. Reducing power
Reducing power is defined as ability of molecule to donate an
electron to oxidant. It has been widely accepted that compounds
which possess high reducing power could be considered as antioxidants,
at least in vitro. The results of the present study demonstrated
that diluted juice (J) exhibited highest reducing power
(Table 2). Mixing the juice with a cocktail consisted of food matrix,
digestive enzymes and bile salts adjusted to pH 5.4 resulted in 44%
decrease in reducing power in DJC compared to J, which is in concordance
with the decrease in total phenolic content and DPPH
scavenging activity. Contrary to the results obtained in DPPH assay,
recorded reducing power of DJ was mildly increased compared to
the DJC. Reducing power of DMC was about 15 times lower than
in J, similarly to the results of DPPH assay. Digestion of matrix
resulted in slight, but statistically significant elevation of reducing
power observed in DM. Since all samples were adjusted to the
same pH value, and if the reducing power attributed to the effect
of digestion of food matrix alone was subtracted, it can be concluded
that enzymatic treatment could favor the release of bound
phenolic compounds resulting in elevated reducing power. This
could be supported by the fact that total phenolic content of
digested juice was also increased compared to the control.