It is difficult to preserve raw chestnuts because they are prone to insects. I heard that if you want to store them, you should shake the raw chestnuts every once in a while. I tried to save some, but even though I shook it as hard as I could every two days, it was almost useless until I reached Grandma's Bridge. After a while, there were still a lot of bugs, and I finally had to shake it. All the carefully stored chestnuts were thrown away.

Chestnut preservation

If the chestnut fruit loses too much water, the sugar content increases abnormally, and the physiological function becomes abnormal, resulting in a decrease in the vitality of the chestnut fruit and a decrease in resistance to various pathogenic bacteria. Also susceptible to disease, mildew, and rot. The following focuses on the current more effective storage technologies. 1. Pretreatment before storage 1. Choose storage-resistant varieties. Generally, mid- and late-maturing chestnut varieties are more resistant to storage. In fact, northern varieties are more resistant to storage than southern varieties. 2. Harvest at the right time. The maturity of chestnuts varies depending on the place of origin and variety. Generally, it is appropriate to harvest when they are fully mature. In addition, you must pay attention to the weather when harvesting. Do not harvest on rainy days or when it is sunny after rain and the dew has not dried. Harvesting prematurely or harvesting immature chestnut fruits by breaking the chestnut buds at one time will not only affect the increase in the weight of the chestnut fruit and the quality of the chestnut fruit, but also cannot withstand storage. 3. Prevent and control pests and diseases. After mechanical damage to chestnut fruits and damage from chestnut pests such as weevils and peach borer, chestnuts are extremely susceptible to infection by pathogens. Therefore, it is necessary to strengthen the prevention and control of chestnut pests before harvesting. During storage and transportation, care should be taken to pack and handle with care to prevent mechanical damage. At the same time, disease prevention treatment before storage should be carried out. For example, use "carbon disulfide" fumigation to kill insects. Soaking the fruits with 500 times of thiophanate or 1000 times of Tekodo for three minutes is effective in preventing and controlling pathogens, but it should be done within 1-2 days after picking the fruits. 4. Selection. Use 10% salt water to select chestnuts to eliminate diseased and insect-infested chestnuts and immature hollow and shriveled grains, which is beneficial to the storage and preservation of chestnuts. 5. Pre-storage. Spread the harvested chestnuts in a cool and dry place to dry. A weight loss rate of about 8% is appropriate. Weight loss rates below 5% or above 12% will affect the storage effect. 2. Storage method 1. Sand storage method. In a cool room or cellar, after spreading 10 cm of wet sand, pile up one layer of chestnuts and one layer of wet sand, covering the top with a sand layer of more than 10 cm, and the height of the pile should not exceed 1 meter. It is advisable to keep the humidity of the river sand at about 65% (hold it into a ball with your hands and spread it out with your hands). Depending on the dryness of the sand, spray water to moisturize it in time. The Guangxi Research Institute believes that the river sand must be clean and sun-dried for 2-3 days, then add 5% clean water dissolved with 0.1% thiophanate, and the accumulation thickness is about 20 cm. It must be turned over and inspected every 5-7 days, combined with humidity control to pick out mold. For bad fruits, the good fruit rate can reach 86.6% after 30 days of storage. This method is mostly used in the north, because the ground temperature in these areas is lower during the chestnut harvest season and the ground temperature rises later. Similarly, rice bran or sawdust can also be used as the storage medium instead of river sand, or a mixture of river sand and sawdust can be used, which has good results. 2. Preservation and storage of Cattail Pudding. Put the chestnuts in bamboo baskets and store them in a cool room. In the early stage, it is beneficial to water retention and nutrient accumulation of chestnut fruits, and plays a certain role in preserving freshness. After 40 days of storage and inspection, the good fruit rate of the product is as high as 95%-98.3%, the water loss rate is ≤2%, and the insect rot rate is about 1.5%. It has good storage effect and high economic benefit. However, in the later stages of storage, the chestnuts lose water and dry out, resulting in serious water loss in the chestnut fruits and poor efficiency. Therefore, this method is feasible as a short-term storage method. It is a simple storage method that can alleviate the conflict of labor shortage during the harvest period. If stored for a long time, other storage methods must be used. 3. Store in plastic bags at room temperature indoors. Soak the "sweated" chestnuts in 70% thiophanate methyl 500 times for 5 minutes, take them out to dry, and put them into a 50 cm x 60 cm plastic bag with several small holes of 1.5 cm in diameter on both sides. , placed in a well-ventilated room, not pressed closely, change the bag and turn it 3 times in the initial stage, and then open or tie the bag mouth tightly depending on the room temperature. Generally, open the bag mouth when it exceeds 10°C, and tie it tightly when it is below 10°C. There is also a method of changing packaging bags, that is, during the high temperature season in the early stages of storage, plastic mesh bags or sacks are used to facilitate heat dissipation and cooling in the bags and to discharge toxic gases, such as ethanol, acetaldehyde, CO2, etc., thereby inhibiting the occurrence of large amounts of mold and mildew. When the temperature drops (below 10°C), mold activity is suppressed, that is, perforated plastic bags are replaced to minimize water evaporation and maintain the freshness of chestnut fruits, that is, to prevent mold in the early stage and to prevent mold in the later stage. Mainly water loss. First store the chestnut fruits in the sand for a period of time (usually one month), and then use plastic bags to store them. The effect is also very satisfactory. 4. Dip and store in dilute acetic acid.

