Catalytic effect of solid metals on thermal stability of olive oils

The influence of a series of metals—iron, copper, tin, and lead—on the thermal stability of olive oils of different origins and refined grades has been studied by applying thermal analysis techniques: thermogravimetry (TG) and derivative thermogravimetry (DTG). From thermogravimetric data it is deduced that iron and tin have a greater influence on oil oxidation, since the degradation rate increases. In the presence of copper and lead, important changes in the degradation rate are not observed, compared with the degradation in the absence of metals. The kinetic parameters, activation energy, and frequency factor of the oil degradation reaction were also calculated. The results obtained for both parameters confirm the negative influence of iron and tin on the oil oxidation process, regardless of the kind of oil tested.