Buttermilk is the slightly sour liquid that remains after churning butter. It’s high in proteins and low in fat, and works well as a wet ingredient in baked goods. The buttermilk you see in the stores isn’t poured out of wooden butter churns and into those papery plastic containers though. It’s derived from the introduction of certain cultures into low-fat milk, creating the fermented beverage currently referred to as buttermilk.
As an ingredient, buttermilk brings acid and moisture to the recipe, as well as a bit of tanginess. When baking soda, an alkaline ingredient, interacts with the acid in the buttermilk, it creates carbon dioxide, or bubbles. This contributes to the fluffy texture associated with baked goods.
If you don’t keep buttermilk on hand, though, you can use one of several substitutes and your recipe should still work.
Lemon juice is highly acidic, and can replace the acids found in buttermilk.
Bring 1 cup of milk to room temperature, or warm it slightly in the microwave. Add 1 tablespoon of fresh lemon juice to the milk and stir. Allow the mixture to stand for several minutes before adding it to your other ingredients.
Vinegar is also acidic, and may be used as a substitute. Use 1 1/3 tablespoons of vinegar and add to 1 cup of room temperature milk and stir.
If using vinegar, use either white vinegar or apple cider vinegar. Neither of these will alter the taste of the final product.
The cultures in yogurt mimic those found in commercial buttermilk. Use 2/3 cup of plain yogurt to 1/3 cup of milk. Bring both ingredients to room temperature before combining them.
Like yogurt, sour cream has similar properties to buttermilk. Combine 1/2 cup of sour cream with 1/2 cup of milk and allow the mixture to stand for several minutes before using. This substitute works well in baked goods with longer cooking times, such as cakes.
Cream of tartar
Cream of tartar is a by-product of the wine fermenting process, and like buttermilk, is acidic. Cream of tartar, though, is available as a fine, white powder and is usually used when whipping egg whites into a meringue. It adds volume and stability to the meringue.
If you dissolve 1 3/4 teaspoons of cream of tartar with 2 tablespoons of milk and add that to 1 cup of milk, you have a substitute for buttermilk.
When using any of these substitutes for buttermilk, bring the ingredients to room temperature first. This creates a more stable mixture for your baking.
Make up a full cup of the substitute for a more even balance between the milk and the acid. Store any leftover mixture in the refrigerator and use within two to three days. Make sure to bring the mixture to room temperature and stir well before using.