Biodiesel quality was accessed by measuring: (i) density, by a hydrometer method according to ISO 3675:1998; (ii) kinematic viscosity, according to ISO 3104:1994; (iii) flash point, using a rapid equilibrium closed cup tester according to ISO 2160:1998; (iv) methyl ester content, using GC analysis according to EN 14103:2003; and (v) acid value, as reported in EN 14104:2003.