Q: Recently I was making some angel food cakes, and I had just a little bit more than the amount of egg white that the recipe calls for. So I beat all of it and added it to the recipe. When it came out of the oven, I found it was so tall, I had to prop it up on cups to turn the pan over. Otherwise it was touching the table. And it had only been cooling for a couple of minutes when the whole cake fell out of the pan! Was that all due to the extra egg?
Answer: Yes; both of those changes can be explained by the extra egg white. The air you beat into the egg white is what makes the cake rise. So by using more egg white, you beat more air into the batter. As it heats in the oven, each tiny air bubble in the whipped whites expands like a little balloon and the cake rises. More little balloons means the cake rises more. In your case, it rose so much it stuck up over the top of the pan.
It’s a similar effect to what you would get if you added extra baking powder or baking soda to a regular cake. The cake would rise more, because they produce tiny air bubbles too. And the extra air bubbles were more than the flour was intended to support. So the cake was probably a little drier than usual. Whether you noticed that difference or not, it meant the cake didn’t stick to the pan. So as the cake cooled, it fell out of the pan more quickly.
In some cases, if you add too much egg white, or baking soda or baking powder, the cake will rise more in the pan — but then as it cools, the cake will collapse in the middle. That’s because there isn’t enough flour or sugar to provide the structure to hold up all the air bubbles. The expanding bubbles stretch the flour walls of the balloons to the point that they start to pop instead of getting stiff. You only had the cake fall out of the pan. If there were even more egg white, the whole cake would have fallen and you’d have a half-high cake. I’m glad yours came out OK!
Mary A. Keith, a licensed dietitian and health agent at Hillsborough County Extension, can be reached at firstname.lastname@example.org.