2.7. Ferrous chelating capacity assay
Capacity of chokeberry juice digests to chelate Fe2+ ions was
determined according to the method of El and Karakaya (2004), with
some modifications. Sample aliquot 200 lL was mixed with 740 lL
of deionised water, 20 lL of 2 mM FeCl2 solution and incubated for
30 min at room temperature. After incubation, 200 lL of 5 mM ferrozine
was added and mixture was incubated for additional
10 min under the same conditions. The absorbance was determined
at 562 nm. Distilled water was used as a control instead of the
sample. The metal chelating capacity was calculated as:
Fe2þ chelating capacity ð%Þ ¼ fðA562c A562sÞ=A562cg 100;
where c and s represent control and sample, respectively.