Green fresh-keeping method for litchis

Abstract

The invention relates to the technical field of food preservation, in particular to a green litchi preservation solution, a preparation method and a preservation method.The green litchi preservation solution comprises 1-5 g / L of L-ascorbic acid, 0.1-0.5 g / L of kojic acid, 0.02-0.08 g / L of salicylic acid, 0.04-0.08 g / L of anhydrous magnesium sulfate, 0.04-0.08 g / L of anhydrous aluminum sulfate and the balance water. Compared with traditional chemical preservatives, the green litchi preservative provided by the invention has the advantages that the addition of chemical bactericides such as prochloraz is avoided, and the food safety guarantee is improved; the harvested litchis are subjected to pre-cooling treatment, soaked in the green fresh-keeping liquid provided by the invention and then subjected to physical irradiation treatment; the green fresh-keeping method for the litchis provided by the invention further reduces the browning degree of the litchis, greatly prolongs the storage period and shelf life of the litchis, and extends the industrial chain and economic value of the litchis.

Description

Technical Field

[0001] The invention relates to the technical field of food preservation, and in particular to a litchi green fresh-keeping liquid, a preparation method and a fresh-keeping method. Background Art

[0003] The reason why litchi fruit is difficult to store and preserve is that litchi fruit matures in the hot and humid summer, and its metabolic activity is high, its respiration intensity is large, and its heat release is high, which causes it to easily turn brown and rot after being harvested, and has a short shelf life. This is not conducive to the storage and transportation of litchi fruit after harvest, as well as the maintenance of its edible value and commercial value.

[0004] In the existing technology, the storage and preservation method of using ice cubes is still common, but this limits the shelf life and appearance requirements of litchi. Although sulfur treatment technology can meet the needs of long-distance transportation, the treated products lack attractiveness on the shelf and have food safety issues. Every year, the loss of litchi due to quality deterioration accounts for more than 20% of the total production. Therefore, it is imperative to solve the problem of lack of storage and preservation technology suitable for litchi in the litchi industry and promote the development of post-harvest storage and transportation capabilities of litchi.

[0005] The current methods of lychee preservation mainly rely on freeze-dormancy preservation and sulfur technology chemical fungicide treatment. Among them, freeze-dormancy preservation has problems such as high cost and poor appearance of fruits after thawing, while broad-spectrum chemical fungicides have food safety risks and poor browning control effects. The environmental and food pollution caused by chemical fungicides (such as prochloraz, carbendazim, cypermethrin, thiabendazole, sulfur dioxide) has attracted widespread attention, and some regions have included them in the list of prohibited uses; in addition, chemical fungicides have not been able to fundamentally control the occurrence of post-harvest diseases of fruits, and the problem of drug resistance also poses a risk to chemical control technology.

[0006] Based on this, the current preservation method of litchi not only faces the dual problems of browning and pests and diseases, but also due to the lagging technology of litchi preservation and insufficient cold chain equipment, it causes a series of industry problems such as large transportation losses, rapid quality decline and high rot rate after litchi is picked. Summary of the invention

[0007] The purpose of the present invention is to provide a green preservation method for lychees, which can effectively preserve the harvested lychees, reduce the browning and rotting of the lychees, and ensure the food safety of edible lychees.

[0008] To achieve the above purpose, the litchi green fresh-keeping liquid provided by the present invention comprises 1-5 g / L of L-ascorbic acid, 0.1-0.5 g / L of kojic acid, 0.02-0.08 g / L of salicylic acid, 0.04-0.08 g / L of anhydrous magnesium sulfate, 0.04-0.08 g / L of anhydrous aluminum sulfate, and the rest is water.

[0009] Furthermore, the preservative includes 2-4 g / L of L-ascorbic acid, 0.2-0.4 g / L of kojic acid, 0.04-0.06 g / L of salicylic acid, 0.04-0.06 g / L of anhydrous magnesium sulfate, 0.04-0.06 g / L of anhydrous aluminum sulfate, and the rest is water.

[0010] Furthermore, the preservative includes 4 g / L of L-ascorbic acid, 0.4 g / L of kojic acid, 0.06 g / L of salicylic acid, 0.05 g / L of anhydrous magnesium sulfate, 0.05 g / L of anhydrous aluminum sulfate, and the rest is water.

