Cookie Chemistry

So last weekend my sister Leah was over and decided to slap together some cookies from scratch and estimation. They kinda ended up a little over-dry, I think because of too much egg white and too much flour. I didn't want to bother her at the time with all I had learned about what ingredients do what from that Good Eats show, but I think she would have appreciated my input.

So I figured I should write down all the cookie chem I know, and make a diagram for easy access scratch estimation cookies. This exaplantion assumes a standard cookie is a properly prepared chocolate chip cookie using the recipe on the back of a tollhouse chocolate morsels pack. So when the explanation justs ends in "makes the cookie drier", you can assume it means drier than a standard cookie.

And for God's sake, remove your cookies before the center sets and becomes brown! Or all I have written here will be for naught!

1. Flour
For the purposes of cookie baking, white flour is best. The modification comes in with the amount of protein (gluten) in the flour.

Low protein or cake flour will make the cookie softer and drier.
HIgh protein flour will make the cookie chewier and moister.

2. Eggs
Eggs make cookies puffy. The ratio of white to yolk will alter the cookie's moisture level.

More whites dry the cookie out.
More yolk makes the cookie more moist.
Replacing eggs with milk will make the cookie thinner.

3. Butter
Using melted butter can help retain moisture in the cookie. Butter causes the cookie spread and become thin.

Replacing butter with shortening will make the cookie more puffy.
Replacing butter with margarine will make the cookie slightly more thin (but you probably wouldn't notice).

4. Baking Soda and Baking Powder
These ingredients cause the cookie to rise. They both produce bicarbonate that nullifies acid in the cookie. Acid causes the cookie to rise. Different amount of baking soda and baking powder will have the most powerful effect on the height and thickness of the cookie.

Baking soda eliminates the most acid and the cookie won't start rising until it's been baked for at least 7 to 10 minutes (most of the baking cycle!) so it makes the cookie thinner.

Baking powder eliminates less acid and has special rising acids in it, so the cookie will start to rise as soon as it gets hot, and it will be puffy.

5. Sugar
The difference between white, brown and darker sugars is the amount of molasses present. Obviously white sugar has the least. Molasses adds moisture and makes the cookie softer and chewier. You can even add molasses directly to the batter instead of sugar to get a chewy ginger snap situation.

White sugar makes for a crispier (not necessarily drier) cookie.
Brown sugar makes a softer cookie.

6. Baking

Cool dough spreads slower and rises more.
Small scoops rise more.