8. Determination of reducing power
The reducing power was measured according to Beretta et al. (2005). A volume of 0.5 ml of sample was homogenized with 1.25 ml of phosphate buffer (0.2 M, pH 6.6) and 1.25 ml of potassium ferricyanide [K3Fe (CN) 6] (1%).
After incubation in a water bath(50◦C/20 min), 1.25 ml of trichloro acetic acid (10%) was added to the mixture. which was then centrifuged at 2000 rpm for 20 min.
The upper layer of the solution (1.25 ml) was mixed with distilled water (1.25 ml).
The absorbance was read at 700 nm after the addition of 0.25 ml of iron chloride (1%).
The results were expressed as antioxidant (Gallic acid) equivalents in mg per 100 g of product (mgAGAE/100 g).
9. Statistical analysis
Data were presented as mean ± standard deviation (SD) of three determinations. Statistical analyses were performed using a one way analysis of variance (ANOVA) in the software STATISTICA 5.5.
Differences were considered significant at *P < 0.05.