Why the same beer tastes different on draught and in a can
Drinkers often swear a beer tastes better on tap. Sometimes it does, sometimes the can wins. The difference is rarely the recipe. It comes from what happens to the beer between the tank and your mouth.
Same beer, different journey
Most breweries fill kegs and cans from the same bright tank. At that moment, the beer is identical. After that, the two travel very different routes: a keg goes cold to a bar and is pushed through lines by gas, a can goes through a filler, sometimes a pasteuriser and then into distribution. Every step can nudge the flavour.
Carbonation and dispense
A can holds exactly the carbonation the brewery set. On draught, carbonation depends on the gas pressure and temperature at the bar. Set the pressure too high and the beer becomes over-carbonated and sharp. Set it too low and it slowly goes flat in the keg. Some beers are poured with a nitrogen mix, which gives a creamy texture a standard can cannot match.
The pour matters too. A good draught pour knocks out some CO2 and builds a head, which releases aroma. Our guide to how to pour beer covers technique.
Freshness and the cold chain
Kegs are usually kept cold from brewery to bar and sold within weeks. Cans may travel further and sit longer, sometimes in warm warehouses and shops. In Indian conditions, that warm storage is often the biggest difference. Heat speeds up staling, which turns fresh hop aroma into caramel, honey or wet cardboard. Our guide to oxidised beer explains the chemistry.
The reverse is also true. A keg that has sat on a slow tap for weeks, or a bar that rarely changes kegs, can serve beer staler than a fresh can from a cold shop.
Draught lines
The beer line is a long, dark, wet tube, an ideal home for yeast and bacteria if it is not cleaned. Dirty lines give buttery, sour or musty flavours. Common guidance is to clean draught lines every two weeks. Bars that skip this serve worse beer than the brewery ever made. Our guide to draught line cleaning has the routine.
Pasteurisation and oxygen at packaging
Some breweries pasteurise cans but not kegs, especially when kegs stay cold and sell fast. Heat treatment helps shelf life but can soften fresh hop and malt character slightly. Our guide to pasteurisation units covers how much heat is involved.
Canning also risks picking up oxygen at the filler. A well-run line keeps it very low. A poorly run one lets in enough to shorten the beer's life noticeably. Kegs pick up much less, because they are purged with CO2 and filled under pressure.
The glass, the can and the temperature
Drinking straight from a can hides aroma, because your nose sits over a small metal opening rather than an open glass. Many people blame the can for a metallic taste. Modern cans are lined, so the beer does not touch bare metal. Much of that impression comes from smelling the can rim while drinking. Pour the can into a clean glass and the difference from draught often shrinks.
Bars serve draught at whatever temperature their system runs. A can from a home fridge may be colder or warmer. Temperature changes how sweet, bitter and aromatic a beer seems. Two glasses of the same beer at 3 °C and 8 °C can taste like different beers.
What a brewery can do about it
Breweries that care about consistency treat both formats as their responsibility. They set carbonation for cans to match what a good bar serves on draught. They measure dissolved oxygen at the filler. They work with bars on line cleaning, gas pressure and keg rotation. They pull beer from venues that will not keep lines clean. They put a clear packing date on cans and ask retailers to store them cold.
Drinkers can help too: buy cans from cold shelves and drink hoppy beers fresh.
Testing it yourself
Buy a can of a beer you can also get on tap. Note the packing date. Drink the draught version and pour the can into a similar glass at the same temperature, ideally on the same evening. Compare aroma, carbonation, bitterness and freshness. You will often be able to point at the cause: a flat keg, a stale can or a dirty line. Being able to name the cause, rather than just preferring one, is what separates a drinker from a taster.
Common questions
Is draught beer fresher than canned beer?
Often, because kegs usually stay cold and sell fast. But a slow-moving keg or a dirty line can serve staler beer than a fresh, cold can.
Why does canned beer taste metallic?
Cans are lined, so the beer does not touch metal. The impression usually comes from smelling the can rim. Pour into a glass and it normally disappears.
Does pasteurisation change beer flavour?
It can soften fresh hop and malt character slightly. Many breweries pasteurise cans but not kegs that stay cold.
How often should draught lines be cleaned?
Common guidance is every two weeks. Dirty lines give buttery, sour or musty flavours.
