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How does yeast affect the taste and smell of beer?
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Beer
Glasses of beer in a bar in Brussels.
Yeast, a type of fungus from the genus Saccharomyces, is the primary driver of beer's flavor and aroma profile. During fermentation, yeast produces hundreds of organic compounds that define a beer's character.1
While ethyl alcohol and carbon dioxide significantly impact sensory perception, yeast also generates specific compounds that create distinct notes:1
- Esters: These contribute fruity aromas, such as banana (isoamyl acetate) and apple (ethyl hexanoate).1
- Higher Alcohols: Compounds like 2-phenyl ethanol add complexity to the beer's profile.1
- Acids and Ketones: Various acids and diketones, such as diacetyl, further shape the flavor.1
- Sulfides: Compounds like dimethyl sulfide can also influence the sensory experience.1
Because these metabolic processes are complex, brewers rely on specific, well-maintained yeast strains to ensure consistency in the final product's taste and smell. The choice of strain and the temperature of fermentation—which differs between ale and lager—are fundamental to the brewing process.12