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Part of my job involves selling beer. I was told by a coworker that visible yeast particulates at the top of a beer bottle indicate that it's not fit for consumption, whereas yeast at the bottom is fine.

Is this true? And if so, does it change depending on whether it's a top-fermenting or bottom-fermenting beer? Does this affect meads and ciders as well?

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Quick answer no. The yeast used should have very little effect on on the expiry date. Things that will affect this more are:

  • Temperature of fermentation
  • Hot side aeration
  • Cold side aeration
  • Pasteurization
  • Filtration
  • Colour of bottle the beer is stored in
  • Type of beer ie % dark malts
  • Live product vs sterile filtered

This list is incomplete. This is an incredibly complex subject, there are PhDs in Brewing/Chemistry handed out for small aspects of each of these topics.

Here is a quick overview presentation of the technical aspects surrounding beer stability and stabilisation.

https://www.craftbrewersconference.com/wp-content/uploads/2015_presentations/F1420_Deniz_Bilge.pdf

  • Awesome, thanks for the reply! Any thoughts re: the statement on visible yeast particulates? – amagnasco Mar 25 '17 at 14:06
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    Visibility of yeast particulates have no affect on weather or not the beer is fit for consumption. Some yeasts do not flocculate (clump) in the same way as others, but a hazy or yeasty beer can be delicious and is almost certainly fit for consumption, unless it smells or tastes 'bad'. – Mr_road Mar 25 '17 at 17:45
  • Thank you so much! That makes a lot more sense to me, particularly given that I know some beers optimize for yeastiness (Hefeweizen). Great answer! – amagnasco Mar 25 '17 at 20:03
  • And some yeasts are naturally "top-fermenting" while others are not. A bottle of beer with yeast in it generally keeps longer and continues to (slightly) change in flavor is it ages. In regards to the "colour of the bottle" - light/sunlight is the #1 factor is a beer going "skunky." Clear is the worst, green is also not great. The trendy practice of adding a lime to a Corona started because it was needed to choke down that crappy, cheap, skunky beer. – PoloHoleSet Mar 27 '17 at 15:31

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