The methyl ester yield samples were analyzed following the EN 14103 standard method using GC-2010 Plus Shimadzu gas chromatography equipment fitted with a flame ionization detector and a capillary column DB-WAX (0.25 mm × 30 m). Helium and nitrogen were used as carrier gas and makeup gas. The oven temperature ramp program was started at 150 °C and held for 5 min, heated up to 190 °C with a rate of 3 °C/min and held for 5 min, then heated up again to 220 °C with a rate of 3 °C/min and held for 5 min. Injector and detector temperatures were 250 °C. Methyl ester yield was calculated by Eq. (1):