Oxidative stabilization of sunflower oil by antioxidant fractions from selected Lamiaceae herbs

This study reports the effect of antioxidant fractions from rosemary (Rosmarinus officinalis), sage (Salvia officinalis), thyme (Thymus vulgaris) and hyssop (Hyssop officinalis) on the oxidative stability of sunflower oil at elevated temperature. In order to isolate antioxidant fractions, method of fractional supercritical extraction with carbon dioxide at 35 MPa and 100?C was applied. Antioxidant fractions were added to sunflower oil, at concentrations of 200 mg/kg oil and samples were stored in an oven maintained at 98?C. Antioxidant activity of the extracts was determined by measuring peroxide values (PV). Among investigated extracts, the rosemary extract was the most effective on retarding lipid oxidation of sunflower oil. The antioxidant activity of the extracts was compared to the activity of butylated hydroxyanisole (BHA) and commercial rosemary extract Flavor' Plus. On the basis of PV assay, antioxidant activity of the investigated plant extracts after 12 h of storage at 98?C followed the order: rosemary extract > BHA > sage extract > Flavor' Plus > thyme extract > hyssop extract.