Buttermilk is a popular ingredient in baking as it can add a light, tangy flavor to baked goods. It is traditionally made from the liquid that remains after churning butter out of cream, but now it is often made from pasteurized skim milk with bacterial cultures added. Buttermilk adds moisture and tenderness to cakes, muffins, pancakes, biscuits, and other baked goods. The acidity of buttermilk helps activate baking powder and baking soda, which helps the doughs rise, creating a light and fluffy texture. Additionally, the acidity of buttermilk helps break down gluten proteins which result in flakier pastry doughs like those used for pies and biscuits.