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Kahm Yeast...Ew?

by Jerri

Even in an airlock container, a vegetable ferment can turn wonky. What is more perplexing, is having the exact same ferment in different jars, side by side, and one is wonkier than the other. The jar on the right - what IS that layer on top? Is it time to freak out?

kahm yeast appearing at the top of fermenting vegetables

You probably did everything the same: sterilization of equipment, same ingredients from the same garden or farmer (hot peppers in my case), same ratios, on the same counter - YOU WORKED SO HARD. Why? Is that one batch ruined?

top view of Kahm yeast on fermenting vegetables

Luckily, the wonkiness was not mold, but instead that interesting phenomenon called kahm yeast. In Sandor Katz's ginormous orange book, €œThe Art of Fermentation,€ he describes kahm yeast as being, €œbeige in color, with a dramatic texture, something like waves or a plate of spaghetti.€  Look closer:

cloudy film known as kahm yeast is common in home fermenting projects

Yup, nailed it. It actually looks quite intricate and dare I say, beautiful? But, can we eat it? Is it harmful like mold?

Katz recommends removing the yeast (he states some yeasts can turn into mold), while other fermenters simply stir it back in. Personally, for my ferments, if it's just barely forming, I mix it back in. But, if I have an actual layer, I take out as much as I can, including a bit of the produce under the produce touching the yeast layer. Bottom line, if it's whit-ish, it's probably harmless kahm yeast€.if it's colorful, you can assume it is mold, so pitch it upon discovery!

This is not my first experience with kahm yeast. A few years ago I had it happen with a batch of pickles. The layer was so thick I could handle it like a rubbery pancake. Now that was weird!

white and foamy kahm yeast

Why does it form? I've read it is due to the sugar being used up and the pH dropping. It tends to happen with sweeter produce like my cucumbers and peppers, but also beets and carrots. It can also occur when the room temp is too warm (certainly not my case in mid-fall and on a cold granite countertop) or when the salt brine has too little salt. I am still dumbfounded since I had the same brine mixture for all three, so not sure it was the salt ratio either!

Eh, life is too short. This is not the end of my fermenting world€I'm over the need to know why only one batch was affected, let alone why it occurred at all. On to my next project!

Get fermented!