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, which is used for thickening and sizing in cooking. There are many kinds, such as sweet potato starch, water bean powder used in Sichuan food, corn starch and so on. 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.

Starch is a nutrient stored in plants and exists in seeds and tubers. The starch content in all kinds of plants is high, including rice 62% ~ 86%, wheat 57% ~ 75%, corn 65% ~ 72% and potato 12% ~ 14%. Starch is an important part of food, so it feels a little sweet to chew rice. This is because amylase in saliva hydrolyzes starch into monosaccharides. After food enters the gastrointestinal tract, it can also be hydrolyzed by amylase secreted by the pancreas, and the formed glucose is absorbed by the small intestine wall and becomes a nutrient for human tissues. Partial hydrolysis of amylopectin can produce a mixture called dextrin. Dextrin is mainly used as food additive, glue, paste, and in the manufacture (finishing) of paper and textiles.

Types of starch

Starch used for thickening, also known as dough powder, is a polysaccharide polymer concentrated by multiple glucose molecules. Cooking starch mainly includes mung bean starch, potato starch, wheat starch, water chestnut starch, lotus root starch, corn starch and so on. Starch is insoluble in water, and when heated to 60℃ with water, it is gelatinized into colloidal solution. Thickening is to use this characteristic of starch.

Mung bean starch

Mung bean starch is the best starch and seldom used. It is made by soaking mung beans in water, grinding and precipitating. Features: enough viscosity, small water absorption, white and shiny color.

potato starch

At present, potato starch is widely used in families. It is made by grinding, washing and precipitating potatoes. The characteristics are: enough viscosity, fine texture, white color, luster better than mung bean starch, but poor water absorption.

wheat starch

Wheat starch is precipitated from wheat bran after washing gluten, or made from flour. The characteristics are: white color, but poor luster, not as good as potato powder, easy to precipitate after thickening.

sweet potato starch

Sweet potato starch is characterized by strong water absorption, but poor viscosity and dark red and black color. It is made of fresh potatoes through grinding, scrubbing and precipitation.

In addition, there are corn starch, water chestnut starch, lotus root starch and water chestnut starch.