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Carb issues- but only with dark grists?

So I just realized that the only time I’ve ever had carbonation issues with bottled beer just happened to be on either porters or stouts. Specifically, the last four batches of porter/stout I’ve bottled have been foamy, bordering on gushers, and overcarbed with a very sharp carbonic tingle to them- like you’d get with a soda. Most have had poor head retention as well, it gushes but recedes quickly, generally disappearing entirely in less than a minute although it’ll reappear if I swirl the glass around a bit (only to disappear again in a few seconds).

It tends to get worse the longer the beer ages, which leads me to believe it’s infection. However, the beers don’t taste noticeably infected, not sour or funky or anything like that…plus it only happens with dark grist beers but has happened on each of the last 4 of such beers. Have never experienced any such issue with any other kind of beer ever. So what the hell is going on, I’m stumped? Guess i could just keg all the porters/stouts, but that seems like a cheap win.

Beers are usually carbed to 2.1-2.2 volumes although last impy stout was at 2.4 because I misjudged final volume into the bottling bucket.

Sounds like it could be an issue with pH and acidity due to the dark roasted malts. What sort of water do you use? Salt additions? I wonder if a touch of sodium bicarbonate (baking soda) added to the boil will bring the pH up enough to prevent this in the future. For me and my own brewing water I know I often have to do this for my own dark beers including porters and stouts – I keep the pH low during the mash, then add the baking soda in the boil to neutralize some of the acid and prevent tartness or harshness. And we’re not talking much – probably just a teaspoon in 5 gallons or something small like that – my software tells me how much to use.

You can also try adding malts that help to stabilize the head including wheat and especially rye. 10% wheat or rye malt can be substituted for part of the base malt of any recipe to give you better head retention. Caramel malts should also help, in theory, if you’re not using much already, although rye malt works the best I’ve seen out of them all.

Also, based on experience, it will probably help if you just tone down your carbonation a bit in the keg. Perhaps your pressure gauge is a little off. Not a big deal if you know it from experience. Personally I prefer most of my beers undercarbonated, and this is especially true for stouts. After all, nitro taps (often used for stouts) really just take all the carbonation out of the beer. Guinness Stout is flat as flat can be. Sure, there’s a nice big head on it… but take the head off and you honestly have a flat beer. There’s no bubbles coming up out of that beer. So if you’re expecting anything close to Guinness, or even if you’re not, just try to go easier on the carbonation in future and you might be much happier with the result.

My water is fairly alkaline so I don’t need much adjustment for dark beers, but I do add a bit of baking soda to the mash to push ph up into the 5.3 range. This is calculated ph though, the dark mash also discolors the colorphast strips (dont have a ph meter) and makes them impossible to read so I can’t be sure I’m in this range.

The issues is only with carbonation related to bottle priming, and only on porters/stouts.

What are you using to prime your bottles? Are you using those little prime tablets? Do you measure an amount of sugar to add to each bottle? Do you dissolve the sugar ahead of time in a little water then bulk add it, or are you adding to each bottle?

In any case, you probably just need to reduce the amount of priming sugar used. Personally I use about 80% of the amounts recommended by most literature, with excellent results. I’d rather have a slightly undercarbonated beer than a gusher any day. However, I have not had any problem with undercarbonation – they all seem to turn out perfect, using less priming sugar than recommended.

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