Orange carotene and yellow xanthophyll together are called carotenoids. Carotenoids are of two types. Carotene and xanthophyll.
(i) Carotene: Carotene is an unsaturated hydrocarbon compound. Its chemical symbol is C40H56O. It is of four types. Carotene a, b, c and d. It absorbs blue-violet light (449-478nm) the most. Color diversity of carotene is most interesting. Green carotene is found in avocados, red in tomatoes, reddish orange in carrots and yellow in various flowers.
(ii) Xanthophyll: Oxygenated carotene is called xanthophyll. Its chemical symbol is C40H56O2. Among the xanthophylls are lutein in green plants, lycoxanthin in tomatoes and zeaxanthin in Bhutra.