Salinity effects on colour and health traits in the pomegranate (Punica granatum L.) fruit peel

Irrigation water salinity effects on colour and health ingredients in the pomegranate peel were studied in two accessions, 'Wonderful' and 'SP-2', grown under a wide range of salinities, 1.2 to 9 dS m^-1. Ripe fruit peels were analysed for phenolics and anthocyanins composition, and antioxidative capacity. Total phenolics concentration and antioxidative capacity were determined by the Folin-Ciocalteau and FRAP assays, respectively. Phenolics and anthocyanins composition was analysed by RP-HPLC. Increased salinity enhanced considerably the overall accumulation of phenolics and anthocyanins, and the antioxidative capacity in both cultivars; the magnitude of the effects was accession dependent. Mono- and di-glucosides of cyanidins, pelargonidins, and delphinidines were detected at proportions that varied with accession and salinity. Increased concentrations of gallotannins, flavonols and ellagic acid derivatives in 'Wonderful', and punicalagins, flavonols and ellagic acid derivatives in 'SP-2' accompanied elevated salinity levels. The results may benefit the pomegranate juice and byproduct valourisation industries, especially in the face of global water quality deterioration.