Soak the selected chestnuts in 1% acetic acid for 1 minute, drain, put them into bamboo baskets lined with pine needles at the bottom, cover them with plastic film, and soak them 4 times a month. After 142 days of storage, the good fruit rate can reach 94%. 5. Soak in clean water or saline-alkali water and store fresh. Put the "sweating" chestnuts into a basket, soak them in water or 2% salt + 2% sodium carbonate solution for 1-2 minutes, then store the basketted chestnuts on the shelf, and repeat them at regular intervals in the future. After soaking the fruit for 140 days, the good fruit rate reaches 84-92%. The principles of this method are: (1) Lower the temperature to reduce respiration; (2) Supplement water; (3) Wash away the debris on the chestnut fruit to reduce bacterial contamination; (4) The pH value increases after the saline-alkali water treatment, Inhibit the activity of certain enzymes, thereby inhibiting germination. 6. Radiation preservation and storage. The Guangxi Institute of Botany uses cobalt to irradiate chestnut fruits. The irradiation dose is 1.1 mCu/(kg·s) (250 roentgens/min). The irradiation doses are 7.7, 15.5, 23, and 31 roentgens/kg (3, 6, 9, and 120,000 roentgens). ), has significant effect on inhibiting germination. More than 7.7 cells/kg (30,000 roentgens), no germination occurred after 7 months of storage, and the good fruit rate was 86%-92% after 103 days of storage. 7. Keep fresh and stored at high temperature. This is the most advanced storage and preservation method for fruits and vegetables at home and abroad. It adopts the conditions of CO2 ≤10%, O23-5%, temperature -1-0℃, and relative humidity 90-95%. It can be stored for four months. Luotian County, Hubei The Supply and Marketing Cooperative Local Products Company and Huazhong University of Science and Technology jointly conducted experiments on chestnut controlled atmosphere storage and built a chestnut controlled atmosphere storage. The carbon molecular sieve nitrogen production technology of this controlled atmosphere preservation equipment is an advanced technology in the country for the preservation and storage of chestnuts. This achievement successfully solved the problems of warehouse insulation, moisture-proofing, sealing, gas regulation, temperature, and humidity control. After 6 months of sampling inspection, the water loss rate was less than 1%, the good fruit rate was 87.5%, and the color The aroma, taste and quality are all in line with the national standards for chestnut fresh fruits and export health standards. The successful research on this preservation technology has provided an ideal method for preserving and storing large quantities of chestnuts, but this method requires a large one-time investment. According to foreign research reports on chestnut controlled atmosphere storage, mature chestnut fruits are better stored at 21°C and 20% O2, while chestnut fruits with higher O2 content or insufficient maturity will suffer greater post-harvest losses. Poor quality. 8. The film should be kept fresh and stored. Various coatings are used to treat chestnut fruits to form a film on them, which can prevent water loss and germination and reduce contamination by diseases and insect pests. Guangxi Institute of Botany (1977) used fruit coating treatment with good results. The weight loss rate during storage was significantly reduced, the spoilage rate was also reduced, and germination was inhibited. Anhui Agricultural University (1994) used non-toxic natural polymer compounds as film-forming substances, containing low-toxic and efficient fungicides and germination inhibitors to make a preservative liquid film. It was stored at room temperature for 150 days. Compared with the control, the good fruit rate was It is above 93.79%, up to 95.32%, the water loss rate is about 3%, and the mildew rate is about 5%. After being stored for 150 days, the chestnuts treated with preservative film still have a pleasant sweetness and maintain their original flavor after artificial tasting. 9. Refrigerated storage to keep fresh. Chestnuts are stored at room temperature. Due to the high water content of chestnut fruits, the respiration and metabolism of chestnut fruits and pathogenic bacteria are very active, which can easily cause the rot of chestnut fruits. Storage at low temperatures can reduce the metabolic activities of chestnut fruits and pathogenic bacteria, reduce water loss, and is beneficial to storage. However, chestnut fruits are recalcitrant seeds and cannot tolerate storage at temperatures below 0°C. Therefore, the most suitable temperature for cold storage is 1-4°C. The specific operation is to pack the chestnut fruits in gunny bags, store them in a cold storage at 1-4°C and a relative humidity of 85-95%, and check them regularly. If the amount of water evaporates is large, you can spray an appropriate amount of water on the sack every 4-5 days. This method can preserve freshness for a long time, but the cost of building a warehouse is high. 10. Store ripe and dried fruits. Ordinary air-dried raw chestnuts have a sweet taste, but they tend to dry out and rot over time. If it is boiled first and then dried in the sun, it can be stored for a long time. The specific method is: Boil the chestnut fruit in boiling water for about 10 minutes to make the pulp ripe but not mushy (the paste will turn into powder after drying), dry it in the sun or oven, and store it in a dry environment with the shell. Although the flavor of ripe dried chestnuts is greatly reduced, chestnuts can be used as food substitutes in mountainous areas with inconvenient transportation, or they can be supplied to the market year-round. Each of the above storage methods has its own advantages and disadvantages. In order to improve the storage effect of chestnuts, sometimes several methods are combined together to obtain good results. For example, the combination of refrigeration and controlled atmosphere, refrigeration and radiation, and storage and liquid film preservation; the combination of plastic bags and liquid film, etc. In addition to the above storage methods, there are also cylinder storage, bran storage, air ion storage, etc.

Although there are many ways to store chestnuts, little progress has been made in this regard. Judging from current reports, the longest effective storage is only about half a year, and annual supply cannot yet be achieved. Most of the research focuses on measures to prevent mildew, water loss, and pests and diseases, but there is not enough research on the physiological changes of chestnuts during storage, especially on the storage of southern chestnuts. In fact, water loss, mildew and rot of chestnuts are directly or indirectly related to the internal physiological and biochemical changes of the seeds. Therefore, while studying storage and preservation, research on the physiology of chestnut storage and preservation should be strengthened