We know you’ve been seeing those sourdough TikToks in your feed for the past few months, watching a content creator carefully knead dough under a ring light, and then carve aesthetically pleasing patterns into the dough before baking it. It may look intimidating, dealing with something that is alive and growing, needs rest, and responds to very particular scientific measurements of flour, water, and movement. But today is National Sourdough Day, so what better excuse to start your sourdough hobby? Here is everything you need to know about sourdough, plus instructions on how to make your own sourdough starter.

How does sourdough work?

Sourdough is most known for its air pockets and tangy taste, and this is all because of the chemistry and acidity of sourdough. A mini ecosystem forms when you mix flour and water, because the water activates “good bacteria” in the flour. Enzymes in the flour split starches into sugar, and then bacteria from the moisture turns these sugars into acid. The pH goes down at this point, so most other microorganisms die in this condition, but this is where the flavor comes from. The yeast from the flour also consumes these sugars, and releases carbon dioxide and ethanol, or gas.

Photo by Adam Bartoszewicz on Unsplash

How to make a sourdough starter

Day 1

Mix one cup of water and one cup of flour in a large bowl. Stir hard, making sure to scrape any excess off the sides. Cover the bowl with a tea towel, and let it sit for 24 hours. Store in a cool, dry place.

Days 2-5

Discard half of the mixture, and then repeat the steps of day one, adding one cup of water and one cup of flour to the remaining half. This process is called “feeding” your sourdough. Cover and let sit for 24 hours, and repeat through day five.

Days 6-7

Continue feeding your sourdough, but do so every 12 hours, as opposed to every 24 hours.

Day 8

There should be enough fermentation in the dough so that you can start baking! You will know if your sourdough is ready when it has doubled in size, and when it bubbles.