Reference Number: 134
An investigation on the odor-active compounds of wholemeal (WWF) and white wheat flour (WF 550) by aroma extract dilution analysis (AEDA) and by quantitative studies revealed a significant number of odor-active compounds, such as (E)-2-nonenal, (E,Z)- and (E,E)-2,4-decadienal, (E)-4,5-epoxy-(E)-2-decenal, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, and vanillin, with high odor activities in both wheat flours. The amounts and, consequently, the aroma potencies of vanillin, (E,E)-2,4-decadienal, and 3-(methylthio)propanal were much higher in the WWF than in the WF 550 samples. Fermentation of suspensions of both flours with lactic acid bacteria did not generate new odorants; however, many compounds, such as acetic acid or 3-methylbutanal, were increased, whereas aldehydes (formed from the degradation of unsaturated fatty acids) were decreased. Comparing the odorant concentrations present before and after fermentation gave evidence that the main influence of the microorganisms on sourdough aroma is to either enhance or decrease specific volatiles already present in the flour. A comparison with literature data indicated that most of these odorants are also important for the bread crumb aroma present after baking of the dough.
SIGNIFICANCE OF THIS STUDY
Recent investigations on rye bread crumb aroma have clearly demonstrated that rye flour already contains a significant number of odor-active compounds which clearly contributed to the crumb aroma of rye bread. The current study focusses on the characterisation and quantification of the key odourants in wholemeal and white wheat flour and also to highlight the changes in flour odourants occurring during wheat sourdough fermentation with lactic acid bacteria. When the researchers performed a sensory test to distinguish the flavour and aroma profile between wheat flour and whole wheat flour, the results of the identification experiments revealed a significant difference between wheat flour (white) and whole wheat flour. The main compounds identified were vanillin followed by dimethyl-2-furanone, 4,5-epoxy-2-decenal, and 2-nonenal as the most odor-active among the 21 aroma compounds characterised in the white wheat flour. Whole wheat flour had an additional six flavour compounds that were not present in white wheat flour making its flavour profile stand out. Most of the odour compounds released come from compounds present in the wheat flour and consequently, the paper concludes that wheat flours are an important source of bread odorants and, therefore, the choice of the flour type should clearly influence the aroma quality of wheat breads.