Understanding the differences between baking soda and baking powder

Understanding the Differences Between Baking Soda and Baking Powder
Anyone who has enjoyed baking at home is probably familiar with baking powder and baking soda, essential ingredients known as leavening agents. But what exactly are leavening agents, and how do you know which one to use in your recipe? In this article, we explore the different leavening agents, the science behind baking powder and baking soda, their distinct roles in baking, and tips for when to use them.

What are leavening agents?

The word “leaven” has an interesting etymology that goes all the way back to Latin (“levamen” or “levamentum,” which means “alleviation” or “a means of lifting”) via old French and middle English (“levain,” meaning sourdough).

From the 14th century onwards, the word leaven came to mean any substance added to dough to produce fermentation, thus, in its modern sense, a leavening agent is what you add to your dough to make it rise.

The three main types of leavening agents

Nowadays, bakers use three main types of leavening agents, depending on the recipe and the end product: chemical leaveners, like baking powder and baking soda; biological leaveners like yeast; physical leaveners, like steam and air; or some combination of the above.

Chemical leaveners are used when making cakes, waffles and some types of quick breads, such as corn bread or muffins. They cause the product to rise thanks to a chemical reaction that is brought on when the leavener is mixed with the other ingredients. More on that later. 

Biological leaveners like yeast, used for making bread and pastries, are so-called because they are made up of microscopic living organisms (fungi and bacteria) that cause the product to rise thanks to biological processes. Baker’s yeast, for example, is a microscopic fungus called saccharomyces cerevisiae, which converts sugar into alcohol and carbon dioxide (a different strain of the same species is also used in brewing, for the same reason). This production of carbon dioxide (CO2) creates tiny pockets of air in the dough, which causes it to rise. During baking, air and steam contained in these pockets will expand, causing the bread to “bloom” (rise) and create bread’s distinctive crumb structure.

Physical leaveners, like steam and air, are also used in certain pastries and work according to a similar process as the creation of the air pockets in bread. The successive layers of butter in puff pastry create an impermeable layer of fat that traps the air and moisture inside. As the product’s temperature exceeds 50°C during baking, the air expands and the moisture evaporates, separating the layers of dough and creating the distinctive texture of puff pastry.

Some recipes call for a combination of physical and biological leaveners. Croissants, for example, are made with leavened puff pastry which incorporates leavened dough but also similar layers of butter and dough as puff pastry. This gives croissants their unique texture, which is a combination of flaky pastry with tender, melt-in-the-mouth dough.

Baking soda vs baking powder

The most widespread forms of chemical leaveners in baking are baking powder and baking soda. These two substances are commonly confused but there is a subtle distinction between them.

Baking soda, also known as sodium bicarbonate (or bicarbonate of soda), is an alkaline powder that reacts when it comes into contact with an acid, producing CO2, which creates bubbles in the dough or batter, causing it to rise. As an alkaline ingredient, it can leave a slightly metallic taste in the end product if the baker does not correctly balance the flavor with acidic ingredients. 

Baking powder, on the other hand, which serves the same purpose, is simply a preprepared mixture of sodium bicarbonate, acid and another food-grade powder such as cornstarch. 

The relative advantages and disadvantages of baking soda and baking powder

The advantage of baking powder is that, because it already contains acid, it can be used in recipes that don’t have other acidic ingredients. As mentioned above, the sodium bicarbonate will not produce its leavening effect unless it comes into contact with acid. This added acid in baking powder also neutralizes the unpleasant alkaline aftertaste. 

Most types of baking powder are “double-acting,” which means that they will cause the products to rise twice: once when mixed with the other ingredients and again when exposed to heat in the oven. 

The advantage of baking soda is that, as it is pure sodium bicarbonate, it is a more powerful leavening agent than baking powder. As an alkaline ingredient, it can also help give the end product a more appetizing golden-brown color by enhancing the Maillard reaction.

Choosing between baking powder and baking soda

It is important to be aware of the products’ respective properties so that you know when best to use each one. In most cases, baking powder will be preferred for home use for reasons of convenience: it already contains both acid and alkaline components, so the chemical reaction will take place automatically, which simplifies recipes and does not impart any unpleasant taste to the end product.

Moreover, double-acting baking powder ensures a controlled rise, resulting in a more consistent end product, as well as allowing greater flexibility in preparation. As the CO2 is released in two phases, the distribution of air pockets is more uniform, making it suitable for making cakes and muffins, which have a relatively dense texture. Furthermore, as the second leavening reaction takes place as the dough or batter is cooked, the preparation can sit for extended periods without losing its leavening potential. This is practical when preparing large baches or when you are making several products at the same time. 

As a rule of thumb, it is fine to use baking soda under two conditions: if the recipe already contains acidic ingredients and when you need a quick leavening reaction. 

Recipes that call for acidic ingredients such as buttermilk, yogurt, vinegar, lemon juice, or brown sugar, for example, can be made with baking soda. The natural acids in these ingredients will activate the chemical reaction with the sodium bicarbonate as well as naturally offsetting the metallic flavor. However, recipes using baking soda should be baked immediately after mixing to take advantage of the production of gas. Inversely, if there are no acidic ingredients in your recipe, you are better off using baking powder. 

Why do some recipes include both?

Some recipes include both baking powder and baking soda to make the most of the properties of each ingredient. In a chocolate cake, for example, baking soda neutralizes the acidity of the cocoa powder while baking powder provides additional leavening to ensure that the cake rises well. In pancakes, the baking soda gives a golden color while the baking powder ensures a second rise in the skillet for a light, fluffy texture. By understanding the complementary characteristics of these two ingredients, you can get the best results in terms of taste, texture and appearance.