a sterile polypropylene nonwoven fabric in an antibacterial solution for 5 to 7 minutes, draining it, and drying it at room temperature until the moisture content is 10 to 15%; The preparation method of the antibacterial liquid comprises the following steps: After diluting the bamboo vinegar liquid to 150-250 mL / L, a bamboo vinegar dilution liquid is obtained; Add curcumin to the bamboo vinegar dilution, stir evenly, then add tea polyphenols, stir evenly; Among them, 0.03-0.07 grams of curcumin are added to each liter of bamboo vinegar dilution; Add 0.01-0.05 g of tea polyphenols to each liter of bamboo vinegar dilution.

[0009] Preferably, in the control method for extending the shelf life of prunes, the bamboo vinegar is diluted to 200 mL / L, 0.05 g of curcumin is added to each liter of the bamboo vinegar dilution; and 0.03 g of tea polyphenols is added to each liter of the bamboo vinegar dilution.

[0010] Preferably, in the control method for extending the shelf life of prunes, the concentration of the methyl jasmonate aqueous solution is 0.01 mmol / L, the atomized particle size is ≤2.0 μm, and the droplet charge-to-mass ratio is 5-8 mC / kg; the process parameters of the electrostatic atomization sprayer for post-harvest preservation of prunes are: elevator speed 12 Hz, conveyor disc rolling angle 3.0°, reversal speed 6.5 Hz, and electrostatic voltage 6-10 kV.

[0011] Preferably, in the method for extending the shelf life of prunes, the mass volume ratio of the amount of 1-methylcyclopropene to the fumigation space is 0.4-0.5 mg / m 3 .

[0012] Preferably, in the control method for extending the shelf life of prunes, the near-ice storage temperature is -1.5 to -1.2°C, the relative humidity is 85 to 87%, the volume concentration of oxygen in the phase temperature storage is 3.5 to 4%, the volume concentration of carbon dioxide is 3 to 5%, and the volume concentration of nitrogen is 85 to 90%.

[0013] Preferably, in the control method for extending the shelf life of prunes, the mass concentration of the aqueous hydrogen peroxide solution is 2-3%, and the atomized particle size is ≤1.0 μm.

[0014] The present invention has at least the following beneficial effects: 1. Comprehensively improve the preservation effect 1. Disinfection to ensure a clean storage environment: Use 75% - 80% anhydrous ethanol to spray and disinfect the phase temperature fresh-keeping warehouse and ventilate it, which can effectively kill most harmful microorganisms in the warehouse, provide a clean storage environment for prunes, reduce the risk of prunes being contaminated from the source, and lay a good foundation for subsequent preservation links.

[0015] 2. Strict harvesting requirements to ensure initial quality: It is clearly required that the harvested prunes are free of pests and diseases, mechanical damage, and the fruit frost remains intact and the sugar content is ≥20%. This ensures the high initial quality of the prunes, and the fruits are more resistant to adverse external factors, reducing the deterioration problem caused by their own defects during storage.

[0016] 3. Efficient pre-cooling inhibits physiological metabolism: Through portable pressure difference pre-cooling, the temperature of prunes can be quickly reduced to 2-2.2℃ for ≤10h, which can quickly inhibit the physiological metabolic activities such as respiration of prunes, delay fruit aging, reduce the consumption of nutrients, and maintain the freshness and taste of the fruit.

[0017] 4. Multi-link processing and coordinated preservation: 1) Electrostatic atomization spraying of methyl jasmonate, under specific concentration, atomization particle size, droplet charge-to-mass ratio and precise spraying process parameters, can evenly act on the surface of prunes, regulate the physiological process of fruits, delay aging, and maintain the firmness and color of fruits.

[0018] 2) 1-methylcyclopropene closed fumigation and uniform distribution of gas effectively inhibits ethylene synthesis, further delays the ripening process of prunes, and prolongs the shelf life.

[0019] 3) Storage at near-freezing temperature under precisely controlled temperature, relative humidity and gas composition can inhibit the physiological activities of prunes to the greatest extent and reduce the loss of water and nutrients.

[0020] 4) Intermittent nano-atomization sterilization of hydrogen peroxide aqueous solution is used to regularly disinfect the environment and prunes, effectively controlling the growth of microorganisms and preventing prunes from rotting and deteriorating due to microbial infection.

