How to Harness Yeast for Baking: 3 Yeast Substitutes

Yeast (Saccharomyces cerevisiae) is a single-cell fungus that converts sugar and starch into two important byproducts: Alcohol and carbon dioxide. When active yeast cultures are mixed into a batter or dough and allowed to ferment, they create the carbon dioxide bubbles that make bread rise. The bubbles become trapped in the dough’s gluten protein structures, creating air pockets; when exposed to heat, those pockets expand and create the interior, or the “crumb.”

There are upwards of 500 different strains of yeast. These naturally occurring “wild” yeasts are a part of everyday life: Miniscule yeast particles float through the air and settle on nearly everything, including plants, animals, surfaces, and humans.

There are two main types of commercial yeast: Brewer’s yeast and baker’s yeast. The former is a wet yeast used in the beer brewing process, and the latter is a dehydrated yeast used as a leavening agent in everything from yeasted doughs like cinnamon rolls and morning buns to boules of rustic country bread. Commercial yeast for baking is sold as active dry yeast, instant yeast, and fresh yeast—variations on dormant yeast cells in granular form.

If you don’t have yeast in your pantry, there are a few alternatives that can help you get the job done:

1. 1. Baking soda: Baking soda, or sodium bicarbonate, is a base, which means it requires an acid to create a chemical reaction—fizzy bubbles of carbon dioxide can give baked goods a light and airy crumb. To substitute for yeast, use equal parts baking soda and an acid such as cream of tartar, buttermilk, or lemon juice.
2. 2. Double-acting baking powder: Baking powder is a ready-made leavening agent since it contains baking soda and dry acid (in this case, cream of tartar). “Double-acting” refers to the two stages of rising caused by the baking powder: The first occurs when it comes into contact with the wet ingredients in a batter or dough, and the second takes place during the bake itself, when the baking powder encounters heat. Use an equal amount of baking powder to substitute for dry commercial yeast.
3. 3. Self-rising flour: Self-rising flour is a soft all-purpose flour blend enhanced with baking powder and salt. When a dough needs a bit of lift but not towering structure—like pizza dough—you can substitute self-rising flour into a recipe that calls for dry yeast.

It’s important to note that any substitute for yeast will result in slightly different final products. As a living organism, yeast is unpredictable and unique, making any attempt at genuine imitation difficult. Ingredients that deliver a moist, fluffy crumb in quick breads and cupcakes, like baking powder, will not result in a stretchy, chewy sourdough loaf.

Yeast occurs naturally, so making your own yeast culture requires harnessing wild yeast and bacteria from your flour and water mix and the air in your kitchen. Here’s how to harness yeast:

• Make your mixture. Combine 100 grams warm (about 100°F) filtered water, 50 grams whole wheat flour, and 50 grams all-purpose flour in a wide-mouth glass jar. Cover with a clean cloth or tea towel secured with a rubber band
• Ferment. Let the mixture ferment for five days. Once fermentation begins, you’ll need to add flour and water to feed the yeast and allow it to grow, developing layers of flavor and enabling the levain (a French term for the fermented water-flour mixture) to make the dough rise. Stir your starter throughout the day, whenever you think of it (at least twice per day).
• Refresh your starter. After a few days, your starter should start to bubble. Once it bubbles, begin refreshing or “feeding” your starter regularly. To refresh your starter, discard all but two tablespoons. Mix a fresh batch of 100 grams each of warm water and flour and combine with the remaining starter. Repeat one to three times a day.
• Refrigerate. You can keep your starter in the fridge so that it requires less refreshing. Feed your starter at least once a week, and take it out of the refrigerator the day before you plan to bake. Refrigeration slows down fermentation, and you want your starter to be very active when it’s time to bake.

When substituting a live sourdough starter in a recipe that calls for instant, use 1 cup where it calls for one packet of commercial yeast, and reduce the water and flour content by half.

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