Monitoring the influence of high-gravity brewing and fermentation temperature on flavour formation by analysis of gene expression levels in brewing yeast

• Published in: Applied microbiology and biotechnology 2008-10, Vol.80 (6), p.1039-1051
• Main Authors: Saerens, S. M. G, Verbelen, P. J, Vanbeneden, N, Thevelein, J. M, Delvaux, F. R
• Format: Article
• Language: English
• Subjects: Alcohol; Amino acids; Applied Genetics and Molecular Biotechnology; Beer; Beer - analysis; Beer - microbiology; Biological and medical sciences; Biosynthesis; Biotechnology; Breweries; Colony Count, Microbial; Enzymes; Ester; Esters; Ethanol - analysis; Fermentation; flavor; Flavoring Agents - metabolism; Food Industry - methods; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Profiling; Higher alcohol; Hydrogen-Ion Concentration; Hypergravity; Life Sciences; Methods. Procedures. Technologies; Microbial engineering. Fermentation and microbial culture technology; Microbial Genetics and Genomics; Microbiology; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Solvents; Studies; Temperature; Temperature effects; Yeast; Yeasts
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-008-1645-5

During fermentation, the yeast Saccharomyces cerevisiae produces a broad range of aroma-active substances, which are vital for the complex flavour of beer. In order to obtain insight into the influence of high-gravity brewing and fermentation temperature on flavour formation, we analysed flavour production and the expression level of ten genes (ADH1, BAP2, BAT1, BAT2, ILV5, ATF1, ATF2, IAH1, EHT1 and EEB1) during fermentation of a lager and an ale yeast. Higher initial wort gravity increased acetate ester production, while the influence of higher fermentation temperature on aroma compound production was rather limited. In addition, there is a good correlation between flavour production and the expression level of specific genes involved in the biosynthesis of aroma compounds. We conclude that yeasts with desired amounts of esters and higher alcohols, in accordance with specific consumer preferences, may be identified based on the expression level of flavour biosynthesis genes. Moreover, these results demonstrate that the initial wort density can determine the final concentration of important volatile aroma compounds, thereby allowing beneficial adaptation of the flavour of beer.