In my last post on the subject, I mentioned I had just brewed a very light cream ale, a beer in which any of this off-flavor would be immediately noticeable. Sadly, I was right about that! It is quite bad. Like my last post, this is mostly a “brain dump” and thus not quite as coherent as it could be. As always, any help is appreciated.
Given the good quality of the water I brewed this with, I am fairly confident the chlorine or pre-existing chlorophenol hypothesis is out. I do have a few new data points to work with and could instead be looking at oxidation. I had previously discounted it due to the fact the flavor develops almost right away. Generally I’ve seen it stated that it takes a long time for oxidation to show up. But there is a little more this time to suggest it.
At bottling, I noticed none of the specific off-flavor, although there was a bit of acetaldehyde. Out of curiosity I opened the last bottle (only about 3/4ths filled) only two days after bottling. It is already quite carbonated, and it poured with a lot of foam. I immediately got the off-smell and tasted it right away, too. This time I thought maybe I was falsely attributing plastic notes due to reading about such an off-flavor online and my shaky confidence about the water. Although it’s not quite “wet cardboard” or other descriptions of oxidation, there’s perhaps a general staleness to it.
The other half of the 2.5 gallon batch went into a Cubitainer (polypin) with half as much priming sugar. I’ve sampled a few pours despite it being only a little carbonated, and so far there is no real hint of the specific off-flavor or smell there. But there is still that general staleness, I think. So perhaps the carbonation is enhancing my perception of the smell, and perhaps then the smell enhances my perception of the flavor.
That is consistent with past experiences, where I have tasted this during active fermentation or after bottling, but not in the wort or flat beer. Indeed, after taking the bottled beer and pouring it repeatedly between two glasses I started to notice it less and less. So although there’s no reason to think it is a result of overcarbonation or anything like that, it’s probably connected to CO2 as far as my perception is concerned.
There were many opportunities for oxidation in this batch:
- First, every beer I’ve made from this 10 lb. bag of pale malt has been bad (#3 & #4 from the last post and this one) Although I am crushing it at home and in used it once right when I got home from the LHBS, it’s possible it was old and stale when I bought it. The same goes for the chichas, which were made with pre-crushed malted corn from who knows when, and the first problematic beer which was made with six-month-old precrushed malt. This is supposed to be quite unlikely, but definitely possible. It would be consistent with the smell & flavor being there right from the get-go. However, the malt seems to taste fine raw.
- Second, in this instance I tried a BIAB, no-sparge mash and let a lot of it drip down from the bag while squeezing it out. Other people have done this many times and report good results, and other beers where I have splashed or dripped a lot (like my popcorn ale and millet saison) had none of this. But hot-side aeration is not impossible, just improbable as far as I can tell so it’s a possibility.
- Third, and perhaps most damning, I intended to do a short cold crash but ended up effectively doing a month-long lagering since the yeast took forever to drop out. Since it was supposed to be short I replaced the airlock with a piece of foil and a rubber band to avoid suckback. That amount of time with that amount of headspace (half of a 5 gallon Better Bottle) can easily cause oxidation, I think.
Without further experiments I can’t quite discount the possibility that something else is wrong and causing the off-flavor/smell in addition to this beer being oxidized and stale. I can test the malt with side-by-side small mashes with the same water and new malt. I can intentionally splash the heck out of another mash to test that. I am not super keen on wasting a month intentionally oxidizing a beer, but hey, it may be necessary.
This is all quite discouraging, of course, but I intend to figure it out. Thankfully I have had good beers before and in between the bad, so I know it’s not impossible.