Alteration of chemical composition and the oxidative stability of bleached pomace-olive oil on activated clays

This work is a contribution to the study of the bleaching process, which is a very important stage in the refining process of vegetable oils and used to reduce or convert undesired constituents to harmless ones from fats and oils. The virgin olive oil, taken as reference, and the pomace-olive oil were bleached in the optimal conditions using Tunisian bleaching earths (South of Tunisia) which were activated in our laboratory and compared with commercial clays. It was shown that activated Tunisian clays are characterized by a very important adsorptive capacity, comparable to that of commercial clays. Also, the physicochemical stability of bleached oils was studied. The fatty acid composition (GC), the triacylglycerol composition (HPLC), and the oxidative stability (UV spectrometry) allowed us to conclude that oils, bleached with the Tunisian activated clays, do not undergo considerable physicochemical alterations and remain corresponding to the international standards for refined oils for human consumption.