jpsloan
Well-Known Member
I've developed an apparent system-wide issue with my beers. Acetaldehyde. This is a relatively new problem, so I'm trying my level best to ferret out how it's popping up in my beer. Here's the skinny...
Two beers in a row... both have that green apple jolly rancher smell and flavor, almost overwhelming when it reaches room temperature. The first is a doppelbock that was brewed in a group brew in early November. It followed what I consider a typical fermentation... six weeks on primary, two day diacetyl rest, then two months' lagering. The 20 gallon batch was split five ways, and we all pitched our own yeasts and brought them home to ferment. The wort was aerated with an aquarium pump and stone. The yeast starter was 1.5L for 4 gallons. Of note is that of the other four guys, none have developed any acetaldehyde character, which leads me to believe the issue had to have begun at the pitch or afterwards.
The next beer was a kolsch, brewed in February. 1L starter, three weeks on primary, then kegged and cold-conditioned for three more weeks before serving. This batch was not significantly aerated.
So, here's what these two beers have in common:
- both fermented in a white plastic ale pale bucket (without gasket)
- both yeasts prepared in a beaker with starter wort, similar sanitation practices, no stir plate used
- both were kegged in separate kegs, but my racking procedure was the same for both (autosiphoned into a cleaned and StarSan'd keg from elevated vessel)
From what I have read, there are four likely culprits for acetaldehyde... unhealthy yeast or underpitching, racking off the yeast too early, re-introduction of oxygen post-fermentation, and bacterial infection. I honestly don't feel that I'm pulling my beer off of the yeast too soon... it's the same fermentation periods that I've followed for four years, and this is the first time this particular off-flavor has popped up. I feel that it's possible that oxygen is creeping into the beer via the ale pales, but it's my understanding that it takes much longer for that to become apparent. O2 can be entering the beer as I rack from vessel to keg, but there is very little agitation, and no more contact with ambient air than any bottling/kegging procedure (I'm assuming).
This leaves me with unhealthy yeast, or contamination as the likely problems.
I wanted to get you guys' input, particularly if anyone has had this problem pop up and solved it... what did you do?
Two beers in a row... both have that green apple jolly rancher smell and flavor, almost overwhelming when it reaches room temperature. The first is a doppelbock that was brewed in a group brew in early November. It followed what I consider a typical fermentation... six weeks on primary, two day diacetyl rest, then two months' lagering. The 20 gallon batch was split five ways, and we all pitched our own yeasts and brought them home to ferment. The wort was aerated with an aquarium pump and stone. The yeast starter was 1.5L for 4 gallons. Of note is that of the other four guys, none have developed any acetaldehyde character, which leads me to believe the issue had to have begun at the pitch or afterwards.
The next beer was a kolsch, brewed in February. 1L starter, three weeks on primary, then kegged and cold-conditioned for three more weeks before serving. This batch was not significantly aerated.
So, here's what these two beers have in common:
- both fermented in a white plastic ale pale bucket (without gasket)
- both yeasts prepared in a beaker with starter wort, similar sanitation practices, no stir plate used
- both were kegged in separate kegs, but my racking procedure was the same for both (autosiphoned into a cleaned and StarSan'd keg from elevated vessel)
From what I have read, there are four likely culprits for acetaldehyde... unhealthy yeast or underpitching, racking off the yeast too early, re-introduction of oxygen post-fermentation, and bacterial infection. I honestly don't feel that I'm pulling my beer off of the yeast too soon... it's the same fermentation periods that I've followed for four years, and this is the first time this particular off-flavor has popped up. I feel that it's possible that oxygen is creeping into the beer via the ale pales, but it's my understanding that it takes much longer for that to become apparent. O2 can be entering the beer as I rack from vessel to keg, but there is very little agitation, and no more contact with ambient air than any bottling/kegging procedure (I'm assuming).
This leaves me with unhealthy yeast, or contamination as the likely problems.
I wanted to get you guys' input, particularly if anyone has had this problem pop up and solved it... what did you do?