I’m cleaning out the deeper recesses of our pantry right now, and I have before me three one-gallon jugs of vinegar, all of which have been opened. :rolleyes: They have ‘best by’ stamps indicating ’00, ’06, and ’09. Are they all still vinegar? Even the oldest one certainly still smells like vinegar. Should I just toss the expired ones? Or should I keep them around for cleaning purposes and use the fresh stuff for cooking/seasoning? Or can I use all three of them for whatever I want? If it still smells like acetic acid, then it’s still good, right? Or is it?
Acids in general, and vinegar in particular are not uncommonly used as preservatives…as in pickling. I wouldn’t hesitate to use vintage vinegar if it passed my nose test, but then I’m pretty frugal. Kevbabe OTOH will pour milk down the sink one day after the “use by” date even when it smells fine.
That raises an interesting question, what the hell can happen to vinegar? You basically already had sugar rot into alcohol by way of yeast, then the alcohol rot into vinegar with bacteria. I’m not sure how much farther you can go.
A quick Google:
Balsamic 3 years
Apple 5 years
Malt, indefinitely
All this provided the product is kept away from light and heat
Under aerobic conditions, to CO2 and Water 
What kind of vinegar is it? From your line " Or should I keep them around for cleaning purposes and use the fresh stuff for cooking/seasoning? " can I assume it’s white vinegar (since I never heard of cleaning with wine, rice or dear god help me balsamic vinegar)? If it is white, it’s fine, but you shouldn’t use it for cooking anyway.
Why not?
Admittedly, I only use white vinegar for pickling, but I do use it.
There’s very little flavor in white distilled vinegar compared to other vinegars.
I’m basically going by Alton Brown’s recommendations from his episode dedicated to vinegar. According to him, regardless of what you’re making, there is a vinegar with a flavor profile which will enhance your food. White vinegar is made from grain alcohol, and has no flavor beyond its acidity.
Of course, he’s used white vinegar to make cottage cheese several episodes later, but he fessed up to it and said that was the sole exception.
When I’m pickling banana peppers, I doubt that this is important.
BTW, my pickled banana peppers are so good they’ll make you cry.
I love it when he crosses lines he’s drawn for himself in the sand. “Stuffing is evil” is the classic, but I’m still waiting to see what other uses his cube-steak-making meat tenderizer thingy has.
Which is what I should have done before I opened my mouth. It took less time to find a reliable answer than it did to compose and proofread (yes, I do that) my OP. From The Vinegar Institute:
To answer muldoonthief’s query, yes—it’s white distilled vinegar.
I’m gonna have to request a cite for that. Or at least post the recipe.
I actually like the taste of white vinegar. It has the bite without anything else getting in the way. Yummy!
Yup, everything else is just dirty vinegar.
Sure.
Pack sliced banana peppers in a jar with some salt and let stand while preparing the vinegar mixture:
1 pint white vinegar
3/4 cup sugar
1 teaspoon celery seed
1 teaspoon mustard seed
The sugar is what does it - it makes a sweeter pepper.
Heat the mixture for 3 minutes, then add to jar, leaving 1/4" at top. Seal and process in a water bath for 10 minutes.
I generally let the pickles go for at least two weeks before eating them - and I always boil eggs and pickle them in the peppered vinegar after I eat all of the peppers.
What about vinegar eels?
Ah, the nostalgia. I believe my first post to the Straight Dope, lo, these many years ago, was “Can vinegar go bad?”
Basically, it is very hard, but not impossible for vinegar to go bad. A friend of mine who was a Chemistry grad student, told me they once found something growing in a bottle of pure NaOH. Compared to that, household vinegar is a downright hospitable environment.
Pure NaOH is a solid, so I’m guessing it was an aqueous solution?
If you leave NaOH solutions out long enough, they will become solutions of Na[sub]2[/sub]CO[sub]3[/sub] or even NaHCO[sub]3[/sub]. This might just be livable, and maybe even act as a source of carbon for some plant life (That’s just guessing). Definitely that was not a NaOH solution by the time they found it. I’m guessing your friend was not an analytical chemist.