Antioxidant effects of rosemary extracts on sunflower oil compared with synthetic antioxidants

The antioxidant activities of ethanol extracts of rosemary (Rosmarinus officinalis L.) (RE) were tested in natural sunflower oil stored at 60 degrees C by measuring their peroxide values (POV), thiobarbituric acid-reactive substances (TBARS), free fatty acid (FFA) content and p-anisidine value (AnV) after regular intervals compared with synthetic antioxidants. After 3weeks of storage at 60 degrees C, sunflower oil containing 200mgkg(-1) rosemary extracts showed lower POVs (75.7 +/- 0.47meqkg(-1)), thiobarbituric acid-reactive substances (TBARS)(0.161 +/- 0.002gmL(-1)), FFA contents (0.45 +/- 0.04mgg(-1)) and AnV (12.4 +/- 0.02) than the control sample. Sunflower oil containing 200ppm butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butylhydroquinone (TBHQ) showed POVs (204 +/- 0.68, 159 +/- 0.55, 20 +/- 0.49meqkg(-1)), thiobarbituric acid-reactive substances (TBARS) (0.171 +/- 0.002, 0.184 +/- 0.002, 0.069 +/- 0.001gmL(-1)), FFA contents (0.34 +/- 0.03, 0.46 +/- 0.03, 0.2 +/- 0.01mgg(-1)) and AnV (14.7 +/- 0.03, 16.5 +/- 0.04, 6.77 +/- 0.01), respectively, after 3weeks of storage at 60 degrees C. These results illustrate that rosemary extracts exhibited very strong antioxidant activity, almost equal to that of synthetic antioxidants (BHA and BHT).