Chestnut (C. Mollisima blume) is a fruit tree belonging to the genus Fabriaceae. It is native to China and is distributed both north and south. Chestnut is rich in nutrients, sweet and nutritious, can be eaten raw, fried, or cooked. It is a traditional Chinese export fruit and enjoys the reputation of “China's Gan Li†in the international market. Chestnuts often cause large losses every year due to starch saccharification, moisture loss, pest infestation, germination and rot, and natural consumption during storage, in order to reduce losses. To extend storage and preservation period, it must be based on the storage characteristics of chestnut for scientific storage. 1. Storage Characteristics Chestnut is a kind of respiration-changing fruit, especially in the first month after harvest, the respiration is very strong. During storage, chestnuts are afraid of heat, fear of dryness, fear of freezing, and fear of water. The chestnut tolerance of northern Chinese cultivars is better than that of southern cultivars. The middle-late-maturing cultivars are stronger than early-maturing cultivars. Chestnuts in drought-prone years in the same region are more resistant to storage. 2. The maturity of chestnut during harvesting is an important factor affecting fruit quality and shelf life. Premature harvesting, high temperatures, fresh chestnut fruit tissue, high water content, high amylase activity, and vigorous respiration are not conducive to storage and preservation; late harvest, chestnut pods fall off, easy to cause losses; suitable harvesting period is Chestnuts crack, nuts are tan, and more than 1/3 of chestnuts are cracking. When harvesting, attention should be paid to changes in the weather. It is not advisable to collect the weather in rainy days, after the rain is clear or when the morning dew is dry, otherwise it is seriously rotted. Harvesting is best carried out after several consecutive days of sunny days, stacked for several days until the chestnuts are completely cracked and the chestnuts are removed. In chestnut production areas in northern China, there are generally two methods for harvesting chestnuts: 1 Picking up natural fruits. The chestnuts picked up by this method have ample development, good appearance and flavor, and are resistant to storage, but they require timely collection. It is best to pick one time each morning; 2 Manually shoot down, after this method is used to collect chestnut fruit, dislocate it in time, the shorter the time, the better, to prevent damage to carivora. In actual production, it can be sprayed with ethephon to ripen and promote chestnut cracking. The time should not exceed 7 days. 3. Pre-storage treatment (1) After harvesting the pods, the temperature of the pods is high, the moisture content is high, and the respiratory intensity is high. Therefore, the pods cannot be concentrated in a large amount, otherwise they are prone to cause heat rot. Should choose a cool, ventilated place, the pod should be spread into a thickness of 0.6m ~ 1.0m, can not be compacted, can insert a bundle of corn stalk every 5m, in order to facilitate ventilation, cooling, 7 days to 10 days after the nuts from the chestnut Remove from the cockroach, remove the pests and fruits and other unqualified chestnuts and spread them indoors for 5 days to 7 days. (2) Insect pest damage The main pest of chestnut is the chestnut real insect. Its adult eggs are produced on the capsule from June to September. The young eggs hatch into the fruit after hatching. There are two methods of prevention and control: water infiltration and fumigation: 1 Insulation with water, put the chestnut in warm water at 50°C, submerge for 45 minutes, kill aphids such as Myzus persicae and Chestnuts, remove them and dry them for storage; 2 fumigation and extermination According to the number of chestnuts, the choice of carton, plastic bag or warehouse for disposal, the commonly used drugs for carbon disulfide, 1 cubic meter space with 50kg dose, fumigation time is 18h ~ 24h, due to carbon disulfide gas is heavier than air, the capacity of Sheng medicine liquid Should be placed above the fumigation tank (room). (3) Preservative treatment with 0.05% of 2,4-D and thiophanate-500 times solution, dipping fruit for 3 minutes; or with a mass concentration of 1000 mg/L of B9, 1000 mg/L of naphthaleneacetic acid, 1 000 mg/L of Cyan With 2% of salt and 2% sodium carbonate solution, fruit soaking can not only reduce decay, but also inhibit the germination of chestnut. 