Determination of free and bound phenolic compounds and their antioxidant activity in buckwheat bread loaf, crust and crumb

- Enrichment of bread with buckwheat flour increase its flavonols and flavan-3-ols content.
- This study highlighted differences between phenolic composition of crust and crumb.
- Rutin is more concentrated in crumb than crust.

This study demonstrated the role of buckwheat flour in improving phenolic compounds in white wheat bread. Three bread samples were obtained by using different buckwheat levels (10, 20 and 30%) in formulations. HPLC-ESI-MS was used to detect the presence of free and bound phenolic compounds in bread loaf, crust and crumb. The phenolic profile changed thanks to the addition of buckwheat flour; in fact, flavan-3-ols and flavonols compounds (i.e. rutin, catechin, etc.) were identified in enriched buckwheat. As expected, the phenolic content increased proportionally to buckwheat flour quantity in bread formulations. The total free phenolic amounts ranged from 109 to 235 mg/kg d.w. in control bread and 30% enriched buckwheat bread, respectively. Bread crusts showed the highest total free and bound phenolic content; however, flavan-3-ols, flavonols and flavones are more concentrated in crumb than crust. Moreover, enriched breads showed higher in vitro antioxidant properties (evaluated by DPPH and ABTS assays) than control one.