In general, water starch is dry starch with water, which together is called water starch. Stir-fried things are usually dry starch, or add dry starch with egg liquid. Starch used for thickening, also known as dough powder, is a polysaccharide polymer concentrated by multiple glucose molecules. Starch used for cooking mainly includes mung bean starch, potato starch, wheat starch, water chestnut starch and lotus root starch. Starch is insoluble in water. When it is heated to 60℃ with water, it will be gelatinized into a colloidal solution. Thickening is the use of this property of starch.