Mahmood Ghasemnezhad; Hossein Meighani; Somayeh Eftekhari
Abstract
To study the evaluation of ripening index on qualitative parameters of three olive cultivars ('Zard', 'Local-Roghani' and 'Arbequin') in Roudbar city of Gilan province, an experiment was carried out according to a factorial based on completely randomized design with three replications in 2014. Fruits ...
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To study the evaluation of ripening index on qualitative parameters of three olive cultivars ('Zard', 'Local-Roghani' and 'Arbequin') in Roudbar city of Gilan province, an experiment was carried out according to a factorial based on completely randomized design with three replications in 2014. Fruits were harvested at ripening index 3.5, 4 and 5 according to the method proposed by the international olive oil council and after oil extraction, its biochemical and qualitative characteristics were assessed. The results showed significant increases in dry mater, peroxide value, free fatty acid, extinction coefficient at 232 and 270 nm, coupled with significant decline in total phenolics and flavonoids, carotenoid and chlorophyll pigments and antioxidant activity with advancing ripening index. Also, significant differences were observed among the olive cultivars in the all above traits. Total phenolics of olive oil in the 'Local-Roghani' cultivar at ripening index 3.5, 4 and 5 respectively with averages of 941.27, 657.74 and 310.32 mg/kg were more than others. However peroxide value, that is an undesirable trait in the olive oil, was higher in the 'Local-Roghani' cultivar. Although the antioxidant activity among olive cultivars was varied at ripening index 3.5 and 4, but no significant differences were observed at ripening index 5. Overall, the results showed that an increasing in the fruit ripening index was accompanied with decreased in the antioxidant compounds and sensitivity to oxidation of olive oil. Therefore, the oils obtained from the fruits at ripening index 3.5 had greater stability and sustainability.