How to Store and Keep Sweet Potatoes Fresh: A Full Breakdown of Techniques and Methods
Storage and Fresh-Keeping Techniques for Sweet Potatoes
Storage methods for sweet potatoes:
1. Timely, damage-free harvest
The timing of the sweet potato harvest is closely related to safe storage. If harvested too early, the temperature is still high and the roots cannot be placed in the cellar for storage after harvest. If harvested too late, sweet potatoes that suffer frost damage in the field are prone to chilling injury during storage. Generally, harvesting begins when the temperature drops to 15°C, and must be completed before frost.
Sweet potato skin is thin and fragile, and it is very easily damaged during harvest and handling. Such damage very easily invites infection by pathogenic fungi, leading to rot. Therefore, sweet potatoes need curing treatment before storage.
The specific method of curing treatment is: immediately after harvest, provide conditions of 30-35°C and 90%-95% relative humidity, and keep them under these conditions for 4-6 days; this allows the damaged surface protective structure to be repaired. Curing treatment should be carried out immediately after the sweet potato harvest; the shorter the interval, the better the effect. During curing, attention must also be paid to ensuring adequate ventilation to prevent the accumulation of CO_2 or oxygen deficiency, or the formation of condensation water. Curing should be carried out in the storage room or cellar. Once curing is finished, the conditions should immediately be changed to the normal storage temperature and humidity, and the sweet potatoes should not be moved again thereafter, to prevent new wounds.
2. Storage conditions
The suitable temperature for sweet potato storage is 13-15°C, and the relative humidity is 85%-90%. Sweet potatoes are especially sensitive to low temperatures, and chilling injury occurs when stored below 13°C. The symptoms of chilling injury are deterioration of the inside of the sweet potato, which turns brown or black, and after steaming it has an off-flavor and hard core.
3. Storage methods and management
1. Indoor storage Choose a well-sealed and warm room, build a ring of flues around the base of the walls, set up a stove for heating, and build a bin on the ground. The bin is 1-1.5 m high and 1.5-2 m wide, and its length depends on the size of the room and the storage quantity. Line the bottom and sides of the bin with an appropriate amount of bean leaves to provide cold protection and insulation. Place the sweet potatoes in the bin; when loading the bin, be sure to handle them gently and set them down lightly to avoid damage, and remove any diseased sweet potatoes. Then light the fire to heat and carry out curing treatment; after curing, lower the temperature through the vent in the window. Thereafter, as the temperature drops, seal the doors and windows, cover the sweet potatoes with 6-9 cm of bean leaves, and when the weather is cold, cover with another layer of straw curtains for cold protection and heat appropriately with a fire.
2. Well-cellar storage Choose a place with high terrain, firm soil, and a low groundwater table, and dig a shaft downward, generally about 1 m in diameter and 5-6 m deep. Leave a soil platform in the exact center of the shaft bottom, then from the bottom of the well dig horizontally to both sides a cave about 1 m wide and about 1.5 m high; after digging in about 1 m, enlarge it further to become a storage chamber. The size of the storage chamber can be determined by the storage quantity. A storage chamber 1.5 m high, 1.5 m wide, and 2-3 m long can generally store 1,500-2,000 kg of sweet potatoes. The mouth of the well cellar should be about 30 cm higher than the flat ground to prevent rainwater or snowmelt from flowing into the cellar. Spread dry sand 10-15 cm thick in the storage chamber, and place the sweet potatoes on it. The sweet potatoes should only fill 70% of the chamber so as to leave room for air exchange; otherwise rot will be worsened by moisture and heat. When workers go down into the well for management, they must be careful to prevent CO2 suffocation inside the well.
1. Timely, damage-free harvest
The timing of the sweet potato harvest is closely related to safe storage. If harvested too early, the temperature is still high and the roots cannot be placed in the cellar for storage after harvest. If harvested too late, sweet potatoes that suffer frost damage in the field are prone to chilling injury during storage. Generally, harvesting begins when the temperature drops to 15°C, and must be completed before frost.
Sweet potato skin is thin and fragile, and it is very easily damaged during harvest and handling. Such damage very easily invites infection by pathogenic fungi, leading to rot. Therefore, sweet potatoes need curing treatment before storage.
The specific method of curing treatment is: immediately after harvest, provide conditions of 30-35°C and 90%-95% relative humidity, and keep them under these conditions for 4-6 days; this allows the damaged surface protective structure to be repaired. Curing treatment should be carried out immediately after the sweet potato harvest; the shorter the interval, the better the effect. During curing, attention must also be paid to ensuring adequate ventilation to prevent the accumulation of CO_2 or oxygen deficiency, or the formation of condensation water. Curing should be carried out in the storage room or cellar. Once curing is finished, the conditions should immediately be changed to the normal storage temperature and humidity, and the sweet potatoes should not be moved again thereafter, to prevent new wounds.
2. Storage conditions
The suitable temperature for sweet potato storage is 13-15°C, and the relative humidity is 85%-90%. Sweet potatoes are especially sensitive to low temperatures, and chilling injury occurs when stored below 13°C. The symptoms of chilling injury are deterioration of the inside of the sweet potato, which turns brown or black, and after steaming it has an off-flavor and hard core.
3. Storage methods and management
1. Indoor storage Choose a well-sealed and warm room, build a ring of flues around the base of the walls, set up a stove for heating, and build a bin on the ground. The bin is 1-1.5 m high and 1.5-2 m wide, and its length depends on the size of the room and the storage quantity. Line the bottom and sides of the bin with an appropriate amount of bean leaves to provide cold protection and insulation. Place the sweet potatoes in the bin; when loading the bin, be sure to handle them gently and set them down lightly to avoid damage, and remove any diseased sweet potatoes. Then light the fire to heat and carry out curing treatment; after curing, lower the temperature through the vent in the window. Thereafter, as the temperature drops, seal the doors and windows, cover the sweet potatoes with 6-9 cm of bean leaves, and when the weather is cold, cover with another layer of straw curtains for cold protection and heat appropriately with a fire.
2. Well-cellar storage Choose a place with high terrain, firm soil, and a low groundwater table, and dig a shaft downward, generally about 1 m in diameter and 5-6 m deep. Leave a soil platform in the exact center of the shaft bottom, then from the bottom of the well dig horizontally to both sides a cave about 1 m wide and about 1.5 m high; after digging in about 1 m, enlarge it further to become a storage chamber. The size of the storage chamber can be determined by the storage quantity. A storage chamber 1.5 m high, 1.5 m wide, and 2-3 m long can generally store 1,500-2,000 kg of sweet potatoes. The mouth of the well cellar should be about 30 cm higher than the flat ground to prevent rainwater or snowmelt from flowing into the cellar. Spread dry sand 10-15 cm thick in the storage chamber, and place the sweet potatoes on it. The sweet potatoes should only fill 70% of the chamber so as to leave room for air exchange; otherwise rot will be worsened by moisture and heat. When workers go down into the well for management, they must be careful to prevent CO2 suffocation inside the well.