Instead of using baking soda or powder to leaven breads, you can make your own leavening agent by fermenting flour and water. It takes a few days, but the developed flavor (and personal touch) it gives is so worth it.

I learned this method from Tartine Bread. Using a 50/50 whole wheat and bread flour mixture, combine 1/2 cup flour mixture and 1/2 cup lukewarm water with your hands in a clear pint container (for viewing fermentation bubbles). It should be the consistency of a thick batter with no lumps. Cover with a kitchen towel and let sit for a few days.

A chemistry lesson: During this time, wild yeast found everywhere (the flour, your hands, etc.) will eat the sugars in the flour and start to ferment. During fermentation, carbon dioxide is one byproduct yielded (you can see the bubbles form). Carbon dioxide is the gas that is instrumental in making bread rise. Lactic acid and acetic acid are both also produced, which give a sour and vinegar taste, respectively. The temperature of the environment has a big impact on the amount of lactic and acetic acid produced and the subsequent flavor of the starter.


*note that both lactic acid and acetic are produced, but one flourishes more under certain circumstances.

For the Tartine country loaf, lactic acid is a more favorable flavor, so leaving the starter on your kitchen counter is better than keeping it in your refrigerator.

After a day or two, the starter will smell like overripe fruit. It still needs a day or two. When bubbles form on the surface and it smells like stinky cheese, it’s properly fermented, ripe, and ready to be fed.

To feed it on the morning you discover it is ripe, scrape off the top layer of dark skin that formed and throw away 3/4 of the starter. Start the feeding process by giving it a handfull of 50/50 flour and lukewarm water, replenishing the batter so the container is about halfway full again.

At this beginning stage of the cycle, the starter will smell sweet and milky. Note how the volume rises for a few hours and then decreases when the cycle is complete. The next morning, once it the cycle is complete, the starter should smell like vinegar. Discard 3/4 of the starter again and replenish with 1 part flour mixture and 1 part lukewarm water.

Continue feeding the starter like this for a few days, until it is rising and falling in a predictable manner. Once you know the cycle of your starter, it’s ready to make a leaven and get to baking!!

If you keep feeding this bad boy every day, you will always have bread starter on hand for baking. I mayyybe have taken mine on vacay (shifty eyes…). My fish? No he stayed here. But the yeast? Yes the yeast needed to be fed.

-everything learned from Tartine Bread, aka the Bread Bible.