What effect does over-mixing batter have when baking?

When batter is over-mixed, the gluten proteins in the flour become overdeveloped, leading to a denser and tougher texture in the baked goods. This is particularly important in products like cakes and muffins, which are typically desired to be light and fluffy. Over-mixing incorporates too much air and can create a structure that is not desirable for these types of baked goods. As a result, items like cake may come out dry or rubbery instead of having the tender crumb that is preferred. This principle is crucial in baking, where the texture and mouthfeel of the final product heavily influence the overall enjoyment and success of the recipe.