Buttermilk is, in short, fermented milk. Its name derives from the fact that it traditionally was the liquid left behind after churning butter. It has high acidity levels, and it is an essential ingredient in recipes like pancakes, for example, where it reacts with a baking soda’s alkalinity to create a leavening action.
How to replace it
Simply use the same amount of milk as the amount of buttermilk indicated in the recipe and add 1 tablespoon of lemon juice or vinegar per cup of milk. Stir and let sit for 10 minutes, or until milk begins to curdle a bit and thicken. Like magic, you have a suitable buttermilk substitute!
The reason it works
By adding something acidic like lemon juice or vinegar to milk, the idea is to create an acidified buttermilk. Milk is protein rich, and this protein is a combination of mostly casein as well as whey protein. When adding the acid to the milk, it changes its pH (acidity) balance and causes the casein to separate from the whey, curdling the milk.
Looking for a few ways to cook or bake with your homemade buttermilk?