Evolution of juice anthocyanins during ripening of new selected pomegranate ( Punica granatum ) clones

Abstract

For five new clones of pomegranate, culti- vated under homogeneous conditions, changes in juice anthocyanin contents during ripening were studied. Six anthocyanin pigments were found to be responsible for the red color of pomegranate juice. These were quanti- tatively and qualitatively analyzed by high-performance liquid chromatography and identified as delphinidin 3- glucoside and 3,5-diglucoside, cyanidin 3-glucoside and 3,5-diglucoside and pelargonidin 3-glucoside and 3,5-di- glucoside. Generally, there was an increase in juice pig- mentation during fruit ripening. In the early fruit-ripen- ing stages, delphinidin 3,5-diglucoside was the main pigment, followed by cyanidin 3,5-diglucoside, while in the later stages, the monoglucoside derivatives cyanidin 3-glucoside and delphinidin 3-glucoside increased con- siderably. The pelargonidin derivatives were always present in small amounts. Previous studies have shown that six anthocyanins are found in the juice of pomegranates, namely del- phinidin 3-glucoside and 3,5-diglucoside, cyanidin 3- glucoside and 3,5-diglucoside, and pelargonidin 3-glu- coside and 3,5-diglucoside (1). The peel contains only the pelargonidin and cyanidin derivatives, and no del- phinidin is detected (5). Anthocyanin content and evolution during the de- velopment and postharvest storage of pomegranates have been studied previously (1). During the first steps of development the 3,5-diglucosides are the main pig- ments present in the juice, with delphinidin glycosides being the main pigment type, while during the optimum harvesting time, the 3-glucosides are the main pigments and the cyanidin derivatives are the predominant com- pounds. The aim of the present work was to evaluate and quantify the anthocyanin content of five different pom- egranate clones with distinctive quality characteristics (acidity, color stability, etc.), and to follow the changes in juice pigmentation, both qualitatively and quantita- tively, during the development of the fruit. The effect of fruit location in the tree was also studied.