raising agents

A baking guide to raising agents, discussing the fundamentals of leavening  

A baking guide to raising agents. The basic rule of baking is that if you want your bake to rise, you have to use some kind of raising or leavening agent. As a baker you have a few options to choose from and knowing the type of raising agents available, how they work and how they differ from each other is crucial to getting the best out of your bakes.  

Raising agents are added to baking mixtures to produce either steam or carbon dioxide. The bubbles add air to the mixture, which is then baked. The air bubbles become locked into the protein structure creating the fluffy crumb we know and love. 

There are three categories of raising or leavening agent, physical, chemical and biological. I’m going to take you through all of them, explaining how they work and why you need them.  

Baking guide to raising agents

Physical leavening agent: Steam 

Some baked goods count on a big burst of steam to get the rise they need. For example, choux pastry is baked at a high temperature for the first 10 minutes, making them expand due to the quick steam production. 

This same process is also present when we bake with butter. Butter consists of around 80% fat and 20% water. When baked this water evaporates creating the steam needed to raise you cake. In a cake butter is not enough on its own but in something like puff pastry it is. Butter and pastry are folded and layered together. When baked the steam creates air pockets between the layers of pastry giving you that flaky quality.  


Biological leavening agent: Yeast 

Fermentation is the process in which yeast cells break down sugar for energy. Yeast thrives on simple sugars. As the sugars are metabolized, carbon dioxide and alcohol are released into the bread dough. These bubbles of carbon dioxide are trapped in the protein structure of the bread giving you that beautiful texture.  

To aid the fermentation of yeast you need to consider some factors. Extreme hot or cold temperature will kill yeast; however, yeast will thrive in a warmer environment. It is best to leave brad to rise in a warm room or proving drawer to work its magic. Salt is a dough retarder, this means that it inhibits the yeast, too much salt in your dough will stop it for rising.   

Yeast is suitable for all bread doughs including enriched doughs used to make things like Chelsea buns. It is not used in cake making because of its strong distinct flavour.  

Types of yeast include compressed yeast, active dry yeast and instant yeast. 


Chemical leavening agents: Baking soda and baking powder 

Baking soda, or bicarbonate of soda, or just bicarb to you and me decomposes to form carbon dioxide that produces leavening. If you’ve ever made a baking soda volcano at school you know that when mixed with an acid it goes off like a rocket. Because of this reaction with acid, bicarb is usually used in acidic bakes. On its own baking soda doesn’t produce much lift, but when combined with acidic buttermilk, yoghurt, vinegar or lemon juice it produces that wonderful lift we are looking for. Despite this, very few recipes call for baking soda alone, it is usually used together with baking powder. There are however a few recipes that use this, soda bread, scones and red velvet cake all combine baking soda with an acidic ingredient as a raising agent.  

Baking Powder 

Baking powders are all made up of the same ingredients: baking soda and cream of tartar. Bicarbonate of soda is alkali and cream of tartar is acidic and the two react with moisture to create bubbles of carbon dioxide.  

Despite their similarities the two ingredients are not interchangeable in baking. They work in different ways and the recipe will have been tailored to suit either baking powder or baking soda.  

You can make your own baking powder by mixing 1-part cornstarch, 1-part baking soda and 2 parts cream of tartar.  


A word on Eggs  

Eggs are technically the fourth type of raising agent, mechanical. For mechanical raising agents to work you have to do something to them. Eggs don’t produce gas, they simply introduce air into the mixture. When we whisk eggs air bubbles form and those air bubbles get trapped in the mixture when we fold them in. This is why we fold in eggs gently so to not lose those precious bubbles. It is this hot air rising that gives the cake the lift.  

Baking guide to raising agents

And there you have it my baking guide to raising agents. Let me know if you found this post helpful and if you want to see more technical style posts in the future.  

For more baking inspiration check out my blog or Pinterest.  

Sarah xx