NUTRACEUTICAL CHARACTERIZATION OF EXTRA VIRGIN OLIVE OILS FROM SARDINIA

Protected Designation of Origin (PDO) labels are important tools, awarded by the European Union, to promote specific quality designations in virgin olive oils (VOO). PDO label ensures that a product is entirely produced in a given territory, from the origin of its raw materials through to the final production process [1]. Extra virgin olive oil from local Sardinian varieties (Bosana, Tonda di Cagliari, Tonda di Villacidro, Semidana and theirs respective synonymies) is included in Protected Designation of Origin "Sardegna" [2]. PDO "Sardegna" can be produced along the whole territory and must be characterized at least for the 80% by the four principal local Sardinian varieties, and their other names. The remaining 20% may include virgin olive oils obtained from other varieties grown in the island. Knowledge of chemical composition of VOOs from local varieties is of great interest for the promotion of products typical of a specific territory, and to improve quality and competitiveness of protected denominations labels. It is known that the health-promoting effects of VOO can be attributed to its high content in molecules such as hydrophilic phenols (phenolic acids, phenols such as tyrosol and hydroxytyrosol, their secoiridoid derivatives, flavonoids, lignans) tocopherols and squalene. These bioactive micro constituents are powerful antioxidant, anti-inflammatory, antimicrobial, and chemopreventive agents [3, 4]. They also contribute to high oil oxidative stability during storage [5]. The aim of the study was to examine the nutraceutical characteristics of monovarietal VOOs of 14 Sardinian varieties included in the PDO 'Sardegna' divided into four main groups (synonyms are reported in brakets): Bosana (Sassarese, Palma); Manna (Tonda di Cagliari, Nera di Gonnos, Maiorca, Sivigliana da Mensa, Confetto); Terze (Tonda di Villacidro, Nera di Oliena, Paschixedda, Terza Grande, Terza Piccola, Corsicana da Mensa); Semidana (Bianca di Villacidro). The results had been compared with those from of 3 Sardinian varieties, not included in the 80% of the PDO composition (Pizz'e carroga, Corsicana da olio, Sivigliana da olio) and 4 Italian: (Coratina, Carolea; Toscana: Frantoio, Leccino). All the varieties were grown under the same agronomic and environmental conditions (University of Sassari Experimental Station, Oristano, 39°54'12" N, 8°37'19" E, 13m a.s.l.) and oils were obtained under same processing and storage conditions. Total phenolic content was determined on methanolic extracts using the Folin-Ciocalteu assay [6]. On the same extracts, qualitative and quantitative analysis of the polar phenolic compounds was carried out by RP-HPLC-DAD and LC-MS [7]. Analysis of squalene was carried out following the saponification method described by Grigoriadou et al [8]. Analysis of ?-tocopherol (?-T) was performed following the method proposed by Psomiadou and Tsimidou [9].The four main groups have shown high concentrations of bioactive compounds. Minimum levels of total phenolics and tocopherols content (both 100 mg/kg) requested by the PDO Sardegna regulation were always achieved with a large margin, suggesting the possibility to raise the quality increasing the actual minimum levels. Furthermore, the varieties included in the DOP Sardegna have distinguished by a high content of squalene (> 5000 mg/kg) particularly evident in Manna and synonymous varieties, Semidana and Bosana. Besides, Maiorca oil was characterized by a good content of total polyphenols (>400 mg GAE/Kg oil) and ?-tocopherol (>300 mg/kg). Interesting results have been obtained from the study of minor varieties, so far not very well characterized from the nutraceutical point of view. Among these, Sivigliana da Olio stood out for a high content of secoiridoids (>400 mg / kg) and lignans, (>35 mg/kg) and a high content of ?-tocopherol (>300 mg/kg) and squalene (>5.000 mg/kg).