Fatty acid methyl esters were determined following extraction of total lipids according to Folch et al. (1957). Methanolysis was performed by applying the catalytic effect of potassium hydroxide and extraction of acids in the form of methyl esters
in heptane. The contents of isolated methyl esters were determined using a gas chromatograph Master GC (Dani Instruments S.p.A., Cologno Monzese, Italy) equipped with a flame ionization detector and a column with polyethylene glycol as the stationary phase (FameWax; 30 m × 0.32 mm × 0.25 μm). Helium was used as the carrier gas, with
a flow rate of 5 ml/min and a split ratio of 1 : 9. The obtained records were analyzed using Clarity software, Version 5.2 and quantified on the basis of known retention times from a standard Food Industry FAME Mix (Restek Co., Bellefonte, USA). The atherogenic index (AI) was calculated according to Chilliard et al. (2003) as follows: