The water content of potato tuber is about 79.5%, carbohydrate 17.2% (sugar l6.8%, fiber 0.4%), protein 2.0% and fat 0.2%. Sugar is almost all starch, with a small amount of glucose, sucrose, fructose, pentosan and dextrin. The average particle size of potato starch is 50μm, which is much larger than other grain starches. It is oval and has markings on the surface.

It has excellent qualities such as low gelatinization temperature, high viscosity, high swelling power, etc. Especially, its viscosity is the largest among all starches, and it is the only starch in nature that combines with the valence of phosphate, so it is not easy to age, so it is an advanced starch used in food industry (such as adding instant noodles). In addition, the size and distribution of cellular starch particles have great influence on the quality of potato cooked food.

Although potato contains only about 2% protein, its amino acid composition is reasonable. Compared with protein from other sources, it is more easily absorbed by people and animals. Potato contains many vitamins, such as VC, VB 1, VB2, vPP, etc., especially vitamin C(0.23mg/g, about four times that of celery and lettuce, and equivalent to leek), and it is not easy to be damaged by heat, so it is a valuable all-round nutritious food. Although the calcium content is not as good as that of sweet potato, the potassium content is equivalent to that of sweet potato. As a food for preventing hypertension, it has attracted attention. Fresh potatoes contain polyphenol oxidase and tyrosinase, which are easy to brown potatoes, so when peeled or cut off, the cut surface exposed to air is easy to brown. It can be prevented by soaking with sulfurous acid solution or washing with water during processing. Due to improper storage, potatoes will contain toxic solanine in bud eyes or green skin, which needs to be removed during processing.