Litchi preservation treatment method

Abstract

The invention discloses a litchi fresh-keeping treatment method which comprises the following steps: picking litchis, pretreating the litchis, removing fruits with diseases and insect pests, damaged and rotten fruits and small fruits, feeding good fruits (or single fruits) with short branches into a fresh-keeping machine system for sterilization and enzyme inhibition treatment, draining water at normal temperature, filling the fruits into a controlled atmosphere fresh-keeping bag, tightening a bag opening, and packaging. And loading into a pressure-resistant and moisture-proof composite paper box (or calcium plastic box) and sealing the box with gummed paper. According to the method, a long-term storage and transportation method depending on ice cubes, foam boxes and cartons is broken through in litchi preservation, the transportation and packaging cost is greatly reduced, and the normal-temperature preservation effect is improved.

Description

Technical Field

[0001] The invention relates to the technical field of fruit and vegetable preservation, and in particular to a litchi preservation treatment method. Background Art

[0002] As a fruit with a unique flavor, lychee is deeply loved by consumers. However, it is extremely difficult to store. After lychees are picked, their quality is very likely to change, just as the ancients described: "the color changes in one day, the fragrance changes in two days, the taste changes in three days, and the color, fragrance and taste are gone in four or five days." This is mainly because lychees mature in high temperature seasons, facing problems such as vigorous fruit respiration and metabolism, easy loss of water in the peel, oxidative browning of polyphenols and pigment degradation, and latent pathogens multiplying in large numbers in a suitable environment, causing disease and rot. These factors interact with each other, causing lychees to quickly lose their commercial value after being picked.

[0003] At present, the common way to preserve lychees at room temperature is to place several ice bags at the bottom of the foam box, put a plastic bag inside the foam box, put the lychees in the plastic bag and seal the foam box, and finally put the foam box into the carton and seal it. In order to enhance the preservation effect, some lychees need to be pre-cooled in advance. However, this preservation method has many defects. On the one hand, the refrigeration capacity of the ice bag is limited, resulting in the shelf life of lychees only lasting 2-3 days; on the other hand, this packaging method is costly. In addition, some lychee varieties are more likely to change color after being treated with ice water, which seriously affects the quality of lychees.

[0004] Ozone is a strong oxidant. Compared with other fungicides, it has the characteristics of broad spectrum, high efficiency, fast and convenient, no residue and no need for heating. At the same time, ozone has a degrading effect on harmful gases such as ethylene, inducing crop disease resistance, and to a certain extent degrading microbial toxins and pesticide residues on the surface of litchi.

[0005] Ultrasonic waves have energy effects, such as the energy released when cavitation is destroyed and the stirring and flowing effects on coal. Ultrasonic technology can be used for breeding in agriculture. Ultrasonic waves are used in the food industry to promote physical and chemical effects, improve efficiency, save raw materials, and improve or enhance product quality. In the preservation of lychees, it can stimulate cell activity, stimulate or inhibit enzyme activity, and inhibit and kill microorganisms. In daily life, ultrasound combined with ozone water is used to preserve and disinfect fruits and vegetables and degrade agricultural residues, but the effect is not ideal. The energy of ultrasonic waves required to achieve a complete sterilization effect is extremely high, and it is very difficult to achieve sterilization and preservation.

[0006] Lasers use the heat, light, and electromagnetic fields of lasers to induce genetic and metabolic changes in biological tissues. Currently, laser mutagenesis is mainly used in agriculture. Fruits and vegetables undergo physiological changes after being treated with lasers, mainly by inhibiting respiration, slowing down water evaporation, inhibiting the growth of pathogens, and inhibiting excessive ethylene production, thereby extending the shelf life. However, due to the concentrated direction and high intensity of lasers, they are prone to damage biological tissues. Summary of the invention

[0007] In view of the deficiencies in the prior art, the present invention provides a litchi fresh-keeping treatment method.

[0008] The present invention discloses a method for preserving litchi, comprising: Picking litchi and pre-processing litchi; Placing litchi in a fresh-keeping machine system for sterilization and enzyme inhibition; Drain the preserved lychees, put them into atmosphere-controlled fresh-keeping bags and then pack them into pressure-resistant and moisture-proof composite cartons or calcium plastic boxes.

[0009] According to one embodiment of the present invention, the pretreatment is as follows: 80% to 85% of the ripe lychees are picked in the early morning, and the dust is removed and the diseased and insect-infested fruits, rotten fruits and small fruits are removed by washing with clean water, and the fruits with short branches or single fruits are sent to the fresh-keeping machine system for treatment.

