Milk + Lemon Juice (Best Option)
1 cup milk + 1 tablespoon lemon juice (let sit 5 minutes)Adding lemon juice to milk creates a mild acidic environment similar to buttermilk, which reacts with baking soda to produce carbon dioxide bubbles essential for leavening. The acidity also helps break down gluten slightly, resulting in a tender texture.
For best results, use whole milk for similar fat content and allow the mixture to sit for 5 minutes to curdle properly. Avoid using skim milk as it may reduce richness.
Compared to buttermilk, this substitute yields a very similar texture and flavor profile, with only a slight difference in tanginess that is generally imperceptible in pound cake.