The molecular formula of starch is (C?H?O?)?.

Starch is a high molecular carbohydrate, a polysaccharide polymerized from glucose molecules. Its basic structural unit is α-D-glucopyranose, and its molecular formula is (C6H10O5)n. There are two types of starch: amylose and amylopectin. The former is an unbranched helical structure; the latter is composed of 24 to 30 glucose residues connected head to tail by α-1,4-glycosidic bonds, with α-1,6-glycosidic bonds at the branches.

Starch is divided into amylose and amylopectin. Amylose is composed of D-hexacyclic glucose connected by α-1,4-glycosidic bonds; the branch positions of amylopectin are α-1,6-glycosidic bonds, and the rest are α-1,4-glycosidic bonds. Amylose contains hundreds of glucose units, and amylopectin contains several thousand glucose units.

In natural starch, amylose accounts for 20 to 26, which is soluble, and the rest is amylopectin. One end of the amylose molecule is a non-reducing end group and the other end is a reducing end group, while the amylopectin molecule has one reducing end group and many non-reducing end groups; when tested with an iodine solution, the amylose liquid showed obvious Dark blue, the iodine absorption amount is 19~20.

When amylopectin comes into contact with iodine, it turns purple, and the iodine absorption amount is 1. Starch can adsorb many organic and inorganic compounds. Amylose and amylopectin have different adsorption properties due to different molecular shapes. Amylose molecules have good molecular extensibility in solution and can easily associate with some polar organic compounds such as n-butanol and fatty acids through hydrogen bonds.

Chemical Properties

Many chemical properties of starch are similar to glucose, but because it is a polymer of glucose and has its own unique properties, the chemical properties of starch are used to change starch molecules in production. Two important categories of starch deep-processed products are available.

The first category is starch hydrolyzate products, which are products with different DPs obtained by using the hydrolytic properties of starch to degrade starch molecules. Under the action of catalysts such as acids or enzymes, starch's α-1,4 glycosidic bonds and α-1,6 glycosidic bonds are hydrolyzed, and various products such as dextrin, oligosaccharides, maltose, and glucose can be generated.