This is the third in a series of 7 “Cake Batter” classes. We’ve been using the traditional “quatre quarts” pound cake recipe as a tool to understand the science of cake batter. In the first class we learned how mixing method affects cake texture. In the second class we learned how to use salt and chemical leavening to improve the cake texture and flavor. The remaining classes in this series will look at each of the original ingredients of the basic pound cake and their respective roles in the cake batter – flour will be up first.
The Baker’s Formula
A successful cake formula balances the four main ingredients-flour, sugar, fat and eggs. Although the quatre quarts recipe seems perfectly balanced because all the ingredients are of equal weight, through our testing we’ve seen that the original recipe does, in fact, make a cake that’s sorta dry, dense and not quite sweet enough for modern tastes.
Each of those ingredients has an important role in the recipe. The flour and eggs form the structure of the cake with a network of proteins and starch. Butter and sugar provide flavor and moisture, but weaken the cake’s structure.
In a successful cake, the ingredients that strengthen the cake structure (flour and eggs) are balanced with the ingredients that weaken the cake structure (sugar and fat). Too much flour and/or eggs will make a cake that is dry and tough. Too much sugar and/or fat will make a cake batter that will not set properly and may even collapse. To create a moist, sweet and tender cake that bakes up with a nice even crumb the four main ingredients have to work together.
So let’s look at the flour. Specifically, wheat flour. Although the four ingredients of the quatre quarts are equal in weight, the flour has the greatest volume.
About Flour in Cake Batter:
Wheat flour is composed of proteins, starch, lipids, sugars and enzymes. The two most important of these components, the starch and the protein, form the cake “crumb”. The cake crumb is a network of starch and protein interspersed with millions of tiny air bubbles. To learn lots of detailed information about the science of flour, and the composition of different flours, please visit the Baking Ingredients – Flour page.
For cake batter, stronger gluten is not desirable so we have to limit it’s formation. How do we do that? We’ve already taken a few steps with our recipe to impede the gluten formation. The reverse creaming method limits gluten formation by coating the flour proteins with fat before liquid is added. Limiting the amount of salt in the recipe helps, since salt will strengthen gluten. The easiest way to control the amount of gluten in the cake batter is to use a flour with a lower protein content.
The obvious choice for cake bakers is cake flour, made from low protein, soft wheat. Not only is cake flour desirable because of the lower protein content, it’s desirable because it’s chlorinated. Chlorination makes cake flour slightly acidic, which weakens the gluten. Chlorination also alters the starch so that it can absorb more liquid and allows the fat in the batter to bind better with the starch. A cake made with chlorinated flour has a stronger starch gel, a weaker gluten network and very evenly distributed fat molecules. The result is a cake with a tender and fine crumb.
In a pinch you can substitute all purpose flour for cake flour. For each cup of cake flour use ¾ cup of all purpose flour plus 2 tablespoons of corn starch. This will lower the protein content, but the results will not be exactly the same since all purpose flour is not chlorinated.
To make a chocolate cake you can replace some of the flour in the recipe with cocoa. Cocoa has starch and protein so it will absorb some water and contribute to the cake structure, as flour does. Replace equal amounts of flour with cocoa. For example, if you add 2 oz of cocoa to a cake batter, reduce the flour by 2 oz.
Baking a Gluten-Free Pound Cake:
With the rising interest in gluten-free baking, I thought I should try baking the pound cake recipe with a commercially prepared gluten-free flour. Although a lot of our efforts with the pound cake recipe have been to avoid forming too much gluten in the batter, some gluten is needed to give the cake it’s structure. Gluten-free recipes use non-wheat flours that don’t contain gluten. When using gluten-free flour, a binding agent must be added to the batter to replace the elasticity lost without the presence of the wheat flour protein.
The flour I used contains rice flour, potato starch, pea fiber, tapioca starch and xanthan gum. The xanthan gum acts as a binder to replace the structure provided by wheat gluten.
First I made our pound cake recipe using the reverse creaming method. The cake made with the gluten-free flour was significantly flatter than the cakes baked with wheat flour. This was not surprising since gluten helps the cake keep it’s shape while it rises in the oven. Without gluten the structure is weaker so the gluten-free cake can’t rise as high as a cake made with wheat flour.
Since I didn’t have to worry about gluten toughening the cake crumb, I tried mixing the cake using the creaming method to incorporate more air bubbles and, hopefully, get some extra rise on the cake. The second test was more successful. The gluten-free cake made with the creaming method baked up a little higher and lighter than the cake made with the reverse creaming method. Once again showing that mixing method does matter for successful baking.
After continued experimentation I created a better Gluten Free Pound Cake recipe. It is available exclusively in my Perfecting Pound Cake eBook.
In the next class we’ll learn all about eggs in cake batter.