[0010] According to one embodiment of the present invention, the fresh-keeping machine system includes an ozone water generator, an ultrasonic machine, a laser machine and a water tank. The ozone water produced by the ozone water generator is injected into the water tank. The ultrasonic machine and the laser machine act on the water tank at the same time, and the lychees are placed in the water tank.

[0011] According to one embodiment of the present invention, the concentration of ozone water in the water tank is 0.2-1 ppm.

[0012] According to one embodiment of the present invention, the ultrasonic intensity of the ultrasonic machine is 0.2-4W / cm 2 , the ultrasonic frequency is 28-400kHz.

[0013] According to one embodiment of the present invention, the laser wavelength of the laser machine is 200-3000nm, and the laser output power is 20-1000W.

[0014] According to one embodiment of the present invention, the lychees are transported to a water tank via a conveyor belt and are subjected to the combined action of ozone water, ultrasound and laser for 2-50 minutes.

[0015] According to one embodiment of the present invention, the lychees treated with sterilization and enzyme inhibition by the fresh-keeping machine system are drained and packed into atmosphere-controlled fresh-keeping bags at room temperature. Each bag weighs 1-2.5 kg. A piece of absorbent paper is placed at the bottom of the bag, and the bag is then placed in an outer packaging carton or calcium plastic box.

[0016] According to one embodiment of the present invention, four circular holes with a diameter of 2 cm are opened on the short sides of the pressure-resistant and moisture-proof composite paper box or calcium plastic box, and a total of eight circular holes with a diameter of 2 cm are arranged on the two short sides; a circular hole with a diameter of 3 cm is arranged in the middle of the long side of the pressure-resistant and moisture-proof composite paper box or calcium plastic box, and a total of two circular holes with a diameter of 3 cm are arranged on the two opposite sides; the atmosphere-controlled fresh-keeping bag filled with lychees is placed into the pressure-resistant and moisture-proof composite paper box or calcium plastic box, the bag mouth is tied tightly, and the box is sealed with tape.

[0017] According to one embodiment of the present invention, the liquid in the fresh-keeping machine system is ozone water or fresh-keeping liquid, which can be used for other fruit and vegetable fresh-keeping treatments; the fresh-keeping machine system power supply is AC 220V or 380V, and the frequency is 50Hz or 60Hz.

[0018] The beneficial effect of the present invention is that through the coordinated action of ozone water, ultrasound and laser, not only can the litchi be sterilized, but also the enzyme activity of the litchi can be inhibited and harmful substances such as pesticide residues can be reduced, and the respiration can be significantly reduced, and finally the shelf life of the litchi can be extended. The room temperature shelf life is extended from the existing 2-3 days to 4-6 days. In addition, since ice bags, foam boxes and pre-cooling treatment of litchi are saved, the preservation and logistics costs are greatly reduced, and the preservation effect is guaranteed. DETAILED DESCRIPTION

[0019] S1: picking litchis and pre-treating them. Specifically, 80%-85% ripe litchis are picked in the early morning, and then the picked litchis are pre-treated, wherein the pre-treatment means: the picked litchis are placed on a fruit washing machine and washed with clean water to remove dust and impurities on the surface of the litchis, and at the same time, the litchis are screened to remove pests, rotten fruits and small fruits, leaving good fruits with short branches or single fruits.

[0020] S2: Place the lychees in the fresh-keeping machine system for sterilization and enzyme inhibition. Specifically, the selected good fruits with short branches or single fruits are sent to the fresh-keeping machine system for treatment through a conveyor belt. The fresh-keeping machine system includes an ozone water generator, an ultrasonic machine, a laser machine and a water tank. First, inject the ozone water produced by the ozone water generator into the water tank, and adjust the water temperature to 40°C. The ozone concentration of the ozone water is 0.2-1ppm. Secondly, start the ultrasonic machine, and the ultrasonic machine acts on the water tank. The ultrasonic intensity of the ultrasonic machine is 0.2-4W / cm 2 , the ultrasonic frequency is 28-400kHz. Then, start the laser machine, the laser machine emits laser and shoots directly into the water tank from above, the laser wavelength of the laser machine is 200-3000nm, and the laser output power is 20-1000W. Finally, the lychees are put into the water tank, and the processing time is 2-50 minutes. It should be noted that the specific processing time depends on the specific variety of lychees. In addition, lychees can also be replaced with other fruits and vegetables.

