One of the most distressing parts of vegetable fermentation is when one goes bad. There are no mysteries in this case, though people often ask how they can know for sure that a ferment is okay to eat. In my experience, you will know. It will stink like you wouldn’t believe and often has various colors that should definitely not exist in that ferment. If those things do not exist – the stench and funny colors – then what you might be seeing on the surface of your vegetable ferment is a harmless yeast called kahm. This is often indicative of things that could have gone better, but is certainly not poisonous or harmful. I actually have no idea whether kahm rhymes with calm, but in either case kahm yeast is nothing to freak out about. Here’s a peek at what it looks like.
I recently opened up a batch of fermented jalapeno slices and found a thin layer of white. I looked at the sides and it didn’t seem to be putting any tendrils down into the ferment itself. It was merely a thin layer of white yeast that I could easily skim from the top. The jalapenos were perfectly edible and tangy, though quite spicy as I left the seeds in.