Chemical Composition and Antioxidant Activity of Actinidia Fruits after Postharvest Ripening

Four Actinidia cultivars ('Hayward', 'Early Green', 'Boerica' and 'Hort 16A') were evaluated few days after harvest (T0) and after shelf-life at 20 degrees C or storage at 1 degrees C until ripe. As expected, flesh firmness decreased dramatically in all the cultivars during the ripening process while soluble solids content increased. In all the cultivars no important changes occurred in ascorbic acid content, total phenolics and total antioxidant activity after ripening at 20 or 1 degrees C. Fructose was the predominant sugar in all the cultivars, followed by glucose and lastly by sucrose. Fructose and glucose increased in 'Hayward', 'Early Green' and 'Boerica' during ripening, while they remained unchanged in 'Hort 16A'. In all the cultivars no change in sucrose content was noticed after shelf- life. The yellow fleshed cultivar ('Hort 16A') showed higher antioxidant activity and higher polyphenol content as compared to 'Hayward', 'Boerica' and 'Early Green', while ascorbic acid content was similar in all the cultivars. 'Hort 16A' had also higher sucrose and total sugars content than the other cultivars. In all the studied cultivars, postharvest ripening at 20 or at 1 degrees C did not affect antioxidant properties and, despite the changes in fruit flesh characteristics, all the fruit kept their initial values of total antioxidant activity, ascorbic acid and total phenolics after shelf-life at 20 degrees C or storage at 1 degrees C.