Baking soda and baking powder look alike, and are both used as raising agents in cooking. But they cannot be used as substitutes because there are significant differences. The chemical composition of baking soda is different from that of baking powder. Many recipes call for the use of both baking soda and baking powder. Care should be taken to ensure that they are still active. Instructions regarding amounts should also be followed precisely.
Baking soda is sodium bicarbonate, which is alkaline or a base.
When baking soda is mixed with an acid, the chemical reaction produces carbon dioxide. That is why recipes calling for the use of baking soda also have one or more acidic ingredients.
If the alkaline content in baking soda is not neutralised by acidity, the product will have a metallic taste.
It is recommended that baking soda should be mixed with dry ingredients before adding liquid, and that the product should be baked immediately. This is because the carbon dioxide produced will start to dissipate if left for too long.
Baking soda raises the pH level in baked goods. This gives them an attractive browned look.
Baking soda as a raising agent is about three to four times more powerful than baking powder.
To test if baking soda is fresh, it should be combined with vinegar. If it bubbles vigorously, it will work.
Baking soda has a number of uses. It is used widely for cleaning household articles. Its alkaline properties are useful in counteracting digestive complaints like acidity.
A study was conducted in 2009 on people who had chronic kidney disease (CKD). It showed that when CKD patients took a small tablet of sodium bicarbonate alongside their regular medical routine, it slowed the decline of kidney function.
Baking powder is a mixture of sodium bicarbonate and acid. It also contains a drying agent.
Baking powder contains acid which may be fast acting or slow acting. The fast acting acid is monocalcium phosphate. As soon this type of baking powder comes into contact with liquid, carbon dioxide is released.
The slow acting acid in single acting baking powder is either sodium acid pyrophosphate or sodium aluminium sulphate. The chemical reaction will occur only when the product is exposed to liquid and heat. In practical terms this means that the product to be baked will start to rise only after it is mixed and put into the oven. The leavening process will not suffer if the product is not baked immediately after mixing.
Two types of baking powder are available – single acting or double acting. The single acting products contain only one type of acid, either fast or slow acting. The double acting product contains both types of acids.
If the baking powder is single acting and contains slow acting acid, the chemical reaction will occur only when the mixture is heated. If the acid is fast acting, the leavening will start when liquid is added.
When baking powder is fresh, it will bubble up when hot water is poured on it.