Metabolomic Insights into Premature Yeast Flocculation: Identification of Galangin as a Key Positive Factor

Premature yeast flocculation (PYF) is a significant challenge that adversely affects beer quality and reduces economic efficiency within the brewing industry. Although previous studies have primarily explored genomic and proteomic factors related to PYF, the underlying metabolic mechanisms remain largely unexplored. In this study, we employed metabolomics to investigate the metabolic differences between unfermented wort samples (WORT) and samples from the 3-d European Brewery Convention (EBC) fermentation test, exhibiting different degrees of PYF severity. We identified 46 differential metabolites in the EBC group including arginine, daidzein, and galangin, while 30 differential metabolites such as daidzein, galangin, and tenuazonic acid were found in the WORT group. Thirteen metabolites were shared between EBC and WORT. Correlation analysis of the PYF36 group demonstrated that the levels of galangin and daidzein were positively associated with fermentation duration. Furthermore, reverse addition experiments confirmed that galangin significantly promoted PYF, as indicated by increased wort clarity, thereby establishing galangin as a positive regulator of this phenomenon. These findings not only deepen our understanding of the metabolic underpinnings of PYF but also provide a practical framework for controlling PYF and enhancing beer production efficiency.