Pomological and phenolic characterization of blood orange cultivars in a Mediterranean environment

Sweet oranges (Citrus sinensis L. Osbeck) are one of the most appreciated fruits both for their peculiar taste and nutraceutical properties. Among them, blood oranges, which are grown in few regions of the world, distinguish from blonde ones also for the presence of additional bioactive compounds. The red colour of blood oranges is due to the amount of anthocyanins which belongs to the larger family of flavonoids. In this work, physicochemical properties, phenolic compounds, and antioxidant potential in 11 blood orange cultivars grown under the same environmental conditions were analysed. The cultivars under investigation were ‘Doble Fina’, ‘Entrefina’, ‘Maltaise Blonde’, ‘Maltaise demi Sanguine’, ‘Moro’, ‘Murtera’, ‘Sanguinelli’, ‘Tarocco Comune’, ‘Tarocco Messina’, ‘Tarocco Rosso’ and ‘Washington Sanguine’. Sucrose was the main sugar in all cultivars and the highest concentration was observed in ‘Maltaise demi Sanguine’, meanwhile ‘Doble Fina’ and ‘Sanguinelli’ showed the highest content of citric acid. Maturity index, obtained by the ratio between sugars and acids, revealed ‘Tarocco Rosso’ with the highest value for its low citric acid content. We analysed the colour of both the peel and the juice, observing the deepest red peel and juice in ‘Sanguinelli’ and ‘Moro’, respectively. Individual and total phenolic compounds were determined. Among anthocyanins, the highest levels were found for cyanidin-3-O-glucoside and cyanidin3-(6”-malonyl)-glucoside. Regarding hydroxycinnamic acids, p-coumaric acid was prevalent in all cultivars, while hesperidin was the predominant flavonoid