A good-quality sauerkraut is expected to have a titratable acidity of 1. 5% - 1. 8% (lactic acid concentration) with a pH between 3. 2 and 2. 8. In addition to lactic acid, there may be other acids at low concentrations, but the titratable acidity is expressed in terms of lactic acid equivalent.

Although canned sauerkraut is in an anaerobic environment, the spores of Clostridium botulinum will either not germinate or if they do germinate, the vegetative cells will not be able to grow and reproduce if the pH is 4.6 or lower. Consequently, this can be called a "commercially sterile" product, in other words, a product that will not spoil at room temperature.

In other words, during fermentation, the lactic acid that's formed thoroughly acidifies the product. Sauerkraut is a world away from the issues plain cabbage sealed in a jar would present.

In essence, you can treat your sauerkraut as you would a jar of unsealed peaches. If it smells fine, go ahead and eat it. The "risk" would have to do with possible mushiness or off-tastes due to the presence of air, but not botulism. There are no documented cases of botulism in sauerkraut for good reason.

Carol

Here is a link that might be useful: U of Maine Microbial Quality and Safety of Food

Most likely it is yeast growth. Does it smell yeasty or real musty ?

I didn't smell it, Linda,until I heard back from here!
I sure didn't want to inhale "something". :-)
It's definitely off color. Brown as opposed to the golden tan color it normally is.

Thank you for confirming my thoughts about the acidity, Carol. I knew it had to be fairly high, but wasn't sure about having been sealed, then unsealed.

Should be good for the compost pile!

Thanks again,
Deanna