Low-carbon fresh-keeping packaging method for litchi at room temperature

Abstract

The application relates to the technical field of fruit fresh-keeping storage, and discloses a low-carbon fresh-keeping litchi normal-temperature storage and transportation packaging method, which comprises the following steps: (1) pretreatment: picking fresh litchis for screening, and then precooling, and precooling to a core temperature of 0-15 DEG C; (2) packaging: performing e-commerce packaging in an operation room at 15-20 DEG C, first putting phase change cold accumulators with a mass ratio of 1:4-6 to the litchis into the bottom of an aluminum foil heat preservation bag, then putting a bacteriostatic fresh-keeping water absorption pad into the aluminum foil heat preservation bag, and then putting the pretreated fresh litchis into the aluminum foil heat preservation bag, and finally sealing the aluminum foil heat preservation bag, and putting the sealed aluminum foil heat preservation bag into a foaming box made of polypropylene plastic foaming material, and sealing the foaming box, and the outer layer being a common paper box with a trademark; the bacteriostatic fresh-keeping water absorption pad contains a water absorption and bacteriostasis compound (3) transportation; the packaging method has the functions of temperature control, bacteriostasis and drying and air permeation, can effectively preserve the litchis, is low-carbon and environment-friendly, simple and efficient, and has strong popularization.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fruit storage, and particularly relates to a low-carbon fresh-keeping litchi normal-temperature storage and transportation packaging method. BACKGROUND

[0002] Litchi is a representative fruit in tropical and subtropical regions, rich in various vitamins, minerals and carbohydrates, and is loved by consumers due to its rich nutrition and sweet taste. However, postharvest litchi is prone to rotting, browning and pathogenic infection, which seriously affects its shelf life and market value. E-commerce logistics is the most important sales mode, which connects supply and demand, reduces intermediate links, and has the advantages of wide sales range and high profit. However, only about 10% of litchi is sold through e-commerce logistics, and the main problems are as follows: 1) litchi is sold in a concentrated period, is prone to rotting and browning, and is difficult to sell over a long distance; 2) the cold chain infrastructure is poor, and the cold chain express cost is high, so the income is difficult to guarantee; 3) the current cold storage and transportation equipment is mainly mechanical refrigerated vehicles, which are not only economical and environmentally friendly, but also may have the phenomenon of “large vehicles transporting small goods”. Therefore, it is particularly important to maintain the storage temperature of food during transportation through other means. At present, the transportation mode used by litchi e-commerce logistics is mainly foam box plus ice, but there are still the following problems: 1) the ice or ice bag (cold accumulator) is not used in a standardized manner, and the fruits near the ice bag are prone to freezing injury and rotting; 2) the weight of the ice bag occupies the actual transportation weight and transportation space of the fruits, increasing the transportation cost. In view of the above problems, the actual transportation environment is considered, and a composite fresh-keeping technology is used to develop a litchi e-commerce logistics cold accumulator with high latent heat, good heat conduction, no corrosion, good circulation performance, long-term cold storage and environmental protection requirements, so as to realize long-distance sales of litchi through e-commerce logistics at normal temperature, effectively reduce the transportation cost, improve the quality of litchi fruits, and promote the sales proportion of litchi through e-commerce logistics, and realize the increase of litchi production and income. SUMMARY

[0003] In view of the above problems, the purpose of the present application is to provide a low-carbon fresh-keeping litchi normal-temperature storage and transportation packaging method.

[0004] The technical content of the present application is as follows:

[0005] The present application provides a low-carbon and universal litchi e-commerce logistics normal-temperature storage and transportation mode and method, and the steps include:

[0006] (1) Fruit pretreatment: picking fresh litchi for screening, and then precooling to a fruit core temperature of 0-15℃;

[0007] The precooling temperature is set to 10-15℃; if the precooling temperature is too low, the litchi is prone to browning during e-commerce logistics, and if the precooling temperature is too high, the litchi produces more water vapor accumulation due to respiratory heat;

[0008] (2) Packaging: packaging is carried out in the operating room at 15-20℃, first put the phase change cold storage agent with a mass ratio of 1:4-6 to litchi into the bottom of the aluminum foil heat preservation bag, then put the bacteriostatic fresh-keeping water absorption pad, then put the pretreated fresh litchi, seal the aluminum foil heat preservation bag, and then put it into the foam box of polypropylene plastic foaming material for sealing;

[0009] The bacteriostatic fresh-keeping water absorption pad comprises three layers, the upper layer is water-permeable non-woven fabric, the middle layer is a water-absorbing bacteriostatic compound, and the lower layer is a water-impermeable film.

