2.4. Oil composition
After oil transesterification according to the method proposed
by Hartmann and Lago (1973), fatty acids composition was determined
in a Varian gas chromatograph, model 3900, equipped with
an automatic sampler, injector split ratio of 75:1; capillary column
Chrompack CP-SIL 88 (100 mx 0.25 mm ID, 0.20 ìm film) with flame
ionization detector (FID) and controlled by a computer running the
STAR ChromatographyWorkstation software. Column temperature
was programmed as follows: initial temperature of 120 ◦C/5 min,
heating from 120 to 220 ◦C (3 ◦C min−1) and from 220 to 235 ◦C
(1 ◦C min−1), hold at a temperature of 235 ◦C for 12 min. Nitrogen
was used as carrier gas at a flow rate of 1 ml min−1 and hydrogen,
at a flow rate of 30 ml min−1, was used as the make up gas. The
injector temperature was set at 270 ◦C, while the detector was set
at 300 ◦C. An injection volume of 1 l was used for all samples and
standards. Identification of fatty acids was performed by comparing
the retention times of the samples with those of known fatty acids.
In all, 37 patterns of saturated, monounsaturated and polyunsaturated
fatty acids were determined (Supelco 37 Component FAME
Mix – 47885-U). The relative amounts of the fatty acids were calculated
from the total area of the peaks in the chromatograms and
the results expressed in g 100 g−1 sample. Unsaponifiable matter
was obtained by the AOCS Ca 6B-53 method (Aocs, 1998).