I have brewed two extract batches with specialty grains in the last few months and have found an off flavor that varies from bottle to bottle. Both batches I sampled early during conditioning and did not perceive, this slightly metallic/savory/spicy off flavor. As they both aged though, the flavor was present in most bottles, save for 1 in every 10 where it was not present. I suspect it is from inconsistent carbonation, possibly due to under mixing during bottling? I have a couple of reasons to believe that is the case. Once after an overly aggressive pour, reducing the remaining CO2, the flavor seemed to dissipate in the brown ale, but this proved difficult to replicate.
Secondly on the other batch, a pumpkin ale, I had two really good bottles in a row and they seemed to have a completely different mouth feel, the next bottle the off flavor appeared again.
Here is the most unusual observation I made. While making dinner tonight I was compelled to add a few flakes of kosher salt to the beer after it was in the glass. The first sip, off flavor present. After adding salt, and considerable foaming, the off flavor seemed to completely disappear, and the mouth feel changed completely.
Very hard to think of what it could be, but the fact that it has gotten stronger with time suggests it is an infection, and the fact that it varies from bottle to bottle strongly suggests that the problem was caused by your bottles or caps, not your beer. You might want to review your process for cleaning and sanitizing bottles before your next brew.
I considered cleanliness and sanitation. I think I’m strait there. Hot PBW soak, bottle brush, rinse with jet inside, rinse outside, full immersion in starsan for 2+ minutes, drain on tree. If it was not two different batches, I would still lean toward contamination, but seems unlikely to me now.
The brown ale was way over carbed, no doubt about it. At the beginning of conditioning I don’t think the flavor was there. When it was fully conditioned, I definitely tasted it in every bottle.
The pumpkin ale, it was tough to tell. It took a long time to condition. And the good bottles have a much softer mouth feel.
I just bottled a Belgian special and I was extra careful with bottle cleaning. I guess I will have to wait a couple weeks and find out.
