Storage preservation is an extremely important treatment method during the post-harvest period of the longan, and proper preservation can prolong the post-harvest life and shelf life of the fruit. Based on the research results over the years, people have put forward a set of storage and transportation methods that are easier to apply and popularize. On this basis, people can also take appropriate supplementary measures based on actual conditions. First, pre-harvest management Longan pre-harvest management work is related to the quality of the fruit, affecting the fruit's resistance to storage. In the entire pre-harvest management process, in addition to strengthening the management of fertilizer and water, and ensuring the vigor of the tree, it is necessary to pay special attention to the prevention and control of pests and diseases. During the storage process, pests and diseases will become the source of infection of other healthy fruits, causing the fruit to rot quickly. Second, harvest time and harvest method 1? The basic principle of harvest: longan fruit harvest generally requires timely, appropriate cooked, light harvesting. Appropriate harvesting requires harvesting when the fruit reaches a suitable maturity. The use of postharvest longan fruits is different, and the required harvest maturity is slightly different. After being harvested locally or processed into longan meat or dried longan on the spot, the maturity of harvest must be above 90%. The fruit used for the production of canned sugar requires a maturity of 89, and the fruits for storage and long-distance transportation should be harvested at eight ripening times. Harvesting is too early, the fruit is not yet fully developed and the quality is poor, so it should not be stored for a long time. Harvested too late, the fruit will appear "back sugar" phenomenon, easy to aging, intolerant storage and transportation. Therefore, the fruits that are to be stored for long-term or medium-term storage should be harvested at a suitable maturity. 2? Harvesting method: generally picking in the morning or evening is better, not in the rain, typhoon days, foggy days or morning dew when the fruit picking. To emphasize the use of the correct method of picking, requires full fruit picking, should be in the base of the ear 3 to 6 cm with 2 pieces of compound leaves cut, fracture should be neat. The ear to be harvested should be handled with care, and heat should be dissipated in the shade to facilitate the preservation of nutrients and extend the preservation period. Third, fruit selection, classification 1? Fruit selection: the quality of the fruit has a great influence on the storage effect. Fruit, fruit, fruit, fruit, fruit, fruit, damaged fruit, malformed fruit, too small fruit and bald stem fruit, wounded fruit, cracked fruit, over ripe fruit, etc. are not resistant to storage, in the selection process Should be strictly removed, so as not to affect the good effect of storage and quality. The fruit selection should be carried out in a cool and ventilated place. It can be done in cold storage or air-conditioned rooms. Select the fruit and remove the leaves on the stem and the long fruit stem. Fruit selection can also be graded on the fruit. 2 grading: Longan grading to achieve the same variety of fruit sales, maturity, consistent shape and size. Longan grading basically uses artificial grading, and can be classified according to the appearance, size, weight, and nutrient content of the fruit. According to the size of each cluster of fruit size classification, or the number of fruit per unit weight of fruit classification, that is, how many fruit per kilogram of points. According to the GB12049-89 National Longan Standard for Buying and Selling Products issued by the State Bureau of Technical Supervision, the longan is classified into three grades: excellent product, first-class product and qualified product. Fourth, anti-corrosion treatment Existing domestic and foreign longan preservation techniques are summed up in the following categories: traditional folk preservation method, low-temperature self-adjusted combination of pesticide antiseptic law, modified atmosphere storage, sulphur dioxide treatment, etc., with suitable sulphur dioxide The treatment of fresh-keeping longan is better, the appearance is better, and the storage period is longer. However, there is a problem of sulfur dioxide residue, which has certain harm to the human body and needs further improvement. Other methods of storage and preservation are difficult to store longan for a long period of time, and the control effect on fruit browning is also not good. 1? Folk traditional preservation law: mainly refers to the blanching treatment method, its main preservation principle is the use of boiling water, hot fruit, play a role in sterilization, and then hang the ear in the air circulation place or blow the fruit dry, it is not easy to grow mold , so as to achieve the purpose of preservation. The specific approach is: The long-stemmed longan fruit in boiling boiling water for 30 to 40 seconds, in order not to scald the flesh for the degree, we must master the blanching time and temperature, blanching time is not effective, blanching time When it is too long, it is easy to cause damage to the fruit, but it accelerates fruit rot. Immediately after the scald is taken out and hung in a cool, ventilated place, dried naturally, or blown dry with a blower to make the peel dry and hard, but the flesh remains fresh. Although the flesh will evaporate part of the water, it will not affect the flavor of the flesh, even It will sweeten. The fruit thus treated will not rot for 15 to 20 days, but will still retain its longan flavor, but the peel will be browned. This method can also be combined with modern cold storage methods, that is, blanching, drying and packing, and the fruits are stored under low temperature conditions. 