Cask ale is beer that continues to mature in the container from which it will be served. Live yeast remains in the cask, allowing a final stage of conditioning in the pub cellar before the beer is pulled to the bar without added carbon-dioxide pressure.
What makes it “live”?
Fermentation creates alcohol, flavour and carbon dioxide. In cask-conditioned beer, yeast remains active after the brewery has filled the cask. During cellar conditioning it develops the beer’s character and provides gentle natural carbonation. The publican must then let the sediment settle, manage the venting and serve the beer while it is fresh.
Cask versus keg
Keg beer is generally clarified or filtered for stability and served under applied gas pressure. It usually has a longer working life once connected. Cask is more delicate, softly carbonated and highly dependent on the skill and turnover of the pub. Neither container automatically guarantees flavour or quality; they are different systems suited to different beers.
Why the handpump matters
The tall handle on the bar operates a beer engine, drawing beer from a cask in the cooler cellar below. Some venues serve straight from the cask by gravity. A handpump is a strong clue that cask is available, although consumers should still look at the pump clip and ask staff if unsure.
How should a good pint taste?
It should taste fresh, naturally carbonated and appropriate to its style. Flatness, vinegar, wet cardboard or dirty-line flavours are not signs of authenticity. Cask is also cool, not warm: cellar temperature is higher than a modern lager font but well below a heated room.
The simple answer: cask ale is living beer finished by the pub. The brewer creates it, but the cellar team completes the job.
Source: CAMRA Learn & Discover