[0021] 5) Special cling paper enhances antibacterial effect: The cling paper is made of sterile polypropylene non-woven fabric soaked in antibacterial liquid containing bamboo vinegar, curcumin and tea polyphenols. The natural antibacterial ingredients work synergistically to expand the antibacterial spectrum, continuously inhibit the microorganisms on the surface of prunes, and provide additional protection for prunes.

[0022] 2. Safety and environmental protection 1. Avoid using antibiotics and other substances that may cause concern to consumers during the entire preservation process. Natural antibacterial ingredients such as bamboo vinegar, curcumin, tea polyphenols, and relatively safe substances in the field of food preservation such as methyl jasmonate and hydrogen peroxide reduce food safety risks and meet consumers' demand for green and healthy food.

[0023] 2. The anhydrous ethanol and hydrogen peroxide aqueous solution used for disinfection and sterilization of the storage environment have little impact on the environment under appropriate concentrations and usage methods.

[0024] 3. Accurate and standardized operation 1. Each operation step has clear parameters and requirements, such as disinfection time, precooling temperature and time, concentration and dosage of preservatives, temperature, humidity and gas composition of the storage environment, spraying process parameters, etc., making the entire preservation process highly operable and controllable.

[0025] 2. It is conducive to achieving standardized production and quality control, ensuring that different batches of prunes can obtain stable preservation effects, and improving the success rate and reliability of prune preservation.

[0026] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0028] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0029] The present invention provides a method for regulating and controlling to prolong the shelf life of prunes, comprising: 1. Disinfection: Before storing prunes, spray the temperature-keeping warehouse with 75% to 80% anhydrous ethanol, disinfect it for 24 hours, and then start circulating ventilation for 8 to 10 hours.

[0030] Effect: By disinfecting the storage warehouse, harmful microorganisms in the warehouse can be effectively killed, providing a clean storage environment for prunes, reducing the risk of prunes being contaminated by microorganisms during storage, and thus extending the shelf life of prunes.

[0031] 2. Harvesting requirements: The harvested prunes must be free of pests and diseases, mechanical damage, and the fruit frost must remain intact, with a sugar content ≥ 20%.

[0032] Effect: Strict harvesting requirements ensure the initial quality of prunes. The absence of pests and diseases and mechanical damage can reduce the damaged parts of the fruit and reduce the possibility of microbial invasion; complete fruit frost helps protect the fruit, reduce water loss and external pollution; high sugar content indicates that the fruit is moderately mature and nutritious, which is more conducive to storage and preservation.

[0033] 3. Pre-cooling treatment: The harvested prunes are precooled to 2-2.2℃, and portable differential pressure precooling is used to quickly cool them to the precooling temperature in ≤10h.

[0034] Effect: Quickly precooling prunes to a suitable temperature can effectively inhibit the respiration and physiological metabolic activities of the fruit, reduce the consumption of nutrients and the loss of water, delay the aging process of the fruit, and lay a good foundation for subsequent preservation treatment.

[0035] 4. Electrostatic atomization spraying: After precooling, methyl jasmonate aqueous solution was electrostatically sprayed on the prunes.

[0036] Effect: Electrostatic atomization spraying allows methyl jasmonate to evenly cover the surface of prunes, better playing its role in regulating the physiological process of fruits. Methyl jasmonate can delay the aging of fruits, maintain the firmness and color of fruits, and improve the storage quality of prunes.

[0037] 5. Fumigation treatment: After electrostatic atomization spraying, 1-methylcyclopropene is used to fumigate the fruits in a closed warehouse at the same temperature for 18 to 20 hours, and then the machine is turned on for 2 to 3 hours to allow air circulation so that 1-methylcyclopropene is fully and evenly distributed in the warehouse.

[0038] Effect: 1-methylcyclopropene can effectively inhibit the synthesis of ethylene in prunes, thereby delaying the ripening of the fruit. After closed fumigation, air circulation ensures that 1-methylcyclopropene is evenly distributed in the warehouse, so that each prune can be fully preserved and the shelf life of the prunes can be further extended.

