Maximising blackcurrant anthocyanins: Temporal changes during ripening and storage in different genotypes

Increasing evidence suggests that anthocyanins, as natural antioxidants, exert anti-carcinogenic, anti-inflammatory, vaso-protective and anti-obesity effects when tested in vitro or in vivo. Blackcurrant (Ribes nigrum L.) berries are a rich source of anthocyanins with concentrations up to 4-fold greater than that of other common fruits. However, there is a paucity of information on how blackcurrant anthocyanins change during ripening on the bush or during postharvest storage, which could lead to better selection of fruits with enhanced health-promoting properties. Accordingly, the present study describes the temporal changes in anthocyanins in different blackcurrant genotypes during the late stages of development or as a result of postharvest storage at different temperatures. In all cases, four major anthocyanins (viz. cyanidin-3-glucoside, cyanidin-3-rutinoside, delphinidin-3glucoside and delphinidin-3-rutinoside) were identified, accounting for over 80% of the total anthocyanin concentrations. Three different development stages (viz. early ripe (ER), fully ripe (FR) or over ripe (OR)) were chosen when fruit were at commercial maturity but presented different colorations. Anthocyanin concentration was nearly double in OR berries than ER, however the temporal changes during ripening were genotype-dependent, with some cultivars reaching maximum concentrations at the FR stage. During postharvest storage anthocyanin synthesis was observed in both ER and FR berries during storage, but ER berries never reached the concentrations of those harvested at FR stage. Storage temperature crucially affected anthocyanin concentrations in FR but not in ER berries. The results from this study may provide both growers and industry with additional information for maximising anthocyanin concentrations in blackcurrant berries.