Week 5: Angel Food Cake

Last week, I settled the meringue stiffness debate. This week, I am going to look into another debate: granulated sugar versus powdered sugar. When making angel food cake, the sugar is roughly divided in two with half of the sugar being incorporated into the meringue and the other half being folded in with the flour. Granulated sugar is almost always used for the first half of the sugar, so here we are really talking about the second half of the sugar that gets folded in with the flour. Proponents of powdered sugar claim that is lighter and folds in more easily, reducing how much the meringue is deflated. There is also usually a small amount of cornstarch in powdered sugar to help keep it from clumping. The cornstarch can help stabilize the meringue by absorbing some water. This supposedly makes a lighter, taller cake that is more tender. I will put this to the test by making two cakes: one with the second half of the sugar being powdered and one using all granulated sugar.

Powdered sugar

Granulated sugar

As I was making the batter, I did find that the powdered sugar incorporated more easily than the granulated sugar. The granulated sugar formed clumpy pockets of dry ingredients, while the powdered sugar dissolved easily into the batter. The results were extremely clear. The batch with powdered sugar had a rise of 7.3 cm, while the batch using granulated sugar only rose to 6.5 cm. Texturally, the batch with granulated sugar was slightly tougher but still very tender overall. These results are drastically different, indicating that the powdered sugar does lead to a better angel food cake.

I also learned something by accident this week as well. Up to this week, I'd been using egg whites left over from my lemon curd tests. These had been frozen and then thawed in the refrigerator for a few days before using. Last week, I finished off the last batch of frozen egg whites, so this week, I used fresh eggs. The difference between older and fresh eggs is pretty drastic. This week using the same recipe with fresh eggs, I got a rise of 7.3 cm, while my best rise last week was 6.7 cm. This is likely due to a combination of two factors. As egg whites age, they lose carbonic acid in the form of carbon dioxide that escapes through the porous shell (or into the container they are being stored in), making them more alkaline. Meringue is more stable in an acidic environment as we discussed last week, but the egg whites become more alkaline as they age, so using the same amount of cream of tartar with fresh eggs creates a more acidic environment. Older egg whites left in the fridge can also lose some water, which gives us less steam for the rise in baking. There was a significant difference between fresh and older egg whites in my tests, so fresh eggs are definitely the way to go.

Next time, I will vary the flour content of my test batches to see if it plays a significant role in the tenderness of the final product.