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Common Beer Off Flavours – Garbage, Gas and yes Fart.

Off Flavour: Mercaptan

Chemical Name: Ethanethiol

ethanethiol common off flavour in beer

What to look for: Trust me when I say you will know when you get it. Think drain, rotting garbage, sulphury or even the aroma of a fresh fart. This is the compound they add to natural gas to give it an aroma.

When does it occur: Can be caused during fermentation by particular yeast strains that are under stress. Also caused by yeast autolysis (basically a yeast cell that has died, ruptures and then releases several off flavours in your beer)

Will it disappear over time? Unlikely and likely that smell will increase substantially.  Serve a beer with substantial levels of mercaptan and you may need to find some new friends.

Tips on how to reduce Mercaptan (ethanethiol)

  • Use the right yeast for the beer style
  • Good sanitisation practices
  • Rack your beer off the yeast cake within 4 weeks of fermentation start

Other Common Off Flavours:

  1. Who put a banana in my beer?
  2. Why does my beer smell like butterscotch or popcorn?
  3. Baby sick in my beer? Yuck


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