OK I've had this question for a long time now.

When I buy a small jar of various tapenades and dips and condiments at
TJ's, when I open it and use a few ounces things are generally fine.
I put the jar in the fridge after opening, but when I take it out and
open it to use again, there is a quarter inch of water in the jar -
far more than condensation in that small space can explain. I figure
it must be fermentation caused by exposure to even that little bit of
oxygen. I can pour out the water, but I begrudge the yeast whatever
sugars or carbs they're eating.

Is there anything one can do about this?

I guess it mostly happens on unpasteurized contents, but that appears
to be a lot of stuff.

It happens with yogurt, too, but we know that's full of live cultures
so that's why they're sold in small containers you're best off eating
all at once.

Thanks,

J.