The generation of aroma compounds from odorless precursors during microbial food fermentation is still a key issue in flavor research, because the odorants formed are considered as natural. However, although the metabolization of free amino acids by the �Ehrlich�-mechanism initiated by yeasts is long-known, e.g., options to modify the flavor of bakery products, for example by exchanging the cereal flour and/or by changing the respective yeast strain, were scarcely explored. In the first part of the lecture, results on the key aroma compounds of doughs prepared from either corn flour or corn malt with two different yeast strains are presented. Isotope labeling studies on four important precursor amino acids then allowed a precise correlation of the yields of each degradation product (aldehyde, alcohol, acid, ester) with the amount of the labeled precursor amino acid administered. Finally, concentrations and enantiomeric ratios in the five aroma compounds related to the parent, diastereoisomeric amino acid (2S,3S)-isoleucine were compared in selected samples of beer, wine, spirits, bread and dairy products. Odor activity values were calculated and were compared on the basis of the odor thresholds of each enantiomer. Options to modify the aroma of fermented products will be discussed.

Microbial amino acid degradation: A valuable tool to modify the aroma of fermented foods

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.