Beer suddenly turned to vinegar a day after maturing - twice

I've got a slightly strange problem on my hands here.

With two different brews I've made (my first two ever), with mostly very different ingredients, my beer has suddenly started tasting like vinegar only a day or so after maturing in the bottle.

A bottle of my most recent brew tasted not-quite-ready at 15 days in the bottle. The next bottle tasted really nice, with no real off-flavours, at 20 days. But just one day later, at 21 days, all the bottles had turned bad and tasted like vinegar.

That batch was made from scratch by mashing malted barley etc. Brewing sugar used was dextrose. All equipment was sterilised.

Strange thing is, the exact same thing happened with my previous batch, which was completely different - made from a Cooper's beer kit.

The only thing these batches had in common was that I used Cooper's carbonation drops (ingredients: "sugar", glucose) for priming. Could this potentially have caused my problem, either by their ingredients or by the fact that I didn't boil them before adding them to each bottle (the instructions didn't say I should)?

Any help would be greatly appreciated

Likely not the carbonation drops, as they are sterile from the factory. The problem here my friend, is probably your sterilization techniques, and perhaps to a lesser degree how you're storing them. When you say "vinegar" I immediately think "airborne bad guys". Maybe for your next batch just go big time over kill on sanitation. It's tough to overdo sanitation, but easy to under-do. Those airborne bad guys can spoil an entire batch real quick so you gotta be careful. The only other thing I can think of is that it is conceivable that if you bottled in clear bottles and left them in direct sunlight that could have skunked them really bad, but I would definitely lean towards the former.

seen any fruit flies around your fermenters?

Thanks, that's interesting. I guess I'll be super-careful about sterilization next time. Got any specific tips for avoiding airborne bugs?

Is it strange that my beer suddenly went bad after about 3 weeks in the bottle? Or is that how it usually goes?

Nope, no fruitflies anywhere.

beer/wine + oxygen = vinegar (simple as that)...check your airlocks

goose1873 said:

beer/wine + oxygen = vinegar (simple as that)...check your airlocks

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Only in the presence of AAB

yes but its doubtful k-meta or other acetic acid bacteria inhibitors were used therefor i think he should check his airlocks...

Could he be mistaking the flavors from lactobacillus contamination for vinegar? Just a thought.

Well, I'm pretty sure I finally figured this one out - it was the airlock / airborne bugs (as a couple of people suggested).

I discovered that my airlock has an indentation up one side of the bit that plugs into the grommet, which I'm pretty sure would have been letting air through. The problem is solved if I push the airlock further into the grommet.

I always thought it was strange that when taking samples out of the tap, the airlock didn't bubble backwards much. And it wasn't bubbling forwards much as my beer fermented either.

Stupid me! I've just put a new batch on with the airlock correctly set up. Here's hoping!

Let us know how this one goes. I doubt that the problem is the airlock. Probably something happening at bottling.

Yeah. Unless there are flies getting in, it's really unlikely that a small slot like that is going to consistently introduce acetobacter.

What's you're cleaning and sanitation regime? From flameout until you've put in the airlock, when racking to secondary (if done) and bottling bucket, and for the bottling gear, caps, and bottles.

goose1873 said:

beer/wine + oxygen = vinegar (simple as that)...check your airlocks

Click to expand...

Beer + oxygen = wet cardboard. You need acetobacter to create vinegar.

SumnerH said:

Yeah. Unless there are flies getting in, it's really unlikely that a small slot like that is going to consistently introduce acetobacter.

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Fruit flies don't need a very big hole to squeeze through to get into the beer. I would say this indentation sounds like the culprit here. That's not to say the OP shouldn't have a thorough review of his sanitation practices before embarking on his next brewventure.

I would save a remaining bottle or two of the old beer and see if it develops a mother. If it does then use that bottle just as you would any starter. Continue propagating it so that you can have your own malt vinegar a plenty for your fish and chips.

Thanks for all the additional responses!

For cleaning, I use a "Bottlewash compound" made of "chlorine and cleaning soda". For sterilization, Sodium Metabisulphite - which apparently releases a gas which sterilizes everything, and you're not supposed to rinse after you use it, since it all evaporates out of the water anyway. Both of these were the recommendation of my local homebrew store - are they alright?

Actually, one of my biggest sanitary concerns is that in most of the beer that went bad, I used priming sugar / carbonation drops that hadn't been boiled and the packet had already been open for a while (although a homebrewing book I have says that its author never experienced a problem by not boiling the priming sugar).

My first batch in which I did boil the priming sugar should be ready to try in a week or so.

