Effect of Processing on phenolic acid composition of dough and bread fractions made from refined and whole-wheat flour of three wheat varieties

Authors: LU, YINGJIAN - University Of Maryland; Luthria, Devanand - Dave; FUERST, E - Washington State University; KISZONAS, A - Washington State University; MORRIS, CRAIG - US Department Of Agriculture (USDA)

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2014
Publication Date: 10/6/2014
Citation: Lu, Y., Luthria, D.L., Fuerst, E.P., Kiszonas, A.M., Morris, C.F. 2014. Effect of Processing on phenolic acid composition of dough and bread fractions made from refined and whole-wheat flour of three wheat varieties. Journal of Agricultural and Food Chemistry. 62:10431-10436.

Interpretive Summary: Wheat provides a good source of bioactive phytochemicals namely phenolic acids. In this study, we investigated the effect of bread-making on the assay of phenolic acids of whole and refined wheat from three wheat varieties, comparing refined (RF) and whole wheat (WW) flour, dough, and bread fractions. The efficacy of two common base hydrolysis methods for the phenolic acid analysis was evaluated. Yields of total phenolic acid (TPA) was 5-17% higher among all varieties and flour types when samples were directly hydrolyzed in the presence of ascorbic acid and EDTA, compared to first extracting soluble and then hydrolyzing insoluble bound acids in the absence of ascorbic acid and EDTA. The quantity of phenolic acids measured in whole wheat fractions was significantly higher than the corresponding refined fractions. The results clearly indicate that the phenolic acids measured do not decrease when preparing bread from refined and whole wheat flour. Thus, the potential phytochemical health benefits of total phenolic constituents appear to be preserved or improved during bread baking. This project was partially supported by the Agriculture and Food Research Initiative Grant no. 2009-02347 from the USDA National Institute of Food and Agriculture

Technical Abstract: In this study, we investigated the effect of bread-making on the assay of phenolic acids of whole and refined wheat from three wheat varieties, comparing refined (RF) and whole wheat (WW) flour, dough, and bread fractions. The efficacy of two common base hydrolysis methods for phenolic acid analysis was evaluated. Yields of total phenolic acids (TPA) was 5-17% higher among all varieties and flour types when samples were directly hydrolyzed in the presence of ascorbic acid and EDTA, compared to first extracting soluble phenolic acids and then hydrolyzing the bound phenolic acids in the absence of ascorbic acid and EDTA. The direct hydrolysis method was then used for the analysis of phenolic acids of flour, dough, and bread fractions. Ferulic acid (FA) was the predominant phenolic acid, accounting for a mean of 59% and 81% of TPA among all refined and whole wheat fractions, respectively. The quantity of phenolic acids measured in whole wheat fractions was significantly higher than the corresponding refined fractions. When comparing refined fractions for the three varieties, TPA and FA content were always highest in WB936, intermediate in Blanca Grande, and lowest in Alpowa. In the whole wheat fractions, TPA and FA content were again lowest for Alpowa but there was no consistent trend for TPA or FA when comparing WB936 and Blanca Grande. The results clearly indicate that the phenolic acids measured do not decrease when preparing bread from refined and whole wheat flour. Thus, the potential phytochemical health benefits of total phenolic constituents appear to be preserved or improved during bread baking. This project was partially supported by the Agriculture and Food Research Initiative Grant no. 2009-02347 from the USDA National Institute of Food and Agriculture.