Abstract
Harvest timing of oil olives is important for oil quality. Concerning the specific features of each cultivar, physiological and quality characteristics during ripening of Koroneiki olives were investigated in two successive years, A and B, from trees on full production. In A, olives were harvested at maturity indices (MIs) 0.9, 1.4, 2.1 and 4, while in B at MIs 1.1, 3.8 and 6.9. MIs ~1, ~4 and ~7 corresponded to green, red and dark purple peel in olives, respectively. Peel color parameters (L*, h° and C*), respiration and ethylene production rates were evaluated along with phenolic compounds and total antioxidant capacity (TAC) in olives of both crop years. Additionally, oil composition and a-tocopherol content were examined in olives harvested in years A and B, respectively. During fruit development, respiration and ethylene productions rates, hydroxytyrosol concentration and linoleic acid increased, while TAC, oleuropein, luteolin-7-O-glucoside, linolenic acid and α-tocopherol values decreased. Positive correlations were found among the attributes determined in both crop years that had a similar course of change during ripening, and vice versa, which could be also related to harvest timing and to quality traits of olive products. At MI ~4, at least all determined variables corresponded to oil of high quality. Practically, an early harvest might result in an olive fruit rich in antioxidants and therefore in oil production of high quality, high stability during storage and long self-life.
Highlights
Olive (Olea europaea L.) is a characteristic species and one of the most important and widespread fruit trees in the Mediterranean basin
Olive oil is unique among other vegetable oils due to its characteristic aroma, that is attributed to its well-balanced composition of fatty acids and the presence of minor components, such as volatile compounds [4]
Unlike seed oils in which polyunsaturated fatty acids are predominated, olive oil is rich in monounsaturated oleic acid, which is less susceptible to oxidation, contributing to the high stability and its long shelf life [2,4]
Summary
Olive (Olea europaea L.) is a characteristic species and one of the most important and widespread fruit trees in the Mediterranean basin. Olive oil is a predominant component of the widely known ‘Mediterranean diet’, to which increasing attention is being paid [2]. The consumption of olive oil is linked to the low incidence of coronary heart disease, cancer and other chronic diseases among the people of the Mediterranean basin [3]. Olive oil is unique among other vegetable oils due to its characteristic aroma, that is attributed to its well-balanced composition of fatty acids and the presence of minor components, such as volatile compounds [4]. Unlike seed oils in which polyunsaturated fatty acids are predominated, olive oil is rich in monounsaturated oleic acid, which is less susceptible to oxidation, contributing to the high stability and its long shelf life [2,4]
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