Main structure of starch

There are two types of starch: amylose and amylopectin. Amylose contains hundreds of glucose units, and amylopectin contains thousands of glucose units. In natural starch, linear chains account for about 22% to 26%, which is soluble, and the rest are amylopectin. When tested with iodine solution, amylose solution appears blue, while amylopectin turns red-brown when contacted with iodine.

Starch is a nutrient stored in plants and exists in seeds and tubers. The starch content in all types of plants is high. Rice contains 62%-86% starch, wheat contains 57%-75% starch, and corn contains 65%-72% starch, and potatoes contain 12%-14% starch. Starch is an important part of food. It feels sweet when chewing rice, etc., because the amylase in saliva hydrolyzes the starch into the disaccharide, maltose. After food enters the gastrointestinal tract, it can also be hydrolyzed by the amylase secreted by the pancreas, and the glucose formed is absorbed by the small intestine wall and becomes a nutrient for human tissues. Partial hydrolysis of amylopectin produces a mixture called dextrins. Dextrine is mainly used as food additive, glue, paste, and in the manufacturing and finishing of paper and textiles. (Editor in charge: Tian Tian)