Antioxidant activity and DNA protection against oxidative damage of bambara groundnut seeds (Vigna subterranea (L.) Verdc.) as affected by processing methods

Abstract

This research investigated the effects of processing by dry heating, boiling, and steaming on the antioxidant activity and DNA protection against oxidative damage of bambara groundnut seeds (Vigna subterranea (L.) Verdc.). Comparing raw and processed samples of bambara groundnut seeds, dry heating caused a significant (P < 0.05) reduction of ferric-reducing antioxidant power (FRAP), metal chelating activity, DPPH• and ABTS•+ radical scavenging activity. The boiling process did not cause a significant difference in FRAP and metal chelating activity and caused smaller losses in DPPH• and ABTS•+ radical scavenging activity than the dry heating and steaming processes. The steaming process caused a significant (P < 0.05) reduction of FRAP, DPPH• and ABTS•+ radical scavenging activity. For DNA protection against oxidative damage, boiled and steamed bambara groundnut seed samples were more effective with a lower minimum concentration (50 µg/mL) than raw and dry heated samples. These results indicated that the boiling process caused smaller losses antioxidant activity than dry heating and steaming. Therefore, boiling was recommended as processing method for bambara groundnut seeds to preserve antioxidant components and antioxidant activity.