In brief, 500 mg of homogenized sample were extracted with 1.6 mL of 2-propanol and 2 mL of cyclohexane (analytical grade from Carl Roth GmBH, Germany) after addition of an internal standard for total fat estimation (glyceryl triundecanoate, Sigma–Aldrich, Spain). After vortex mixing and overnight maceration at 4 °C, aqueous NaCl was added (1%; 2.8 mL), thoroughly mixed and centrifuged at 5000 rpm for 5 min, and the upper phase was transferred to derivatization vials.