[0039] 6. Storage near ice temperature: The fumigated prunes are stored at near-freezing temperature in a temperature warehouse.

[0040] Effect: Under precisely controlled near-ice temperature storage conditions, that is, temperature of -1.5 to -1.2°C, relative humidity of 85 to 87%, oxygen volume concentration of 3.5 to 4%, carbon dioxide volume concentration of 3 to 5%, and nitrogen volume concentration of 85 to 90%, the physiological activities of prunes can be inhibited to the greatest extent, the loss of water and nutrients can be reduced, and the freshness and taste of the fruit can be maintained.

[0041] 7. Intermittent nano-atomization sterilization: During the storage period, hydrogen peroxide aqueous solution was used to perform intermittent nano-atomization sterilization on the environment and prunes, with the interval between each sterilization being 15 to 18 days.

[0042] Effect: Intermittent nano-atomization sterilization can effectively control the number of microorganisms in the storage environment and prevent prunes from rotting and deteriorating due to microbial infection. Nano-atomization allows the hydrogen peroxide aqueous solution to be evenly distributed in the environment and on the surface of prunes, improving the sterilization effect. At the same time, the sterilization interval is controlled, which can ensure the sterilization effect without causing excessive chemical damage to the prunes.

[0043] 8. Cling film related: A piece of 18cm×25cm cling paper is placed in the pre-cooled prune fruit for every two kilograms of prune; the cling paper is prepared by soaking a sterile polypropylene non-woven fabric in an antibacterial liquid for 5 to 7 minutes, draining, and drying at room temperature until the moisture content is 10 to 15%; the preparation method of the antibacterial liquid comprises the following steps: diluting bamboo vinegar liquid to 150 to 250mL / L to obtain a bamboo vinegar dilution liquid; adding curcumin to the bamboo vinegar dilution liquid, stirring evenly, and then adding tea polyphenols, stirring evenly; wherein, 0.03 to 0.07 grams of curcumin are added to each liter of the bamboo vinegar dilution liquid; and 0.01 to 0.05 grams of tea polyphenols are added to each liter of the bamboo vinegar dilution liquid.

[0044] Effect: The special fresh-keeping paper uses sterile polypropylene non-woven fabric and antibacterial liquid containing bamboo vinegar, curcumin and tea polyphenols, which has good antibacterial properties. These natural antibacterial ingredients work synergistically to expand the antibacterial spectrum, continuously inhibit microorganisms on the surface of prunes, provide additional protection for prunes, and further extend the shelf life of prunes.

[0045] 9. Specific parameter settings and effects after optimization In order to ensure the best effect of post-harvest plum preservation, the following are the specific parameter settings and their expected effects that have been verified and optimized in detail: 1) Antibacterial liquid formula Bamboo vinegar dilution ratio: 200 mL / L Curcumin dosage: Add 0.05 g per liter of bamboo vinegar dilution Addition amount of tea polyphenols: add 0.03 g per liter of bamboo vinegar dilution Effect: Optimization of cost-effectiveness: The specific proportion of antibacterial liquid ingredients can maximize cost-effectiveness while ensuring the antibacterial effect.

[0046] Inhibit microbial growth: Experimental verification shows that the antibacterial liquid at this ratio can effectively inhibit the growth of microorganisms on the surface of prunes without adversely affecting the quality of prunes.

[0047] 2) Spraying of methyl jasmonate aqueous solution Concentration: 0.01 mmol / L Atomized particle size: ≤2.0 μm Droplet charge-to-mass ratio: 6-7 mC / kg (optimized range) Electrostatic atomization sprayer process parameters: Hoist speed: 12 Hz Conveyor plate rolling angle: 3.0° Reverse speed: 6.5 Hz Electrostatic voltage: 7-8 kV (optimized range) Coefficient of variation of spraying uniformity: ≤5% Pure hourly productivity: 350~450 kg / h Effect: Uniform and efficient coverage: Precise concentration, atomization particle size, droplet charge-to-mass ratio, and process parameter settings of the electrostatic atomization sprayer can ensure that methyl jasmonate acts evenly and efficiently on the surface of prunes, maximizing its role in regulating the physiological processes of the fruit.

[0048] Operational stability and repeatability: The setting of these parameters also ensures the stability and repeatability of the operation, which is conducive to achieving standardized preservation processing.