4. Storage methods (1) Indoor storage This is a traditional method of storage, including storage and sluice. 1 piled up, used more in the south, that is, in the shade of the indoor floor, a layer of corn stalks or straw, and then shop 5cm ~ 6cm thick sand, according to chestnuts and sand 1:2 ratio mixed stacking, interaction Layers, each layer thickness of about 3cm ~ 6cm. The final sand cover is 3cm to 7cm covered with straw and has a height of about 1m. 2 trenches, generally used in northern regions. After the chestnut is harvested, stir it in wet sand and bury it in the room. Before the soil is frozen, the chestnuts piled indoors are put into trenches excavated outdoors for winter storage. The groove width is 1m to 1.5m, and the ditch depth is 0.8m to 1m. The length is determined by the storage volume. Before entering the ditch, first 10cm thick sand in the ditch, and then chestnut and wet sand mixed in a ratio of 1:2 into the ditch, below the ditch about 20em, and then covered with wet sand, and Mizoguchi flat, and finally covered with soil. It is not advisable to cover the soil prematurely, and it should be carried out in stages as the temperature drops. The final thickness of the soil cover is about 40 cm. In order to ventilate, at the same time as chestnut fruit, about 10m thick vertical straw bundles with a diameter of about 10cm, down to the ditch bed, the upper end exposed to the ground. (2) Cave storage has the characteristics of simple structure, low construction cost, good storage effect, and suitable for storage at the place of origin. Must be fumigated with 40% formalin or sulfur prior to storage. When the chestnut fruit enters the kiln, when the outside temperature is lower than the kiln temperature, the kiln door is opened and the air inlet and outlet ducts are opened to fully ventilate the air and open overnight. The limit of cooling is controlled at around 0°C. Too high or too low is not good for storage. When the humidity in the kiln is lower than 90%, artificial water spray humidification must be performed. Spraying 0.03% potassium permanganate solution can also prevent the spread of mold. (3) Stairs are stored in a cool indoor or ventilated warehouse, with storage racks. Each shelf is 3 layers, 3m long and 2m wide. The roof of the rack is made of bamboo and shaped like a ridge. Each basket was loaded with 25kg chestnuts, stacked on a shelf, and then covered with a 0.08mm thick polyethylene tent, ventilated once every 2h. (4) Refrigerated at a cold storage temperature of 0°C to 1°C and a relative humidity of 80% to 85% in a cold store, use sacks to wrap chestnuts, 90kg/bag, 6 bags to 8 bags, leaving enough channels for Reduce cool ventilation. When the relative humidity of the air is lower than 80%, water can be sprayed outside the package. This method can be stored for up to 1 year with minimal germination. (5) Atmosphere storage in cold storage, simple air conditioning storage with thin film or perforated film bags, 0.05mm thick film bags can be lined in tweezers, cartons or wooden boxes. 1cm less than the hole, the pitch is 5cm, with 500 times thiophanate solution soaked fruit 10min, dried and then bagged, each bag containing 20kg ~ 25kg chestnut fruit. This method can be used to store chestnut fruit until March of the following year. The rotting fruit rate is only 1% to 2%. 5. Precautions (1) Prevent the moisture content of wind-dripping sun-dried fruit under the tree to be 49.5%. After heat-dissipating and sweating, the water content drops to 40.13%. At this time, slight water loss occurs; when the water content drops to 28.56% When it is severely dehydrated, when it falls to 18.92%, it is seriously dehydration, that is, it is air-dried. At this time, chestnut kernels cannot germinate. If water is added, it will rot and become inedible in less than a month. (2) Watering can not be too much Lizi is hi and damp, but afraid of water. The purpose of watering is to keep the chestnuts moist, to replenish evaporated water and to lower the temperature. However, the watering is too much, and the chestnuts cannot be well ventilated and breathable, which easily causes rot. (3) Avoid strong odors and dirt Pollution Strong odors and bacterial infections will cause chestnut rot. It is strictly forbidden to have objects with stronger odors such as chemical fertilizers, paints, alcohols, etc., close to or hold chestnuts and store them in storage. Rotten chestnuts are picked up in time to prevent transmission and corrosion of other chestnuts.
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