Q: About a month or so ago I decided my bread making skills had improved enough to try keeping a starter. I followed Alton Brown's starter recipe and put the whole thing in a mason jar in my fridge. Weekly I make a loaf of bread and feed the starter. This week the starter started expanding like crazy and keeps overflowing the jar.
Did I do something wrong? I added and removed the same amount as usual. Should I just wipe off the overflow and keep using it? Or start from scratch? Help! - Sent by Julianna
Editor: Julianna, congrats on stepping up to the sourdough! From your description and from what we see in your picture, it looks like you've done a wonderful job getting your starter going. You didn't mention any abnormal aromas or off-colors in your description, so our guess is that your starter is happy and healthy. And apparently very active!
So why all the crazy overflow? We can think of a few things that might be going on.
The first is simply that it took a little while for your starter to really get going, and the proportion of yeast living in there is now much greater than it was when you initially started. More yeast means more carbon dioxide being produced which means that you'll see more expansion in your starter. Plus, it's been warm outside, which makes yeast even more active.
We're guessing you're getting the overflow either while the starter is out on the counter right after being refreshed or soon after you put it in the fridge? Storing your sourdough in the fridge will temporarily suspend fermentation (and therefore expansion), but only once the starter cools down to refrigerator temperature. The yeast will keep multiplying and working away right up until then.
Also, your problem might simply be that you need to store your starter in a larger container. Just after being refreshed, the starter should only fill the storage container half-way or even a little less. This gives it plenty of room to expand and deflate. If the lid is on too tightly, it's also possible that too much pressure is building up inside from the carbon dioxide being produced. When the lid eventually pops off, the starter would bubble out just like soda from a can that's been shaken!
We like to store our starter in a simple plastic container with a tight-fitting, but not locking, lid. If pressure starts building up, the lid cracks open on its own and vents off some of that carbon dioxide.
Definitely keep using your starter and keep making your bread! Let us know how it all works out.
Does anyone else have any advice for Julianna and her over-active starter?
Related: Recipe: Beginner Sourdough Loaf