[0049] Reduce mechanical damage: By optimizing the transmission and spraying speed, the mechanical damage rate can be controlled to less than 3%.

[0050] 3) 1-Methylcyclopropene fumigation Dosage: Space mass volume ratio is 0.4~0.5 mg / m³ Effect: Delaying the ripening process: The appropriate dosage ratio of 1-methylcyclopropene can effectively inhibit ethylene synthesis, delay the ripening process of prunes, and avoid the adverse effects that may be caused by excessive dosage.

[0051] Stable and reliable: Precise mass-to-volume ratio control ensures stable and reliable fumigation treatment results.

[0052] 4) Storage conditions near freezing temperature Temperature: -1.5~-1.2℃ Relative humidity: 85-87% Gas composition: Oxygen: 3.5-4% Carbon dioxide: 3-5% Nitrogen: 85-90% Effect: Optimal storage environment: The precise near-ice temperature storage condition parameter setting creates the best storage environment for prunes. In this environment, the physiological activities of prunes can be suppressed to the greatest extent, and the loss of water and nutrients is minimized, thereby extending the shelf life of prunes and maintaining the high quality of the fruit.

[0053] 5) Sterilization with hydrogen peroxide solution Mass concentration: 2-3% Atomized particle size: ≤1.0 μm Effect: Efficient and safe sterilization: Appropriate mass concentration of hydrogen peroxide aqueous solution and small particle size atomization can ensure good sterilization effect while reducing chemical damage to prunes.

[0054] Strong guarantee: Precise parameter control makes the sterilization process more efficient and safer, providing strong guarantee for the preservation of prunes.

[0055] 6) Humidity of cling film The humidity control of the cling film is crucial to the preservation of prunes. The ideal humidity should ensure that the cling film can effectively inhibit bacteria, but will not cause moisture to condense on the surface of the fruit due to excessive humidity, thus causing problems such as mold.

[0056] The best range of humidity for cling film Moisture content: 10-15% Reasons and Effects Inhibits microbial growth: Maintaining proper humidity (10-15%) can activate the ingredients in the antibacterial solution (such as bamboo vinegar, curcumin and tea polyphenols) and enhance its antibacterial properties.

[0057] Too low humidity may weaken the activity of these ingredients and affect the antibacterial effect; while too high humidity may promote the reproduction of microorganisms.

[0058] Prevent excessive water loss: Appropriate humidity helps slow down the evaporation of water inside the prunes, maintaining the firmness and taste of the fruit.

[0059] If the humidity is too low, the plastic wrap may absorb too much moisture from the fruit, causing the fruit to lose water and wilt; conversely, too high humidity may cause condensation to form, increasing the risk of mold.

[0060] Protect the fruit surface: A moisture content of 10-15% can make the cling film soft and not easy to break, better fit the surface of the fruit, provide a physical barrier and reduce mechanical damage.

[0061] At the same time, this humidity level also prevents the plastic wrap from being too wet and sticking to the surface of the fruit, causing unnecessary damage.

[0062] Operational convenience: Cling paper that has been dried to a moisture content of 10-15% at room temperature is easier to handle and use. It is neither too wet to be difficult to operate nor too dry to become brittle and fragile.

[0063] Preparation method Soaking time: Soak the sterile polypropylene nonwoven fabric in the antibacterial solution for 5 to 7 minutes to ensure that the antibacterial components are fully absorbed.

[0064] Drain and dry: After draining, dry naturally at room temperature until the moisture content reaches 10-15%. The moisture content can be monitored by regular weighing or using a hygrometer to ensure that the optimal humidity range is reached.

[0065] Practical application suggestions Regular inspection: In actual application, the humidity of the cling film should be checked regularly to ensure that it is always within the ideal range. If the humidity is found to be too high or too low, the preparation process or storage conditions should be adjusted in time.

[0066] Environmental control: The environment for storing and using cling film should maintain constant temperature and humidity as much as possible to avoid the influence of external factors on the humidity of cling film.

[0067] In summary, controlling the moisture content of cling film between 10% and 15% can maximize the protection of the quality of prunes and extend their shelf life while ensuring the antibacterial effect. This humidity level is not only conducive to the function of cling film, but also ensures the convenience and safety of operation.

