Influence of endogenous ferulic acid in whole wheat flour on bread crust aroma

The influence of wheat flour type (refined (RWF)/whole (WWF)) on bread crust aroma was investigated. Differences were characterized by aroma extract dilution analysis and quantified utilizing stable isotope surrogate standards. For RWF breads, five aroma compounds were higher in concentration, 2-acetyl-1-pyrroline, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 2-phenylethanol, 2-acetyl-2-thiazoline, and 2,4-dihyroxy-2,5-dimethyl-3(2H)-furanone, by 4.0-, 3.0-, 2.1-, 1.7-, and 1.5-fold, respectively, whereas three compounds were lower, 2-ethyl-3,5-dimethylpyrazine, (E,E)-2,4-decadienal, and (E)-2-nonenal by 6.1-, 2.1-, and 1.8-fold, respectively. A trained sensory panel reported the perceived aroma intensity of characteristic fresh refined bread crust aroma was significantly higher in RWF compared to WWF crust samples. Addition of 2-acetyl-1-pyrroline, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 2-phenylethanol, 2-acetyl-2-thiazoline, and 2,4-dihyroxy-2,5-dimethyl-3(2H)-furanone to the WWF crust (at concentrations equivalent to those in the RWF crust) increased the intensity of the fresh refined bread crust aroma attribute; no significant difference was reported when compared to RWF crust. The liberation of ferulic acid from WWF during baking was related to the observed reduction in these five aroma compounds and provides novel insight into the mechanisms of flavor development in WWF bread.