engleski

Characterization of five Istrian monovarietal olive oils based on sterols, triterpene dialcohols and fatty acids profile

The objective of this research was to characterize five monovarietal olive oils obtained from autochthonous cultivars grown in Istria, Croatia (Buža, Buža puntoža, Istarska bjelica, Rosinjola and Bova) on the basis of sterols, triterpene dialcohols and fatty acids profile. Therefore, fruits from three trees per cultivar were handpicked at the same ripening degree (RI =2.5 - 3, except Istarska bjelica which matures later than other cultivars) and processed separately under the same conditions in order to obtained monovarietal oils. Determination of the composition and content of sterols and triterpene dialcohols, as well as fatty acid composition, was conducted according to methods adopted by EEC regulations (Commission Regulation (EEC) No 2568/91). Analyses were performed using a gas chromatograph with flame ionization detector. Tested monovarietal olive oils fulfilled the demands of the current EU legislation required for virgin olive oils regarding sterols and triterpene dialcohols. Different monovarietal oils showed different sterol profile, although β-sitosterol, Δ5-avenasterol and campesterol were the most abundant sterols in all samples. Higher values of β-sitosterol were determined in Buža and Bova oils (88%), while in Istarska bjelica oil the lowest value (67%) was detected. The highest total sterol content was determined in Bova oil (2964 ± 458 mg/kg), while the lowest was in Istarska bjelica oil (1451 ± 42 mg/kg). Regarding the content of triterpene dialcohols, erythtrodiol and uvaol, significantly the highest value was found in Istarska bjelica oil. Considering the fatty acid profile, Rosinjola and Istarska bjelica oils showed the highest levels of monounsaturated fatty acids, while Buža oil had the highest level of polyunsaturated fatty acids. Bova oil showed the highest level of saturated fatty acids. Higher oleic/linoleic ratio detected in Rosinjola and Istarska bjelica oils indicated their higher oxidative stability when compared to other investigated oils. Since olive oil composition differentiates oils according to cultivar, the information obtained could be very useful to understand the potential of autochthonous cultivars in producing high quality monovarietal olive oils with specific characteristics.

cultivar; fatty acids; olive oil; sterols; triterpene dialcohols

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