The Effect of Refining Processes on the Physiochemical Characteristics of Olive Oils Extracted From Two Olive Cultivars (Bladi & Arbequina)

Olive oil is a valuable and popular oil among the oils consumed and the demand for its production and consumption is increasing continuously. Therefore, the purpose of this study is to evaluate the effect of refining operation on the physico-chemical characteristics of virgin and refined olive oils. Two olive cultivars (Bladi and Arbequina) were collected from Fadak Farm (Iran – Qom region). The oils were extracted, bleached and deodorised using two different conditions. The first batch was bleached and deodorized at 50 for 30 minutes and the second batch was bleached at 70 and deodorized at 135 for 45 minutes. Tests concerned with the determination of fatty acid composition, free fatty acid content, peroxide value, conjugated dienes and trienes, total poly phenols, colour and induction periods were carried out on the oils. The results indicated that moisture, oil content of whole fruit, kernel and pulp were significantly different. Fatty acid compositions were not affected after the two treatment methods with the exception of Bladi variety that slight changes concerned with saturated and unsaturated acids occurred. The total polyphenols in Bladi and Arbequina varieties in the first treatment were 51.87% and 34.92% and in the second treatment were 68.67% and 92.67%, respectively. Conjugated dienes and trienes for each sample after the treatment decreased and increased respectively and the change after the second treatment was higher. The application of higher temperature for longer period affected both oils qualitatively. However the changes in acidity and peroxide values were similar.