Effect of sprouting and light cycle on antioxidant activity of Brassica oleracea varieties

The antioxidant activity of sprouts from four Brassica oleracea varieties was evaluated using “in vitro” methods (total phenolic and flavonoid content; radical scavenging assays: DPPH, hydroxyl and peroxyl; and Ferrous Ion-chelating Ability Assay). Light cycles and sprouting influenced the potential antioxidant activity of sprouts and significant differences were observed between varieties. Generally, antioxidant activity decreased with sprouting and increased in the presence of light, whose discriminant effect was highly significant (P < 0.001). Red cabbage sprouts produced under light cycles showed the highest antioxidant activity (57.11 μg mL−1 Ferrous Ion-chelating Ability, 221.46 μg mL−1 Hydroxyl radical scavenging, 279.02 μg mL−1 Peroxyl radical scavenging). Among the traditional Portuguese brassica varieties, Penca cabbage sprouts produced under light presented higher antioxidant capacity, and also higher phenolic and flavonoid content (54.04 mg GAE g−1 d.w. extract and 21.33 QE g−1 d.w. extract, respectively) than Galega kale. The phenolic content of Brassica sprouts had a significant contribution to the antioxidant capacity.