The stability to oxidation of olive oil added to tomato puree and the changes in the overall antioxidant properties of the product were investigated in relation to heating time and storage. Olive oil oxidative stability increased with the storage time as a consequence of the protective action of the naturally occurring antioxidants of tomato. Unexpected results were found in the case of the heat-treated tomato-oil mixtures. The shelf life of the lipid fraction greatly increased as the heating time increased. This result was attributed to the antioxidant activity of the Maillard reaction products formed during the heating process and/or the consumption of the lipid oxidation products as they were involved in the Millard reaction. Nevertheless, the improvement of the product shelf life caused a loss of the overall antioxidant properties.
