Leavening
Leavening is what makes dough and batter rise, such as yeast, baking soda, baking powder, steam or whipped air. Here is how each works and when to use it.
Also called Leavening agent, Raising agent, Leaven.
Leavening is anything that makes a dough or batter rise by filling it with gas. As it bakes, the gas expands and the structure sets around it, giving bread, cakes and pastries a light texture. The British often say "raising agent". There are three main types: biological (yeast), chemical (baking soda and baking powder) and mechanical or physical (air and steam).
Why it works
Gas bubbles start small. Heat makes them expand, and water in the dough turns to steam and adds to them. The flour proteins and egg set around the bubbles, holding the risen shape.
How to use it
| Leavener | How it makes gas | Used in |
|---|---|---|
| Yeast | Ferments sugar into carbon dioxide over hours | Bread, pizza, brioche |
| Baking soda | Reacts with an acid in the batter | Buttermilk pancakes, cookies, soda bread |
| Baking powder | Soda plus a dry acid; reacts with liquid, then again with heat | Cakes, muffins, biscuits |
| Whipped eggs or cream | Traps air bubbles | Sponge cake, meringue, soufflé |
| Steam | Water turns to steam in a hot oven | Puff pastry, choux pastry, popovers |
As a rough guide, use 1 to 2 teaspoons of baking powder per 125 g (1 cup) of flour, or 1/4 teaspoon of baking soda per 125 g of flour when there is enough acid in the recipe.
Substitutes
- 1 teaspoon of baking powder can be replaced by 1/4 teaspoon baking soda plus 1/2 teaspoon cream of tartar.
- Baking soda cannot be replaced by baking powder one-for-one. You would need about three times as much, which can change the taste.
How to store it
Keep chemical leaveners dry and sealed. Test baking powder by stirring a teaspoon into hot water; it should fizz well. Test baking soda with a splash of vinegar.
Common mistakes
- Using too much baking soda, which tastes soapy and metallic and browns food too much.
- Letting a batter with chemical leaveners sit too long before baking.
- Using water that is too hot for yeast. Yeast slows and starts to suffer above about 50°C (122°F), and dies around 60°C (140°F).
- Overproofing a yeast dough so it collapses. See proof.
Related terms
- Baking sodaBaking soda is sodium bicarbonate, a strong leavening that needs an acid to work. In the UK it is bicarbonate of soda, in Ireland bread soda.
- Baking powderBaking powder is a mix of baking soda, a dry acid and starch that makes cakes and muffins rise. Here is how much to use and how to test if it is fresh.
- YeastYeast is a living fungus that makes bread rise. Fresh, active dry and instant yeast explained, with conversions, temperatures and what goes wrong.
- ProofTo proof is to let shaped dough rise one last time before baking. Use the poke test to tell when bread is ready, underproofed or overproofed.
- Choux pastryChoux pastry is a cooked dough of water, butter, flour and eggs that puffs hollow in the oven. It makes eclairs, cream puffs, profiteroles and gougères.
- MeringueMeringue is egg whites whipped with sugar into a glossy foam, baked crisp or used soft on pies. Here are the French, Swiss and Italian methods and fixes.