The antioxidant capacity was measured using the 2,2-diphenyl-
1-picrylhydrazyl (DPPH) decolorization assay (Brand-Williams,
Cuvelier, & Berset, 1995) A 6.1 105 mol/L DPPH methanolic solution
was prepared immediately before use. The DPPH solution
was adjusted with methanol to an absorbance of 0.7 (0.02) at
515 nm in a 3 mL capacity cuvette (1 cm length) at 25 C (Lambda
25 UV, VIS spectrophotometer, Perkin Elmer Instruments). Coffee
extracts (50 mL) were added to DPPH solution (1.95 mL). After
mixing, the absorbance was measured at 515 nm after exactly
1 min, and then every minute for 18 min at 25 C. Calibration was
performed with Trolox solution (a water-soluble vitamin E analog)
and Total antioxidant capacity was expressed as mmol Trolox per g
of ground coffee