The investigation of minor and rare Tunisian olive cultivars to enrich and diversify the olive genetic resources of the country

Abstract

Extra virgin olive oil is a basic element of the Mediterranean diet which is linked to multiple health benefits. It is particularly rich in monounsaturated fatty acids, which among fat substances are the most active for the prevention of cardiovascular disorders, and poor in saturated fats, responsible for the increase in blood cholesterol levels and directly linked to pathology. The quality of an oil is strongly influenced by many factors, including the harvesting stage of olives. To ensure that the maximum benefits of flavour and health are extracted, the maturity index must be considered; in fact, very important minor compounds such as phenols, tocopherols, chlorophylls and carotenoids, but, also, the physicochemical characteristics, depend on it. In order to enrich and to diversify the olive oil production of the country, seven rare Tunisian olive cultivars were considered, Adheffou, Barouni, Boudaoud, Chemlali Chouamekh, Fougi Gtar, Zarrazi Gtar and Zarrazi Zarzis and compared to the two main cultivars, Chemlali Sfax and Chetoui. Best quality oils are produced from olives at early stages of maturity, but, some minor cultivars showed an opposite trend. In fact, the results obtained highlight that olives of Barouni and Chemlali Chouamekh cultivars, at an advanced ripening index, produced quality oils with high tocopherol and oleic acid contents. Moreover, Fougi Gtar and Zarrazi Gtar cultivar olive oils were characterized by the highest content of chlorophyll and total tocopherols. The opposite trend was observed for Barouni cultivar olive oils. Zarrazi Zarzis and Zarrazi Gtar cultivar olive oils were the richest in luteolin; Adheffou cultivar olive oils were the richest in apigenin; Boudaoud cultivar olive oils were the richest in rutin, and together with Chemlali Sfax and Chetoui cultivar, were the richest in verbascoside. Finally, Boudaoud and Chemlali Chouamekh cultivar olive oils were the most abundant in oleic acid.