Picking and storage of longan

Longan is a good thing, it tastes very sweet, everyone likes to eat it, let's see what nutrients our fresh longan has? How to pick and store it?

Fresh longan tastes nutritious and is a treasure for the whole body

As the first batch of fruits announced by the Ministry of Health in 1988 as both food and medicine, longan is a treasure from head to toe. Its fruit, leaves and flowers can all be used as medicine.

Longan Meat

Longan meat nourishes the heart, calms the mind and resists aging

Red bean, wolfberry, longan and black chicken soup

According to the introduction of the Quanzhou Longan Exhibition held by Hong Zesheng, the vice mayor of Quanzhou City, Fujian Province, in Beijing recently, longan, also known as "Guiyuan", is rich in nutrition and has significant medicinal effects. It is recorded in many classic medical works. For example, "Shennong's Herbal Classic" and "Compendium of Materia Medica" say that longan has the effects of strengthening yang and replenishing qi, nourishing blood and calming the mind, strengthening the stomach and kidneys, moisturizing the skin and beautifying, and prolonging life. Japanese medical research has found that longan also has anti-cancer effects.

After peeling the dried longan fruit, it can be mixed with other foods to make soups, porridge and other drinks. It can also be stewed with chicken, duck, and ribs. It can also be made into dried longan, longan paste, longan preserves, longan wine, etc.

In terms of diet therapy, 10 grams of longan pulp combined with 5 grams of ginseng and 5 grams of poria cocos, brewed with boiling water, can be drunk as a brain-awakening and intellectual tea. It is especially suitable for candidates who are mentally fatigued, inattentive, and restless.

The right amount of longan combined with wolfberry, red dates, and glutinous rice to make porridge can nourish the heart, calm the nerves, strengthen the spleen, and replenish blood. Stewing turtle with longan and jujube can nourish yin and produce blood.

Picking and storage of fresh longan

Picking fresh longan

Longan fruit is harvested in August and September under high temperature and high humidity. Because the fruit has high water content and sugar content, and the respiration intensity is particularly strong, the physiological and biochemical changes of the fruit after harvest are drastic. The fresh fruit is very easy to turn brown and deteriorate, and it is very difficult to store. At a normal temperature of 25℃, the fruit begins to turn brown within 1 day, the peel turns brown in 5-6 days, and all deteriorates and rots within a week. Appropriate low temperature can extend the storage period of longan. At the same time, the storage effect is better when certain chemical agents are used and combined with gas conditioning factors. After 40 days of storage, it is still fresh, high-quality and excellent in flavor.

Longan is a non-respiratory peak fruit. It has no obvious respiratory peak, but its respiratory intensity is very high, 2-3 times that of bananas, citrus and other fruits. The ethylene release is always kept at a low level, much lower than bananas, pears and other fruits. There is no obvious ethylene peak, which shows that longan fruit is not sensitive to ethylene. Longan is very easy to brown after being picked. It starts to brown within 1 day at 25℃, and the peel turns brown in 5-6 days.

Harvesting and post-harvest processing of longan

The maturity and harvesting time of longan varies according to the region, variety, use and climate. Longan fruits for storage should be harvested when they are fully mature. The standard for the maturity of longan fruit is that when the skin changes from green to light brown or yellowish brown, the surface becomes thin and smooth, the fuzz falls off, the flesh changes from hard to soft and elastic, the raw green smell disappears, and the core changes from red to black (except for red core varieties), it can be harvested in about 15 days. Different post-harvest treatments should be carried out according to specific conditions.

Harvesting should be done in the morning or evening on a sunny day. In the morning, it is best to harvest after the dew has dried. It should not be harvested at noon when the sun is strong, on rainy days, or when there is a typhoon, because the fruits harvested under these conditions are prone to deterioration and disease. When picking, it is not advisable to pick too deep at the base of the ear. It should be cut with fruit picking shears at the 1-2 compound leaves below the base of the ear, and the tree should not be injured. The fruits should be picked and placed gently, stacked neatly, and some leaves should be placed at the bottom of the basket as padding when putting them in the basket. The picked fruits should not be dried in the hot sun, but should be placed under the shade of trees or sent to the warehouse for sorting and packaging. Before packaging, the ear should be trimmed, bad and cracked fruits should be removed, and the leaves on the ear should be preserved for storage.

After harvesting, longan fruits are best stored in plastic turnover boxes or crates, with each box holding about 12 kg for easy transportation and storage. When packing, the fruit clusters should face outwards and the fruit branches should face inwards, and they should be packed and placed with care. They should be handled promptly after harvesting, preferably harvested, processed, and stored on the same day.

Selection of longan storage varieties

There are many varieties of longan, with about 400 cultivars in China. As longan varieties have long been propagated by seedlings in some places, the same variety in different regions has great differences in quality, and there are also some rare and precious varieties, such as Bingtangrou and Dongbi. They are not only of good quality, but also more durable. The storage resistance of Quanzhou is also good, with a good fruit rate of more than 95% after 50 days of storage. Among some varieties in Fujian, Fuyan, Chike, Shuizhang, etc. are not resistant to storage.

Longan Antiseptic Treatment

The combination of drug preservation, plastic bag packaging and low-temperature storage can achieve satisfactory storage and preservation effects. Preservatives include: Xinkeyuan Fruit and Vegetable Preservative No. 2, carbendazim (fumigant containing 50% sec-butylamine), sec-butylamine plus gibberellin, carbendazim, methyl thiophanate, tebuconazole, etc.

Fumigation of fruits with chlorpyrifos: Put the longan loose fruits in a 0.04 mm thick plastic bag, use 0.1 ml of the drug per kilogram, absorb it with an old cloth, put it in the bag, seal it tightly for 24 hours, and then open the bag and refrigerate it. If the storage volume is large, use 14 grams of the drug per cubic meter of storage capacity and fumigate it in a closed warehouse. You can also soak the fruit with the drug, soak it in 10-15 times the original solution for 5 minutes, take it out to dry, and store it in a bag.

Sec-butylamine can be used for fumigation as well as fruit washing. The appropriate fumigation dosage is 0.15 ml/kg fruit. The longan fruit stored in a plastic bag is sealed and fumigated for 24 hours. For fruit washing, soak the fruit for 10 minutes in a 30-fold dilution of the original solution, dry it, and bag it for refrigeration. The effect of fumigating fruit with sec-butylamine is better than soaking it.

Longan Anti-browning Treatment

Low temperature storage at 5-7℃ or quick freezing at -23℃ can effectively prevent browning. Boiling at 100℃ can also kill enzymes and prevent browning. Storage at 5-7℃ and 90%-95% relative humidity with 6%-8% oxygen and 4%-6% carbon dioxide can prevent browning.

Wash the fruit with a 3% citric acid and 2% sodium bisulfite solution, or a 100-fold solution of poly-lecithin, dry it slightly, and pack it in a 0.04 mm thick polyethylene film bag, 500 grams per bag, seal and refrigerate. Or soak the fruit with a 0.5% citric acid plus 0.03% vitamin C solution or a 1% citric acid solution, which has a significant effect on delaying the browning of the peel and the deterioration of the flesh.

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