Quality Characteristics and Antioxidant Activity during Fruit Ripening of Three Monovarietal Olive Oils Cultivated in China

Numerous olive cultivars have been planted in China, mainly to reap the health benefits of olive oil. This study characterized the quality and investigated the antioxidant activity of olives harvested at three different maturation stages, defined by the skin color of the olives (black, purple, and green), from three newly introduced olive cultivars (Barnea, Manzanilla and Kadesh) grown in China. The oleic acid content of olives from all three olive cultivars decreased significantly during maturation, whereas the linoleic acid content increased. The highest content of total phenols was recorded in Manzanilla cultivar (284.94 mg kg(-1)), whereas the lowest was recorded in Kadesh cultivar (134.82 mg kg(-1)). In addition, a total of 13 individual phenolic compounds were obtained, and their concentrations were significantly influenced by the cultivar and maturity (P < 0.05). Secoiridoids were the main group of phenolic compounds, but their quantity decreased during maturation. The content of secoiridoids in the Manzanilla cultivar was significantly higher than that of the Barnea and Kadesh cultivars. In general, a significant decrease (P < 0.05) in the values of antioxidant activity and the contents of pigments, alpha-tocopherol, and squalene occurred during maturation. Furthermore, principal component analysis was used to classify the nine olive oil samples according to the cultivar and ripening degree.