Buttermilk (Best Option)
1 cup buttermilk per 1 cup whole milkButtermilk works well because its acidity reacts with baking soda or baking powder in the recipe, enhancing leavening and creating a tender crumb. The moisture content is similar to whole milk, maintaining the bread's texture.
To ensure success, use the same amount as whole milk and adjust leavening agents if necessary to balance acidity. Watch for a slightly tangier flavor, which complements zucchini bread.
Compared to whole milk, buttermilk produces a slightly denser but moister loaf with a subtle tang that can enhance the overall flavor profile.