carotenoids, important class of plant pigments whose red, orange, and yellow colours complement the green of chlorophyll and the blue and red of anthocyanins. They come from the chloroplasts in green grapes. Carotenoids are terpenoids with 40 carbons and belong to the lipid group of organic compounds. They include two main groups—xanthophylls and carotenes—which are prominent in grapes and provide the skin colour of so-called white grapes and are associated with vine leaf colours in autumn; carotenes also form a substrate for synthesis of many flavour compounds and flavour precursors. Carotenoids serve as accessory pigments in the process of photosynthesis.