[0021] Ozone water has a degrading effect on harmful gases such as ethylene, inducing crop disease resistance, and to a certain extent can degrade microbial toxins and pesticide residues on the surface of litchi; the ultrasonic wave emitted by the ultrasonic machine acts on the litchi in the water tank, and the ultrasonic wave can stimulate the activity of the cells, while at the same time inhibiting the litchi enzyme, and also has the effect of inhibiting and killing microorganisms; but it is difficult to achieve a deeper sterilization effect by relying solely on ultrasonic waves, so more energy needs to be introduced; the laser machine emits a laser into the water tank to provide more energy. In addition, the laser of the laser machine will cause physiological and biochemical changes in the microorganisms in the litchi pulp, thereby inhibiting the respiration of microorganisms, slowing down water evaporation, inhibiting the growth of pathogens, and inhibiting excessive production of ethylene.

[0022] S3: Take out the lychees and drain them. Specifically, after the ozone water, ultrasonic machine and laser machine have processed the lychees, the lychees are sent out by the conveyor belt in the water tank, and the lychees on the conveyor belt are put into plastic baskets, each plastic basket is put into 10 kg of lychees, and the plastic baskets are placed indoors at room temperature to drain the water.

[0023] S4: The drained lychees are placed in a controlled atmosphere fresh-keeping bag and packed. Specifically, after the lychees are drained at room temperature (without running water), the drained lychees are bagged and packed. The bagging process is to place the lychees in a controlled atmosphere fresh-keeping bag. Each fresh-keeping bag can hold 1-2.5 kg of lychees. In order to avoid the situation where the lychees are not completely drained, absorbent paper can be placed at the bottom of the fresh-keeping bag. In this embodiment, the fresh-keeping bag is a controlled atmosphere fresh-keeping bag with a patent number of "ZL200810027883.X". The combination of the controlled atmosphere fresh-keeping bag can further reduce the respiration of microorganisms on the lychees and prolong the shelf life of the lychees.

[0024] For packing, the air-conditioned fresh-keeping bag containing lychees is placed in a box. The box is made of a pressure-resistant and moisture-proof composite carton or calcium plastic box, which has better pressure resistance and moisture resistance to improve the protection of lychees. In addition, round holes are opened on the short side of the box, among which four 2cm round holes are opened on one side of the short side, and a total of eight round holes are opened on the two opposite sides; similarly, a 3cm round hole is opened on each of the opposite sides of the long side of the box, and there are a total of ten round holes on the long and short sides; the ten round holes in the whole box fully guarantee the gas exchange inside and outside the box, and give full play to the regulating effect of the air-conditioned fresh-keeping bag on O2 and CO2; the air-conditioned fresh-keeping bag containing lychees is tied tightly, put into a composite carton or calcium plastic box, and finally sealed with adhesive tape for mailing.

[0025] To sum up, it is still difficult to achieve a deeper bactericidal and enzyme-inhibiting effect by relying solely on the combination of ultrasound and ozone water. Using laser to shoot ozone water into the water tank can not only overcome the problem of laser concentration and high intensity that can easily cause biological damage, but also organically combine the transverse electromagnetic waves emitted by the laser and the longitudinal waves emitted by ultrasound. When further combined with ozone water, the three work together to greatly enhance the bactericidal and enzyme-inhibiting effects and greatly enhance the preservation effect of litchi.

[0026] A number of embodiments are listed below for further description, see below for details: Embodiment 1 On July 4, 2024, Nuomici lychees were collected from Guanyin Pavilion Town, Boluo County, Huizhou City, Guangdong Province, packed in gas-controlled fresh-keeping bags, and tested using the online all-in-one gas concentration detector of Shenzhen Honey Egg Technology Co., Ltd. The test environment temperature was 2-5°C. The specific test parameters are as follows:

[0027] From the respiration equation C6H 12 O6+6O2->6CO2+6H2O shows that its characteristics are the absorption of O2 and the release of CO2. Ethylene (C2H4) is a hormone that promotes fruit ripening. Ethylene increases cell permeability and accelerates respiration. It can be seen that the O2 concentration of litchi treated by the fresh-keeping machine system increases, indicating that the consumption of O2 is small, and the CO2 concentration decreases, indicating that the release is small, and C2H4 also decreases significantly. From the above data, it can be seen that it clearly shows that the respiration of litchi is greatly inhibited.

