Six anthocyanin pigments were found to be responsible for the red colour of pomegranate juice (cv 'Mollar'). These were analysed quantitatively and qualitatively by HPLC and identified as delphinidin 3-glucoside and 3,5-diglucoside, cyanidin 3-glucoside and 3,5-diglucoside and pelargonidin 3-glucoside and 3,5-diglucoside. The fruit skin contained only the cyanidin and pelargonidin derivatives. Generally, there is an increase in juice pigmentation with fruit ripening. During early maturation stages the 3,5-diglucosides were the main pigments and the delphinidin-based derivatives were the predominant compounds. In late maturation stages the proportion of monoglucosides increased to reach values similar to or higher than those of the diglucosides, and the cyanidin-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 development of anthocyanins was also tested in fruits produced in two different orchards, and in fruits from different locations in the tree. Red coloured fruits, located in the outer parts of the tree, and yellow fruits, on the inner branches, were analysed. The juices obtained with the seed coats of both fruit types, and from the two orchards selected, showed the same anthocyanin profile. However, the total amount of pigments in the juice was generally smaller in those fruits with reddish skins (outer fruits), than in those with yellow skins (inner fruits). As juice pigmentation is one important quality factor in pomegranate, these results could be used in on-line determinations of the pomegranate quality by non-destructive physical methods.
