Sourdough starter looking weak, or maybe even a little (gasp!) moldy? Don’t panic! You can revive a weak sourdough starter and get it back in shape with some time and TLC.
A few weeks ago, I pulled my sourdough starter out of the refrigerator, took the lid off the jar, and paused. I knew right away something wasn’t right.
Wimpy and deflated, it didn’t have any of the bubbles that signify a healthy starter. The smell had changed from a pleasant sour scent to something different and just off. And what was that white film hovering on top? Not mold?!
For months before that, my sourdough starter lived a happy life in the door of my refrigerator. I’d pull it out every week or so, sometimes twice a week, and bake up a big batch of something yummy. After feeding it with fresh flour and water, it would go rest in the fridge door until called upon again.
But it had clearly taken a turn for the worse. I hadn’t been baking as often because life tends to happen every once in a while with a big, busy family. It was starved, neglected, and in need of some quick intervention if I was going to save it from a sad ending in the compost pile.
I also really needed to bake and didn’t have the time to start a new sourdough starter. I was determined to save this one.
How Far Gone is Too Gone?
Now I realize that anyone whose kitchen mantra is When in doubt, throw it out might have just suffered heart trauma because I said I was determined to save my starter. My starter that was growing some mold. That one.
Usually we don’t save things with mold. We throw them away, and quickly. Sort of like the bookcase we found in my basement this summer.
Part of our basement is finished with a carpeted floor. We have a toy kitchen down there and it was situated next to the bookshelf. While “cooking” their toy food, darling daughters Miss H and Miss C decided they needed to use real water. Real water that splashes, spills on the floor, gets carpet wet, and seeps into the carpet under the adjacent bookshelf unbeknownst to the adults of the house until of course they smell mold, start decluttering, find the moldy bookshelf, and start tearing out carpet. Lovely.
That kind of mold we need to get rid of ASAP. But a little mold on the top of a starter may not be a death sentence.
Microbes are an amazingly resilient bunch of critters. When a sourdough starter is molding, its microbes are out of the balance. Under the right conditions, though, the microbes can get back in balance and the mold will disappear.
A little mold floating on the top of a starter? Likely savable. Mold growing through the entire starter and all over the container storing it? Like our bookshelf, too far gone.
Reviving a Weak Sourdough Starter Step by Step
So back to my starter. It clearly smelled slightly moldy and had the starts of mold floating on its surface. The mold wasn’t growing through it, though, and the jar sides were mold-free. Not pleasant, indeed, but still savable.
And save it I did! Here’s how you can revive a weak (and maybe even a little moldy) sourdough starter:
Step 1. Pour off or spoon out the moldy layer. It’s not crucial to remove every trace of mold, but it’s best to get out as much as possible.
Step 2. Pour out the remaining starter from its storage container into a clean measuring cup.
Step 3. Thoroughly wash the sourdough starter container to remove any other bits of mold with hot soapy water. Don’t worry about any dried starter that doesn’t want to wash off the sides.
Step 4. Return the starter to the jar or container, then feed with a generous amount of fresh flour and water. I had about 1/2 cup of starter left and fed it with about 2 cups flour and water each.
Step 5. Leave it out to ferment, lightly covered with cheesecloth or a thin kitchen towel. If you can do this by an open window, that’s ideal since the extra airflow will bring in friendly microbes. If not, any room with airflow will be fine.
Step 6. Watch for bubbles. This might take 8-12 hours depending on how weak your start is. Those good microbes need some time to work through the extra flour and water. If no bubbles appear after that time, you’ll likely need to start a new sourdough starter.
Step 7. Once it is bubbly, consider your starter as good as new!
It’s also smart to consider why your starter molded or got really weak so it doesn’t happen again. In my case, I was storing it in the door of the fridge, which is the warmest area of it, and not baking for weeks at a time. Warmer temperatures mean a starter needs fed more, but that wasn’t happening.
Lesson learned: I need to keep my starter in the back of the fridge if I’m not baking regularly instead of in the door.
I’m glad to have my healthy starter back, smelling pleasantly sour, looking perky and bubbly, and living in the fridge without a trace of mold. Now, how about some sourdough bread?