Dominance and influence of selected Saccharomyces cerevisiae strains on the analytical profile of craft beer refermentation

This study investigated the influence of Saccharomyces cerevisiae strains inoculated at the refermentation phase on the analytical profile of craft beer. After preliminary screening of 33 S. cerevisiae strains, four were selected and used in bottle refermentation trials. To attribute the flavour profile of the refermented beers to the inoculated strains, molecular characterization was carried out using a mini‐satellite protocol of amplification with inter‐δ primers. Fingerprinting analysis of 500 isolates showed that all of the inoculated strains used in the bottle refermentation dominated the process. The main analytical characters across the bottle refermentation trials were similar, while there were distinctive and significant variations in the volatile compounds. In particular, when compared with the starter strain used as control, the bottle refermentation trials using the DBVPG 2170, DBVPG 2187 and L951 S. cerevisiae strains showed significantly higher levels of the volatile compounds that are responsible for fruity and flowery aromas (i.e. isoamyl acetate, ethyl octanoate, ethyl dodecanoate phenyl ethyl acetate, β‐phenyl ethanol). This study indicates that the proper refermentation process results in the dominance of the selected starter strain, which produces fermentation compounds that show a specific analytical profile and give the craft beer its distinctive bioflavour. Copyright © 2014 The Institute of Brewing & Distilling