Other than that, my sanitation procedure goes like this: after cleaning and sterilizing my plastic fermenter, removing and paying special attention to the tap, I fill it with my just-boiled wort and put the lid on. While the wort cools, I sit a cup over the hole that's meant for the airlock, to stop anything big getting in. When the wort has cooled to about 30 degrees C (86 F), I take a sample to measure OG, pitch the yeast. Previous times, before pitching the yeast, I've aerated the wort by repeatedly filling a glass jug (sterilized with boiling water) with wort from the tap, then letting it splash back into the fermenter (this most recent time I didn't do this, though). I then add the airlock (which I've just boiled, and filled with boiling water).

While fermenting, the lid never comes off. I take samples to test gravity out through the tap (sometimes I remove the airlock when I do this, to stop water bubbling in). Lately I've been taking the lid off to add (boiled) bulk priming sugar, then leaving everything to settle for half an hour or so before bottling.

When bottling, I clean and sterilize all my bottles (mostly glass), the caps and my "brew bottler" (long tube with valve that pokes into the bottle to avoid oxidation). I think I've now settled on bulk priming, by adding boiled sugar/water to the fermenter before bottling, but previously I've boiled sugar in water and added this to each bottle, with a (perhaps hastily) sterilized spoon. And before I was doing that, I was, as mentioned above, laxly adding unboiled sugar/carbonation drops to each bottle. (Sterilized) crown caps are then attached with a two-lever capper, which doesn't come into contact with the brew. Bottles are inverted to ensure a good seal.

Can anyone spot any problems? I really appreciate all this help

Few of things:
1. Use Starsan or Iodophor for santising. Sodium Metabisulphite isn't going to do the job well enough or fast enough.
2. Don't ferment in a bottling bucket. The spigots are traps for things to grow when you primary in there. Trub will build up and flow out of the tap when you open it and potentially get stuck in it where you can't see. You may think the spigot is clean, but it may not be. That could easily be the source of your infections.
3. Aerate by dropping the wort into the fermenter from a height and if needed cap the bucket and shake it to aerate more.
4. Don't use the tap to pull samples while fermenting - goes along with #2, since you shouldn't have a tap to check with. But if you continue to primary in a bottling bucket (called that for a reason!) then don't take samples from the tap for the reasons i described above.
5. You won't get an infection from dry sugar going into your beer. If the carb tabs got wet, there could be issues, but if they are, and have been, dry then they are just fine.

Gremlyn1 said:

Few of things:

2. Don't ferment in a bottling bucket. The spigots are traps for things to grow when you primary in there. Trub will build up and flow out of the tap when you open it and potentially get stuck in it where you can't see. You may think the spigot is clean, but it may not be. That could easily be the source of your infections.

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I agree with Gremlyn, but I ferment in a bottling bucket as well. If you must continue doing so, soak that spigot in a strong bleach solution for several days. I do this every few batches and haven't had any problems yet. I've seen a bunch of nasty crud start forming in the spigots and it exists in places you can't clean out. It takes bleach to get the job done. My $0.02.

Ah, interesting, so fermenters with taps are a no-no? Out of curiosity, are these intended for some other purpose, or are they just a trap for noobs like myself?

So I guess what I need is a carboy with just a small opening at the top.

Would a "fermentation pail" with a wide, sealing plastic lid, in which is a hole for the airlock, be ok? It doesn't have a tap, and looks like this:



Or is that just asking for more trouble, and should I really just get a carboy?

I should add, I intend to do only one stage of fermentation before bottling - I can't quite justify buying two new fermentation vessels at this stage.

I'll get some better sterilizer too.

Thanks again, this is extremely helpful

The fermenter you pictured is perfectly fine, as well as doing only primary. I onyl started pseudo-secondary-ing when I started kegging, and that's just because I bulk age the beer in the keg for a week or two before chilling and carbing it. The buckets with a spigot are for bottling. You transfer from the fermenter to the bottling bucket (which already contains your sugar solution), and then bottle from the spigot. If you're transferring correctly, you'll avoid getting a lot of trub in the bottling bucket and therefore keeping it from getting stuck in the spigot.

Cool, I guess I'll get one of those then.

Or, actually, would it work to use my current fermenter/bottling bucket, but just not have the tap on it, and instead screw in the plug which came with it which replaces the tap? Or is this, again, just asking for more trouble?

just buy another bucket or two. I think you'll find to brew more styles of beer and keep a good pipeline you'll want another primary or 3 anyway. Also off subject, I noticed that you " no chill" and pitch your yeast at 86f. That is way too hot unless you are shooting for a saison. You may get some unintended flavors by pitching that high. I no chill as well and pitch the next day at between 65-72f depending on the style and have had no real issues from it. Be careful this hobby is addictive, it doesn't take long before you think another $500 in this hobby won't hurt this month. Next thing you know you got couple hundred lbs of grain, bunch of equipment, and a thin wallet.