What compounds are primarily responsible for producing off-flavors like band-aid, clove, and peppery notes in beer?

Phenols are primarily responsible for producing off-flavors such as band-aid, clove, and peppery notes in beer. Phenolic compounds are a class of compounds that can be derived from various sources, including the ingredients used in brewing (like grains and hops) and the yeast used during fermentation.

When yeast undergoes fermentation, it can produce phenolic compounds that contribute distinct flavors to the beer. For example, certain strains of yeast, particularly those used in Belgian and Saison styles, can produce phenols that create clove and peppery notes. Additionally, some phenolic compounds can also have a medicinal or plastic-like aroma, which is reminiscent of band-aids.

Understanding the role of phenols in off-flavors is essential for brewers and tasters alike, as controlling the fermentation process, including temperature and yeast selection, can help mitigate unwanted phenolic flavors while promoting desirable characteristics in the final product.