Why does baking soda need an acidic ingredient in baked goods?

In baking, baking soda (sodium bicarbonate) requires an acidic ingredient to function effectively as a leavening agent. This necessity arises from the following chemical and culinary factors:

• Gas Production: Baking soda is a base that reacts with acids—such as buttermilk, yogurt, or cream of tartar—to produce carbon dioxide gas. These gas bubbles expand during heating, creating the light, porous structure essential for breads and cakes.12
• Neutralization: Without sufficient acid, unreacted baking soda remains in the dough, leaving it overly alkaline. This alkalinity causes flavor deterioration (often described as bitter or soapy), undesirable discoloration, and excessive browning.314
• Leavening Efficiency: Adding an acidic substance promotes vigorous gas evolution and maintains the dough's acidity within a favorable range, ensuring proper volume and texture.4

To simplify this process, many bakers use baking powder, which is a pre-mixed combination of baking soda and acidic compounds.25