[0011] Furthermore, the lychee green fresh-keeping liquid is prepared according to the following steps:

[0012] Take 100-500 g / L of L-ascorbic acid and 10-50 g / L of kojic acid, use water as a medium, and fully dissolve them to obtain a 100-fold concentration of mother solution A;

[0013] Take 2-8 g / L salicylic acid, 4-8 g / L anhydrous magnesium sulfate, and 4-8 g / L anhydrous aluminum sulfate, and use water as a medium to fully dissolve them to obtain a 100-fold concentration of mother solution B;

[0014] Using ice water as a medium, dilute the A mother solution 100 times, stir evenly and let stand for 10 to 20 minutes;

[0015] Add the same amount of B mother liquor as that of the A mother liquor to the diluted A mother liquor, and stir again to obtain the lychee green fresh-keeping liquid.

[0016] Furthermore, the temperature of the ice water is 4-10°C.

[0017] The present invention also provides a green preservation method, comprising:

[0018] The harvested lychees are subjected to a precooling treatment, wherein the precooling treatment comprises placing the lychees in ice water for precooling so that the temperature of the lychee core reaches the precooling temperature;

[0019] Soaking the pre-cooled lychees in the green fresh-keeping liquid;

[0020] The soaked lychees are drained of water and placed in an irradiation device for irradiation treatment.

[0021] Furthermore, the temperature of the ice water is 4-10°C, and the pre-cooling temperature is below 10°C.

[0022] Furthermore, the pre-cooled lychees are soaked in the green fresh-keeping liquid for 3 to 5 minutes.

[0023] Furthermore, the irradiation device also includes a conveyor belt, and the lychees that have been drained of water are placed on the conveyor belt to be conveyed to the irradiation device for irradiation treatment, wherein the conveyor belt speed is 2 to 5 meters per second; the height of the lychees placed on the conveyor belt is less than 6 centimeters, or the lychees on the conveyor belt are placed in a single layer.

[0024] Furthermore, the irradiation energy is 300 to 600 Gy.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention provides a new green fresh-keeping liquid when used, which ensures the food and environmental safety of litchi preservation.

[0027] 2. The present invention provides a green preservation method for litchi when used, which adopts a preservation method combining immersion in a preservation solution and physical irradiation to reduce the browning degree of litchi fruit and greatly extend the shelf life of the fruit; it also does not require ultra-low temperature freezing, greatly reduces production costs, and has high feasibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0029] Figure 1 This is a schematic diagram of the preservation effect of three batches of harvested lychees after being treated with the preservation method provided by the present invention and stored;

[0030] Figure 2 A schematic diagram showing a comparison of the fresh-keeping effects of "Heli" lychees after storage at 4°C for 41 days in Example 5 provided by the present invention;

[0031] Figure 3 Schematic diagram of the litchi preservation method in each embodiment. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] See also Figure 1-3The present invention provides a litchi green fresh-keeping liquid, comprising 1-5 g / L of L-ascorbic acid, 0.1-0.5 g / L of kojic acid, 0.02-0.08 g / L of salicylic acid, 0.04-0.08 g / L of anhydrous magnesium sulfate, 0.04-0.08 g / L of anhydrous aluminum sulfate, and the remainder being water.

[0034] Specifically, the preservative includes 2-4 g / L of L-ascorbic acid, 0.2-0.4 g / L of kojic acid, 0.04-0.06 g / L of salicylic acid, 0.04-0.06 g / L of anhydrous magnesium sulfate, 0.04-0.06 g / L of anhydrous aluminum sulfate, and the rest is water.

[0035] Preferably, the preservative includes 4 g / L of L-ascorbic acid, 0.4 g / L of kojic acid, 0.06 g / L of salicylic acid, 0.05 g / L of anhydrous magnesium sulfate, 0.05 g / L of anhydrous aluminum sulfate, and the remainder is water.

[0036] The method for preparing a chemical preservative solution comprises the following steps:

[0037] Take 100-500 g / L of L-ascorbic acid and 10-50 g / L of kojic acid, use water as a medium, and fully dissolve them to obtain a 100-fold concentration of mother solution A;

[0038] Take 2-8 g / L salicylic acid, 4-8 g / L anhydrous magnesium sulfate, and 4-8 g / L anhydrous aluminum sulfate, and use water as a medium to fully dissolve them to obtain a 100-fold concentration of mother solution B;

[0039] Using ice water as the medium, dilute the A mother solution 100 times, stir evenly and let stand for 10 to 20 minutes; preferably, the temperature of the ice water is 4 to 10°C.

[0040] Then, add the same amount of B mother liquor as that of A mother liquor to the diluted A mother liquor, and stir well again to obtain the lychee green fresh-keeping liquid.

