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Experimenting with Saccharomyces cerevisiae (sourdough fermenting adventures)

Updated: Mar 16


I am always looking for more "work" (aka, fun things to experiment on). I tend to do this type of exploration in the kitchen, which my lab mates are always thankful for. I have been meaning to do a sourdough starter since I started grad school, but have never found the right time. It has been such a tumultuous summer that I figured if I didn't do one now, I'd never get to it!

So here's my experiment on a sourdough starter from scratch (literally flour and water - no helpers from friendly neighborhood starters, although SF is legendary for this stuff). I had to restart it a few times, so I'll share with you where I went wrong the first time.

Learn from my mistakes. DO NOT:

  • Use metal utensils or containers

  • Use plastic storage containers. ONLY USE GLASS

  • Use tap water

  • Feed every 12 hours for the first week. It isn't necessary and it makes you feel incredibly guilty when you miss one since you're stuck taking care of your actual (lab) experiments for your thesis...

Here's what you should do:

  • Use glass storage containers (like a wide-mouth mason jar)

  • Use a sturdy wood chopstick to stir

  • Use distilled water

  • Cover your glass container with a paper towel and a rubber band instead of a lid

Creating a culture of millions of S. cerevisiae:

  1. Add 4 oz. RYE flour and 4 oz. distilled water (BY WEIGHT) to a wide-mouth 16 oz. mason jar. Stir with a wooden chopstick until there are no lumps. Cover with a paper towel and secure with a rubber band. Make sure the edges of the mason jar don't have anything on them, otherwise you'll end up with a sticky mess that the paper towel won't let go of in the morning. Rye flour is great to start with because it has more natural yeast than bleached flour. If you only have white flour, that's ok! All flour has yeast in it.

  2. Let sit on a shelf out of direct sunlight at ~20ºC for 24 hours.

  3. Add 4 oz. WHITE flour and 4 oz. distilled water and stir again. Let sit again for 24 hours.

  4. Separate out half of the mixture into another identical mason jar and add your 4 oz. of flour and water to each. If you don't want to end up with a yeast monster, I suggest you start baking now, or handing out starter babies to your friends. We call this leftover starter the "discard".

  5. Repeat the last step for at least three more days, or until you get nice bubbles in the starter and it consistently doubles in size every 24 hours.

  6. After you have a starter that can grow and smells fruity, it can go in the fridge in the same container that you mixed it in.

Super easy instructions for taking care of your new yeast babies:

  • Feed your starter once per week using the same 4 oz. 1:1 ratio of flour and distilled water. Before you feed it, make sure you take out half of it as the discard! Let it sit out overnight right after you feed it before you put it back in the fridge.

  • Use/give away/throw away the discard every week - a great excuse to have fresh bread. It makes 2 loaves with this favorite recipe: https://www.kingarthurflour.com/recipes/extra-tangy-sourdough-bread-recipe.

  • If you want it to bake before your once per week feeding time, just feed it extra that week to get the discard! Super easy.

  • If there is a film of grey liquid on the starter, don't throw it out! This makes the starter more tangy.

  • If you want sourdough to be more tangy, use more flour in your ratio. Less tangy, use more water.

Fun facts about sourdough! Sourdough starters are special because of the yeast AND the bacteria produced - you have to cultivate both to get that sour taste. This is why the distilled water is important, you don't want to chlorinate your bacteria! Two types of acid are produced in sourdough bread baking: lactic and acetic acid. Acetic acid gives that sour taste, and the slower you proof the dough, the more you produce! Therefore longer rising time = better tasting sourdough (in my opinion). This is achieved by rising at a lower temperature, often in the fridge.

I have learned a lot about baking with sourdough starters and I hope you'll find it just as interesting! If you are at UC Berkeley or SFSU RTC, give me a shout and I'll share some of mine!




Are you a fellow procrastibaker? Follow me on Instagram for more creations that I don’t have time to blog about @rlitanner


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© 2019 Richelle Tanner

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