[0010] The formula of the composite phase change cold storage agent is 0.4-0.6% gellan gum, 0.8-1.2% xanthan gum, 0.8-1.2% erythritol, 0.8-1.2% sodium alginate, 2-4% glycerol, 0.8-1.2% NH4Cl, 0.8-1.2% KCl, 0.1-0.3% potassium sorbate, 0.8-1.2% Al2O3 nanoparticles, and the rest is deionized water.

[0011] The phase change temperature of the composite phase change cold storage agent is 0-4℃, the phase change latent heat is 130-138J / kg, there is no supercooling and phase separation phenomenon; it can release energy for a long time, keep the packaging environment at a relatively low temperature, inhibit respiration and rot, and has a long-term cold storage effect;

[0012] The preparation method of the composite phase change cold storage agent is to heat glycerol, NH4Cl, KCl, sodium alginate, and composite nanoparticles and water in a water bath at 40-50℃ for 40-50min, then add the remaining components and stir uniformly, and then perform ice bath at 0-3℃ for 30-40min to obtain the composite phase change cold storage agent.

[0013] The composite nanoparticles are obtained by mixing Al2O3 nanoparticles and nano-titanium dioxide with a mass ratio of 3:1-3; the added composite nanoparticles have a large specific surface area, can promote the non-uniform nucleation of hydrates, and the synergistic effect of the two kinds of nanoparticles can improve the energy storage density and thermal conductivity.

[0014] The water-absorbing bacteriostatic compound is prepared by adding 10-15wt% of modified β-cyclodextrin to 11-15:21-27 of activated carbon and zeolite as wall material, compounding lemon grass essential oil and eucalyptus essential oil with a mass ratio of 1:1-3 as core material, embedding the wall material and core material with a mass ratio of 10:1, and then freeze-drying.

[0015] The preparation of the modified beta-cyclodextrin is that beta-cyclodextrin is added into an olefin anhydride at a mass ratio of 11-14:1-3, then stirred for 40-50 min, the pH is adjusted to 5-7, then 10-20 wt% of a sodium silicate solution is added, then high-speed stirring is carried out at 3000-4000 rpm for 10-20 min, and then heating is carried out at 70-80 DEG C for 8-12 min; the anhydride can improve the cationic performance and introduce a hydrophobic group; the sodium silicate solution cooperates with high-speed stirring to increase the cavity structure of the cyclodextrin and improve the inclusion action thereof.

[0016] The heat treatment is heating at a pressure of 3-6 MPa and a temperature of 90-100 DEG C for 3-5 h.

[0017] The water absorption and bacteriostasis compound can slowly release orange flower alcohol, linalool, citronellal and the like during transportation to inhibit the growth of microorganisms in the packaging bag, and due to the moderate release rate, the fruit peel is not damaged; the activated carbon and the zeolite can adsorb carbon dioxide gas generated by the respiration of the fruit, reduce the anaerobic respiration of the fruit, and reduce the generation of peculiar smell substances and rot; the bacteriostasis and preservation pad can effectively isolate the fruit from direct contact with the cold storage agent to avoid freezing injury to the fruit.

[0018] The aluminum foil heat preservation bag is an aluminum foil bag with a pearl cotton inner layer, and the pearl cotton inner layer is coated with a high molecular waterproof layer with a thickness of 2-4 mm.

[0019] The coating mode of the high molecular waterproof layer is that a hydroxyl resin and a hydroxyl silicone oil are mixed and coated on the pearl cotton at a mass ratio of 1:0.1-0.4, and the pearl cotton inner layer is formed by a hot press machine together with hot melt adhesive and cold non-woven fabric; the hydroxyl silicone oil can improve the water resistance, antibacterial property and mechanical property of the resin with a hydroxyl group, the high molecular waterproof layer can be stacked in a large size in the cotton fiber and has water absorption and oxygen isolation capacity; the cold non-woven fabric has water permeability and air permeability, is easy to dry, does not accumulate water, and reduces the rot of the contact surface between the fruit and the packaging bag.

