Off-flavours and taints


In an ideal world everyone would have enough to eat, a nice place to rest their head, good companions, and enough money for what they need in life. Beer would only contain the flavours that the brewer intended to be there. ‘Foreign flavours’ would be foreign to such beers. Unfortunately, few have yet mastered the path to Brewing Nirvana. Their beers have flavour defects in one form or another. These can be categorized as off-flavours or taints. In my experience, otherwise knowledgeable beer folk often get a bit confused about what the difference is between an off-flavour and a taint. This short post provides a brief explanation and examples.


Off-flavours are odours, tastes and mouthfeel characteristics which have been formed in the product or process through chemical or biochemical reactions, sometimes with the involvement of enzymes and / or microorganisms. To an extent, process and product design pre-dispose a product to development of off-flavours and constant vigilance is needed on the part of the brewer to resist this flavour inertia.

Examples of off-flavours include:

  • Acetaldehyde
  • Acetic
  • Astringent
  • Burnt-rubber
  • Butyric
  • Diacetyl
  • DMS
  • Ethyl acetate
  • H2S
  • Indole
  • Isovaleric
  • Lactic
  • Leathery
  • Lightstruck
  • Mercaptan
  • Mousy
  • Onion
  • Oxidized
  • Papery
  • Tobacco
  • 4-Vinyl guaiacol
  • Yeast bite


Unlike off-flavours, taints are foreign to both the product and process. They come from ‘outside’, getting into the product via vectors such as liquids, solids and gases.

Examples of taints include:

  • Alkaline
  • Bell pepper
  • Bromoanisole
  • Bromophenol
  • Chloroanisole
  • Chlorocresol
  • Chlorophenol
  • Cresol
  • Earthy
  • Iodoform
  • Metallic
  • Mouldy

In addition to the basics of using good quality raw materials, well maintained and well designed brewing equipment, well thought out recipes and processes, and – of course – skilled, experienced brewers to make your beer, a highly trained taste panel is a great help in the fight against off-flavours and taints. Once tasters have been taught to reliably recognize each of the flavour attributes listed above, eliminating the defect is made so much easier.

4 thoughts on “Off-flavours and taints

  1. Step 1 is organoleptically identifying the off flavour or taint.
    Step 2 is understanding how to control / eliminate the problem
    Step 3 is sustainably doing so!

    1. Absolutely Craig!

      Step 1 relies on training prior to the occurrence of the off-flavour or taint problem. Sometimes I have to laugh when people say (for example) that they’ve never had a bromoanisole problem before, especially when the answer to my next question is “I’ve never smelled bromoanisole before”. So how would they know?

      Step 2 is easier said than done and it’s something we’ll spend some time on trying to help with this blog. Brewing textbooks are often a bit woolly on the details of dealing with problems in my experience.

      Step 3 is million dollar payoff (literally). ‘All’ you have to do is not to do again what you did before! Only thing is, that advice has to followed by every single one of your colleagues too. A constant battle against entropy, but one that has to be fought.

  2. One thing that seems clear is the importance of concentration. Levels of taint and off-flavour that trigger a consumer complaint may be higher than the concentration at which one would wish to identify as an early warning of production problems. Therefore not only is the timing of training important but targeting the appropriate strength of flavour to train people with. Of course some flavours will present different attributes at different concentrations which may be another point for discussion.

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