Cookie Science

Okay, so last night I was sitting in bed, munching on a bedtime cookie (yeah, like you’ve never done that . . . .)

And while enjoying the chewy little devil, I started thinking about the texture and why it was nice and chewy, instead of brittle and crunchy. (I think about stuff like this a lot, I don’t know why . . .).

So, I decided to spend some time studying the chemistry of cookies to see if I could unearth the answer to that question. Turns out it can be based on a number of variables, so I thought I would collect them and write them down.

Obviously, the ingredients are the primary factor. So, lets take a look at them individually.

First, we’ll talk about flour. The majority of cookie recipes use all-purpose or pastry flour. But bread flour, which has a high protein content, and cake flour, which is high in starch, both produce cookies that tend to keep their shape and not flatten out or “spread” in the baking process. This is because of the gluten in the bread flour and the absorbant starch in the cake flour, which act to produce a similar results.

Next, we’ll add fat. Fat has an important role in the spread of a cookie. All things being equal, the more fat you use, the flatter and crispier your cookie will be. Using less fat results in cookies that are puffier, or “cake-like”. The majority of cookies are made with either butter, margarine or shortening. Whipped spreads should not be used for baking. (I know, they’re “healthier”, but they are primarily whipped water, will reduce to nothing in the baking process and end up tasting like crap. If you have to sit and worry about every morsel of butter that goes into your system, you have bigger issues than butter and you shouldn’t be baking cookies anyway.)

Of the three, shortening and margarine tend to be more temperature stable, and will help cookies keep their original unbaked shapes. Butter melts at right about 99 degrees fahrenheit –which is a much lower temperature than the melting point of other solid fats--resulting in a “melt-in-your-mouth” burst of flavor (because that just happens to be your own body temperature, give or take a few tenths of a degree).

But, cookies made with butter tend to spread out. Since butter is an essential ingredient for some cookies, such as shortbreads, if they are not holding their shape, you should lower the amount of butter in the recipe. You can also get the same result by lowering the, amount of sugar, or baking soda in the recipe.

Then there are baking powder and baking soda to consider. Baking powder and baking soda are used as levening agents in cookies. (You can also use stiffly beaten egg whites in some delicate cookies, but you have to blend it in gently so you don’t ’break” the foam.) Baking soda is actually bicarbonate of soda. Baking powder is a combination of bicarbonate of soda and cream of tartar. Why? Because Cream of tartar is acidic and sometimes you want your dough to be acidic. Baking soda neutralizes the acidity of the dough, which is what allows the cookies to brown in the oven. When you use baking powder, it does not reduce the acidity in the dough. So the cookies will turn out to be puffier and they will not brown as much.

Okay, now we’ll add the sugar. Sugar liquefies during the baking process. But the type you use will alter the product coming out of the oven. White sugar makes a crisper cookie than brown sugar or honey. Cookies made from brown sugar will absorb moisture after baking, helping to ensure that they stay chewy. Most chocolate chip cookie recipes contain both brown and white sugars. If you lower the amount of sugar called for in a cookie recipe, the final baked cookie will be puffier than its high-sugar counterpart.

You add eggs (or other liquids) to the cookie dough to act as an agent to bind the dry ingredients.. Liquids can either cause cookies to puff up or spread. If you use egg , you end up with a puffy, cake-like texture. If you use a tablespoon or two of water or other liquid instead of egg, it helps the cookies spread into flatter and crisper rounds. If you use only egg yolks to bind the dough, you end up with a rich tasting cookie with a generally crisper texture. If you use only egg whites, you end up with a cookie that is dry and cakey. You can alter this by adding extra sugar, but it ends up being a really sweet cookie, like a macaroon.

You can also alter your finished product by the mechanical processes you use.

Mixing

Mixing is important to the finished product. Some recipes call for you to cream the fat and sugars together until light-colored and fluffy. Other cookies call for almost a sandy texture, which you accomplish by cutting the fat into the flour. If you over-mix, you will add too much air into the dough. When that goes away in the baking process you end up with a big, flat cookie. The best route is to follow the recipe instructions. Or if you’re winging it, like I do, make sure that once you get all your dry and wet ingredients together, mix until just combined.

Temperature

Unless the recipe says differently, ingredients should be at room temperature before mixing. However, once its mixed, cookie dough can be chilled before baking so it holds its shape better. Rolled and cut-out cookies should be refrigerated before baking for sharper, clearer edges. Drop cookies, such as chocolate chip or oatmeal cookies, can be at room temperature before baking; the spoonfuls of dough will spread and flatten out to the desired result.

Equipment and Baking

Different baking sheets and ovens produce different results. Thin baking sheets convey to much heat and the cookie bottoms will brown too fast. Special insulated baking sheets allow air movement and help cookies bake much more evenly. Jellyroll pans (semi-thick rimmed baking sheets) are a really good baking tool. No matter which type you use. You have the choice of greasing the baking surface, using parchment paper or a nonstick pan liner. Each of these last two choices makes cookie removal and clean-up really easy.

Baking Temperature

Follow the recipe guidelines for baking temps. But cookies are usually baked in at a medium temperature of 350 degrees F. And only for eight to twelve minutes, depending on the size of the cookie. Then if you wish to enjoy chewy cookies, allow them to cool on the pan for three to five before transferring to a cooling rack. For crispier cookies, let them cool for only one minute on the baking sheet before transferring to a wire rack.

Hope this helps you understand more about cookie science. Now, go make some cookies.