I recently tried an experiment with using strong dandelion flower & stem infusion and malt syrup. I was unable to obtain or culture a yeast starter in sufficient time so the wort sat for approx a week and started to spontaneously ferment in that time. I assumed we'd end up with sour ale or something along those lines but unfortunately the brew became highly viscous - almost syrupy. My best guess is something other than yeast got busy inside the carboy and maybe went to work on the proteins or whatever else came from the dandelion.

I tasted it and it was a bit sour - not unpleasant other than the fact that it's so thick makes it a bit disgusting. Does anyone have any idea what organism, specifically, would cause such a change and turn liquid into a thick substance like this?

  • 1
    Maybe spread it on toast?
    – Willk
    May 18, 2020 at 0:09
  • hehe.. nah. that wouldn't work it's more like the consistency of a runny nose May 18, 2020 at 2:09

1 Answer 1


Well, a bacterium, of course... But there are quite a few bacteria which will thicken the ferment (some of them benign and some harmful). Without in-depth testing it would be impossible to know which ones were in your sample. (If I had to guess I'd say acetobacter.)

  • It could also be a yeast, I think there are a few types that can produce mucin-like substances.
    – bob1
    May 17, 2020 at 20:36

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