I often get asked when and why we use baking soda instead of baking powder in a recipe so here is a vey brief blog – open to discussion – on this.
Baking soda or bicarbonate of soda is an alkaline that is added to baking mixtures to balance out acid ingredients like yoghurt, buttermilk, sour cream, fruit, cocoa and vinegar. Baking soda reacts instantly when moistened so it is important to get the mixture into the oven quickly. The bubbles formed help to leaven and lighten baking. Baking soda is generally best dissolved in milk or yoghurt prior to adding to the mixture and if adding as a dry ingredient make sure that you combine it with flour etc… and sift it into the mixture to ensure it is evenly dispersed. Modern baking soda is finer than it used to be so modern recipes will often add it with dry ingredients and older recipes will ask for it to be dissolved first.
Recipes such as Gingerbread and banana cake predominately use baking soda, because they have added acid substances like bananas, brown sugars, golden syrup, and sometimes buttermilk or yoghurt. The baking soda, looks to neutralise these acids and make the cake more palatable. You will also notice that the baking soda in banana cake or loaf reacts with the banana to give it a flecked deeper colour whereas if you use baking powder you will get a much paler cake.
Often chocolate cake will have baking soda as cocoa is acidic – Dutch processed cocoa however is alkaline and doesn’t react to baking soda.
Baking powder is a mixture of baking soda and an acid such as Tartaric acid or what cooks call cream of tarter. When the two of these substances are combined and given heat like in a cooking process, the acid and alkali react together and create gas (carbon dioxide) which creates bubbles in the mixture and therefore create aeration and expansion which will lighten cakes and muffins. The general rule is mixing 1 cup of flour with 1 teaspoon of baking powder to get the desired effect.
Most baking powder used now is double acting which means it reacts to moisture and also to heat – therefore you will have some reaction when the batter is mixed and another when the batter is cooked. Therefore you can wait for up to about 20 minutes before baking without impacting on the end result.
Too much baking powder will cause a bitter after taste – sometimes you will notice this with scones as they can be high in baking powder. It can also cause cakes to rise quickly and then collapse.
When making pikelets, recipes will often have baking soda and cream of tarter as opposed to baking powder. You can use baking powder but many proficient pikelet makers say that you get better results by adding soda and cream of tarter.
Raising agents such as baking soda, baking powder and cream of tarter will lose their effectiveness over time. They need to be replaced after 6 months although baking soda will last longer than baking powder.
To test whether your baking powder is still effective, mix 1 teaspoon of baking powder with 1/2 cup of hot water – it should bubble immediately.
To test baking soda, mix 1/2 teaspoon baking soda with 1 tablespoon of vinegar – it should bubble immediately.
While most of this is science, some of baking success does boil down to the individual cook!