Influence of Freezing Steps on Color Attributes, Phytochemical Contents and Antioxidant Capacity of Green Beans

Abstract

Chlorophyll and phytochemical contents, antioxidant capacity and color attributes of green beans (Phaseolus vulgaris L.) after washing, blanching and freezing processes were evaluated. The hue angle values showed that the frozen beans had a bright yellow-greenish color. Chlorophyll a and b, total carotenoids, total phenolic and total flavonoid contents significantly decreased during processing steps (washing, blanching and freezing). The antioxidant capacity measured by ABTS method significantly decreased during freezing process steps ranged from 494.20 μmol trolox 100 g -1 of fresh green beans to 437.54 and 342.13 μmol trolox 100 g -1 (on dry weight basis) of blanched and frozen green beans, respectively. A plot of antioxidant capacity of green beans measured by DPPH or ABTS assay versus phytochemical compounds studied showed a strong positive correlation with total phenolics (R 2 = 0.9847 and 0.9609, respectively) and total flavonoids (R 2 = 0.9963 and 0.9636, respectively).