Though they get super popular in fall, sweet potatoes are a highly nutritious vegetable enjoyed year-round in many households. They contain high amounts of vitamins A and C, along with beta-carotene and no fat or cholesterol. Another positive attribute of the sweet potato is its ability to stay fresh for up to a month(!) if stored correctly. Recycled air will cause them to turn bitter and hard, so keep them hidden away in a dark, cool place like your pantry—not your fridge. They can go bad quickly if not properly stored, and there are several signature signs of a spoiled sweet potato.
Examine the sweet potato for signs of decay. Decay in sweet potatoes can be seen as dark brown spots or small craters on the surface. Decayed spots can be cut away from the rest of the potato, but the bitter taste may linger throughout.
Run your fingers over the skin of the potato. If the skin is highly wrinkled and dehydrated, then the sweet potato may be going bad.
Look for any small sprouts or roots coming from the sweet potato. Freshly growing roots will be slightly lighter than old roots, which are totally harmless. Fresh roots are a sign that your sweet potato is spoiled.
Cut into the sweet potato and look for any dark brown spots on the inside of the flesh. These spots can sometimes be difficult to spot on the outside. If they are on the inside, your sweet potato is unfortunately bad.