Raw powder (white powder), also known as bean powder and water chestnut powder, is made from broad beans or water chestnut. Raw flour has a wide range of uses and can be used as a seasoning for cooking, bean jelly and pancake stalls. Mainly used for sizing and sieving of meat raw materials. In Chinese food, it refers to starch, and in cooking, it is used for thickening and sizing. There are many kinds, such as sweet potato starch, water bean powder used in Sichuan cuisine and corn starch. Raw flour is starch, which can have many kinds, generally referring to corn starch.

Starch is a high molecular polymer of glucose, which is hydrolyzed into maltose in disaccharide stage and glucose is obtained after complete hydrolysis. Starch includes amylose and amylopectin. Amylose contains hundreds of glucose units while amylopectin contains thousands of glucose units. In natural starch, about 22% ~ 26% is linear and soluble, and the rest is amylopectin. When detected by iodine solution, amylose solution is blue, and amylopectin turns red-brown after contacting with iodine.