May 21, 2021

What the ‘Taint’ is that – Part 4

Pints in a row

Part 4:

Welcome to the final instalment of our series on common beer taints and how to avoid them. This time it’s ‘Oxidisation’ – literally caused by the air we breathe.

Humans can’t live without it, but oxygen is one of beer’s biggest enemies.

No. 4 Oxidisation

(Sometimes also referred to as ‘oxidation’ or by the scientific term trans-2 nonenal)

How to detect it:

The most common manifestation of this taint is beer which tastes like cardboard! It might also remind you of licking an envelope. If the beer is heavily oxidised, it can start to taste leathery or even like sherry.


Drinkers might say:

“This beer feels funny at the side of my mouth”, “It’s like a mouthful of wet newspaper”, “Reminds me of the dog’s towel”, “Tastes like cardboard”, or “Tastes stale.”

What causes it:

Oxidisation happens when beer comes into contact with the air. The main cause is from kegs that have been broached and left on sale for too long. Lockdowns and intermittent trade have made this far more of a common fault. It can also happen at the keg-filling stage, but this is far rarer.


Always aim to sell a keg within 5 days. If you receive complaints about papery, ‘cardboardy’ beer, take the offending keg off sale and review how quickly the beer is selling compared to other products on the bar. You may find that you can’t justify the number of beers you have on sale right now – consider reducing the range temporarily. Ensure line connectors fit properly and keg changing procedures are carried out quickly and efficiently.

We hope you’ve found our series on taints useful and that it helps you raise the bar on beer quality and, of course, serve the tastiest beer imaginable!

If you have questions about any of the taints we’ve seen in this series, or would like to talk to us about any beer quality issues, please contact us at, or call us on 01638 563237.



Photo by Proriat Hospitality on Unsplash

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