[0041] The preservation method provided by the present invention comprises:

[0042] The harvested lychees are subjected to precooling treatment, wherein the precooling treatment includes placing the lychees in ice water for precooling so that the temperature of the lychee core reaches the precooling temperature;

[0043] Specifically, the newly harvested lychees are precooled in ice water at a temperature ranging from 4 to 10°C, and a thermometer is inserted into the lychee fruit to measure the temperature of the fruit core. When the temperature of the lychee fruit core reaches below 8°C, the precooling treatment is completed.

[0044] Next, soak the pre-cooled lychees in green preservative liquid;

[0045] Specifically, soak the pre-cooled lychees in lychee preservative liquid for 3 to 5 minutes, take them out and naturally drain the water until no water is dripping. At this time, you can use PE fresh-keeping bags or fresh-keeping boxes to store the lychees.

[0046] Then, the soaked lychees are drained of water and placed in an irradiation device for irradiation treatment.

[0047] Specifically, electron beam irradiation sterilization technology uses high-speed electrons in a high-voltage electric field to break the chemical bonds of substances and reshape the molecular structure, thereby effectively killing microorganisms and parasites on the surface and inside of food, inhibiting the physiological activities of fruits, and thus extending the shelf life of fruits. Electron beam irradiation, as a cold sterilization physical technology, has a short processing time, high sterilization efficiency, and can better maintain its original sensory quality, nutrition and flavor. It has the advantages of safety, efficiency, greenness and environmental protection.

[0048] In actual irradiation treatment, an electron beam with an energy of no more than 10 MeV or an X-ray with an energy of no more than 5 MeV generated by an electron accelerator is used for irradiation treatment, wherein the irradiation energy may be 300 to 600 Gy.

[0049] The irradiation device usually includes a conveyor belt, and the soaked lychees are placed on the conveyor belt. The conveying speed of the conveyor belt is 2 to 5 m / s or 3 to 4 m / s to ensure that the lychees on the conveyor belt can be effectively irradiated.

[0050] When the lychees are placed on the conveyor belt, the height of the lychees on the conveyor belt is less than 6 cm. Specifically, the lychees should be placed in a single layer on the conveyor belt. The single layer means that the lychees are not stacked. When the conveyor belt transports the lychees to the irradiation device, the irradiation device is used to generate 400 to 500 Gy of irradiation energy, and the lychees on the conveyor belt are irradiated once, further ensuring that each lychee is effectively irradiated.

[0051] The green fresh-keeping method for lychees provided by the present invention is used to process the harvested lychees, which can not only ensure the safety of edible lychees and the environment, but also reduce the browning degree of lychee fruits, greatly prolong the shelf life of lychee fruits, and at the same time, does not affect the sugar content and acidity of edible lychees.

[0052] Embodiment 1:

[0053] A litchi preservative liquid, the formula of which is as follows by weight:

[0054] L-ascorbic acid 1g / L, kojic acid 0.1g / L, salicylic acid 0.02g / L, anhydrous magnesium sulfate 0.04g / L, anhydrous aluminum sulfate 0.04g / L, and the rest is water.

[0055] When preparing litchi preservative solution:

[0056] Prepare 100 times the concentration of A mother solution: take 100g / L L-ascorbic acid and 10g / L kojic acid in water as the medium and fully dissolve them;

[0057] Prepare 100 times the concentration of mother solution B: use water as the medium, take 2g / L salicylic acid, 4g / L anhydrous magnesium sulfate, and 4g / L anhydrous aluminum sulfate, and fully dissolve them.

[0058] Then use ice water at a temperature of 4°C as the medium to dilute the mother solution A to 1 time, stir evenly, let it stand for 10 to 20 minutes, then add the mother solution B in an amount equal to the mother solution A, stir well to obtain the litchi green preservative solution.

[0059] The process of the method for preserving lychees in Example 1 is as follows Figure 3 As shown,

[0060] Pretreatment: The freshly picked "Fei Zi Xiao" lychee fruits are immediately placed in ice water for precooling. When the core temperature reaches below 10°C, they are taken out and naturally drained, and then placed in a 10°C cold storage for sorting. The precooled lychee fruits are manually sorted to remove leaves, insect-infested fruits, damaged fruits and small fruits.

[0061] Soaking liquid:

[0062] Soak the pretreated lychee fruits in the lychee preservative solution for 5 minutes, then take out the lychee fruits and drain the water naturally;

[0063] At this time, you can choose to put the lychees into plastic baskets covered with two layers of dry absorbent paper on all sides, store them in a 4°C cold storage, and wait for the next process, or directly transfer the drained lychees to irradiation disinfection treatment.

