2.5.4. Antioxidant capacity
2.5.4.1. Ferric-reducing/antioxidant power. Ferric-reducing/antioxidant
power (FRAP) was performed according to the method
described by Liu, Qiu, Ding, and Yao (2008) with some modifications.
In brief, 50 ml of the supernatant above obtained (diluted if
necessary) were mixed with 3 ml of freshly prepared FRAP reagent
and the reaction mixtures incubated at 37 C for 30 min. Absorbance
at 593 nmwas determined against distilled water blank. The
FRAP reagent included 0.01 mol/l TPTZ (2, 4, 6-tripyridyl-s-triazine)
solution in 0.04 mol/l HCl, 0.02 mol/l FeCl3 solution and 0.3 mol/l
acetate buffer (pH3.6) in proportions of 1:1:10(v/v). Aqueous
solutions of ferrous sulfate (0e1000 mmol/l) were used for calibration.
The tests were performed in triplicate. The results for each
cracker and GBF are expressed as mmol of Fe (II)/g oil-free dry basis
and mmol of Fe (II)/g dry basis, respectively.