Traditional and novel approaches to wild yeast detection and identification

Wild yeast is any yeast not deliberately introduced to the beer production chain. Wild yeasts are unwanted since they can cause fermentation problems and quality defects in the final product even when present at low levels. The most feared wild yeast strains belong to the same species as top (Saccharomyces cerevisiae) and bottom fermenting (Saccharomyces pastorianus) yeast strains, which makes their differentiation from culture yeast difficult. During the past years, detection and identification methods for wild yeasts have progressed relatively little compared to those for bacteria. The general trend in the methodology development has been from phenotypic through biochemical to genetic approaches. Side by side, technological advances have led to better sample treatment methods, higher automation level and / or miniaturisation. Furthermore, many applications have been commercialised. This presentation intends to give an overview with representative examples about the various approaches used to wild yeast detection and identification. The main emphasis is in the traditional and genetic methods. Finally, new integrated approaches, not yet applied to wild yeasts, will be presented as possible methods for the near future.