The Anatomy of a Toll-House Cookie

Every time I burn cookies (and yes, it does happen from time to time), I start thinking about what caused the recipe to go awry. In order to do this, one needs to understand what role each ingredient plays in creating a consumable structure (yes, I went there).

Adding to the complexity of the cookie is the fact that it is a baked product. As anyone in the back kitchen of a restaurant will tell you, there is quite a difference between cooking over the stove and baking in the oven. For the most part, stove top cooking allows for a great deal of improvisation (With notable exceptions of course. A fair amount of French sauces, for example).

Baking seems to be at the far end of the spectrum, requiring not just precision of ingredients, but precision of timing. Change the ingredients of a cookie recipe, and one must consider the amount of time the cookies must be baked in the oven. This is where I typically make my mistakes.

Due to this relationship between ingredients and baking time, I thought it best that I understand exactly the reasons why certain things belong in certain cookies. I could have done this exercise with any cookie, but felt the Toll-House Cookie was one that most everyone could relate with.

The ingredient list looks as follows:

  • 2 1/4 cups all-purpose flour
  • 1 teaspoon baking soda
  • 1 teaspoon salt
  • 1 cup (2 sticks, 1/2 pound) butter, softened
  • 3/4 cup granulated [white] sugar
  • 3/4 cup packed brown sugar
  • 1 teaspoon vanilla extract
  • 2 eggs
  • 2 cups (12-ounce package) NESTLE TOLL HOUSE Semi-Sweet Chocolate Morsels
  • 1 cup chopped nuts

There are flaws in this ingredient list, which should be recognizable by anyone who does a fair amount of baking. Namely, the ingredients are measured by volume, rather than by weight. With cookies, this may not be an issue (unless one is cramming flour into their cup containers), but it is something of which a baker should be aware. But as I am not making these cookies, merely examining the ingredients, I’ll let it slide…for now.

The Dry ingredients

Flour: According to Harold McGee and his book On Food and Cooking flour brings, flour brings to the table both proteins and starches. When moisture is added to flour and then baked, the end result is a mesh-like structure that McGee calls a gluten network. The threads of the network are made from the protein glutenin. These threads are quite elastic, and depending upon the other ingredients in the batter, can lead to the chewiness of the batter.

Coating these threads is another protein called gliadin, which help gives plasticity to the batter. In cookie dough, these proteins are less apparent for a variety of reasons, mostly due to the type of flour used, but for other reasons as well.

But proteins only make up 10% of any type of flour. The bulk of flour’s composition, nearly 70% worth, comes from starch. Starch is what falls between the threads of the gluten network, sucking up any moisture that comes its way. As it holds moisture, it also is responsible for the moistness of the cookie, and helps set the cookies structure as it bakes. The starch also tenderizes the any gluten structures during baking, ensuring that the end cookie is chewy, but not rubbery.

Baking Soda: This is the leavening agent that provides the carbon dioxide bubbles that helps makes the cookie softer or tender. Think of it as the gas that goes into a balloon. The more gas created, the larger the balloon (and the perception that it’s also lighter). Too much gas and …well…just be careful with the leavening agent.

So why Baking Soda and not some other leavening agent? Baking Soda is an alkaline base, which works to balance out the acidity of the molasses found in the brown sugar.

Salt: While salt can be tasted and can be considered a bit of a flavoring agent, its real role is that of a binding agent. As McGee puts it “The electronically positive sodium and negative chlorine ions cluster around the few charged portions of the glutenin proteins, prevent those charged portions from repelling each other, and so allow the proteins to come closer to each other and bond more extensively”.

Or as I put it – Were you ever part of a group of friends who got along famously, and loved one another. Then one of the friends moved away, and the rest started fighting amongst themselves and finally stopped seeing one another? That friend that initially moved away that seemingly held the group together? Yeah, they were the salt of the group.

The Wet Ingredients

Butter: The fat of the cookie, and lubricates the solids of the flour and sugar, encouraging them to slide apart and spread out. Depending on how thin or thick you want your cookie depends on how much butter you add.

Oh, and butter is also 15% water, so it does add moisture which the starch and sugar both are more than willing to suck up.

Granulated Sugar: Wait, sugar is a wet ingredient? It is if you cream it with the fat (which is what this recipe calls for). Adding sugar to fat creates air bubbles, which in turn gives texture to the cookie when combined with the flour.

Speaking of the flour, sugar combined with heat is added to starch, starch reaches its gelatinous boiling point sooner rather than later. This is likely the bit that gets to burning if left in the oven just a little too long. However, controlled well, it will also make the cookie a bit crisper (and drier).

Oh, and it adds sweetness as well.

Brown Sugar: Same as the granulated sugar but with the added benefit of adding the slight, deep, dark flavor of the molasses. This adds acid as well which needs to be cut by the baking soda, so it’s a trade off of sorts.

Vanilla Extract: Adds a slight bit of moisture and a whole lot of flavor. And what a flavor it is. In this recipe, the brown sugar, the vanilla, and the chocolate are the Holy Trinity.

Eggs: This gives the majority of the moisture to the cookie dough. The proteins of the eggs help bind the proteins of the flour to one another. If you want a more cake like chocolate chip cookie, use egg yolks only.

Chocolate Chips: It’s the star attraction, the headlining act, the reason everyone comes to the show. The flavor. But don’t discount the type of chocolate chip, as (depending on the chip) you can have one that melts into a gooey glop of pure heaven, or one that retains its chip shape.

Nuts: I prefer my chocolate chip cookies sans nuts, but as it’s part of the recipe, they should be accounted for. Flavor certainly plays a part, but don’t forget that the nuts also provide a bit a structure to the cookie, as well as altering the result mouthfeel. I’d also hazard a guess that a bit of oil is added when you through in some nuts, enough to add a bit of additional flavor but not enough to really make that big of a difference baking-wise.

This was fun for me. I’ll have to do this again with other recipes.