2? Low-temperature storage combined with anti-corrosion agent This method is a kind of fresh-keeping technology that is studied by the longan preservation workers. It is also the most commonly used method in business. The longan is not resistant to storage, and it is quickly degraded at room temperature. The combination of low-temperature drug storage is currently the safest method of preservation. There are a variety of agents suitable for longan preservation, some of which are widely used, and some of which are self-administered by researchers. They are still in the experimental stage and have certain preservation effects. Here are some of the more common and effective anti-corrosion preservation technology. (1) sec-butylamine preservative preservation: There are two methods for the use of sec-butylamine: fumigation and fruit-immersion, and fumigation is more effective than dipping. Fumigation treatment method is longan fruit into a plastic bag, with 0.15ml/kg concentration of sec-butylamine smoked fruit, sealed for 24 hours, open the bag mouth, stored in 6-8 °C refrigerator. The method of soaking the fruit is to dilute the sec-butylamine stock solution 30 times, soak the fruit for 10 minutes, collect and dry it, bag it, and store it in a refrigerator at 6~8°C. After storage for one month, the good fruit rate of fumigation was 99.05% on average, the good fruit rate was 97.3% in the fruit-dip method, and only 39.6% in the control group not treated with sec-butylamine. The application of sec-butylamine fumigation in the production of thin film large account closed storage combined with low-temperature storage is good, able to keep fresh for 38 days. (2) Other types of preservatives: Tests have shown that carbendazim, thiophanate-methyl, benzoic acid, texdol, imazalil, 2,4-D, gibberellin, cytokinin, etc. all have longan fruits. A certain degree of preservation and preservation. The formula of Longan Antiseptic and Preservative A was screened out by South China Agricultural University. The fresh-keeping effect was better than the above-mentioned various agents. It was stored at room temperature for 7 days and the good fruit rate was 87.0%. Based on this, adding 2,4-D and gibberellin have a better effect. 3? Sulfur dioxide preservation method: Among the various methods of preservation of longan, the effect of the treatment with sulfur-sulfur is best. Thailand first learned from the grape's sulphur dioxide preservation method, used sulfur dioxide to preserve fresh longan, and used this technology in commercial production and circulation. It is a mature longan preservation technology. The use of smoked sulfur treatment combined with refrigeration, longan fruit storage period and shelf life have been greatly extended, the effect is very good. During fruit storage, peeling does not occur. Fumigation process: fruit picking, fruit selection, packing, entering the smoke room, fumigation, row of sulfur dioxide gas, fruit, pre-cooling, listing or storage. Sulfur dioxide can be prepared by burning sulphur or directly using pure sulfur dioxide gas to control the concentration and quickly fumigate for about 20 minutes. Fifth, packaging, pre-chilled longan post-harvest plastic turnover box, 0.04 mm thick polyethylene film bag jacket, storage effect compared with other types of packaging the best, convenient storage and transportation, but the cost is higher. The use of plastic film packaging (0.02 ~ 0.04 mm thick polyethylene, polypropylene bags) and bamboo sticks package storage effect is slightly inferior to the plastic turnover box, but the impact is not great, and the cost is low. It can also be packed in wooden boxes, calcium plastic boxes or cartons with vents. Mark the outside of the package with the trademark, product name, grade, weight, place of manufacture, specific marking and packaging date. Sixth, the best storage temperature for longan storage is 3 ~ 5 °C, humidity 90% ~ 95%, 35 days after storage, the good fruit rate is still more than 90%. The optimum temperature is slightly different for different varieties, but the storage temperature cannot be higher than 8°C or lower than 0°C. If the temperature is too low, it will cause cold damage or frostbite. If the temperature is too high, the fruit will not be able to control the metabolism and it will accelerate the aging of the fruit. Deterioration. Temperature changes should be avoided during storage. In addition to cryogenic storage, it can also be combined with modified atmosphere or spontaneously controlled atmosphere storage, and its effect is better than simply cryopreservation. The suitable gas ratio for storage of longan fruits is CO2 4% and O2 6-8%. High CO2 concentration (?13%) or low (?3%) are not conducive to longan storage, and have side effects. VII. Sales After the longan is stored on shelves, the key indicator is the shelf life, which is how long the longan can be sold on the shelf. When longan moves from room temperature to cold, there will be condensed water on the surface of the fruit, which will lead to rapid browning of the peel. Therefore, it is possible to adopt a gradual warming method when leaving the storehouse. On the shelf, the lower the temperature, the longer the shelf life. Therefore, if possible, the freezer should be used for sales, and the sales period can be appropriately extended. In short, to do a good job of longan storage and transportation, must pay attention to the post-harvest commercial processing links, and interlocking in order to achieve good results. China Agricultural Network Editor
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