Antioxidant activity of ginger extract in sunflower oil

The antioxidant activity of dichloromethane extract from ginger was evaluated during 6 months of storage of refined sunflower oil at 25 and 45degreesC. Free fatty acid (FFA) content, peroxide value (POV) and iodine value (IV) were used as criteria to assess ginger extract as an antioxidant. After 6 months of storage at 45degreesC, sunflower oil containing 1600 and 2400ppm ginger extract showed lower FFA contents (0.083 and 0.0800/6) and POVs (24.5 and 24.0meqkg(-1)) than the control sample (FFA contents 0.380%, POV 198.0meqkg(-1)). Sunflower oil containing 200ppm butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) showed FFA contents of 0.089 and 0.072% and POVs of 26.5 and 24.7meqkg(-1) respectively after 6 months of storage at 45degreesC. Similarly, after 6 months of storage at 45degreesC, IVs of sunflower oil containing 1600 and 2400ppm ginger extract were 80 and 92 respectively, higher than that of the control sample (53). However, IVs of sunflower oil treated with 200ppm BHA and BHT were 94 and 96 respectively after 6 months of storage at 45degreesC. These results illustrate that ginger extract at various concentrations exhibited very strong antioxidant activity, almost equal to that of synthetic antioxidants (BHA and BHT). Ginger extract also showed good thermal stability and exhibited 85.2% inhibition of peroxidation of linoleic acid when heated at 185degreesC for 120min. Therefore the use of ginger extract in foods is recommended as a natural antioxidant to suppress lipid oxidation. (C) 2003 Society of Chemical Industry.