Sweet potato is rich in nutritional value, and it is very beneficial to the body to eat it frequently. It has high water content, tender tissue, thin skin and easy to be damaged. It is easy to be damaged by cold damage and infected with diseases, so it is necessary to pay special attention to rotting during storage. How to keep sweet potatoes in winter without rotting? Let's get to know.
How to preserve sweet potato in winter
1. Storage of sweet potato in cellar:
Select a place with high terrain, solid soil and low groundwater level, and dig a shaft down, generally about 1 m in diameter and 5-6 m in depth. The size of the storage room depends on the storage capacity. The storage room should be padded with 10-15 cm thick dry sand, on which sweet potatoes should be placed. The sweet potato can only be filled 70% full, so as to leave a place for air exchange. Otherwise, it will become more rotten due to humidity and heat.
2. Storage of sweet potato in shed and cellar:
Generally, the cellar is about 2m wide, 3-4m long and 2m deep. It is necessary to avoid the direct contact between sweet potato and pit wall.
3. Storage of sweet potato in cellar:
The structure of the cellar is similar to that of the common houses, but the walls and roofs are very thick, the walls and roofs are sealed, the windows are opened, and there are heating channels, which can be used for high temperature callus treatment. There are two kinds of cellars: big cellar (storage capacity of 10000-50000 kg) and small cellar.
4. Storage of sweet potato in the room:
Sweet potato is afraid of cold, when the temperature is too low, it will be frozen, forming a hard core, not cooked and boiled; if the temperature is too high, it will sprout, and the best room temperature is controlled at about 15 ℃. Sweet potato was wet, it is easy to cause bacteria damage, resulting in decay, the best placed in a ventilated wooden box for preservation. If there is no wooden box, board shall be padded at the place where sweet potatoes are stacked and against the wall, and then cover some things on the potato pile to prevent moisture. In the warm day, the window should be opened properly for air exchange to keep the indoor air fresh and prevent the cold wind from blowing in. The sweet potato bought from the market should be put in the sun for several hours to reduce the water content of the wound and promote healing. When using, it should be handled gently to avoid bruises.
5. Slice, dry and preserve sweet potato:
Slice the sweet potato and put it on the room or in a sunny, dry and ventilated place to dry. Be careful not to get caught in the rain or snow. After drying, store it in a dry place indoors and soak it before eating.
Reasons for rotten sweet potato cellar:
Chilling injury refers to that the metabolism of potato block is destroyed when it is under 9 ℃ for a long time. Generally, it is easy to produce cold damage in 10 days under the temperature of 8-9 ℃, or 6 days under the temperature of 5-6 ℃, or 3 days under the temperature of 2-3 ℃; when the temperature drops to - 1.3-2 ℃, it is easy to produce cold damage, and it is easy to cause bacteria invasion and a large number of rotten pits after suffering from cold damage or cold damage; In the early stage of storage, the temperature is high, the respiration of the potato body is vigorous, the moisture in the potato pile rises, and it condenses into water drops when it is cold. The potato body is prone to rot and disease due to the wet damage. The main diseases causing the rotten pit in the storage period include black spot, soft rot, dry rot and nematode disease.
Comprehensive measures to prevent and cure the rotten pit of sweet potato:
Sweet potato harvest should be controlled when the local ten day average temperature drops to 14 ℃ to 15 ℃. Generally, it should be harvested before and after the beginning of winter in the first ten days of November, and harvest in sunny days. During operation, pay attention to fine collection and transportation, and try to prevent digging, scratching and bumping. Before entering the cellar, scrape away the old soil on the cellar wall and smear it with lime slurry. Remove 15cm thick old soil at the bottom of the cellar. After removing the old soil, sprinkle the upper lime and smoke the cellar with sulfur. Use 50g sulfur per cubic meter, ignite it, close the pit mouth and smoke for 1 to 2 days, and then open the vent hole. Spray 1% copper sulfate solution or 50 times formaldehyde solution in the cellar, or mix formaldehyde and potassium permanganate, and fumigate in a closed manner.
After the sweet potato is put into the cellar, do not seal the cellar too early. Pay attention to ventilation and heat dissipation to prevent the cellar from burning. Keep the temperature of 15 ℃ to 20 ℃ and 90% relative humidity. After the winter solstice, the cold wave is frequent and the temperature is low. It is advisable to keep the temperature in the cellar between 12 ℃ and 13 ℃. After the beginning of spring, the weather is cold and hot, and the temperature is variable. At this time, sweet potato starts to sprout, the resistance is weakened, and it is easy to rot. therefore, when the weather turns warm, it should be ventilated and cooled in time.
Family preservation of sweet potato
1、 Indoor fresh storage method: sweet potato is afraid of cold, when the temperature is too low, it may be frozen, forming a hard core, not cooked, not rotten; if the temperature is higher than 18 ℃ for a long time, it will sprout again. Therefore, it is best to control the room temperature at about 15 ℃. Sweet potato was wet, it is easy to cause bacteria damage, causing rot. Therefore, it's best to keep it in a ventilated wooden box. If there is no wooden box, board shall be padded at the place where sweet potatoes are stacked and against the wall, and then cover some things on the potato pile to prevent moisture. In the warm day, open the window properly to change the air, so as to keep the indoor air fresh, but prevent the cold wind from blowing in. The sweet potatoes bought from the market should be put in the sun for a few hours (do not put out overnight), so as to reduce the water content of the wound and promote the healing. When using them, they should be handled gently to avoid bruises.
2、 Drying and preservation method after steaming: after steaming, cut each sweet potato into 3-4 pieces, and put them on the room or in a sunny, dry and ventilated place for drying. After the sweet potato is steamed, the water evaporates slowly, and it takes a long time to dry. Be careful not to get wet. After drying, store in a dry place indoors. Before eating, steam it with water.
3、 Cut and dry: wash and cut sweet potatoes, dry them on a drying pad, and then they will become sweet potato silk, which can be steamed and eaten in rice.