Loss of the green pigment chlorophyll to unmask yellow carotenoids is a desirable part of the ripening process in many fruits, such as peaches and yellow cultivars of apples.
Carotenoids are isoprenoid molecules that are common to all photosynthetic tissues. They are divided into the hydrocarbon carotenes, such as lycopene and β -carotene or xanthophylls, typified by lutein. Provitamin A carotenoids, most importantly beta-carotene, followed by alpha-carotene, are those which are converted into vitamin A in the body and help protecting against infection, night blindness and eye disease.
Carotenoids are localized in subcellular organelles (plastids), i.e. chloroplasts and chromoplasts. In chloroplasts, the carotenoids are chiefly associated with proteins and serve as accessory pigments in photosynthesis, whereas in chromoplasts they are deposited in crystalline form or as oily droplets.
In carotenogenic fruits and fruit vegetables, ripening is usually accompanied by enhanced carotenogenesis as chlorophylls decompose and the chloroplasts are transformed into chromoplast.
Ripening process of fruit