[0020] The main material of the foam box is polypropylene plastic foaming material, and the wall thickness is greater than or equal to 20 mm.

[0021] (3) finally, a common paper box is loaded, and transportation is carried out.

[0022] The beneficial effects of the present application are as follows:

[0023] The application provides a low-carbon fresh-keeping litchi normal-temperature storage and transportation method, which comprises the following steps: pretreating litchi, and then performing fresh-keeping packaging on the litchi by using a packaging material containing phase change cold storage agent, bacteriostatic fresh-keeping water absorption pad and aluminum foil heat preservation bag, wherein the phase change cold storage agent contains expanded loose components, can load nanoparticles for synergistic effect, can effectively promote hydrate nucleation, has good mass transfer performance, has high thermal conductivity, and has high temperature regulation capacity; the bacteriostatic fresh-keeping water absorption pad contains a water absorption and bacteriostasis composite, and the water absorption and bacteriostasis composite is prepared by compounding modified beta-cyclodextrin and porous materials and loading essential oils; the aluminum foil heat preservation bag is coated with a high molecular waterproof layer, can absorb the water vapor generated by respiration of litchi in the bag and condensed water, and can increase the air permeability of the pearl wool and reduce the rot rate of the fruits; the packaging method has the functions of temperature control, bacteriostasis and drying and air permeability, can effectively preserve litchi, is low-carbon and environmentally friendly, simple and efficient, and has strong popularization. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The application discloses a packaging method for litchi. DETAILED DESCRIPTION

[0025] The application will be further described in detail through specific implementation examples and the accompanying drawings, and it should be understood that the examples are only used for describing the application and are not used for limiting the protection scope of the application, and various equivalent modifications of the application made by those skilled in the art after reading the application all fall within the scope defined by the claims of the application.

[0026] Unless otherwise specified, all raw materials and reagents of the application are conventional market raw materials and reagents.

[0027] The application discloses a packaging method for litchi. Figure 1

[0028] Example 1

[0029] A low-carbon and universal litchi e-commerce logistics normal-temperature storage and transportation mode and method, the steps of which comprise:

[0030] (1) Fruit pretreatment: picking fresh JG red glutinous litchi for selection, and then precooling in a cold storage, and precooling to a fruit core temperature of less than or equal to 15 DEG C; the precooling temperature is set to 13 DEG C;

[0031] (2) Packaging: packaging in an 18 DEG C operation room, first putting phase change cold storage agent with a mass ratio of 1:5 with respect to the litchi in the bottom of an aluminum foil heat preservation bag, then putting a bacteriostatic fresh-keeping water absorption pad, and then putting the pretreated fresh litchi, sealing the aluminum foil heat preservation bag, and then putting the sealed aluminum foil heat preservation bag into a polypropylene plastic foaming material foam box for sealing;

[0032] ​The preparation method of the composite phase change cold storage agent is that 3% glycerol, 1.0% NH4Cl, 1.0% KCl, 1.0% sodium alginate, 1.0% composite nanoparticles obtained by mixing Al2O3 nanoparticles and nanometer titanium dioxide at a mass ratio of 3:2, and 91.3% water are heated in a water bath at 45 DEG C for 45 min, then 1.0% xanthan gum, 0.5% gellan gum and 0.2% potassium sorbate are added and stirred uniformly, and then ice bath is carried out at 2 DEG C for 35 min to obtain;

[0033] The antibacterial and fresh-keeping water absorption pad comprises three layers, the upper layer is a water-permeable non-woven fabric, the middle layer is a water-absorbing and antibacterial composite, and the lower layer is a water-impermeable film; the water-absorbing and antibacterial composite is prepared by adding 13 wt% of modified β-cyclodextrin to active carbon and zeolite at a mass ratio of 13:24 for heat treatment to prepare a wall material, compounding lemon grass essential oil and eucalyptus essential oil at a mass ratio of 1:2 to form a wall core, embedding the wall material and the wall core at a mass ratio of 10:1, and then freeze-drying to obtain the water-absorbing and antibacterial composite; the preparation of the modified β-cyclodextrin comprises the following steps: adding olefin anhydride to β-cyclodextrin at a mass ratio of 11-14:1-3 and stirring for 45 min, adjusting the pH to 6, adding 15 wt% of a sodium silicate solution, stirring at a high speed of 3500 rpm for 15 min, and then heating at 75 DEG C for 10 min; the heat treatment is carried out at a pressure of 5 MPa and a temperature of 95 DEG C for 4 h;

