I am so glad I came across your website. I have a batch of red onion ferment I am not sure is safe to try. I have quite a bit of experience with kimchi, but this is the first time I have tried fermenting onion. The recipe was just onion and salt, and the onions were supposed to give enough juice to keep them covered, but they did not and so the top layer was exposed to air. They were fermenting for about 2 weeks at about 19 degrees C. A layer of white film developed on top of the onions. It smells like fresh yeast. I have never had this issue before. Any idea what is it, and is the onion safe to consume? Thanks so much,Magdalena Denenberg
Glad you found the site before you tossed the onions—they should be tasty. You are correct in that the film developed due to onions on that weren’t fully submerged under the brine. The is kahm yeast, harmless but not so tasty. You will want to scoop off this top layer and then the rest will be fine. I also suggest putting the good part in a smaller jar now that it is ready to refrigerate. Less air in the jar makes it less likely that you will see a film like this this.
Happy to help.
Enjoy the onions,