How does the cookie rise?

1. Leavening agents:

* Baking soda: This chemical leavening agent reacts with an acid (like buttermilk, brown sugar, or lemon juice) to produce carbon dioxide gas, which creates bubbles in the batter and makes the cookie rise.

* Baking powder: This is a double-acting leavening agent that releases carbon dioxide both when mixed with wet ingredients and when heated in the oven.

2. Steam:

* As the dough bakes, the water in it turns into steam. This steam expands, creating pockets of air that help the cookie rise.

3. Air trapped in the batter:

* When you cream butter and sugar, you incorporate air into the batter. This air expands during baking, contributing to the rise of the cookie.

4. Gluten development:

* While cookies are typically made with low-gluten flours, gluten does form during mixing. Gluten helps to create a structure that traps the air and gas bubbles, allowing the cookie to rise.

5. Fat content:

* The fat in butter and shortening helps to create a tender cookie that doesn't rise too much. Fat also traps air in the batter.

The interplay of these factors determines how much a cookie rises.

Here are some additional points:

* Overmixing the dough can lead to excessive gluten development, resulting in tough cookies.

* Using too much leavening agent can cause the cookies to spread too much.

* Chilling the dough before baking can help to prevent overspreading.

Overall, the rise of a cookie is a delicate balance of ingredients, mixing techniques, and baking temperatures. Understanding these factors allows you to bake cookies that are perfectly light and airy!