Why is it necessary to make milk sour in a pancake recipe?

While some recipes might call for buttermilk or sour milk, this isn't necessary to make pancakes.

Here's why you might see sour milk in some pancake recipes:

* Tenderness and Flavor: Sour milk or buttermilk adds a slight tanginess to the pancakes, which some people find more flavorful. It also helps create a more tender crumb by reacting with baking soda to produce carbon dioxide bubbles, which makes the pancakes light and fluffy.

* A Substitute for Baking Powder: If a recipe doesn't include baking powder, sour milk can act as a leavening agent, reacting with baking soda to create the rise.

If you don't have sour milk, you can easily make your own by adding a tablespoon of lemon juice or white vinegar to a cup of regular milk. Let it sit for about 5 minutes, and it will curdle, creating the same effect as buttermilk.

However, most pancake recipes rely on baking powder for leavening, and regular milk works perfectly fine. You can certainly experiment with sour milk if you want to add a little tang, but it's not essential.