Oil properties measured were: (i) acid value, by volumetric titration as reported in NP EN ISO 660:2002; (ii) water content,
by coulometric Karl Fischer titration, according to ISO 8534:996; (iii) iodine value by volumetric titration using Wijs reagent,
according to the standard ISO 3961:1996; and (iv) oxidation stability at 110 C, according to EN 14112.