Sweet potato roots are referred to as “green” immediately after harvest and are usually not as sweet as cured sweet potatoes. Commercially, most roots are cured immediately after harvest to improve flavor and storage life. Curing the sweet taters heals cuts and reduces decay and shrinkage in storage because it allows the “skin” to thicken and to reform, in effect healing bumps and bruises. Curing also converts some starches to sugars, enhancing flavor.
Curing should be started immediately after harvest and continued for 4 to 7 days at 80 to 85 degrees and 90 to 95 % relative humidity with good air circulation and ventilation. 100% relative humidity should be avoided so that the surface of the sweet potatoes will not be completely wet, which promotes disease. The warmer the soil temperature when roots are harvested, the quicker they will cure.
Long-term storage areas should be maintained at 55 to 60 degrees with 85 % relative humidity and with sufficient venting to produce a total volume change of air at least once a day. Above 60 degrees, internal breakdown, shrinking and sprouting can occur. Temperatures below 55 degrees may cause hardcore, a disorder where a whitish, hard area appears in the cooked sweet potato.