[0068] Summarize Through the above optimization measures, the effect of post-harvest fresh-keeping of prunes can be significantly improved: Enhanced effect: Ensure that the key ingredients and parameters in each processing step are optimized to maximize their functions.

[0069] Improve operational stability: The optimized parameters ensure operational stability and repeatability, which is conducive to achieving standardized fresh-keeping processing.

[0070] Protect fruit quality: By precisely controlling each processing link, potential damage to the fruit is reduced, ensuring high fruit quality.

[0071] Maximization of economic benefits: Reasonable selection and adjustment of parameters achieves optimization of cost-effectiveness and improves the economic feasibility of the overall treatment.

[0072] These improvements not only improve the post-harvest preservation of prunes, but also provide solid technical support for large-scale industrial applications.

[0073] Experimental Results In order to evaluate the effect of the method for extending the shelf life of prunes of the present invention, comparative experiments of Examples 1 to 10 and Comparative Examples 1 to 3 were conducted. The following is a detailed experimental design, implementation steps and result analysis.

[0074] Experimental conditions and sample processing Experimental Subjects: Freshly harvested prune (Prunus virginiana) fruits.

[0075] Experimental environment: All experiments were conducted under the same initial conditions, including temperature, humidity, etc.

[0076] Experimental period: 40 days.

[0077] Example 1 Processing steps: Disinfection: Use 75% anhydrous ethanol to spray and disinfect the phase temperature fresh-keeping warehouse to ensure a sterile environment. After 24 hours, turn on the circulating ventilation system for 9 hours to remove residual ethanol gas.

[0078] Harvesting and pre-cooling: Choose high-quality prunes, that is, those without pests and diseases, mechanical damage, complete fruit frost, and sugar content of not less than 20%. Use portable differential pressure pre-cooling equipment to quickly cool the harvested prunes to 2.0℃, and the pre-cooling time is strictly controlled within 10 hours.

[0079] Electrostatic atomization spraying: After precooling, electrostatic atomization spraying is performed using a 0.01 mmol / L aqueous solution of methyl jasmonate. By precisely controlling the atomized particle size (≤2.0 μm) and the droplet charge-to-mass ratio (6 mC / kg), combined with optimized electrostatic atomization spraying machine process parameters, a uniform and efficient spraying effect is achieved.

[0080] 1-Methylcyclopropene fumigation: After electrostatic atomization spraying, the prunes were immediately placed in a temperature chamber for 1-methylcyclopropene closed fumigation. By precisely controlling the fumigation time (19 hours) and the amount of 1-methylcyclopropene (space mass volume ratio 0.45 mg / m³), the ethylene production and respiration of the fruit were effectively inhibited.

[0081] Near-freezing temperature storage: The fumigated prunes are placed in a phase temperature warehouse at -1.5℃ for near-freezing temperature storage, and the relative humidity is controlled at 86%, and the gas composition in the phase temperature warehouse (oxygen volume concentration 3.75%, carbon dioxide volume concentration 4%, nitrogen volume concentration 88.25%). Intermittent nano-atomization sterilization is performed every 16 days using a 2.5% mass concentration of hydrogen peroxide aqueous solution.

[0082] Experimental results: Shelf life: about 30 days.

[0083] Quality changes: The fruit remains firm and delicious, with almost no mold or rot.

[0084] Commerciality: The fruit has excellent appearance and taste, high commerciality and high market acceptance.

[0085] Example 2 On the basis of Example 1, the following steps are added: A piece of 18cm×25cm cling film was placed in the pre-cooled prunes for every two kilograms of prunes. The cling film was made of sterile polypropylene nonwoven fabric, which was soaked in antibacterial liquid for 6 minutes, drained, and dried at room temperature until the moisture content was 35%. The antibacterial liquid was made of bamboo vinegar diluted to 200 mL / L, with 0.05g of curcumin and 0.03g of tea polyphenols added per liter.

[0086] Experimental results: Shelf life: about 35 days.

[0087] Quality changes: The fruit firmness is more stable, the taste is more delicious, and there is almost no mold or rot.

[0088] Commerciality: The fruit has excellent appearance and taste, extremely high commerciality, and very high market acceptance.

