Starch can be regarded as a high polymer of glucose. In addition to food, starch is used industrially to make dextrin, maltose, glucose, alcohol, etc. It is also used to make printing paste, sizing of textiles, gluing of paper, pressing of pharmaceutical tablets, etc. It can be extracted from corn, sweet potatoes, wild acorns and kudzu root, which contain starch.
There are two types of starch: straight-chain starch and branched-chain starch. Straight-chain starch contains a few hundred glucose units and branched-chain starch contains a few thousand glucose units. The straight chain accounts for 20% to 26% of the natural starch, which is soluble, while the rest is branched starch. When tested with iodine solution, the straight chain starch solution appears blue, while the branched chain starch turns red-brown when it comes in contact with iodine.
Starch is a nutrient stored in the plant body, stored in the seeds and tubers, all types of plants have a high starch content, rice contains 62% to 86% starch, wheat contains 57% to 75% starch, corn contains 65% to 72% starch, and potatoes contain more than 90% starch. Starch is an important part of food, chewing rice, etc. feel some sweetness, this is because the amylase in the saliva will be starch hydrolysis into disaccharides - maltose. After food enters the stomach and intestines, it can also be hydrolyzed by salivary amylase secreted from the pancreas, and the glucose formed is absorbed by the wall of the small intestine and becomes a nutrient for human tissues. Partial hydrolysis of branched chain starch yields a mixture called dextrin. Dextrins are mainly used as food additives, glues, pastes, and in the manufacture of paper and textiles, etc.