Oxidative stability of refined olive and sunflower oils supplemented with lycopene-rich oleoresin from tomato peels industrial by-product, during accelerated shelf-life storage

Tomato peels by-product from a Tunisian industry was used for the extraction of lycopene-rich oleoresin using hexane solvent maceration. Tomato peels oleoresin, TPO, exhibited competitive free radicals scavenging activity with synthetic antioxidants. The efficacy of TPO in stabilizing refined olive (ROO) and sunflower (RSO) oils was investigated for five months, under accelerated shelf-life, compared to the synthetic antioxidant, butylated hydroxytoluene (BHT). TPO was added to ROO and RSO at four different concentrations, namely 250, 500, 1000 and 2000 mu g/g and BHT standard at 200 mu g/g. Lipid oxidation was tracked by measuring the peroxide value, acidity, conjugated dienes and trienes. Results suggested the highest efficiency of 250 mu g/g and 2000 mu g/g of TPO, referring to 5 mu g/g and 40 mu g/g of lycopene, for the oxidative stabilization of ROO and RSO, respectively. The protective effect of TPO against the primary oxidation of these refined oils was significantly correlated to their lycopene contents.