2.3. Fatty acid composition and oil content determination
The fatty acids were extracted from ground seed by hexane and trans-methylated in 2N KOH methanolic solution according to Conte et al. (1989), with some modifications. Fatty acid methyl esters (FAMEs) were analysed by a gas chromatography-FID detector (Carlo Erba HRGC 5300 MEGA SERIES) on a capillary column Restek RT x 2330 (30 m × 0.25 mm × 0.2 μm) with oven temperature programming (170 °C initial temperature for 12 min, followed by a gradient of 20 °C/min to 240 °C, for 3 min), helium as carrier gas at 1 ml/min and split mode 40:1. The detector and injector temperature was 260 °C.
Chemical standards were used for identification of individual fatty acids. The internal normalization method (ISO 5508, 1998) was used to determine the fatty acid composition. Residual oil content was determined by the standard Soxhlet extraction method using hexane as solvent.