Sweet potato peeled black consider oxidation or deterioration, general oxidation can be eaten, but the deterioration can not be eaten. 1. oxidation: the sweet potato ketone, sweet potato ketone alcohol, polyphenols and oxygen react to produce quinones, and then further oxidation and polymerization of brown pigment and melanin, belonging to the normal oxidation can be eaten normally, it is generally recommended that sweet potatoes peeled into the water to reduce the degree of oxidation. 2. spoilage: due to the sweet potato stored for a long time, the internal structure of the changes that occur, corruption, blackening of the situation, while becoming hard and bitter, deterioration occurs, this situation is not recommended for consumption, consumption is easy on the body, resulting in food poisoning. After peeling sweet potatoes, it is recommended to consume them as soon as possible, and it is best to discard them when they become blackened, so as not to affect your health. If you feel unwell after eating sweet potatoes, please seek medical advice.