[0064] Irradiation disinfection treatment: Select an electron beam instrument with an energy of no more than 10MeV generated by an electron accelerator, place the lychee fruits soaked in the preservative solution on a tray of a conveyor belt with a conveyor belt speed of 2 to 5 m / s, and transport the lychees to the electron beam irradiation device for a single irradiation under 300Gy irradiation conditions for physical preservation and disinfection treatment.

[0065] Storage: The lychee fruits that have been pretreated, treated with fresh-keeping liquid and irradiated with electron beam are placed in a plastic basket covered with two layers of dry absorbent paper and placed in a vacuum fresh-keeping cold storage at 4°C and a relative humidity of 90-95%.

[0066] Comparative Example 1:

[0067] The difference between the comparative example and Example 1 is that the litchi preservative solution used in the comparative example includes 1-5 g / L of L-ascorbic acid, 0.1-0.5 g / L of kojic acid, 0.02-0.08 g / L of salicylic acid, and the rest is water.

[0068] Comparative Example 2:

[0069] The difference between Comparative Example 2 and Example 1 is that the litchi preservative solution used in Comparative Example 2 is added with a traditional chemical fungicide, prochloraz, the effective ingredient of the prochloraz mother solution is 450 g / L, and is diluted 1500 times with water to treat litchi fruits.

[0070] Table 1 is a table showing the fresh-keeping effects of the "Fei Zi Xiao" lychees treated with Example 1, Comparative Example 1 and Comparative Example 2 when the lychee fruits were stored at 24°C for the third day. Each group of experiments was repeated more than 3 times.

[0071] Table 1

[0072] Grouping Good fruit rate (%) Browning rate (%) Sugar content (%) Example 1 68 32 14.4 Comparative Example 1 42 58 14.0 Comparative Example 2 64 26 14.5

[0073] Table 2 is a table showing the preservation effects of the "Fei Zi Xiao" lychees treated with Example 1, Comparative Example 1 and Comparative Example 2 when the lychee fruits were stored at 24°C for 5 days. Each group of experiments was repeated more than 3 times.

[0074] Table 2

[0075] Grouping Good fruit rate (%) Browning rate (%) Sugar content (%) Example 1 38 62 13.6 Comparative Example 1 12 88 13.0 Comparative Example 2 31 69 13.1

[0076] It can be seen that the lychee preservative solution provided by the present invention, due to the addition of anhydrous magnesium sulfate and anhydrous aluminum sulfate, under the action of the preservative solution whose components are L-ascorbic acid, kojic acid, salicylic acid, anhydrous magnesium sulfate, anhydrous aluminum sulfate, and the rest is water, avoids the addition of chemical fungicides such as prochloraz, etc., compared with traditional chemical preservatives, and not only improves food safety; at the same time, it reduces the browning degree of the lychee peel and ensures the good fruit rate of the lychee preservation.

[0077] Embodiment 2:

[0078] A litchi chemical preservative liquid, the formula of which is as follows by weight:

[0079] L-ascorbic acid 5g / L, kojic acid 0.5g / L, salicylic acid 0.08g / L, anhydrous magnesium sulfate 0.08g / L, anhydrous aluminum sulfate 0.08g / L, and the rest is water.

[0080] When preparing litchi preservative solution:

[0081] Prepare 100 times the concentration of A mother solution: take 500g / L L-ascorbic acid and 50g / L kojic acid in water as the medium and fully dissolve them;

[0082] Prepare 100 times the concentration of mother solution B: use water as the medium, take 8g / L salicylic acid, 8g / L anhydrous magnesium sulfate, and 8g / L anhydrous aluminum sulfate, and fully dissolve them.

[0083] Then use ice water with a temperature in the range of 10°C as the medium to dilute the mother solution A to 1 time, stir evenly, let it stand for 10 to 20 minutes, then add the mother solution B in an amount equal to the mother solution A, stir well to obtain the litchi green preservative solution.

[0084] The process of the method for preserving lychees in Example 2 is as follows Figure 3 As shown,

[0085] Pretreatment: The freshly picked "Fei Zi Xiao" lychee fruits are immediately placed in ice water for precooling. When the core temperature reaches below 8°C, they are taken out and naturally drained, and then placed in a 10°C cold storage for sorting. The precooled lychee fruits are manually sorted to remove leaves, insect-infested fruits, damaged fruits and small fruits.

