(unintentionally) sour beer

[Hoochin'Fool]

So I just bottled an imperial stout, og was 1.119, fg is 1.040 -- definitely finished, it's been at 1.040 for the last 2 weeks.
Anyways, it tastes kind of sour. I've made this same recipe before several times, and it's never tasted sour before. There was absolutely nothing "weird" looking in the wort, no odd smells, either.

The only thing I can think of, is that my water lately isn't actually as basic as it used to be, and with all the darker malts used, it got too acidic. Minnesota has had ridiculous amounts of rain the last 4 months or so (for any fellow minnesotans, my water comes from the Jordan aquifer). I didn't notice any sour taste after the mash, but maybe the high gravity masked it?

I'm prepared to let it sit for a year, so with any luck it'll taste ok by then.

Next batch will definitely use 100% RO water (plus salts)

 

[mashdar]

With OG of 1.1+, 1.040 sounds more like a stalled fermentation. Unless you used a ton of lactose or something? Where did past versions end?

You probably wouldn't taste sourness from dark malt; the yeast naturally adds 10x or more H+ during fermentation.

I assume you don't have a pH meter handy?

If pH<4.0, it's probably an infection. If pH>4.2, might not be infected.

esit: PS aging is a perfect idea. If you want to go wild, pitch some brett and oak!

 

[Hoochin'Fool]

Correct, no pH meter. Recipe is here. When I pitch with 2 dry yeast packets, FG has ranged between 1.036 and 1.040 (done it twice now, lol). When I pitch on top of a full yeast cake, FG is down around 1.026 to 1.032 (done that 3 times).

 

[mashdar]

If the only perceptual problem is acid, people sometimes neutralize with baking soda (? verify not powder). I'm no expert on that, but it sounds like a thing that is done.

 

[tracer bullet]

If pH<4.0, it's probably an infection. If pH>4.2, might not be infected.

OK, so that's an interesting idea.

I've had two RIS's go "sour". One started several months into aging, where it began taking on the classic sour beer twang, with a hint of raspberries. I stuck a pressure gauge onto the gas post and watched it climb, telling me there was fermentation happening. The second was simply bad off the bat, I think, coming out of the fermenter it didn't smell good and tasted like the above.

The thing is though, I've got good practices (I think) and these 2 beers are basically the only beers I've had go bad on me. I'm not holding any brewing records but that's like 100 batches or so.

So, a pH issue could convince someone their beer's gone bad. for other reasons than pH?

 

[G_robertus]

Correct, no pH meter. Recipe is here. When I pitch with 2 dry yeast packets, FG has ranged between 1.036 and 1.040 (done it twice now, lol). When I pitch on top of a full yeast cake, FG is down around 1.026 to 1.032 (done that 3 times).

Though I brew stouts that finish at 1.030-1.040 (or higher) relatively regularly, with this grist I'd say it has stalled a bit. I'd expect 1.030-1.035 or so with just 14% specialty malts. I would personally pitch 4 sachets as well, but I like to be on the safe side here.

Not the point here though. I've tried to infect high gravity beers myself and it's actually pretty hard to do in my experience. Most bacteria won't take this amount of alcohol. Brettanomyces might. I'm sceptical of an actual infection, although it's not impossible. Can you describe the acidity you taste? I've had one particular recipe turn out rather tart as well and it hasn't aged out well, even after being in a barrel. It did improve somewhat, but it's still very tart. I suspect that different sources for ingredients compared to what I normally use might be the cause. Did you switch brands on any ingredients by any chance? For this particular tart beer I used Fawcett malt (and Halcyon as base for the first time), but normally I'd use mostly Crisp or Paul's with Munton's or Crisp MO. I'm not quite sure which of the ingredients is to blame, but I'm also not looking to recreate this brew.

 

[Hoochin'Fool]

Though I brew stouts that finish at 1.030-1.040 (or higher) relatively regularly, with this grist I'd say it has stalled a bit. I'd expect 1.030-1.035 or so with just 14% specialty malts. I would personally pitch 4 sachets as well, but I like to be on the safe side here.

Not the point here though. I've tried to infect high gravity beers myself and it's actually pretty hard to do in my experience. Most bacteria won't take this amount of alcohol. Brettanomyces might. I'm sceptical of an actual infection, although it's not impossible. Can you describe the acidity you taste? I've had one particular recipe turn out rather tart as well and it hasn't aged out well, even after being in a barrel. It did improve somewhat, but it's still very tart. I suspect that different sources for ingredients compared to what I normally use might be the cause. Did you switch brands on any ingredients by any chance? For this particular tart beer I used Fawcett malt (and Halcyon as base for the first time), but normally I'd use mostly Crisp or Paul's with Munton's or Crisp MO. I'm not quite sure which of the ingredients is to blame, but I'm also not looking to recreate this brew.

Just slightly sour, VERY boozy, and flat. Since it's already bottled now (I skipped adding any bourbon, figured it was too questionable of a brew to risk wasting more than some bottle caps), I'm going to let it sit it for a month, check one bottle for any gusher issues, and see if it can be improved with a touch of baking soda in the glass. If it's a gusher, I'll probably just dump the rest without bothering to see how they develop.

I keep a stocked pantry (in tightly wrapped plastic bags, then stored in buckets) and the only "new" grain in this batch was some Briess Light Roasted Barley. I just munched a couple kernels of this malt, and it tasted like normal (which is to say, a bit burnt/ashy).

 

[G_robertus]

But you've used the same brand before? Then I doubt it's that. Changes in your water could definitely be the cause as well by the way, like you said in your first post. I'm not sure how much your water fluctuates, but especially with lower ABV stouts or less flavour-packed stouts you would probably notice it if your alkalinity was off. I'm still a bit doubtful, because I don't think I treated my water for my first imperial stout and I didn't notice any acidity. I did with my first Irish stout though.

I suppose your plan is a good one, just see whether anything changes or you get highly carbonated beer.

 

[Hoochin'Fool]

Sampled first bottle from this batch. The sour tang is much more subdued, but still noticeable. Bottle was NOT a gusher, so that probably rules out any infections. But there was almost no foam at all -- wondering if the bottling yeast was forgotten in my initial "welp, let's just bottle this and hope" despair.