Dependence between colour and individual anthocyanin content in ripening grapes

Three red grape cultivars of different coloration (Flame seedless, Exotic and Monastrell), grown in Murcia (southeast Spain) were analysed during ripening for external colour and individual pigment content. The application of the CIRG colour index, calculated from the coordinates hue angle (h), lightness (L*) and chroma (C*) of the CIELAB colour space, and defined as [(180-h)/(L* + C*)], permitted an objective evaluation of the colour at the different ripening stages. External colour and anthocyanic profile were closely linked. Cyanidin-3-glucoside was the most abundant pigment in Flame seedless (low pigmented cultivar), while malvidin-3-glucoside was the main anthocyanin in the cultivars Monastrell and Exotic (both of them with a high pigment content). Data derived from the study of the ratios between anthocyanins with different degree of hydroxilation and/or methoxylation leads to know information on differences between grapevines linked to the synthesis of these pigments. (C) 1999 Canadian Institute of Food Science and Technology. Published by Elsevier Science Ltd. All rights reserved.