[0034] The main material of the aluminum foil heat preservation bag is an aluminum foil bag with a pearl cotton inner layer, and the pearl cotton inner layer is coated with a high molecular waterproof layer with a thickness of 3 mm; the coating method of the high molecular waterproof layer is that hydroxyl resin and hydroxyl silicone oil are mixed at a mass ratio of 1:0.3 and coated on the pearl cotton, and the pearl cotton inner layer is formed by hot pressing the hot melt adhesive and the cold non-woven fabric through a hot press; the main material of the foam box is polypropylene plastic foaming material, and the wall thickness is greater than or equal to 20 mm;

[0035] (3) Finally, a common paper box is loaded. The packed lichis are placed at 25 DEG C for one week, and the results show that the fruits are less browned in the first 3 days, a small amount of fruits are browned in 7 days, there is no mildewed fruit, and no rot phenomenon, and the appearance is good.

[0036] Example 2

[0037] A low-carbon and universal litchi e-commerce logistics normal-temperature storage and transportation mode and method, the steps of which include:

[0038] (1) Fruit pretreatment: picking fresh "Jingganghongnu" lichis for screening, and then precooling in a cold storage, and precooling to a fruit core temperature of less than or equal to 12 DEG C; the precooling temperature is set to 10 DEG C;

[0039] (2) Packaging: Packaging was carried out in an operating room at 15℃. First, phase change cold accumulators with a mass ratio of 1:4 to litchi were placed at the bottom of an aluminum foil heat preservation bag, then a bacteriostatic fresh-keeping water absorption pad was placed, followed by the pre-processed fresh litchi, the aluminum foil heat preservation bag was sealed, and then the foam box of polypropylene plastic foaming material was sealed;

[0040] The preparation method of the composite phase change cold accumulator is as follows: 2% glycerol, 0.8% NH4Cl, 0.8% KCl, 0.8% sodium alginate, 0.8% composite nanoparticles obtained by mixing Al2O3 nanoparticles and nanometer titanium dioxide with a mass ratio of 3:1, and 93.5% water are heated in a water bath at 40℃ for 40min, then 0.8% xanthan gum, 0.4% gellan gum and 0.1% potassium sorbate are added and stirred uniformly, and then ice bath is carried out at 0℃ for 30min to obtain the composite phase change cold accumulator;

[0041] The bacteriostatic fresh-keeping water absorption pad comprises three layers, the upper layer is a water-permeable non-woven fabric, the middle layer is a water-absorbing bacteriostatic composite, and the lower layer is a water-impermeable film. The water-absorbing bacteriostatic composite is prepared by adding 10wt% modified β-cyclodextrin to active carbon and zeolite with a mass ratio of 11:21, heat treating to prepare a wall material, compounding lemon grass essential oil and eucalyptus essential oil with a mass ratio of 1:1 as a wall core, embedding the wall material and the wall core with a mass ratio of 10:1, and then freeze-drying to obtain the water-absorbing bacteriostatic composite. The modified β-cyclodextrin is prepared by adding olefinic anhydride to β-cyclodextrin with a mass ratio of 11:1 and stirring for 40min, adjusting the pH to 5, adding 10wt% sodium silicate solution, stirring at 3000rpm for 10min, and then heating at 70℃ for 8min. The heat treatment is carried out at a pressure of 3MPa and a temperature of 90℃ for 3h.

