DPPH assay was conducted with a method described by
Brand-Williams, Cuvelier, and Berset (1995)
with modifications. Different dilutions of the crude extracts were prepared. Fifty
ml of the diluted crude extract was mixed with 950 ml of 0.3 mmol/l DPPH solution in a cuvette and held for 30 min at room temperature. The absorbance was then read at 515 nm. EC50 (g flour/g DPPH), which is the
concentration of the antioxidant that caused the decrease of DPPH radicals to half of its initial concentration, was determined from the graph of the equivalent amount of the sample in DPPH solution (g flour/g DPPH) and radical scavenging activity (%). The latter parameter was calculated from equation