Phenolic acid contents and antioxidant activities of wheat milling fractions and the effect of flour extraction rate on antioxidant activity of bread

The amounts of free and bound phenolic contents, antioxidant activity and phenolic acids of nine different wheat varieties grown in Turkey and of their milling fractions (thick bran, thin bran, and flour) were determined. Furthermore, total phenolic content and antioxidant activity of the different extraction rate flours (65%, 75%, and 100%) and breads made from those flours were evaluated. The free and bound phenolic content of wheat varieties ranged from 656.80 to 900.64 and 1095.73 to 1376.33 mg GAEq./kg defatted wheat dm, respectively. In wheat, thick bran fraction has shown the highest phenolic content and antioxidant activity. Ferulic and vanillic acids were determined in free phenolic extracts obtained from the studied wheat varieties and their milling fractions. Syringic and p-coumaric acids were determined as well as ferulic and vanillic acids in bound phenolic extracts. Total phenolic content and antioxidant activity of breads increased with an increase in flour extraction rate.