The FRAP assay was done according to Benzie and
Strain (1996) with some modifications. The stock solutions
included 300 mM acetate buffer (3.1 g C2H3NaO2 Á 3H2O
and 16 mL C2H4O2), pH 3.6, 10 mM TPTZ (2, 4, 6-
tripyridyl-s-triazine) solution in 40 mM HCl, and 20 mM
FeCl3 Á 6H2O solution. The fresh working solution was
prepared by mixing 25 mL acetate buffer, 2.5 mL TPTZ
solution, and 2.5 mL FeCl3 Á 6H2O solution and then
warmed at 37 1C before using. Fruit extracts (150mL) were
allowed to react with 2850 mL of the FRAP solution for
30 min in the dark condition. Readings of the colored
product [ferrous tripyridyltriazine complex] were then
taken at 593 nm. The standard curve was linear between
25 and 800 mM Trolox. Results are expressed in mM TE/g
fresh mass. Additional dilution was needed if the FRAP
value measured was over the linear range of the standard
curve.