Buttermilk (Best Option)
1 cup buttermilk per 1 cup whole milkButtermilk works well because its acidity reacts with baking soda or baking powder, enhancing leavening and resulting in a lighter texture. It also provides moisture and some fat, similar to whole milk.
For best results, use fresh buttermilk and slightly reduce other acidic ingredients if present to maintain balance. Stir buttermilk gently into the batter to avoid overmixing.
Compared to whole milk, buttermilk produces a slightly tangier flavor and a more tender crumb, often considered desirable in quick breads like banana or zucchini bread.