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Common Beer Off Flavours – Baby vomit, cheesy and off milk

Off Flavour: Butyric

Chemical Name: Butyric Acid

Butyric Acid

What to look for: Any parent will know this smell well. Think of off milk, rancid, cheesy and the all important baby vomit.

When does it occur: Bacterial infection during the wort production.  It can be introduced through an infection in sugar adjuncts (honey, maple syrup, candi sugar). If the bacteria exists in your mash it can become more pronounced after packaging. It can also occur with sour mashes in aerobic conditions.

Will it disappear over time? Once it’s there, it’s infected and will increase over time within your packaged beer. It’s time to drain pour it.

Tips on how to reduce Butyric Acid

  • Sanitise, Sanitise, Sanitise
  • Taste sugar adjuncts before adding to wort to make sure there isn’t an infection
  • Keep your sour mash above 32 degrees Celsius and away from outside air

Other Common Off Flavours:

  1. Who put a banana in my beer?
  2. Why does my beer smell like butterscotch or popcorn?
  3. Did someone fart in my beer?


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