[0086] Soaking in preservative solution: Soak the pretreated litchi fruits in litchi preservative solution for 3 minutes, then take out the litchi fruits, drain the water naturally, put them into a plastic basket covered with 2 layers of dry absorbent paper on all sides, and store them in a 4℃ cold storage.

[0087] Irradiation disinfection treatment: Select an electron beam instrument with an energy of no more than 10MeV generated by an electron accelerator, place the lychee fruits soaked in the preservative solution on a tray of a conveyor belt with a conveyor belt speed of 5 m / s, and transport the lychees to the electron beam irradiation device for a single irradiation under 400Gy irradiation conditions for physical preservation and disinfection treatment.

[0088] Storage: The lychee fruits that have been pretreated, treated with fresh-keeping liquid and irradiated with electron beam are placed in a plastic basket covered with two layers of dry absorbent paper and placed in a vacuum fresh-keeping cold storage at 4°C and a relative humidity of 90-95%.

[0089] In Comparative Example 3, a single 1-fold A mother solution was used to treat litchi fruits, and other treatment conditions were consistent with those in Example 2.

[0090] Comparative Example 4:

[0091] The difference between Comparative Example 4 and Example 2 is that in Comparative Example 4, a single 1-fold B mother solution is used to treat litchi fruits, and other treatment conditions are consistent with those in Example 2.

[0092] Comparative Example 5:

[0093] The difference between Comparative Example 5 and Example 2 is that in Comparative Example 5, no chemical preservative solution is used to treat the litchi fruit, and only physical irradiation is used to treat the litchi fruit. Other treatment conditions are consistent with those in Example 2.

[0094] Table 3 is a table showing the fresh-keeping effects of the "Fei Zi Xiao" lychees treated with Example 2, Comparative Example 3, Comparative Example 4 and Comparative Example 5 when the lychee fruits were stored at 24°C for the third day. Each group of experiments was repeated more than 3 times.

[0095] Table 3

[0096]

[0097]

[0098] Table 4 is a table showing the fresh-keeping effects of the "Fei Zi Xiao" lychees treated with Example 2, Comparative Example 3, Comparative Example 4 and Comparative Example 5 when the lychee fruits were stored at 24°C for 5 days. Each group of experiments was repeated more than 3 times.

[0099] Table 4

[0100] Grouping Good fruit rate (%) Browning rate (%) Sugar content (%) Example 2 76 24 14.6 Comparative Example 3 13 87 15.2 Comparative Example 4 20 80 14.6 Comparative Example 5 8 92 14.4

[0101] Embodiment 3:

[0102] A litchi preservative liquid, the formula of which is as follows by weight:

[0103] L-ascorbic acid 4g / L, kojic acid 0.4g / L, salicylic acid 0.06g / L, anhydrous magnesium sulfate 0.05g / L, anhydrous aluminum sulfate 0.05g / L, and the rest is water.

[0104] When preparing litchi preservative solution:

[0105] Prepare 100 times the concentration of A mother solution: take 400g / L L-ascorbic acid and 40g / L kojic acid in water as the medium and fully dissolve them;

[0106] Prepare 100 times the concentration of mother solution B: use water as the medium, take 6g / L salicylic acid, 5g / L anhydrous magnesium sulfate, and 5g / L anhydrous aluminum sulfate, and fully dissolve them.

[0107] Then use ice water with a temperature in the range of 6°C as the medium to dilute the mother solution A to 1 times, stir evenly, let it stand for 20 minutes, then add the mother solution B in an amount equal to that of the mother solution A, stir well to obtain the litchi green preservative solution.

[0108] The process of the method for preserving lychees in Example 3 is as follows Figure 3 As shown,

[0109] Pretreatment: The freshly picked "Fei Zi Xiao" lychee fruits are immediately placed in ice water for precooling. When the core temperature reaches below 10°C, they are taken out and naturally drained, and then placed in a 10°C cold storage for sorting. The precooled lychee fruits are manually sorted to remove leaves, insect-infested fruits, damaged fruits and small fruits.

[0110] Soaking in preservative solution: Soak the pretreated litchi fruits in litchi preservative working solution for 4 minutes, then take out the litchi fruits, drain the water naturally, put them into a plastic basket covered with 2 layers of dry absorbent paper on all sides, and then store them in a 4℃ cold storage.

[0111] Irradiation disinfection treatment: Select an electron beam instrument with an energy of no more than 10MeV generated by an electron accelerator, place the lychee fruits soaked in the preservative solution on a tray of a conveyor belt with a conveyor belt speed of 3 meters per second, and transport the lychees to the electron beam irradiation device for a single irradiation under 500Gy irradiation conditions for physical preservation and disinfection treatment.

