2.7.3. FRAP assay
The FRAP assay was performed according to Benzie and Strain
(1996) with some modifications. The stock solutions included
300 mM acetate buffer pH 3.6, 10 mM TPTZ (2,4,6-tripyridyl-s-triazine)
solution in 40 mM HCl, and 20 mM FeCl36H2O solution.
Fresh working solution was prepared by mixing 25 mL acetate buffer,
2.5 mL TPTZ solution, and 2.5 mL FeCl36H2O solution and this
solution was then warmed to 37 C before use. Fruit extracts
(150 lL) were allowed to react with 2850 lL of FRAP solution for
30 min in the dark. Readings of the coloured 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 lM TE/g dry mass as mean of three replicates.