1. 40 minutes. Wash the sweet potatoes and do not need to dry them. Wrap the sweet potatoes in tin foil. Put it in the oven at 200 degrees and bake for 40 minutes.

2. Sweet potato is a complete and rich natural nourishing food, containing protein, fat, polysaccharide, phosphorus, calcium, potassium, carotene, vitamin A, vitamin C, vitamin E, vitamin B1, Vitamin B2 and 8 amino acids. According to scientists' analysis, its protein content is 7 times more than that of rice; its carotene content is 3.5 times that of carrots; its vitamin A content is 100 times that of potatoes; its sugar, calcium, vitamin B1, and vitamin B2 contents are all higher than those of rice and flour. Each 100g edible portion of fresh potato cubes contains 29.5g of carbohydrates, 0.2g of fat, 20mg of phosphorus, 18mg of calcium, and 0.4g of iron. These substances play an important role in promoting the activity of human brain cells and secreting hormones, enhancing the body's disease resistance, improving immune function, and delaying mental decline and body aging. The Japanese Ministry of Health has listed it as an important food for dietary therapy.