CHANGES IN POMEGRANATE JUICE PIGMENTATION DURING RIPENING

Six anthocyanin pigments were found to be responsible for the red colo ur of pomegranate juice (cv 'Mollar'). These were analysed quantitativ ely and qualitatively by HPLC and identified as delphinidin 3-glucosid e and 3,5-diglucoside, cyanidin 3-glucoside and 3,5-diglucoside and pe largonidin 3-glucoside and 3,5-diglucoside. The fruit skin contained o nly the cyanidin and pelargonidin derivatives. Generally, there is an increase in juice pigmentation with fruit ripening. During early matur ation stages the 3,5-diglucosides were the main pigments and the delph inidin-based derivatives were the predominant compounds. In late matur ation stages the proportion of monoglucosides increased to reach value s similar to or higher than those of the diglucosides, and the cyanidi n-based derivatives were the predominant substances. The concentration of pigments in juice obtained from mature pomegranates ranged between 50 and 100 mu g of anthocyanin per gram fresh weight of arils. The de velopment of anthocyanins was also tested in fruits produced in two di fferent orchards, and in fruits from different locations in the tree. Red coloured fruits, located in the outer parts of the tree, and yello w fruits, on the inner branches, were analysed. The juices obtained wi th the seed coats of both fruit types, and from the two orchards selec ted, showed the same anthocyanin profile. However, the total amount of pigments in the juice was generally smaller in those fruits with redd ish skins (outer fruits), than in those with yellow skins (inner fruit s). As juice pigmentation is one important quality factor in pomegrana te, these results could be used in on-line determinations of the pomeg ranate quality by non-destructive physical methods.