The aroma profile of wheat bread crumb influenced by yeast concentration and fermentation temperature

The consumers of today have an increasing interest in high quality bread with appealing aroma. The scope of this work is to investigate how aroma in wheat bread crumb is influenced by different fermentation conditions: amount of yeast (20, 40 and 60 g/kg flour) and fermentation temperature (5,15 and 35 degrees C). Dough samples were fermented to equal height and baked, and the aroma compounds from the bread were extracted by dynamic headspace extraction and analyzed by gas chromatography mass spectrometry. Quantification of the aroma compounds was performed by multiple headspace extraction. The most aroma active compounds identified were 3-methylbutanal, (E)-2-nonenal, 3-methyl-1-butanol, and 2,3-butanedione. Increasing the yeast concentration was found to increase formation of the majority of the compounds formed from the yeast metabolism, with 2,3-butanedione and phenylacetaldehyde as the most aroma active compounds. High fermentation temperature (15 and 35 degrees C) increased formation of many lipid oxidation compounds, with hexanal and heptanal having the highest odor activity values. Low fermentation temperature (5 degrees C) was found to increase formation of the three esters ethyl acetate, ethyl hexanoate, and ethyl octanoate, with ethyl hexanoate having the highest odor activity value. The odor activity values of the esters were generally low. (C) 2012 Elsevier Ltd. All rights reserved.