Conventional brewer's yeast: Saccharomyces

The Saccharomyces yeasts play a pivotal role in the definition of beer characteristics being the main responsible of the metabolization of wort components, with production of compounds affecting beer aroma and flavor. The first part of this chapter reviews the growth, physiology, and metabolism of Saccharomyces, with emphasis on specific characteristics related to the brewing process. The second part describes Saccharomyces species involved in brewing, in particular the two yeasts traditionally associated with beer production, which are ale and lager yeasts. Furthermore, it is reported a description of unconventional Saccharomyces species playing a role in brewing process, with emphasis on the potentiality of the new yeasts to satisfy the demand of craft beer producers to create special and innovative beers. The last part deals with the aspects related to the handling of Saccharomyces starters in brewing, in particular to the advantages and limitations of using yeast recycle (repitching of yeast).