Opinions on off flavor

Hey, folks. I have an American Brown ale that has an acrid bitterness/metallic-like-flavor to it. I was thinking at first that I may have over carbonated the beer. However, even when I pour a sample and shake the carbonation out it still has that flavor. I also thought it might be that my mash pH had been lower than expected (I didn't measure it this time.) and therefore maybe my beer's pH was too low. Well, I removed the carbonation form some and took a pH reading. It ended up being right in the middle of the recommended finishing range, at 4.25. I've also read that metals in the brewing process could cause the off flavor, but the only metals that would have come in to contact with the beer (short of some brass in the faucet, but I've taken a sample directly from the keg, with the same taste) would have been stainless steel. My water report (which admittedly was from probably a year ago...the water is from a well) didn't detect any iron. The bucket I used for this brew was brand new. I used a brand new auto-siphon with silicon tubing for the transfer to the keg. Anyways, does anyone have any ideas?

I had the same sort of off-flavor a while back when I used dark grains in a beer but not a stout. I had made an ESB that was brown, and there was a slight hint of metallic flavor in the finish. I never did really nail it down, but about two months later I got a water report. I really think that it was the combination of my water chemistry and the dark grains.

I don't know if this could be your issue, but it's a thought. What is your water chemistry like?

Yooper said:

I had the same sort of off-flavor a while back when I used dark grains in a beer but not a stout. I had made an ESB that was brown, and there was a slight hint of metallic flavor in the finish. I never did really nail it down, but about two months later I got a water report. I really think that it was the combination of my water chemistry and the dark grains.

I don't know if this could be your issue, but it's a thought. What is your water chemistry like?

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Straight out of the tap: Ca 87 Mg 9 Sulfate 21 Cl 4 Sodium 5 Alk 214 Bicarb 261. However, I treated the water with slaked time to lower the alkalinity (to about 51 based on an aquarium kH kit. In hind site I probably should have mixed some of my tap water back in with that (and done a sample mash before the main brew day).

The treated water should have looked something like this, roughly: Ca 60's Mg 9 Sulfate 21 Cl 68 Sodium 5 Alk 51 Bicarb 60ish.

afr0byte said:

The treated water should have looked something like this, roughly: Ca 60's Mg 9 Sulfate 21 Cl 68 Sodium 5 Alk 51 Bicarb 60ish.

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Looks great.

I have no clues, then.

It still could be that the mash pH was a bit too low- but that would be a "tart" off flavor I think, and not metallic.

The wort tasted great when I took my OG, too. It seems like it could be something on the cold side. I've not read of any infections causing this kind of off flavor, but I'd imagine it's a possibility. I did have a problem with a frozen hose on this batch, so it probably took me ~30 minutes to chill instead of < 10 minutes. I ended up pitching colder than I'd planned...around 60. I suppose the chocolate malt was kind of old (a year or so), but dark malts like that aren't supposed to go bad, for the most part.

Not sure this will help you, but I found this list to be helpful in understanding faults in beer.

http://www.bjcp.org/faults.php

I suppose it could be some kind of yeast originating phenol. It's hard to describe the exact off-flavor, since there was a fair amount of amarillo in the beer that might be combining with the phenol. Admittedly I didn't use pure oxygen until about 12 hours, but it wasn't at high krauesen yet, so this shouldn't be a problem from what I've heard/read, but I had dropped the wort, in effect, by placing my boil kettle about 3 feet off of the ground and draining the wort in to my fermenter that was sitting on the floor. I suppose another knock of the yeast might be that I believe it was from the same batch of poorly performing US-05 that was the cause of a thread around here a while back. Also, the yeast had stalled, presumably because of overnight temp swings (I had a temp controller on it, but the heating pad I was using for heat sometimes only really heats up on one side or another.). So, I had gently rocked the carboy to resuspend some of the yeast, and I warmed the bucket up to about 68 initially. I eventually ramped it up to about 72 since the beer stopped about 3 points above where I'd expected it to stop.

UPDATE: My latest guess, based on the current, flavor is that perhaps the flavor is autolysis. Now that the CO2 saturation has settled a bit more the beer seems to have more of a burnt rubber off flavor. I suppose that could come from having the heating pad taped to the side of the bucket. Fortunately for my most recent beer I had it in a chest freezer with a heat lamp (a couple feet away from the bucket) providing a more diffuse heat. When I took a gravity sample of that beer it didn't seem to have the off flavor. It tasted quite clean actually, though I shouldn't have used the carafa special I instead of the chocolate malt (It's a brown porter that I may add coffee or vanilla to.).

afr0byte said:

UPDATE: My latest guess, based on the current, flavor is that perhaps the flavor is autolysis. Now that the CO2 saturation has settled a bit more the beer seems to have more of a burnt rubber off flavor. I suppose that could come from having the heating pad taped to the side of the bucket. Fortunately for my most recent beer I had it in a chest freezer with a heat lamp (a couple feet away from the bucket) providing a more diffuse heat. When I took a gravity sample of that beer it didn't seem to have the off flavor. It tasted quite clean actually, though I shouldn't have used the carafa special I instead of the chocolate malt (It's a brown porter that I may add coffee or vanilla to.).

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If you're having trouble keeping fermentation temps warm enough, there are a couple of things you could try. Once is just using yeast strains that work at a lower temperature. Nottingham is great down to 57 degrees, pacman is great at 60 degrees, and I use S04 all the time at 62 degrees. I never ferment ales above 64 or so, and I noticed that S05 gets a hint of peachy flavor under 65 degrees so I don't use it often. You could also use California lager yeast at 58 degrees.

The next thing you could try if you can not maintain 60 degrees without help is to try putting your fermenter in a water bath and using a very small aquarium heater in the water bath. That takes some playing with (so you don't get too warm) but it would be a lot more dependable than a heating pad.

That said, I don't think it necessarily is autolysis because autolysis actually tastes "meaty" and not really metallic. A beer with autolysis with have a flavor someone described to me as "hot dogs".

Huh, I've heard autolysis described as meaty too, but when I searched Google for "burnt rubber flavor beer" John Palmer's site came up with a section on autolysis where he mentions the burnt rubber flavor: At a minimum, a beer that has experienced autolysis will have a burnt rubber taste and smell and will probably be undrinkable. Also, my heating problems aren't so much maintaining a temperature above 60, it's more of a problem of the temperature dropping over night causing the yeast to drop out towards the end of fermentation.

EDIT: Admittedly, that section is about lager brewing, but I would imagine the same off flavor could apply to ale yeast.