[0112] Storage: The lychee fruits that have been pretreated, treated with fresh-keeping liquid and irradiated with electron beam are placed in a plastic basket with two layers of dry absorbent paper on all sides and placed in a reduced pressure warehouse at 4°C and a relative humidity of 90-95%.

[0113] Comparative Example 6:

[0114] The difference between the comparative example and Example 3 is that in Comparative Example 6, a single 1-fold A mother solution is used to treat litchi fruits, and other treatment conditions are consistent with those in Example 3.

[0115] Comparative Example 7:

[0116] The difference between the comparative example and Example 3 is that in Comparative Example 7, a single 1-fold B mother solution is used to treat litchi fruits, and other treatment conditions are consistent with those in Example 3.

[0117] Comparative Example 8:

[0118] The difference between the comparative example and Example 3 is that in Comparative Example 8, no chemical preservative solution is used to treat the litchi fruit, and only physical irradiation is used to treat the litchi fruit. Other treatment conditions are consistent with those in Example 3.

[0119] Table 5 is a table showing the fresh-keeping effects of the "Fei Zi Xiao" lychee fruits treated with Example 3, Comparative Examples 6, 7 and 8 when stored at 4°C for the 10th day. Each group of experiments was repeated more than 3 times.

[0120] Table 5

[0121] Grouping Good fruit rate (%) Browning rate (%) Sugar content (%) Example 3 86 14 16.6 Comparative Example 6 38 62 15.4 Comparative Example 7 48 52 16.2 Comparative Example 8 30 70 14.7

[0122] Table 6 is a table showing the fresh-keeping effects of the "Fei Zi Xiao" lychees treated with Example 3, Comparative Example 6, Comparative Example 7 and Comparative Example 8 when the lychee fruits were stored at 4°C for 21 days. Each group of experiments was repeated more than 3 times.

[0123] Table 6

[0124] Grouping Good fruit rate (%) Browning rate (%) Sugar content (%) Example 3 76 24 15.9 Comparative Example 6 13 87 14.9 Comparative Example 7 20 80 14.5 Comparative Example 8 8 92 15.1

[0125] Embodiment 4:

[0126] A litchi green fresh-keeping liquid, the formula of which is as follows by weight:

[0127] L-ascorbic acid 4g / L, kojic acid 0.4g / L, salicylic acid 0.06g / L, anhydrous magnesium sulfate 0.05g / L, anhydrous aluminum sulfate 0.05g / L, and the rest is water.

[0128] When preparing litchi preservative solution:

[0129] Prepare 100 times the concentration of A mother solution: take 300g / L of L-ascorbic acid and 30g / L of kojic acid in water as the medium and fully dissolve them;

[0130] Prepare 100 times concentrated B mother solution: take 6g / L salicylic acid, 5g / L anhydrous magnesium sulfate, and 5g / L anhydrous aluminum sulfate in water as the medium and fully dissolve them;

[0131] Then, using ice water at a temperature in the range of 4 to 10°C as a medium, dilute mother solution A to 1 time, stir evenly, let stand for 15 minutes, then add mother solution B in an amount equal to mother solution A, stir evenly, and obtain litchi green preservative solution.

[0132] In Example 4, the fresh-keeping method for litchi is as follows Figure 3 As shown,

[0133] Pretreatment: The freshly picked "Heli" lychee fruits are immediately placed in ice water for precooling. When the core temperature reaches below 10℃, they are taken out and naturally drained, and then placed in a 10℃ cold storage for sorting. The precooled lychee fruits are manually sorted to remove leaves, insect-infested fruits, damaged fruits and small fruits.

[0134] Soaking in preservative solution: Soak the pretreated litchi fruits in litchi preservative solution for 5 minutes, then take out the litchi fruits, drain the water naturally, put them into a plastic basket covered with 2 layers of dry absorbent paper on all sides, and then store them in a 4℃ cold storage.

[0135] Irradiation disinfection treatment: Select an electron beam instrument with an energy of no more than 10MeV generated by an electron accelerator, place the lychee fruits soaked in the preservative solution on a tray of a conveyor belt with a conveyor belt speed of 3 to 4 m / s, and transport the lychees to the electron beam irradiation device for a single irradiation under 500Gy irradiation conditions for physical preservation and disinfection treatment.