[0089] Moisturizing effect: The use of plastic wrap slows down the loss of water in the fruit and maintains the firmness and taste of the fruit.

[0090] Example 3 to Example 10 The only difference from Example 2 is the antibacterial solution formula. The antibacterial solution formulas of Examples 3 to 10 are shown in Table 1.

[0091] Table 1 Antibacterial liquid formula of Example 3 to Example 10 Summary of experimental results: Example 3: The shelf life is about 33 days, the quality changes well, and the commercial value is high.

[0092] Example 4: The shelf life is about 34 days, the quality changes well, and the commercial quality is high.

[0093] Example 5: The shelf life is about 34 days, the quality changes well, and the commercial value is high.

[0094] Example 6: The shelf life is about 34 days, the quality changes well, and the commercial value is high.

[0095] Example 7: The shelf life is about 34 days, the quality changes well, and the commercial value is high.

[0096] Example 8: The shelf life is about 34 days, the quality changes well, and the commercial value is high.

[0097] Example 9: The shelf life is about 34 days, the quality changes well, and the commercial value is high.

[0098] Example 10: The shelf life is about 34 days, the quality changes well, and the commercial value is high.

[0099] Comparative Example 1: Traditional cold chain transportation and storage methods Processing steps: Choose prune fruits that are free of pests and diseases, mechanical damage, and have intact frost.

[0100] After the prunes are naturally air-dried at room temperature, they are placed in an ordinary refrigerator and precooled to 0°C for 24 hours.

[0101] Use ordinary cold chain transportation methods, ensure that the transportation temperature remains between 2 and 5°C, and the transportation time does not exceed 24 hours.

[0102] After arriving at the destination, the prunes are placed in an ordinary cold storage, the temperature is controlled at 3-5°C, and the humidity is maintained between 90-95%.

[0103] No additional sterilization measures were used.

[0104] Experimental results: Shelf life: about 10 days.

[0105] Quality changes: The hardness of the fruit decreased significantly, the taste deteriorated, and some fruits showed slight mold.

[0106] Commercial quality: The fruit has poor appearance, reduced overall commercial quality and low market acceptance.

[0107] Comparative Example 2: Method according to patent application number 202210592807.3 Processing steps: After being harvested, the 80%-ripe prune fruits were placed in a closed space and fumigated with 20 μmol / L methyl jasmonate for 3 hours.

[0108] Place the naturally air-dried prunes in a portable box, put an ice box in the box, and add 1-MCP preservative powder (one bag of 0.3g 1-MCP for every 4.0-5.0kg of prunes) to ensure that the fruits are transported to the target city within 24 hours.

[0109] After arrival, put it in a 0℃ cold storage for pre-cooling in time. The specific pre-cooling time is based on the surface temperature of the fruit reaching 0℃.

[0110] Place 18cm×25cm natamycin antibacterial cling paper in the fully pre-cooled prunes, two sheets for every 4.0-5.0kg of prunes.

[0111] Entering the low-temperature storage stage, the temperature is controlled at 3-5°C and the humidity is maintained between 90-95%.

[0112] Experimental results: Shelf life: about 15 days.

[0113] Quality changes: The hardness of the fruit is improved compared with that of comparative example 1, but some fruits still have the phenomenon of fruit frost loss and reduced taste.

[0114] Commerciality: The appearance and taste of the fruit are better than those of Comparative Example 1, but there is still a certain quality decline problem, and the market acceptance is medium.

[0115] Comparative Example 3 Compared with Comparative Example 2, the improvements are as follows: After being fully pre-cooled, 18cm×25cm cling paper is placed in the prunes, two sheets for every 4.0-5.0kg of prunes. The cling paper is made of sterile polypropylene nonwoven fabric, which is soaked in antibacterial liquid for 6 minutes, drained, and dried at room temperature to a moisture content of 35%. The antibacterial liquid is composed of bamboo vinegar diluted to 200 mL / L, 0.05g of curcumin and 0.03g of tea polyphenols per liter.

[0116] The rest is the same as Example 2.

[0117] Experimental results: Shelf life: about 20 days.

[0118] Quality changes: The fruit firmness is maintained well, the taste is improved compared with comparative example 2, and the fruit frost loss is reduced.

