How to detect off flavours

While some so-called off-flavours can be appropriate in certain styles others are not and may kill a little bit of your soul. Here's a quick guide to the most common off-flavours


Diacetyl: Appropriate in small amounts in pale ales and stouts, it tastes like butter or butterscotch. It's never any good in most lagers and would be a sign of improper brewing techniques.

DMS: Expected in some pale lagers like American lights, Dimethyl Sulphide tastes like cooked corn or tomato sauce. Proper brewing will make sure this compound evaporates out of your beer.

Acetaldehyde: Low amounts of this compound are ok in beers like a Biere de Garde but if anything else tastes like green apples or paint then your beer fermented at too high a temperature.

Cheese: Very bitter IPAs can have a hint of cheese but beers that taste like stale cheese

How to detect off flavours

While some so-called off-flavours can be appropriate in certain styles others are not and may kill a little bit of your soul. Here's a quick guide to the most common off-flavours


Diacetyl: Appropriate in small amounts in pale ales and stouts, it tastes like butter or butterscotch. It's never any good in most lagers and would be a sign of improper brewing techniques.

DMS: Expected in some pale lagers like American lights, Dimethyl Sulphide tastes like cooked corn or tomato sauce. Proper brewing will make sure this compound evaporates out of your beer.

Acetaldehyde: Low amounts of this compound are ok in beers like a Biere de Garde but if anything else tastes like green apples or paint then your beer fermented at too high a temperature.

Cheese: Very bitter IPAs can have a hint of cheese but beers that taste like stale cheese or sweaty socks have high levels of isovaleric acid, which comes from old hops.

Medicinal: No beers should ever taste like mouthwash, antiseptic or plasters. If you find one that does then chlorophenols from chlorinated water or bleach-based cleaners got in contact with the beer.

Butyric Acid: Never appropriate, if your beer tastes like baby puke then it got infected with the clostridium butyricum bacteria either in the wort production phase or after packaging.

Oxidation: If your English Old Ale has a hint of sherry-like oxidation, thatís acceptable. Otherwise, beers that taste like wet cardboard or paper are too old or the wort was splashed around.?

Sulfidic: Classic ales from Burton-on-Trent can have a sulfur-like character from hydrogen sulfide that is known as Burton Snatch. Smells of rotten eggs or sewage are unappealing but go away quickly after serving.

Lightstruck: When beers in green or clear bottles are put in contact with sun or fluorescent light, a photochemical reaction with the hops takes place and it tastes like burned rubber or skunk.

Acidic: If you're not drinking a lambic, gueuze or other purposely-sour beers with wild yeast strains then you shouldn't taste vinegar in high concentrations, which would be indicative of an acetobacter infection.