Rotten vinegar

[Dianabanana]

For the second time this year, I have discovered that a bottle of red wine vinegar in my cupboard has gone bad. The first time I unfortunately discovered it by tasting; this time, luckily, I smelled it first. Rotten. Truly disgusting.

Both bottles had a big glob of dark, slimy fungus floating around in them. Now this cannot possibly be the "mother," can it? It's not all cobwebby like the stuff in Dr. Bronner's apple cider vinegar--it's dark and more "silty" looking.

I have never heard of vinegar going bad and never experienced it before, so I am puzzled as to how this could happen twice in just a few months. These are just cheap grocery store brands--I think the first one was Four Monks and this one is Pompeiian.

What do you make of this?

[Toliver]

My first guess would also be that it's a mother forming. Though why it would have a rotten smell is beyond me.

[Dianabanana]

Also, I have read that all commercial vinegar is pasteurized. So where is this coming from? If it's coming from my kitchen, it seems unlikely that the same diabolical contaminant could find its way into two bottles through the tiny little shaker slots in the caps.

And just to clarify, it smelled and tasted absolutely horrid. I've tasted Dr. Bronner's and although the taste isn't as clear as normal vinegar, it's nothing like this.

[Alcuin]

I've had a bottle of Apple Cider vinegar that was bad before. If I recall, it was ruined from the start though and it was unpasteurized. But I have experienced the potent stench of rotten vinegar before and can testify to its badness.

This only happened to me once and I thought it was weird too. Isn't vinegar supposed to keep off things like mold and bacteria?

[jgm]

I'm no chemist. . .but the situation suggests an acidity problem.

Interesting topic!