[0119] Commercial properties: The appearance and taste of the fruit are better than those of comparative example 2, and the market acceptance is relatively high.

[0120] It can be seen from the above experimental results that the optimal condition regulation method provided by the present invention has significant advantages, especially Example 2 performs the best: Significantly extend the shelf life: Compared with the traditional cold chain transportation and storage method (Comparative Example 1) and the existing technology (Comparative Example 2), the method of the present invention can significantly extend the shelf life of prunes from about 10 days to 35 days.

[0121] Improved quality: Example 2 not only extends the shelf life, but also significantly improves the quality of prunes, including fruit hardness, taste and appearance, making the fruit more commercially available and nutritious.

[0122] Environmental friendliness: The present invention adopts a variety of natural ingredients (such as bamboo vinegar, curcumin and tea polyphenols), reduces the use of chemical substances, and is more environmentally friendly and healthy.

[0123] Easy to operate: The invention is easy to operate, easy to implement and control, relatively low in cost, and suitable for large-scale commercial applications.

[0124] Moisturizing effect: The fresh-keeping paper introduced in Example 2 not only enhances the antibacterial effect, but also plays a moisturizing role, further slowing down the water loss of the fruit and maintaining the hardness and taste of the fruit.

[0125] In addition, Comparative Example 3 also showed better results than Comparative Example 2, indicating that the application of the antibacterial liquid formula and the cling film can indeed significantly improve the preservation effect and quality of prunes.

[0126] The experimental summary is shown in Table 2.

[0127] Table 2 Experimental summary Through the above experimental results, it can be clearly seen that the optimal condition regulation method provided by the present invention has significant advantages in extending the shelf life of prunes and improving the quality of fruits, especially Example 2 performs well in many aspects, showing its great potential in practical applications. This shows that the present invention not only has a scientific basis in theory, but also has extremely high feasibility and superiority in practice.

[0128] The effect of Example 2 is better than that of Examples 6, 7, 9, and 10, mainly due to the following key factors: 1. Balance of antibacterial liquid ingredients In Example 2, the antibacterial liquid formula used is bamboo vinegar diluted to 200 mL / L, with 0.05 g of curcumin and 0.03 g of tea polyphenols added per liter. The ratio of each component in this formula has been optimized, which can effectively inhibit the growth of microorganisms and extend the shelf life without causing negative effects on the fruit.

[0129] Bamboo vinegar: has good antibacterial properties and can effectively inhibit mold and other pathogens.

[0130] Curcumin: As a natural antioxidant, it not only has antibacterial effects, but also can enhance the fruit's resistance to stress.

[0131] Tea polyphenols: They also have antioxidant and antibacterial properties, helping to maintain the freshness of the fruit.

[0132] 2. Suitability of ingredient concentration Although similar combinations of ingredients are used in Examples 6, 7, 9, and 10, the concentrations of some ingredients are changed. For example: Example 6: The curcumin concentration was increased to 0.06 g / L, which may have exceeded the optimal concentration range, resulting in its effect being inferior to that of Example 2.

[0133] Example 7: The curcumin content was further increased to 0.07 g / L. Too high a concentration may have an adverse effect on the fruit surface or produce adverse interactions with other ingredients.

[0134] Example 9: The tea polyphenols were increased to 0.04 g / L, which may have changed the overall chemical properties of the antibacterial solution and thus affected its efficacy.

[0135] Example 10: Tea polyphenols increased to 0.05 g / L. Similarly, higher concentrations may cause unwanted side effects or reduce the effectiveness of other ingredients.

[0136] These slight changes may affect the overall performance of the antibacterial solution, making their effects less ideal than those in Example 2.

[0137] 3. Best match of comprehensive effects In Example 2, the ratio of the three ingredients (bamboo vinegar, curcumin, and tea polyphenols) reached an optimal balance point, which not only enhanced the antibacterial effect, but also avoided the potential problems caused by excessive concentration. In addition, the use of cling film also played a role in moisturizing and continuously releasing antibacterial ingredients, further improving the overall fresh-keeping effect.

