What's the difference between baking soda and baking powder, and can I substitute one for the other?

Question

Understand the difference between baking soda and baking powder and when you can swap them.

Answer 1

Baking soda is pure sodium bicarbonate and needs an acid to activate, while baking powder is baking soda plus an acid and a starch, making it a complete leavening agent that activates with liquid and heat; they are generally not interchangeable.

Detailed Explanation:

Understanding the difference between these two leavening agents is key to successful baking:

• Baking Soda (Sodium Bicarbonate):
  • Composition: 100% pure sodium bicarbonate.
  • Activation: Requires an acid (like buttermilk, yogurt, lemon juice, vinegar, brown sugar, or cocoa powder) and moisture to react and produce carbon dioxide gas, which creates bubbles and makes baked goods rise.
  • Reaction Time: Reacts immediately upon contact with acid and moisture.
  • Use Case: Used in recipes that already contain acidic ingredients. Using it without enough acid will leave a bitter, soapy taste.
• Baking Powder:
  • Composition: A mixture of baking soda, one or more powdered acids (e.g., cream of tartar, sodium aluminum sulfate), and a starch (like cornstarch, which absorbs moisture and prevents premature reaction).
  • Activation: Most common types are 'double-acting,' meaning they produce gas in two stages: once when mixed with liquid at room temperature, and again when exposed to heat in the oven.
  • Reaction Time: Produces gas both during mixing and during baking.
  • Use Case: Used in recipes that don't have enough acidic ingredients to activate baking soda, or when a more sustained rise is desired.

Substitution: Substituting them directly is usually not recommended. If you swap baking soda for baking powder, your baked good might not rise properly and could taste bitter. If you swap baking powder for baking soda, it might not rise enough (due to lack of extra acid) or could be overly dense.

Pro Tip:

If a recipe calls for both baking soda and baking powder, it usually means there's an acidic ingredient that needs the soda, but also needs the extra lift from the powder, or the batter is too heavy for just one leavener.