[0042] The main material of the aluminum foil heat preservation bag is an aluminum foil bag with a pearl cotton inner layer, and the pearl cotton inner layer is coated with a high molecular waterproof layer with a thickness of 2mm. The coating method of the high molecular waterproof layer is as follows: hydroxyl resin and hydroxyl silicone oil are mixed with a mass ratio of 1:0.1 and coated on the pearl cotton, and then the pearl cotton inner layer is formed by hot pressing the hydroxyl resin and hydroxyl silicone oil, hot melt adhesive and cold non-woven fabric. The main material of the foam box is polypropylene plastic foaming material with a wall thickness of ≥20mm.

[0043] (3) Finally, a common paper box is loaded. The packaged litchi is placed at 25℃ for one week, and the results show that the fruit is less brown in the first 3 days, and a small amount of fruit is brown in 7 days, without mold and rot, and the appearance is good.

[0044] Example 3

[0045] A low-carbon and universal litchi e-commerce logistics normal temperature storage and transportation mode and method, the steps of which include:

[0046] (1) Fruit pretreatment: pick fresh "Jinggang Hongnu" litchi for screening, then precool in the cold storage, precool to the fruit core temperature of 15℃; the precooling temperature is set to 15℃;

[0047] (2) Packaging: packaging in the operating room at 20℃, first put the phase change cold accumulator with a mass ratio of 1:6 to litchi in the bottom of the aluminum foil heat preservation bag, then put the antibacterial preservation water absorption pad, then put the pretreated fresh litchi, seal the aluminum foil heat preservation bag, and then put it into the foam box of polypropylene plastic foaming material for sealing;

[0048] The water absorption and bacteriostasis composite is prepared by adding 15wt% of modified β-cyclodextrin to activated carbon and zeolite with a mass ratio of 15:27 to prepare wall material by heat treatment, and compounding lemon grass essential oil and eucalyptus essential oil with a mass ratio of 1:3 as wall core, embedding the wall material and wall core with a mass ratio of 10:1, and then freeze-drying to obtain; the preparation of the modified β-cyclodextrin is to add olefin anhydride to β-cyclodextrin with a mass ratio of 14:3 and stir for 50min, adjust the pH to 7, then add 20wt% of sodium silicate solution, stir at high speed for 20min at 4000rpm, and heat at 70-80℃ for 12min; the heat treatment is heating at 6MPa and 100℃ for 5h;

[0049] The preparation method of the composite phase change cold accumulator is to heat 4% of glycerol, 1.2% of NH4Cl, 1.2% of KCl, 1.2% of sodium alginate, 1.2% of composite nanoparticles obtained by mixing Al2O3 nanoparticles and nanometer titanium dioxide with a mass ratio of 3:3, and 89.1% of water in a water bath at 50℃ for 50min, then add 1.2% of xanthan gum, 0.6% of gellan gum, and 0.3% of potassium sorbate and stir uniformly, and then perform ice bath at 3℃ for 40min to obtain;

[0050] The antibacterial preservation water absorption pad comprises three layers, the upper layer is water-permeable non-woven fabric, the middle layer is water absorption and bacteriostasis composite, and the lower layer is water-impermeable film; the water absorption and bacteriostasis composite is prepared by adding 15wt% of modified β-cyclodextrin to activated carbon and zeolite with a mass ratio of 15:27 to prepare wall material by heat treatment, and compounding lemon grass essential oil and eucalyptus essential oil with a mass ratio of 1:3 as wall core, embedding the wall material and wall core with a mass ratio of 10:1, and then freeze-drying to obtain; the preparation of the modified β-cyclodextrin is to add olefin anhydride to β-cyclodextrin with a mass ratio of 14:3 and stir for 50min at low speed, adjust the pH to 7, then add 20wt% of sodium silicate solution and stir at high speed for 20min; the heat treatment is heating at 6MPa and 100℃ for 5h;

[0051] The aluminum foil heat preservation bag is mainly made of an aluminum foil bag with a pearl wool inner layer, the pearl wool inner layer is coated with a high polymer waterproof layer, and the thickness is 4mm; the coating method of the high polymer waterproof layer is that the hydroxyl resin and the hydroxyl silicone oil are mixed and coated on the pearl wool in a mass ratio of 1:0.4, and the hot melt adhesive and the cold non-woven fabric are formed into the pearl wool inner layer by a hot press;

[0052] (3) Finally, a common paper box is loaded. The packaged lychees are placed at 25 DEG C for one week, and the results show that the fruit on the surface of the lychees is less brown for the first 3 days, a small amount of fruit is brown for 7 days, there is no mildew fruit, and no rot phenomenon, and the appearance is good.