[0136] Storage: The litchi fruits that have completed the pretreatment, fresh-keeping liquid treatment and electron beam irradiation treatment in sequence are placed in a plastic basket covered with two layers of dry absorbent paper on all sides, placed in a reduced pressure warehouse with a relative humidity of 90-95%, and stored at 24°C and 4°C, respectively.

[0137] Comparative Example 9:

[0138] The difference between Comparative Example 9 and Example 4 is that a single chemical broad-spectrum fungicide, prochloraz, is used in Comparative Example 9, the effective ingredient of prochloraz mother liquor is 450 g / L, and water is used to dilute 1500 times to treat litchi fruits. Other pre-cooling treatment and storage conditions are consistent with Example 4.

[0139] Table 7 is a table showing the fresh-keeping effects of the "Heli" litchi fruits treated with Example 4 and Comparative Example 9 when stored at 24°C for the 5th day. Each group of experiments was repeated more than 3 times.

[0140] Table 7

[0141] Grouping Good fruit rate (%) Browning rate (%) Sugar content (%) Example 4 78 22 15.4 Comparative Example 9 26 74 15.1

[0142] Table 8 is a table showing the fresh-keeping effects of the "Heli" litchi fruits treated with Example 4 and Comparative Example 9 when stored at 4°C for the 21st day. Each group of experiments was repeated more than 3 times.

[0143] Table 8

[0144] Grouping Good fruit rate (%) Browning rate (%) Sugar content (%) acidity(%) Example 4 74 26 14.8 0.57 Comparative Example 9 22 78 14.7 0.70

[0145] Embodiment 5:

[0146] A litchi green fresh-keeping liquid, the formula of which is as follows by weight:

[0147] L-ascorbic acid 4g / L, kojic acid 0.4g / L, salicylic acid 0.06g / L, anhydrous magnesium sulfate 0.05g / L, anhydrous aluminum sulfate 0.05g / L, and the rest is water.

[0148] (1) A method for preparing a chemical preservative solution, comprising the following steps:

[0149] When preparing litchi preservative solution:

[0150] Prepare 100 times the concentration of A mother solution: take 100g / L L-ascorbic acid and 10g / L kojic acid in water as the medium and fully dissolve them;

[0151] Prepare 100 times the concentration of mother solution B: use water as the medium, take 6g / L salicylic acid, 5g / L anhydrous magnesium sulfate, and 5g / L anhydrous aluminum sulfate, and fully dissolve them.

[0152] Then, using ice water at a temperature in the range of 4 to 10°C as a medium, dilute mother solution A to 1 time, stir evenly, let stand for 10 to 20 minutes, then add mother solution B in an amount equal to mother solution A, stir evenly, and obtain litchi green preservative solution.

[0153] In Example 5, the fresh-keeping method for litchi is as follows Figure 3 As shown,

[0154] Pretreatment: The freshly picked "Heli" lychee fruits are immediately placed in ice water for precooling. When the core temperature reaches below 10℃, they are taken out and naturally drained, and then placed in a 10℃ cold storage for sorting. The precooled lychee fruits are manually sorted to remove leaves, insect-infested fruits, damaged fruits and small fruits.

[0155] Soaking in preservative solution: Soak the pretreated litchi fruits in litchi preservative solution for 5 minutes, then take out the litchi fruits, drain the water naturally, put them into a plastic basket covered with 2 layers of dry absorbent paper on all sides, and then store them in a 4℃ cold storage.

[0156] Irradiation disinfection treatment: Select an electron beam instrument with an energy of no more than 10MeV generated by an electron accelerator, place the lychee fruits that have been chemically preserved on a tray of a conveyor belt with a conveyor belt speed of 2 to 5 m / s, and transport the lychees to the electron beam irradiation device for a single irradiation under 600Gy irradiation conditions for physical preservation and disinfection treatment.

[0157] Storage: The lychee fruits that have been pretreated, treated with fresh-keeping liquid and irradiated with electron beam are placed in plastic baskets covered with two layers of dry absorbent paper, placed in a reduced pressure warehouse with a relative humidity of 90-95%, and stored at 4°C.

[0158] Comparative Example 10:

[0159] The difference between Comparative Example 10 and Example 5 is that in Comparative Example 10, the lychee fruits are only subjected to precooling treatment and are not immersed in fresh-keeping liquid and physically irradiated. Other packaging and storage conditions are the same as those in Example 5.

[0160] Comparative Example 11:

[0161] The difference between Comparative Example 11 and Example 5 is that in Comparative Example 10, the litchi fruits are treated by immersion in a fresh-keeping liquid, and the litchi fruits are not treated by physical irradiation. Other pre-cooling treatment, packaging and storage conditions are the same as those in Example 5.

