Starch is a substance composed of two polysaccharides called amylose and amylopectin. Starch exists as a stored substance in plant cells. Starch is stored in storage organs like seeds, fruits, tubers, etc.; the primary sources of starch are rice, wheat, potatoes, etc.
Properties of starch
(i) Starch is an odorless, colorless, tasteless, and white powdery biochemical substance with many benefits.
(ii) Starch is insoluble in water, ether, and alcohol at an average temperature.
(iii) Starch turns blue in the presence of iodine solution.
(iv) Starch can be broken down into dextrin and maltose into glucose at high temperatures.
Test for starch:
Starch turns blue in an iodine solution, and that is because the amylose component of starch binds iodine molecules to form complex compounds. As a result, the electron orbitals of the iodine atoms change and absorb sunlight, producing a blue color on the sample.
Uses of starch:
(i) Starch is mainly used as food for living organisms.
(ii) Most of the glucose produced in photosynthesis is converted into starch that can be used for different functions.
(iii) Starch is used to manufacture glucose, alcohol, and distilled liquor in many industries.
(iv) Starch is converted into glucose that provides energy and carbon molecules to the organism.
(v) Starch is also used to prepare paper and glue for a lot of work.