If you substitute buttermilk for regular milk in a recipe for muffins, you must increase the quantity of baking powder.

Question

Quizplus · Accepted Answer

Buttermilk is more acidic than regular milk, which can affect the leavening process if baking soda is present. Typically, when using buttermilk instead of regular milk, you might decrease the amount of baking powder and add baking soda to balance the acidity, not increase the baking powder.

If You Substitute Buttermilk for Regular Milk in a Recipe