species
Saccharomyces cerevisiae
The species behind all ale, and behind bread and wine — fermenting warm and generating the esters and phenols that give ale its fruit and spice.
Cerevisiae ferments warm, typically 16–24 °C, and rises to the surface during vigorous fermentation, which is where "top-fermenting" comes from. Warm fermentation is the reason ale carries so much yeast-derived flavour: ester and phenol production both increase sharply with temperature.
It cannot ferment melibiose, which is the classical laboratory test distinguishing it from lager yeast.
Behaviour
| Scientific name | Saccharomyces cerevisiae |
|---|---|
| Fermentation temperature | 16–24°C |
| Apparent attenuation | 68–85% |
| Flocculation | variable |
| Esters | high |
| Phenols | low |
Used in
- Berliner Weisse
A very low-strength sour wheat beer: sharply lactic, bone dry, lightly sparkling and enormously refreshing.
- Gose
A lightly sour German wheat beer with added salt and coriander — tart, savoury and unusually thirst-quenching.
- Lichtenhainer
A historical Thuringian smoked wheat beer that is also lightly sour — an unusual combination of smoke and lactic acidity.
- Sahti
A Finnish farmhouse ale filtered through juniper branches and fermented with baking yeast — banana, juniper and no hops.
Questions
What is the difference between ale yeast and lager yeast?
They are different species. Ale yeast (Saccharomyces cerevisiae) ferments warm and produces fruity esters and spicy phenols as a by-product. Lager yeast (Saccharomyces pastorianus) ferments cold, works more slowly, and produces very little of either — which is why lagers taste clean and malt-and-hop-driven while ales taste fruity.
Evidence
What BeerHQ knows about this, and how. Every statement carries the state of the evidence behind it rather than being presented flatly as fact.
Louis Pasteur’s work in the 1860s and 1870s established that fermentation is caused by living microorganisms and that beer spoilage is microbial, which made deliberate control of both possible for the first time.
Backed by a source
Sources: Beer: The Story of the Pint — print; Beer: Tap into the Art and Science of Brewing — print