Physicochemical characterization and antioxidant activities of Chongqing virgin olive oil: effects of variety and ripening stage

This study characterized the quality, composition and antioxidant activities of olive oil from four olive varieties grown in Chongqing, southwest of China. With the fruit skin turned from green to semi black, the percentage of oleic acid decreased while the percentage of linoleic acid increased. The highest concentrations of total phenolic content, total flavonoid content and total antioxidant activity were found in the Coratina olive oils, in which the lowest content of oleuropein was also observed. Significant differences of fatty acid composition at sn-2 position were observed among the varieties, with the percentage of oleic acid at sn-2 position in Picual olive oils were significantly higher than that of other varieties ( p  < 0.05). In addition, the different varieties of olive oil samples were divided into three categories by principal component analysis (PCA), and the quality of Coratina olive oils were greatly affected by fruit ripening stage. With the fruit ripening, the levels of hydroxytyrosol, rutin, total phenolics, total flavonoids and antioxidant activities in Coratina olive oil all declined. This work can provide guidance for the harvesting time and processing of olives in Chongqing.