[0138] 4. Experimental results verification Through actual experiments, it can be observed that the prunes of Example 2 have better hardness, taste and appearance during the shelf life, and almost no mold or rot, and have very high commercial value and market acceptance. Although other examples also have good performance, they are slightly inferior in some aspects such as the length of the shelf life and the quality of the fruit.

[0139] in conclusion In summary, the reason why Example 2 showed better effects was that it achieved an optimal balance in the selection of antibacterial liquid components and the setting of concentrations, ensuring the maximization of the synergistic effect between the components while also avoiding the negative effects caused by too high or too low concentrations. This optimized configuration made Example 2 perform well in extending the shelf life of prunes and maintaining fruit quality, becoming the best choice among all experimental groups.

[0140] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A method for extending the shelf life of prunes, characterized in that: include: Disinfection: Before storing prunes, spray the temperature-keeping warehouse with 75% to 80% anhydrous ethanol. After 24 hours of disinfection, start the circulating ventilation for 8 to 10 hours. Harvesting requirements: Harvested prunes must be free of pests and diseases, mechanical damage, and the fruit frost must remain intact, with a sugar content of ≥20%; Precooling treatment: precool the harvested prunes to 2-2.2℃, and use portable differential pressure precooling to quickly cool them to the precooling temperature for ≤10h; Electrostatic atomization spraying: After precooling, methyl jasmonate aqueous solution is used to electrostatically spray the prunes; Fumigation treatment: After electrostatic atomization spraying, use 1-methylcyclopropene to fumigate the fruit in a closed temperature warehouse for 18 to 20 hours, and then start the machine for 2 to 3 hours to allow air circulation; Storage at near-freezing temperature: The fumigated prunes are stored at near-freezing temperature in a temperature warehouse; Intermittent nano-atomization sterilization: During the storage period, hydrogen peroxide aqueous solution is used to perform intermittent nano-atomization sterilization on the environment and prunes, with the interval between each sterilization being 15 to 18 days.

2. The method for extending the shelf life of prunes according to claim 1, characterized in that: Place a piece of 18cm×25cm plastic wrap for every 2kg of prunes after precooling; The fresh-keeping paper is obtained by soaking a sterile polypropylene nonwoven fabric in an antibacterial solution for 5 to 7 minutes, draining it, and drying it at room temperature until the moisture content is 10 to 15%; The preparation method of the antibacterial liquid comprises the following steps: After diluting the bamboo vinegar liquid to 150-250 mL / L, a bamboo vinegar dilution liquid is obtained; Add curcumin to the bamboo vinegar dilution, stir evenly, then add tea polyphenols, stir evenly; Among them, 0.03-0.07 grams of curcumin are added to each liter of bamboo vinegar dilution; Add 0.01-0.05 g of tea polyphenols to each liter of bamboo vinegar dilution.

3. The method for extending the shelf life of prunes according to claim 2, characterized in that: Dilute the bamboo vinegar to 200mL / L, add 0.05g of curcumin per liter of bamboo vinegar dilution; add 0.03g of tea polyphenols per liter of bamboo vinegar dilution.

4. The method for extending the shelf life of prunes according to claim 1, characterized in that: The concentration of methyl jasmonate aqueous solution is 0.01mmol / L, the atomized particle size is ≤2.0μm, and the droplet charge-to-mass ratio is 5-8mC / kg; the process parameters of the electrostatic atomization sprayer for post-harvest fresh-keeping of plums are: elevator speed 12HZ, conveyor disc rolling angle 3.0°, reversing speed 6.5HZ, and electrostatic voltage 6-10kV.

5. The method for extending the shelf life of prunes according to claim 1, characterized in that: The mass volume ratio of 1-methylcyclopropene to the fumigation space is 0.4-0.5 mg / m 3 .

6. The method for extending the shelf life of prunes according to claim 1, characterized in that: The near-freezing storage temperature is -1.5 to -1.2°C, the relative humidity is 85 to 87%, the volume concentration of oxygen in the phase temperature warehouse is 3.5 to 4%, the volume concentration of carbon dioxide is 3 to 5%, and the volume concentration of nitrogen is 85 to 90%.

7. The method for extending the shelf life of prunes according to claim 1, characterized in that: The mass concentration of the hydrogen peroxide aqueous solution is 2-3%, and the atomized particle size is ≤1.0 μm.

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