How To

Bicarb soda, baking powder, baking soda: what’s the difference?

How well do you know your raising agents? What's the difference between powders and sodas? And can you swap them, or leave them out altogether? Let's get to the bottom of it...
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What is baking powder?

Baking powder is a raising agent consisting mainly of two parts cream of tartar to one part bicarbonate of soda. The acid and alkaline combination, when moistened and heated, gives off carbon dioxide which aerates and lightens a mixture during baking. Baking powder is the raising agent added to plain flour to make self-raising flour.

Storage: Once opened, baking powder has a shelf life of up to six months, so always check the use-by-date before buying. Baking powder begins to lose its ability to leaven (rise) baked goods when it absorbs moisture, so store it in an airtight container in a cool dry place.

To check that it’s still active: Stir about ½ teaspoon of the baking powder into ¼ cup of tap-hot water. Active baking powder will cause the water to bubble.

moist whole orange cake

This divine moist orange cake uses baking powder to help create a lighter texture.

What is baking soda and bicarbonate of soda?

Baking soda is the American term for bicarbonate of soda, also known as bi-carb soda or carb soda. It’s an alkaline, and along with cream of tartar (an acid), it’s a component in baking powder.

Can I leave the bi-carb soda out of a recipe? Bi-carb soda makes the cake more spongy in texture and its colour more golden, and in some cases it forms part of the raising agent. It’s best to use it when it’s specified in a recipe. A small amount is fine, but a large amount will make a cake taste like soap. Usually 1 teaspoon of soda in a family-sized cake is the maximum amount used. Measure it carefully, level off the spoon properly, and make sure it’s sifted well as it does clump.

Bi-carb soda helps add a soft texture to these delicious carrot cupcakes.

What is cream of tartar?

Cream of tartar is an acid and a relative of tartaric acid. It’s the acid component in baking powder, working alongside bicarbonate of soda – an alkaline – to make a raising agent. Cream of tartar stabilises egg whites while they’re being beaten, making them stronger. This is particularly important in cakes such as angel food cakes, where the egg whites determine the whole structure of the cake. It’s also used in confectionery-making to help stop crystallisation.

Strawberries and cream sponge cake

Cream of tartar helps this strawberries and cream sponge cake turn out lighter than air!

How do you make self-raising flour?

The following proportions are equal to 1 cup of self-raising flour: 1 cup plain flour + 2 teaspoons baking powder, or 1 cup plain flour + 1 teaspoon cream of tartar + ½ teaspoon bicarbonate of soda.

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