Author Topic: Diacetyl?  (Read 615 times)

Offline lindak

  • Cellarman
  • **
  • Posts: 41
    • View Profile
Diacetyl?
« on: February 23, 2017, 03:06:22 AM »
Last Nov. I brewed a honey pale--  nothing exotic 9lbs 2-row,1lbs crystal 15, 1.5lbs honey added last 20 minutes of the boil.  Cascade hops for bittering and aroma additions.  Here's where I need help:   The keg was a nice, dry pale ale.  Nothing too great, but we finished it.  I bottled 7 bottles and just remembered them now.  The bottles are very different--  I would say a somewhat sweeter flavor close to butterscotch.  I am thinking maybe I had an infection that took hold at the room temp bottles, but didn't grow in the immediately refrigerated kegs?  Could aging without an infection cause this?  Ideas? Thanks!

Offline santoch

  • Brewmaster
  • *****
  • Posts: 879
  • North Bend, WA
    • View Profile
    • WAHA
Re: Diacetyl?
« Reply #1 on: February 23, 2017, 03:49:01 AM »
You are probably right that it is likely an infection.

A non-infected beer will tend to LOSE diacetyl over time, particularly if it is kept warmer.
Pediococcus is known for throwing Diacetyl, lactic acid, and acetic acid (vinegar).  My bet is that's what's wrong.



Mt. Si Brewing Society
Washington Homebrewer's Association (WAHA)
BJCP GM2/Mead Judge

Offline Mythguided Brewing

  • 1st Kit
  • *
  • Posts: 23
  • Mississippi Gulf Coast
    • View Profile
Re: Diacetyl?
« Reply #2 on: March 01, 2017, 09:24:09 PM »
+1 on the possibility of infection, but...

Did you bottle from the keg, or did you split your batch between the keg and whatever didn't fit in the keg, you bottle-conditioned?  If the latter, perhaps you provided a bit too much priming sugar in your bottles, which was not completely metabolized (leaving some residual sweetness, and maybe some diacetyl too)?  If your keg was more highly carbonated than the bottles, that can throw of your taste perception of clean vs. sweet (at least, it does for me).

Offline lindak

  • Cellarman
  • **
  • Posts: 41
    • View Profile
Re: Diacetyl?
« Reply #3 on: March 02, 2017, 01:57:53 AM »
Thank you both for the feedback.  I kegged 5 gallons and had enough left for some bottles.  I used carb drops because I wasn't sure how how much brew I might be able to siphon cleanly off the yeast cake.  The bottles conditioned for a long time-- okay, I forgot them for a few months.  They were probably in the low 60s degrees.   There is almost a slightly sweet vanilla flavor-- maybe caramel more than butterscotch. 

Given the lower temp, the yeast may not have gotten to all the sugar.  I'll focus more on the carbonation on the next one I drink.  I think I may have one bottle I haven't chilled.  I may let that one spend a week in a warmer spot and compare and contrast. 

Live and learn. 

Offline reverseapachemaster

  • Official Poobah of No Life.
  • *
  • Posts: 3102
    • View Profile
    • Brain Sparging on Brewing
Re: Diacetyl?
« Reply #4 on: March 02, 2017, 04:11:08 PM »
A little oxidation in the bottle could account for a sweeter, caramel or sherry-like flavor rather than diacetyl.
Heck yeah I blog about homebrewing: Brain Sparging on Brewing