I have a batch of King Arthur sourdough starter that I mixed up several months ago and have been using ever since. I keep it in the refrigerator and feed it with 100 g of AP flour and 100 g of water once a week. I have made several hybrid loaves with it with no issues. I have noticed that at the end of the week when I am ready to feed it, it seems to have an orange-pink coating that has a strong citrus smell. I assume that it is some kind of fungus. I live in north Florida. It does not seem to be harmful in any way; I've made several loaves since I noticed it and have never gotten sick.

Any idea what it might be?

UPDATE Here is a picture of the starter. In the lower left, you can see an orange tint.

enter image description here

  • Any chance you have a picture of this coating?
    – LSchoon
    May 12, 2020 at 19:52
  • I’ll try to get one later this week when I feed the monster and update my question.
    – Ralph
    May 12, 2020 at 20:43

1 Answer 1


I'm pretty confident you can get rid of that with the Ed Wood "washing" process.

  1. Stir hooch into starter. This stuff the microflora make to protect themselves.
  2. Increase the volume 3-5 times with water
  3. Stir until homogenous
  4. Pour off 4/5ths of it
  5. Tip in flour and stir until homogenous
  6. If not a consistency you like then add more flour or water
  7. Wait until it has risen double or triple
  8. Repeat several times

Lactobacilli and yeast are just a lot more active than moulds when at room temperature, they will outcompete the mould spores. If there were a toxin you'd just be diluting it, but I've heard of people reviving prized cultures that had gone completely black.

Good luck!

  • Just to confirm (since OP asked to identify the orange tint): you think it is a mould?
    – LSchoon
    May 15, 2020 at 7:41
  • @goboating Thanks. I have “backups” of the original King Arthur sourdough culture that I dried and froze right after I bought it. In fact, I completely restarted the starter from one of the frozen chips when this citrus problem started. It came back. I was just concerned that it might be toxic, but now I agree that it might just be lactobacillus, and nothing to worry about.
    – Ralph
    May 15, 2020 at 9:57
  • I can't tell from the pic what it is. There are indeed pink moulds, bacteria and other microflora. Lactobacilli are the most abundant microorganism on the planet. If you give them the right conditions, they will win.
    – goboating
    May 15, 2020 at 11:06

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