2.2. Fatty acid (FA) and triacylglycerol (TAG) compositions
The FA compositions were determined by gas chromatography (GC) using the AOCS official method Ce 1-62(AOCS, 2009). Conversion of FA to fatty acid methyl esters (FAME) was based on the method described by Hartman and Lago (1973). Analysis was performed in a Clarus 600 gas chromatograph (PerkinElmer, USA) equipped with a flame ionization detector (FID) and a DB-WAX capillary column (length 30 m, internal diameter 0.25 mm, film thickness 0.25 μm; Agilent Technologies, USA), in the following operating conditions: Helium (carrier gas) at a flow rate of 1.78 mL/min, FID temperature of250°C, injector at 250°C, injection volume of 1 μL, column temperature ramp from 50°C to 250°C at 10°C/min. Individual FA peaks were identified by comparing retention times to an external standard (FAME mix C8-C24; Sigma-Aldrich, USA). Retention times and peak areas were evaluated via Total Chrom software (version 6.3.2, PerkinElmer, USA). Results were expressed as relative percentages of mass of total FA.
TAG compositions were calculated from FA data via combinatorial analysis using the method described by Antoniosi Filho, Mendes, and Lanças (1995). In this method, a model of random distribution (no preference to position sn-1,3 and sn-2) of FA in glycerol was used, hence only bulk FA composition was necessary as input data.