Originally Posted by GotGarlic
We're talking about an eight-year-old jar of mustard here. I opened the jar and what little was in there looked a bit crusty. I wasn't worried about it being spoiled. I just decided I didn't want it anymore and tossed it in the recycling bin.
Last year some Facebook friends got into counting vinegars and I found an old bottle of malt vinegar with just a little residue on the bottom. I didn't count that one
So yes, it takes a while, but it happens.
Powdered vinegar can be purchased. I would suspect that just like many acids, once the water evaporates, you have a powder residue of what makes vinegar, vinegar. So yep, I'm in the camp that thinks mustard can dry out. I wonder if you can purchase powdered mustard from what was once prepared mustard, you know, with the dried vinegar as well as the ground mustard seed. For campers, backpackers, and food storage fans, it would be a great, lightweight way to carry a tasty condiment. Just add a little water.
I would even think that prepared mustard could be freeze-dried.
Seeeeeya; Chief Longwind of the North