I have been hearing about people putting cornstarch in their cookies for some time now. Everyone claiming that it makes the cookies ridiculously soft and fudgy. This has been nagging at me. Everyone who’s tried it swears by it, but nobody ever talks about why! So I finally decided to give it a go, and of course, it does work! Surprisingly well. These cookies turned out to be some of the softest, most dense and fudgy cookies I have ever baked.
I was thinking about the science behind this the other day and trying to do some research as to why cornstarch has this effect in baked goods. And while I haven’t found one definitive answer, this is what I’ve concluded: We know that cornstarch and flour are both starches or course, and their main purpose in baking is the hold structure. However, flour has gluten in it and this gluten reduces the thickening power of flour. Therefore, cornstarch is about twice as powerful of a thickening agent compared to flour. By adding some cornstarch to the mixture you can have a dough that has far more liquid and fat in it compared to the flour and it will still hold it’s shape. Liquid and fat create moistness and softness in a cookie, so this is my theory. The cookie will be able to stand tall and hold it’s shape because of the thickening power of cornstarch while having a high ratio of fat and liquid. I’m sure there are more in depth sciency things behind it, but I love having these epiphanies!