Biochemical characterization of olive oil samples obtained from fruit mixtures and from oil blends of four cultivars grown in Central Tunisia

Blends of olive oils obtained from four cultivars (Olea europaea L. cv. Chemlali, Chetoui, Oueslati and Koroneiki) were produced by two different methods of blending: processing fruit mixtures or mixing monovarietal oils, using the same proportions of selected cultivars. The obtained blends were biochemically characterized to evaluate quality, and the two methods were compared. The results indicated that the most successful formulations are mainly F8 (60% Chemlali x 20% Oueslati x 20% Koroneiki) characterized by the highest contents of phenols and an elevated oxidative stability, and F5 (50% Chemlali x 50% Koroneiki) containing the highest MUFA level and the highest oxidative stability. The effect of the blending process on pigments and volatiles cannot be easily regulated, unlike phenols, fatty acid composition and OS, all of which positively correlated to the fruit mass ratio in the blend. Results suggest that processing fruit mixtures of different cultivars resulted in a better oil quality than that of oils obtained by the common oil blending method. This blending procedure offers a possibility to modulate the contents of antioxidants, fatty acids and volatile compounds in virgin olive oil, and therefore, its quality and sensorial characteristics.