So often I read through recipes that call for the addition of an acidic ingredient to ensure that the Baking soda/ Baking powder reacts, and the cake rises. However, Baking soda/powder reacts to produce the required gases once it is heated in the cooking process. So why do the authors of these recipes insist that there is an acidic component to their cakes??
Sodium bicarbonate (baking soda) is an alkaline (base). It’s water soluble.
When heated to 180°F (80°C), sodium bicarbonate undergoes a thermal decomposition reaction in which one molecule of CO2 to every two molecules of sodium bicarbonate is released (1:2 ratio of CO2 molecule to sodium bicarbonate molecules).
But when the alkali is mixed with an acid, it creates a different chemical reaction. An acid chemical reaction produces a 1:1 CO2 molecule to sodium bicarbonate molecule. So full leavening is achieved with half the amount of molecules. Plus, as soon as the sodium bicarbonate comes in contact with water and acid, it triggers the chemical reaction. So leavening begins without heating to 180°F (80°C).
In a creamed butter better, if it sat until it reached 180°F without the leavening activated, the creamed butter would be already be melted, so unable to capture the CO2 in the butter pockets to create good lift. In a dough or batter without creamed butter, the activation would occur long after starch gelatinization (122°F/50°C), and protein denaturation (144°F/60°C). These reactions create the structure of the baked goods. If leavening happened at the end of these chemical reactions, there would be very little lift
Baking powder is a mix of sodium bicarbonate and acids.
Most baking powders contain two acids.
Baking powders are double-acting, meaning they activate, go dormant then activate a second time.
The first activation happens when the acid comes in contact with water. The second activation happens when the acid reaches a temperature of 140°F/50°C, so below the temperature of the completion of starch gelatinization and protein denaturation.
