DISAPPEARANCE OF CHLOROPHYLLS AND CAROTENOIDS DURING THE RIPENING OF THE OLIVE

Although the colour of olives changes from green to yellow, turning co lour, purple and black according to the stage of ripeness, chlorophyll a is always the major chloroplastic pigment followed by chlorophyll b . Carotenoids are also present as minor components. Among these, lutei n and beta-carotene are worthy of mention, while neoxanthin, violaxant hin and antheraxanthin are present in lower proportions. The concentra tion of the chlorophylls and the carotenoids decreases gradually as ha rvesting approaches. When the colour of the fruit is predominantly gre en, the percentage decrease of the carotenoid fraction is higher than that experienced by the chlorophyll fraction. In the latter fraction a t this stage chlorophyll b is preferentially degraded. In contrast, in the yellow colour stage, the disappearance of chlorophylls is noticea bly higher than that of carotenoids, the levels of which tend to be ma intained with minimal pigment degradation at this stage. This faster d egradation of the chlorophylls allows the coloration due to the carote noids to be seen in the fruit. From this moment onwards, once the stag e of ripening has begun, the rate of degradation of the chlorophyll fr action increases to almost twice that of the carotenoid fraction, and chlorophyll a disappears faster than chlorophyll b. The ratio of lutei n to beta-carotene decreases as ripening advances reflecting the highe r rate of degradation of lutein.