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

Abstract

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.

New Lager Brewery Strains Obtained by Crossing Techniques Using Cachaça (Brazilian Spirit) Yeasts

“…Three of the most important aroma compounds in beer are 3-methylbutyl acetate (with a banana-like aroma), ethyl acetate (with an alcoholic, fruity, but also solvent-like aroma) (9), and 3-methylbutanol (fruity and sweet) (30). In general, the production of 3-methylbutyl acetate and ethyl acetate was found to be significantly higher in the hybrids than in parental strains (Fig.…”

“…Therefore, homothallism can be important to select cachaça yeast strains resistant to different types of stress (26,29). Nevertheless, and from a breeding perspective, the use of spores that display homothallic behavior is not appropriate, forcing the deletion of the HO gene and at same time generating a genetically modified yeast cell (30,31).…”

Effects of Barley (Hordeum Vulgare L.) Variety and Growing Environment on Beer Flavor

“…The approval process, in its final steps, involves elimination of potential varieties based on negative contributions to beer flavor. Examples of such negative flavors include, but are not limited to, excessive dimethyl sulfide (DMS), diacetyl, and aldehydes resulting from lipoxygenase activity (19,31,41).…”

Study of the production and release of aromas during winemaking carried out by different Saccharomyces species and hybrids

“…This reaction is mediated by acetyltransferases codified by genes ATF1 and ATF2 (Fujii et al, 1994(Fujii et al, , 1996Fujiwara et al, 1999;Lilly et al, 2006;Saerens et al, 2008Saerens et al, , 2010Verstrepen et al, 2003). Besides, the effect of esterases codified by IAH1 and TIP1 is also important for the final concentration of acetate esters in the wine (Horsted et al, 1998;Lilly et al, 2006;Saerens et al, 2008Saerens et al, , 2010.…”

“…Saerens et al, , 2008Saerens et al, , 2010. Besides, in the final concentration of ethyl esters in the wine it must be taken into account the effect of esterases codified by IAH1 and TIP1 (Horsted et al, 1998;Lilly et al, 2006;Saerens et al, 2008Saerens et al, , 2010.…”