Buttermilk

Buttermilk is often produced commercially by adding bacterial cultures to milk and allowing fermentation, which transforms sugars into acids. They might also add probiotics and flavorings.

Due to its acidity, buttermilk can have the same leavening effect as a baking powder when used with baking soda. To replace 1 teaspoon (5 grams) of baking powder, simply add 1/2 cup (122 grams) of buttermilk and 1/4 teaspoon (1 gram) of baking soda. Be careful to reduce the amount of other liquid you add to your recipe to make up for the amount of buttermilk used in order to maintain the ideal texture and consistency of your final baked product. For example, if you add 1/2 cup (122 grams) of buttermilk, you should half the number of other liquids you add to the recipe.