What is the Difference between Bicarbonate of Soda and Baking Powder? And How are Both Used?

Baking powder and baking soda are two basic baking ingredients that give  magic to our cakes, cookies and pastries. But nearly every baker has encountered this scenario: you're following a recipe which calls for baking powder but you only have baking soda. The question is can you substitute?

spoon with bicarbonate soda and baking powder
Baking essential – bicarbonate of soda & baking powder

What's the real difference?

While both baking soda and baking powder are leavening ingredients, they are chemically different. And the major difference is that baking soda (also called sodium bicarbonate) is a base or alkaline. If you have been baking for a while, you may notice in various recipes calling for baking soda that something acidic is also included, such as vinegar (like when you are making red velvet cake), yoghurt (for chocolate and vanilla-base cakes) or lemon juice. When acid and alkaline both come into contact, bubbles or carbon dioxide are formed. This forms the leavening in your dough or batter. While baking soda will still bubble up when heated, it needs to react with acid so it doesn't produce that metallic taste – the last thing you want your cake, brownie or cookie to have.

Baking powder, on the other hand, is a mixture of baking soda and acid, and some corn starch to keep the two different chemicals dry and separated. Most baking powders available in local stores are labelled 'double acting' which means that when used, part of the leavening occurs the minute the baking powder comes in contact with water, and the rest occurs once it is heated. Baking powder is often used for recipes containing non-acidic ingredients like Dutch-processed cocoa and whole milk. Meanwhile, baking soda (since it needs to react with acid), is used more often for recipes that have acid-containing ingredients like natural cocoa and yoghurt.

Can you substitute one for the other?

Fortunately, yes. And it isn't too hard. You just have to remember the rule of thumb: baking soda is three times as powerful as baking powder. So if the original recipe calls for 3 teaspoons of baking powder, you only need a teaspoon of baking soda as substitute. You will also need a teaspoon of acid (such as vinegar or lemon juice) for every 1/2 teaspoon of baking soda.

Conversely, if the recipe calls for one teaspoon baking soda and you're using baking powder as a substitute, you need 3 teaspoons of it. But wait – here's another gem of fact: Baking powder already contains salt so if you're controlling the salt in your baked goods, leave it out as you proceed with the rest of the baking process.

Okay, let's do a quick recap. The next time you bake, there's no need to rush to the store to buy baking soda. Just reach out for some baking powder, triple the amount called for, and leave out the salt. No baking powder and only have baking soda? Divide the required amount by three and adjust the acid in your ingredients. That easy. J

Why do some recipes use both?

Like most bakers out there, you've probably wondered why some recipes call for both baking soda and baking powder. If they are both leavening agents and do pretty much the same thing on baked goods – why use them both at the same time?

It all boils down to the need for acid. As we mentioned earlier, baking soda needs some acid to activate and produce the carbon dioxide which leavens the batter. To make sure that there is enough acid to neutralise the soda, baking powder is added at the same time in some recipes (particularly those that have no or fewer acid-containing ingredients). Also, both can be added for that nice brown colour and tangy flavour.