[0028] Embodiment 2 On July 7, 2024, local lychees were purchased in Taimei Town, Boluo County, Huizhou City, Guangdong Province. They were washed with clean water in a fruit washing machine to remove dust and impurities, and pest-infested fruits, rotten fruits, and small fruits were removed. Good fruits with short branches were selected and put into the fresh-keeping machine system for processing. First, 0.6ppm ozone water was obtained through an ozone water generator, and the ultrasonic machine was turned on. The water temperature was adjusted to 40℃ and the ultrasonic intensity of the ultrasonic machine was 0.5W / cm 2, the ultrasonic frequency is 80kHz, the laser machine is started, the laser is shot into the water tank, the laser wavelength of the laser machine is 650nm, and the laser output power is 30W; the lychees are sent into the water tank along the conveyor belt, taken out after 40 minutes of processing, and packed in plastic baskets, each plastic frame holds 10 kg, and then the plastic baskets are placed indoors to drain at room temperature 28°C. After draining, the lychees are put into controlled atmosphere fresh-keeping bags (controlled atmosphere fresh-keeping bags with patent number "ZL200810027883.X"), and a piece of absorbent paper is put into each controlled atmosphere fresh-keeping bag. The weight of each controlled atmosphere fresh-keeping bag is 1.5 kg. The mouth of the controlled atmosphere fresh-keeping bag with lychees is tied tightly, and put into a pressure-resistant and moisture-proof composite carton, and then the carton is sealed with adhesive tape, and handed over to Jitu Express to Pu'er City, Yunnan Province, Xingtai City, Hebei Province and Wuhan City, Hubei Province respectively. It took more than four days to receive the goods. The lychees are 100% intact, sweet in taste, and customers are satisfied.

[0029] Embodiment 3 The ozone water in this embodiment can be replaced by clean water or fresh-keeping liquid.

[0030] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for preserving litchi, characterized in that: include: Picking litchi and pre-processing litchi; Placing litchi in a fresh-keeping machine system for sterilization and enzyme inhibition; Drain the preserved lychees, put them into atmosphere-controlled fresh-keeping bags and then pack them into pressure-resistant and moisture-proof composite cartons or calcium plastic boxes.

2. The method for preserving litchi according to claim 1, characterized in that: The pretreatment is as follows: 80% to 85% ripe lychees are picked in the early morning, and the dust is removed by washing with clean water, and diseased and insect-infested fruits, rotten fruits and small fruits are removed. The fruits with short branches or single fruits are sent to the fresh-keeping machine system for processing.

3. The method for preserving litchi according to claim 1, characterized in that: The fresh-keeping machine system includes an ozone water generator, an ultrasonic machine, a laser machine and a water tank. The ozone water produced by the ozone water generator is injected into the water tank. The ultrasonic machine and the laser machine act on the water tank at the same time, and the lychees are placed in the water tank.

4. The method for preserving litchi according to claim 3, characterized in that: The ozone water concentration in the water tank is 0.2-1ppm.

5. The method for preserving litchi according to claim 3 or 4, characterized in that: The ultrasonic intensity of the ultrasonic machine is 0.2-4W / cm 2 , the ultrasonic frequency is 28-400kHz.

6. The method for preserving litchi according to claim 5, characterized in that: The laser wavelength of the laser machine is 200-3000nm, and the laser output power is 20-1000W.

7. The method for preserving litchi according to claim 6, characterized in that: The lychees are transported to the water tank via a conveyor belt and treated with ozone water, ultrasound and laser for 2-50 minutes.

8. The method for preserving litchi according to claim 7, characterized in that: Drain the lychees that have been treated with sterilization and enzyme inhibition by the fresh-keeping machine system and put them into controlled atmosphere fresh-keeping bags at room temperature. Each bag weighs 1-2.5 kilograms. Put a piece of absorbent paper at the bottom of the bag and put it into an outer packaging carton or calcium plastic box.

9. The method for preserving litchi according to claim 8, characterized in that: Four circular holes with a diameter of 2 cm are opened on the short sides of the pressure-resistant and moisture-proof composite carton or calcium plastic box, and a total of eight circular holes with a diameter of 2 cm are set on the two short sides; a circular hole with a diameter of 3 cm is set in the middle of the long side of the pressure-resistant and moisture-proof composite carton or calcium plastic box, and a total of two circular holes with a diameter of 3 cm are set on the two opposite sides; put the controlled atmosphere fresh-keeping bag containing lychees into the pressure-resistant and moisture-proof composite carton or calcium plastic box, tie the bag tightly, and seal the box with tape.

10. The method for preserving litchi according to claim 1, characterized in that: The liquid in the fresh-keeping machine system is ozone water or fresh-keeping liquid, which can be used for the preservation of other fruits and vegetables; the power supply of the fresh-keeping machine system is AC 220V or 380V, and the frequency is 50Hz or 60Hz.

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