Potato is the most soluble food-fibre-rich plant that can serve as therapeutic food, with better effects on obesity, diabetes, high cholesterol, customary constipation, hemorrhoids, stomach disease, oesophagus cancer, lung cancer and intestine cancer caused by too low fibre intake. It regulates appetite, enhances appetite and supplements diet fibres. Sour sauce is a combination of co-ordinated, mutually reinforcing and sour。