Baking powder, bread soda, yeast or whipped egg whites are all used to add air to baking. Baking powder and bread soda are two widely used ingredients yet people are often confused about the differences. Both are leaveners, which means they help the baking rise, however they are chemically different.
Bread soda is scientifically known as a base ingredient, the opposite of an acid.
Once an acid — such as yoghurt, buttermilk, lemon juice, vinegar, or dark sugars like treacle — are added a chemical reaction starts which releases carbon dioxide. This forms little bubbles which help your baking to rise. Baking soda is potent, you want to use just enough to react with the amount of acid in the recipe.
As well as being a raising agent it has a distinctive taste, too much it will leave your bread or scones tasting metallic.
Baking powder, which is most commonly used in cake making, is a mixture of bread soda, cream of tartar, which is acidic, and usually cornstarch. Since baking powder already contains an acid to neutralise the bread soda, it is most often used when a recipe does not call for any additional acidic ingredients.
When the chemicals in baking powder become moist and warm they start to react and give off carbon dioxide, which is why it is important to get your cake into the oven quickly once the wet and dry ingredients have been mixed.
Some recipes call for both baking powder and baking soda. These recipes contain an acidic ingredient, however the carbon dioxide created from the acid and bread soda is not enough to leaven the volume in the recipe. That is why baking powder is used as well to add the necessary lift.
It is best to store both bread soda and baking powder in an airtight container in a cool, dry place. Both become stale and less potent, so it is worth keeping an eye on the best before date.
Preheat your oven to 200 degrees and line a flat baking tray with parchment.
Stir the flour, bread soda, sea salt and cinnamon together until completely combined. Make a well in the centre and add the buttermilk. Bring it together to form a dough and knead in the sultanas.
Form the dough into a round, slightly flattened shape and place it on the prepared baking tray. Cut a cross in the top and pierce each of the four corners.
Bake for 35 minutes or until it is baked through and sounds hollow when you tap the base. Allow to cool on a wire rack.
Pre heat the oven to 200 degrees and line a 2lb baking tin with parchment.
Stir the flour, caster sugar, baking powder and the zest in a bowl.
Add in the olive oil, lemon juice and the room temperature water, stir everything until completely combined. Scoop the mixture into the tin and bake for about 45 minutes until baked through. Allow to cool for about 10 minutes before adding the icing.
Mix the icing sugar with enough lemon juice to make a thick liquid. Pour this over the cake while it is still in the tin and allow to cool in the tin.
Line a 2lb loaf tin with parchment and pre heat your oven to 170 degrees.
Place the treacle, syrup and butter in a heavy based saucepan and gently melt them together. Set aside to cool slightly.
Sieve the baking powder, bread soda, flour and spices together and stir in the caster sugar.
Stir the cooled butter mixture into the whisked egg and add this to the dry ingredients. Combine everything well and then scoop it into the prepared tin.
Bake for about 50 minutes or until baked through.