Antioxidant properties of raw and processed cabbages

To study the effect of polyphenolics on antioxidant activities of cabbages, the amounts of total phenolics, total flavonoids, antioxidant capacity and individual phenolic compounds in raw and processed cabbages were determined. Fresh and pickled red cabbages exhibited the highest total phenolic contents (393.1+/-10.8 mg and 366.3+/-3.6 mg gallic acid equivalents/100 g fresh sample, respectively). Fresh and pickled red cabbages were also highest in flavonoids (108.1+/-9.3 mg and 72.4+/-4.4 mg catechin equivalents/100 g fresh sample, respectively). The antioxidant capacity (expressed as vitamin C equivalent antioxidant capacity) ranged from 57.1 to 695.6 mg vitamin C equivalents/100 g fresh sample, where raw and pickled red cabbages exhibited the highest antioxidant capacity. There was a good linear relationship between the total phenolics and antioxidant capacity (r2=0.9743), and between the total flavonoids and antioxidant capacity (r2=0.9557); however, the relationship between the ascorbic acid content and antioxidant capacity was very low (r2=0.1442). The antioxidant capacity of raw and processed cabbages was highly correlated with their contents of polyphenolics. Kaempferol, quercetin, and apigenin were the major flavonoids existing in cabbages except for raw and pickled red cabbages, where cyanidin was the predominant flavonoid (73.6-117.7 mg/kg). In the red cabbages, cyanidin was the major contributor to the antioxidant capacity as well as the content of total phenolics and flavonoids.