[0162] Comparative Example 12:

[0163] The difference between Comparative Example 12 and Example 5 is that in Comparative Example 12, the litchi fruits are treated by single physical irradiation, and the litchi fruits are not treated by immersion in a preservative solution. Other precooling treatment, packaging and storage conditions are the same as those in Example 5.

[0164] Table 9 is a table showing the preservation effects of Example 5, Comparative Examples 10, 11 and 12 on "Heli" lychee fruits when stored at 4°C for 41 days. Each group of experiments was repeated more than 3 times.

[0165] Table 9

[0166] Grouping Good fruit rate (%) Browning rate (%) Sugar content (%) acidity(%) Example 5 74 26 15.7 0.51 Comparative Example 10 20 74 15.5 0.45 Comparative Example 11 44 66 16.6 0.46 Comparative Example 12 16 84 16.7 0.48

[0167] Combination Figure 1 , Figure 2 It can be seen that the green preservation method for lychees provided by the present invention is to pre-cool the harvested lychees, soak them in lychee preservation liquid and sterilize them by irradiation, which can not only ensure the safety of edible lychees and the environment, but also reduce the browning degree of lychee fruits, and at the same time, does not affect the sugar content and acidity of edible lychees.

[0168] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to the above embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A litchi green fresh-keeping liquid, characterized in that: It includes L-ascorbic acid 1-5g / L, kojic acid 0.1-0.5g / L, salicylic acid 0.02-0.08g / L, anhydrous magnesium sulfate 0.04-0.08g / L, anhydrous aluminum sulfate 0.04-0.08g / L, and the rest is water.

2. The lychee green fresh-keeping liquid according to claim 1, characterized in that The preservative includes 2-4 g / L L-ascorbic acid, 0.2-0.4 g / L kojic acid, 0.04-0.06 g / L salicylic acid, 0.04-0.06 g / L anhydrous magnesium sulfate, 0.04-0.06 g / L anhydrous aluminum sulfate, and the rest is water.

3. The lychee green fresh-keeping liquid according to claim 1, characterized in that The preservative includes 4 g / L L-ascorbic acid, 0.4 g / L kojic acid, 0.06 g / L salicylic acid, 0.05 g / L anhydrous magnesium sulfate, 0.05 g / L anhydrous aluminum sulfate, and the rest is water.

4. The lychee green fresh-keeping liquid according to claim 1, characterized in that The litchi green fresh-keeping liquid is prepared according to the following steps: S1. Take 100-500 g / L of L-ascorbic acid and 10-50 g / L of kojic acid, use water as a medium, and fully dissolve them to obtain a 100-fold concentration of A mother solution; S2, dissolve 2-8 g / L salicylic acid, 4-8 g / L anhydrous magnesium sulfate, and 4-8 g / L anhydrous aluminum sulfate in water as a medium to obtain a 100-fold concentration of mother solution B; S3, using ice water as a medium, dilute the A mother solution 100 times, stir evenly and let stand for 10 to 20 minutes; S4. Add the same amount of B mother liquor as that of the A mother liquor to the diluted A mother liquor, and stir well again to obtain the litchi green fresh-keeping liquid.

5. The litchi green fresh-keeping liquid according to claim 4, characterized in that: The temperature of the ice water is 4-10°C.

6. A green preservation method for litchi, characterized in that: include The harvested lychees are subjected to a precooling treatment, wherein the precooling treatment comprises placing the lychees in ice water for precooling so that the temperature of the lychee core reaches the precooling temperature; Soaking the pre-cooled lychees in the green fresh-keeping liquid; The soaked lychees are drained of water and placed in an irradiation device for irradiation treatment.

7. The green preservation method for litchi according to claim 6, characterized in that: The temperature of the ice water is 4-10°C, and the pre-cooling temperature is below 10°C.

8. The green preservation method for litchi according to claim 6, characterized in that: The precooled lychees are soaked in the green fresh-keeping liquid for 3 to 5 minutes.

9. The green fresh-keeping method for litchi according to claim 6, characterized in that: The irradiation device also includes a conveyor belt, and the lychees that have been drained of water are placed on the conveyor belt to be conveyed to the irradiation device for irradiation treatment, wherein the conveyor belt speed is 2 to 5 meters per second; the height of the lychees placed on the conveyor belt is less than 6 centimeters, or the lychees on the conveyor belt are placed in a single layer.

10. The green preservation method of litchi according to claim 6, characterized in that: The irradiation energy is 300-600Gy.

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