Squalene content of the major varieties used in the production of the PDO “Sardegna” virgin olive oil

Squalene (6,10,15,19,23‐hexamethyl‐2,6,10,34 14,18,22‐tetracosahexaene), a metabolic precursor of sterols, is a functional lipid of high importance for food, pharmaceutical and cosmeceutical sector. The main health benefits attributed to this hydrocarbon is its chemopreventive and photooxidative properties and its protection against coronary heart diseases [1]. The richest dietary source of squalene is virgin olive oil. The lower risk of cancers (eg. breast, colon) reported in the Mediterranean populations related to those of Northern Europe or USA, has been also correlated to the higher consumption of squalene though this edible source [1]. From the technological point of view, its presence in virgin olive oil showed a protective effect under photooxidation conditions [2]. In autoxidation studies squalene exerted a weak antioxidant activity due to competitive oxidation phenomena with the lipid substrate [3,4]. The present study aimed at examining squalene content in the oils obtained from the major varieties used in the production of the PDO “Sardegna”, i.e. Bosana, Tonda di Cagliari, Tonda di Villacidro, Semidana, etc [5]. The olive samples were obtained from certified trees belonging to the collection of the Experimental Station “A, Millela” of the University of Sassari (DIPNET), located in San Quirico Fenosu (Oristano, Sardinia). Oil was extracted at a small scale industrial mill (Sintesi 80, Mori TEM). Squalene content was determined by RP-HPLC using UV detection after oil saponification and extraction of the unsaponifiable fraction. The findings for the major varieties are compared with values for other local Sardinian or Italian varieties and also with those for Greek varieties grown in Sardinia or Greece. Squalene content variability among the different oils ranged from low to high values (e.g. ~45%). The results are discussed with regard to maturation index within the same variety, irrigation regime and geographical origin. Squalene is characteristic of a variety but when different ones are used in the production of a PDO product, this attribute is smoothen out and cannot be used to support the registered name.