DPPH radical scavenging activity was determined following the same DPPH assay described by Faithong and
Benjakul (2012). Soluble fraction (1.5 ml) was added to 1.5 ml of 0.15 mM 2, 2 diphenyl-1-picrylhydrazyl (DPPH)
in absolute ethanol. The mixture was mixed vigorously and allowed to stand at room temperature in the dark for 30
min. The absorbance of the solution was measured at 517 nm using a V630 UV-Vis spectrophotometer (Jasco,
Japan). The blank was prepared in the same procedure, except the distilled water was used instead of the sample. A
standard curve was prepared using 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) in the range of
10-60 μM. The scavenging activity was expressed as μmol Trolox equivalents (TE)/g sample.