SUSANNE PROCOPIO (1), Fei Qian (1), Reiner Springer (1), Thomas Becker (1)
(1) Technische Universität München-Weihenstephan, Lehrstuhl für Brau- und Getränketechnologie, Freising, Germany
Organoleptic characteristics of beer mainly depend on the
aroma-active substances produced by yeast during fermentation. In
particular, volatile higher alcohols and esters are determined by the
nitrogen and carbohydrate composition of fermentation wort. Especially
amino acid assimilation by yeast influences the synthesis of higher
alcohols via the Ehrlich pathway. Of all secondary metabolites, higher
alcohols are of great interest, because they are generally produced by
yeast in the highest absolute concentrations. Furthermore, esters whose
syntheses are linked to the concentration of their corresponding alcohol
are very important because of their responsibility for the highly
desired fruity, honey, and perfume-like aroma in beer. Even though they
are only present in trace quantities they can affect beer flavor well
below their threshold value. However, the absolute amount of
aroma-active compounds is not really relevant for the flavor of
fermented alcoholic beverages. The relationship between the different
volatiles is more important. This can be explained by synergy effects of
the aroma-active substances. Thus, it is possible that very low aroma
concentration can regulate sensory profiles. Many studies have been
carried out to optimize the technical parameters in brewing process in
order to control beer flavor. Nevertheless, few studies have been
carried out on the effect of specific substrate composition in the media
to create certain aroma profiles in beer. Therefore, an exact defined
fermentation media was developed to consequently diversify important
substrate compounds. Here, amino acid variations premeditated by a
design of experiment have been performed in fermentation trails in
laboratory scale using lager and ale brewing strains. Significant
results in amino acid composition have been found by measuring
aroma-active metabolites via GC-FID. This might help to control defined
amounts of flavored substances in fermented beverages and how it is
possible to generate specific sensory effects.
Susanne Procopio was born in Gießen, Germany. She graduated with a
Dipl. Agr.-Biol. degree from the University of Hohenheim in Stuttgart,
Germany, where she also prepared her diploma thesis in molecular
biotechnology in 2008. Since 2009 she has been a Ph.D. student at the
Lehrstuhl für Brau- und Getränketechnologie, Technische Universität
München, working in the field of yeast genetics and aroma profiling.
VIEW PRESENTATION
