I pulled my sourdough starter out of the fridge to add to a recipe today and found it covered in mold. This is a relatively new starter (3 weeks or so?), and it was last fed on 4/16.
I follow Ken Forkish’s method in “Evolutions in Bread.” To lay out what I’ve done:
* Started with a 50:50 whole wheat flour and water, then gradually converted to feeding with white flour per his instructions.
* After seven days of building up the starter, it went into the fridge where it remains permanently aside from feedings. The starter showed signs of life throughout the buildup process with bubbles on the surface.
* Ken recommends feeding once every 7-10 days by discarding all but 50g and then adding 200g each of white flour and water. After a feeding, I leave it out for about 24 hours, then it goes back into the fridge.
* I don’t switch containers every time I feed it, but I do try to put it into a new container every 2-3 feedings.
* I built the initial starter in a 2qt. Cambro. I ordered a King Arthur glass crock a few weeks ago and transferred the mature starter into it where it currently lives.
* All containers are cleaned to the best of my ability. No dishwasher, so everything is hand washed with Dawn and air-dried.
I use King Arthur for all of my flour (wheat for the initial build, all-purpose for feeding). I use NYC tap water (in an old building — could this be the issue?) brought to the temperatures he recommends.
The very first time I tried building this starter, I found mold along the sides of the container on Day 7, prior to even reaching the refrigeration stage. I assumed this was because I didn’t do a sufficient enough job scraping down the sides? The second attempt seemed to be going much better until today. I even used 100g of the levain in a white bread a week ago and it tasted awesome!
As far as I can tell, I’m following all instructions exactly. Can anyone help diagnose where I’m going wrong or what may be contributing to the mold buildup? Im suspecting it may be our tap water but am certainly not an expert in this area.
by NeonCream_
6 Comments
You should post this over on the sourdough subreddit. r/sourdough I think.
Mold doesn’t grow in healthy starter because the conditions are unsuitable.
You’re adding a lot of flour and water and making conditions where it can grow.
I strongly suggest that your ratio when feeding is 1:1:1 of flour, water, and old starter.
Then give it a day of being warm in your kitchen before going in the fridge.
Serious question: was this ever a starter? From what you wrote, it looks like you’re trying to spontaneously create one by leaving flour and water out. While some people say this works, the mold is telling me that you never managed to harness the good bacteria and wild yeasts that would create a functional starter.
My advice would be to ask someone for some live starter and to build it up from that.
Read this 4 part guide on sourdough baking and starter (you can make a smaller starter than the instructions, but this has the right process and maintenance). You normally want two weeks of maintaining before you use it. Also do not keep the first week of discard, put it in the compost.
https://www.kingarthurbaking.com/learn/guides/sourdough
What’s your room temp? Try discard until you have 50g, add 25g water and 25g flour. Making the total 100g. Do this daily. For more than 7 days. Your starter wasn’t active enough before you did the fridge thing. And you maybe you’re feeding too early. Really depends on temp and flour. I would add a dash of rye flour to your wheat flour.
Sounds like you put it in the fridge too soon. I’d go at least two weeks.