[0053] Comparative Example 1

[0054] Comparative Example 1 is different from Example 1 in that the composite phase change cold accumulator of Comparative Example 1 is replaced by a common cold accumulator purchased on the market, and other conditions are the same; the packaged lychees are placed at 25 DEG C for one week, and the results show that the fruit on the surface of the lychees is brown, there are mildew points, and no rot phenomenon, and the appearance is general.

[0055] Comparative Example 2

[0056] Comparative Example 2 is different from Example 1 in that the aluminum foil heat preservation bag of Comparative Example 2 is not coated with a high polymer waterproof layer, and other conditions are the same; the packaged lychees are placed at 25 DEG C for one week, and the results show that the fruit on the surface of the lychees is brown, there are mildew fruits, and no rot phenomenon, and the appearance is general.

[0057] Comparative Example 3

[0058] Comparative Example 3 is different from Example 1 in that the bacteriostatic fresh-keeping pad of Comparative Example 3 does not add modified β-cyclodextrin, and other conditions are the same; the packaged lychees are placed at 25 DEG C for one week, and the results show that the fruit on the surface of the lychees is brown, there are mildew fruits, and no rot phenomenon, and the appearance is general.

[0059] Control group

[0060] The control group is that the fresh lychees are not pre-cooled, directly packaged in a common plastic bag, and an ordinary ice bag on the market is added at the bottom of the box, in order to prevent fruit frostbite, a layer of water absorption paper is placed on the ordinary ice bag, and the packaged lychees are sealed and placed at 25 DEG C for one week, and the results show that the lychees are severely brown, there are many mildew fruits, a small amount of rot phenomenon appears, and the appearance is poor.

[0061] Each index determination method:

[0062] Browning index: The browning index was calculated according to the method described in the article of Wu Dan et al. (2024), and the browning of the pericarp was divided into four grades according to the proportion of the browning area to the pericarp area: 0 grade for no obvious browning spots, 1 grade for less than 1 / 4, 2 grade for 1 / 4-1 / 2, 3 grade for 1 / 2-3 / 4, and 4 grade for more than 3 / 4. The browning index (BI) was calculated according to the method of Zhang et al. (2018).

[0063] Soluble solids: The soluble solids were detected by adding 6-7 drops of litchi pulp juice at the mirror groove of the digital refractometer.

[0064] Vitamin C content determination: The detection was performed according to the method of GB 5009.86-2016 National Food Safety Standard for Determination of Ascorbic Acid in Food.

[0065] The litchis of the examples and the comparative examples were detected periodically during storage and transportation, and the detection results are shown in Table 1.

[0066] Table 1 Change of browning rate of litchi pericarp

[0067]

[0068]

[0069] From Table 1, it can be seen that the browning index of the litchi during storage and transportation by the method of the examples of the present application is lower, the appearance is maintained higher, and the quality of the litchi is better.

[0070] Table 2 Change of soluble solids content of litchi pulp

[0071]

[0072] From Table 2, it can be seen that the soluble solids content of the litchi during storage and transportation by the method of the examples of the present application is higher, and compared with the control group, the taste of the litchi after storage and transportation is better.

[0073] Table 3 Change of vitamin C content of litchi pulp

[0074]

[0075] From Table 3, it can be seen that the change of the vitamin content of the litchi stored and transported by the method of the examples of the present application is significantly higher than that of the comparative examples within 3 days, and the nutritional quality of the litchi can be better maintained during storage and transportation at room temperature.

[0076] In conclusion, from the comparative example 1, the composite nanoparticles added in the composite phase change cold storage prepared by the application can improve the energy storage density and heat conduction performance of the cold storage, has higher phase change latent heat and phase stability, can long-acting store cold, and realizes the preservation and storage of litchi at room temperature; from the comparative example 2, the aluminum foil heat preservation bag of the application is coated with a high molecular waterproof layer, has the functions of water absorption, water resistance and oxygen permeation and adsorption, and provides a litchi with an environment which is not easy to rot and easy to store; from the comparative example 3, the bacteriostatic waterproof pad of the application adds porous materials and bacteriostatic essential oil, and also adds modified beta-cyclodextrin with cationic performance and excellent cavity performance, has excellent bacteriostatic agent loading effect, can enhance the adsorption performance of the porous materials, and plays a slow release role on the bacteriostatic essential oil, and can improve the preservation effect on litchi.

