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Yeast makes the beer
Fermentation converts wort into beer while creating aroma, flavour and texture along the way.
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Brewing ingredient · Yeast
Yeast explained: the ingredient that turns wort into beer — and creates far more than alcohol.
Yeast consumes fermentable sugars and produces alcohol and carbon dioxide, but the interesting part is everything else it leaves behind: fruit, spice, sulfur, dryness, body and the character that separates one fermentation from another.
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Strain choice matters
Different yeasts handle sugar, temperature and flavour production differently.
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Healthy fermentation matters
Pitching, nutrition, oxygen at the right stage and temperature control all influence the finished beer.
Ale yeast and lager yeast are useful families, not personality tests
Ale strains often ferment warmer and can produce more obvious fruity or spicy character. Lager strains are commonly run cooler and are often chosen for a cleaner profile, although modern brewers use a wider range of temperatures and methods than the simple textbook split suggests.
Where do banana, pear or clove-like notes come from?
Yeast can create esters that seem fruity and phenolic compounds that seem spicy. Those flavours may be central to weissbier or Belgian beer, while the same intensity would feel out of place in a very clean lager.
What does attenuation mean?
It describes how much of the available fermentable material the yeast has consumed. Higher attenuation usually means a drier finish; lower attenuation can leave more residual body and sweetness-like malt character.
Can yeast create faults?
Yes. Stressed, unhealthy or incomplete fermentation can leave excessive diacetyl, acetaldehyde, sulfur or other unwanted character. The same compounds can also appear at low or stylistically appropriate levels, so context still matters.
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Put it to work
If this page has done its job, the next glass should make a little more sense.