Starch is a carbohydrate which is composed of two polysaccharides called amylose and amylopectine. They are polymers of glucose.
Structure of starch: Starch is present as a resent food in plant bodies. Glucose, formed during photosynthesis is mostly turned into starch. Starch is usually granular. The shape and structure of starch grains vary from plant to plant.
Structure of starch
Occurance: Starch is mostly found in seeds, fruits, tubers etc. Starch is composed of two polysaccharides mentioned below:
- Amylose: The glucose molecules of amylose mutually remain attached to carbon 1-4. Usually, an amylose is composed of 200 to 1000 molecules of glucose. Amylose has an unbranched chain of molecules.
- Amylopectin: Besides the bonding of glucose molecules with carbon 1-4 of amylopectin, glucose molecules also remain attached to ∞-1-6. Usually, an amylopectin is composed of 2000-200000 glucose molecules. Amylopectin has a branched chain of glucose molecules.
Both amylose and amylopectin give rise to a lot of ∞-D, glucose units at the end of hydrolysis. So, starch is composed of numerous glucose molecules.
Usage of starch:
(i) Starch is used as a food.
(ii) It is used as an indicator during titration
(iii) It is used to produce glucose and alcohol in the laboratory.
(iv) Used in the paper mills.
(v) Starch is also used to manufacture flour.
