Using a calibrated curve of ascorbic acid concentration vs. I (%), the results can easily be expressed as the equivalent ascorbic acid concentration. The antioxidant activity of the antioxidants selected was also determined by this method. 1 g of ascorbic acid was equivalent to approximately 0.981 ± 0.021 g of ferulic acid, 0.779 ± 0.023 g of quercetin, or 0.898 ± 0.038 g of green tea extract.