Chloroplasts mature into pigment producing chromoplasts in the tomato fruit. Chloroplasts begin thylakoid degeneration in the green stage, as the fruit stops photosynthesis and enters the yellow stage. Now the chromoplast's main pigment synthesis is shifted to the carotenoid pigment family, to a linear red carotene called lycopene that gives tomatoes, pink grapefruit, apricots, red oranges, watermelon, rosehips, and guava their red color. It also produces small amounts of its orange cyclisation product, beta-carotene, the precursor to vitamin A.
Chromoplasts of deep red colored fruits contain lycopene crystals within the lumina (inner space) of the plastid’s restructured membrane sacs. The membrane sacs are derived from the inner envelope thykaloid membrane as the chloroplast matured during the ripening process. Lycopene is a carotenoid pigment that acts as an antioxidant. Lycopene's configuration enables it to inactivate free radical's electrochemical imbalance so they cannot damage cells.
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