1. Black spots appear on the skin of sweet potato, which are mostly caused by the pollution of black spot pathogen. Sweet potato has black spots and soft rot, the skin of sweet potato has brown or black spots, or it is dry and concave, and the sweet potato heart becomes hard and bitter. At this time, you can't eat it any more, because the toxin discharged by the black spot pathogen contains sweet potato ketone and sweet potato ketone alcohol, which makes sweet potato hard and bitter and highly toxic to human liver. The toxins contained in sweet potatoes are heat-resistant, so eating raw or cooked sweet potatoes with dark spots will be poisoned. Therefore, once the sweet potato has dark spots, hardness, bitterness and musty taste, don't eat it again. Sweet potatoes have dark spots, and you can't eat them even if you cut them off. The toxin produced by the growth and reproduction of sweet potato black spot pathogen can not be removed by cutting off the epidermis alone. Especially in the case that the black spots of sweet potatoes have been distributed by more than one third, you must never eat them again. Once eaten, gastrointestinal symptoms such as nausea, vomiting and diarrhea usually occur within 24 hours. Severe cases may even have high fever, headache, asthma, blurred vision, blood drawing, hematemesis, coma and even death.
2. Cracked oxidized sweet potato black spots have no effect. If there are black spots on the sweet potato, it doesn't matter if it is not attacked by black spots. Just cut off the black spots. For example, when sweet potatoes are harvested, their roots collide with each other and there are wounds after the collision. The milk contained in sweet potatoes flows out easily. Because milk contains a lot of polyphenol antioxidants, it will also form black spots when combined with oxygen in the air. This black spot has no adverse effect on human health. Just cut it and eat it.
3. The black spot of sweet potato after callus treatment had no effect. After the sweet potato is harvested, the sweet potato tuber is usually placed in an environment with a temperature of 29-30 degrees and a humidity of 90-95% for 4- 10 days, so that the wound of the sweet potato tuber epidermis forms a black cork layer, just like a scab caused by human skin injury, to prevent the invasion of pathogenic bacteria. This treatment is called callus treatment. Just when eating, cut it off for beauty.