Triacylglycerols of the olive fruit (Olea europaea L.): characterization of mesocarp and seed triacylglycerols in different cultivars by liquid chromatography and C-13 NMR spectroscopy

Triacylglycerols of mesocarp and seed oils extracted from olive fruits of d ifferent cultivars were characterized. The analysis of the profiles of the triglyceride isomers which were determined by HPLC, evidenced that ECN 48 ( OOO-OOP) and ECN 46 (OLO) triglycerides were the major components of mesoca rp and seed oils, whereas triglycerides acylated with the linoleoyl chain a ppeared to be more abundant in seed oil, i.e. LLL (ECN 42), OLL-PLL (ECN 44 ), and POL-OLO (ECN 46). Mesocarp and seed oils, likewise the cultivars dif fered significantly (P < 0.05) with regard to all the triglyceride componen ts. C-13 MMR spectroscopy based on carbonyl carbon resonances of triglyceride a cyl chains was applied to carry out the regiospecific analysis of triacylgl ycerols. Acyl chain composition, chain distribution among 1(3)- and 2-glyce rol positions, and chain 2-positional specificity, were determined. The res ults confirmed that two different pools of fatty acids esterified at 1(3)- and 2-positions in triacylglycerols of mesocarp and seed oils exist, the sa turated chains being by almost 100% at 1(3)-positions. 2-positional specifi city evidenced that the oleoyl chain moved away from a pure random model le ss than the linoleoyl chain. 2-Distribution and 2-specificity data of oleoyl and linoleoyl chains along with linoleoyl 1(3)-distribution values, appeared to discriminate significa ntly (P<0.05) mesocarp and seed oils, but no cultivar discrimination was ac hieved. The effect of fatty acid concentration on their distribution between triacy lglycerol positions and the low variability of 2-positonal specificity valu es of unsaturated chains over a wide range of vegetable oils were highlight ed.