Claims

1. A low-carbon, room-temperature packaging method for preserving and transporting lychees, characterized in that, The steps include: (1) Fruit pretreatment: Fresh lychees are picked and screened, and then pre-cooled until the core temperature is 0-15℃; (2) Packaging: Packaging is carried out in an operating room at 15-20℃. First, a composite phase change cold storage agent with a mass ratio of 1:4-6 to lychees is placed at the bottom of the aluminum foil insulated bag. Then, an antibacterial and fresh-keeping absorbent pad is placed in the bag. After that, pre-treated fresh lychees are placed in the bag. The aluminum foil insulated bag is sealed and then placed in a foam box made of polypropylene plastic foam material and sealed. The antibacterial and fresh-keeping absorbent pad consists of three layers: the upper layer is a water-permeable non-woven fabric, the middle layer is a water-absorbing and antibacterial composite material, and the lower layer is a water-impermeable membrane. The composite phase change cold storage agent is formulated as follows: 0.4-0.6% gellan gum, 0.8-1.2% xanthan gum, 0.8-1.2% erythritol, 0.8-1.2% sodium alginate, 2-4% glycerol, 0.8-1.2% NH4Cl, 0.8-1.2% KCl, 0.1-0.3% potassium sorbate, 0.8-1.2% Al2O3 nanoparticles, with the remainder being deionized water; The composite phase change cold storage agent is prepared by heating glycerol, NH4Cl, KCl, sodium alginate, composite nanoparticles and water in a water bath at 40-50℃ for 40-50 minutes, then adding the remaining components and stirring evenly, and then subjecting it to an ice bath at 0-3℃ for 30-40 minutes. The composite nanoparticles are obtained by mixing Al2O3 nanoparticles and nanoparticles in a mass ratio of 3:1-3; The preparation of the water-absorbing and antibacterial complex is as follows: activated carbon and zeolite with a mass ratio of 11-15:21-27 are added to 10-15wt% of modified β-cyclodextrin and heat-treated to prepare a wall material; lemongrass essential oil and eucalyptus essential oil are compounded at a mass ratio of 1:1-3 to form a wall core; the wall material and wall core are embedded at a mass ratio of 10:1; and then freeze-drying is performed to obtain the final product. The modified β-cyclodextrin is prepared by adding β-cyclodextrin to olefinic anhydride at a mass ratio of 11-14:1-3 and stirring for 40-50 min. After adjusting the pH to 5-7, 10-20 wt% sodium silicate solution is added and stirred at high speed at 3000-4000 rpm for 10-20 min, followed by heating at 70-80℃ for 8-12 min. (3) Finally, pack it into a regular cardboard box and transport it.

2. The method for low-carbon preservation and room-temperature storage and transportation packaging of lychees according to claim 1, characterized in that, The pre-cooling temperature in step (1) is set to 10-15℃.

3. The method for low-carbon preservation and ambient temperature storage and transportation packaging of lychees according to claim 1, characterized in that, The heat treatment involves heating for 3-5 hours at a pressure of 3-6 MPa and a temperature of 90-100°C.

4. The method for low-carbon preservation and room-temperature storage and transportation packaging of lychees according to claim 1, characterized in that, The aluminum foil insulated bag in step (2) is an aluminum foil bag with an inner layer of pearl cotton. The inner layer of pearl cotton is coated with a polymer waterproof layer with a thickness of 2-4mm.

5. A low-carbon preservation method for room-temperature storage and transportation of lychees according to claim 4, characterized in that, The coating method of the polymer waterproof layer is as follows: hydroxyl resin and hydroxyl silicone oil are mixed at a mass ratio of 1:0.1-0.4 and coated on pearl cotton, and then formed into the inner layer of pearl cotton by hot melt adhesive and cold-feel non-woven fabric through a hot press.

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