1. Pre-harvest treatment can be used to spray longan trees with 500-750 times puerarin or 0.02% 2,4-D solution, or a mixture of the two, which can prolong the postharvest storage time of longan. It can usually be sprayed about 2 weeks before picking. 2. The timely harvesting of Longan for the Northern Luck can be harvested in 8.2--8.8 ripe trials, while the longan for selling or processing longan longan should be harvested only when the maturity is 8.6-9.5. It should be done before 10 o'clock in the morning on sunny or cloudy days to increase the sugar, amino acid and vitamin content of the fruit. When fruit is harvested, it should be cut at the base of the ear under the 1-2 compound leaves at the fruit cutting, so as to avoid injury to the tree body, it should be light and easy to avoid mechanical damage. 3, color protection and color protection can be combined with fruit washing, grading before treatment, remove rotten fruit, fruit cracking, fruit damage and disease and fruit. According to the requirements of the fruit supplier, one of the following methods can be used for color protection: (1) 0.5% vitamin C solution with 0.5% citric acid, or 2 minutes with 1% citric acid solution. (2) 2% sodium sulfite, 1% citric acid, 2% saline solution soaked for 2 minutes. 4. Fresh-keeping treatment (1) The mechanism of preservation of liquid chemical agents is that the agents can form a transparent film on the surface of longan fruits quickly after they are dissolved in water, which can effectively seal the stomata, reduce the respiratory intensity, and delay the aging of fruits. Antiseptic effect. Commonly used preservatives and preservation methods are as follows: A, Tektronix. It is a suspension concentrate, odorless, odorless, and highly stable. It is effective against Penicilliosis, Green mold, Trichoderma, Gray mold, Fusarium wilt, Black pedicel, Brown pedicel and Anthrax. Use ice water (below 12°C, 3-6°C is better) to dilute 300-400 times liquid for 1 minute. B, Paihai. It is a new-generation contact killer that can effectively control crown rot, black rot, penicillium, green mold, green mold, and anthrax. It is highly efficient, low in toxicity, low in residue, to users and consumers. Safe and other advantages, after release of 250 times for a milky white suspension, its suspension, adhesion and good spreading, can be used to soak fruit for 1 minute. C. Tecdo and Prodigin are used together. With the concentration of 0.1% of Texpron and Propionine, add 0.02% GA3 to mix the fruit for 1 minute. After the fruit is treated as described above, the fruit is blown dry or dried with an electric fan, and then packaged with a non-toxic, breathable, water-permeable fresh-keeping film, placed on ice (with a ratio of fruit to ice of 1-3:1). In the polystyrene foam box, the special fresh-keeping composite bags and bamboo basket packaging made of polyalkylene resin outside the box are more suitable for long-distance transportation. (2) Preservation of solid preservatives 1 Sulfur fumigation treatment produces sulphur dioxide gas by burning sulphur to achieve sterilization, bleaching and other effects. The amount of homemade sulphur dioxide fresh-keeping tablets (each tablet of 0.62g) was about 0.25% of the fruit weight, that is, 3-4 pieces of fresh-keeping tablets per kilogram of longan fruits were placed on the bottom and upper layer of the packaged fruits. 2 Kejiling fumigation treatment 0.1mL per kilogram of longan fruit, can be used to absorb the liquid rags first, and then with the longan together in a plastic bag, tie the bag mouth. 3 The amount of sec-butylamine fumigated per kilogram of longan per kilogram of dried fruit treated with sec-butylamine was 0.15 mL. The longan fruit was placed in a 0.04-0.06mm thick polyethylene film bag and sealed and fumigated for 24 hours. After the fumigation was completed, the bag was degassed and then refrigerated. 4 Chinese herbal medicine coated fresh-keeping paper The fresh-keeping paper is made from 100 parts, giant knotweed, galangal, and licorice made of traditional Chinese medicine powder, and then mixed with oxidized starch. It is used to package longans at room temperature (Southern summer) for 8 days. The good fruit rate is over 91%; if it is stored and transported at low temperature (temperature 3-6°C, relative humidity 70-90%), it will be fresh for 1 month and the good fruit rate will reach 95%. The fruit color is good and the flavor changes little . The preparation method of Chinese herbal medicine fresh-keeping paper is: Weigh one hundred parts of 350g, Polygonum cuspidatum 300g, Galangal 500g, and licorice 100g, pulverize and sifter (above 40 mesh) into powder; another starch 200g, potassium permanganate 1.2 g, borax 1.5g, sodium hydroxide 1g, water 100mL, heated to 90-95 ° C, continued stirring for 20-30 minutes, the cooling is to become oxidized starch liquid, Chinese herbal powder and oxidized starch liquid mixed in a 1:2 ratio, Then evenly coated on ordinary wrapping paper, dried in the dryer or stove (60-80 °C), and then made into different specifications of the packaging paper or packaging bags, stacked in a solid package, and then non-toxic plastic Film is well packaged. (3) The fresh-keeping bag preservation method adopts a poly-olefine resin processed plastic film composite multi-layered bag with multi-layer structure to keep fresh, can reflect more than 95% of light, so that the temperature inside the bag is still not significantly increased under direct sunlight. Its moisturizing properties are excellent, and it can create a low oxygen and high carbon dioxide storage environment in the bag. 5. Longan Luck Cold Chain Supporting Technology Longan adopts color protection → Liquid fresh-keeping → Solid-state preservation → Foam cream plus ice → Special storage bag outside the box → Bamboo basket or wooden box outside the bag → Cold storage or air-conditioned storage in the wholesale market A series of comprehensive preservation methods can achieve planned marketing. Such as cold storage temperature is maintained at 3-6 °C (relative humidity 75-90%, the same below), storage for 1 month, good fruit rate of about 97%; cold storage temperature is maintained at 9-14 °C, storage for 21 days, good fruit rate Still about 93%. Longan cryopreservation should not be below 1°C to prevent cold damage. Small batches of fruit vendors and fruit merchants in large and medium-sized cities should have freezer facilities; they are exported to foreign countries and domestic northeast, northwest and north China regions. Refrigerated trucks that still use trains (maintaining 4-6°C) have good transport results, high fruitful rates, and large profits. The open wagon of the train is also faster than the automobile, and the fruit is less affected by vibration and resonance. The good fruit rate is high and the moving fee is still low.
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