Effect of cooking on the total antioxidant capacity and phenolic profile of some whole-meal African cereals.

BACKGROUND: At present, sorghum, fonio and millet are not placed as important commodities in the North American and European food basket, but their importance as an ingredient in multigrain and gluten-free cereal products is highlighted. Thus, the phenolic profile, evaluated by LC/MS/MS, the total phenolic content, assessed by Folin-Ciocalteu assay, and the total antioxidant capacity were measured in three African whole grains, i.e., sorghum (Sorghum bicolor ssp. bicolor), fonio (Digitaria exilis) and pearl millet (Pennisetum glaucum L.), before and after a cooking procedure. RESULTS: After cooking process, soluble phenolic acids significantly increased in sorghum, whereas bound ones and anthocyanins significantly decreased. In millet, the cooking process significantly enhanced soluble phenolic acids without affecting those bound, whereas in fonio a slight but significant decrease of almost all the soluble phenolic acids was observed beside a significant increment of bound ones. Finally, cooking process negatively affected both total phenol content and total antioxidant capacity. CONCLUSION: This is one of the few reports dealing with the antioxidant compounds of these three African whole grains in which also the effect of cooking was evaluated. Data suggested that to improve their antioxidant properties specific cultivars should be selected and the cooking procedures carefully considered.