Dear Ms. Lori and students,
You’ve got to know your dough. Whether you want chewy cookies or crispy dunkers, it’s all about chemistry. Especially, when it comes to the flour.
At the wheat lab on the Washington State University campus where my friend Doug Engle works, scientists test out different kind of flours to find out which kind works best. They’ve got baking down to a science.
Different types of wheat grown in the west come into the lab for testing. Their first stop is the flour mill.
The machinery at the mill grinds up wheat kernels and makes them explode. When the kernels explode, they turn into tiny flour particles that will impact how the cookies look and taste.
While an explosion might sound like it damages the wheat kernel, it actually happens fast enough to keep tiny storage compartments for the long, sugary chains of molecules—the starches—from blowing apart. You need starch in your flour to help soak up the liquids in the dough and help give the cookies their form. If the storage compartment, or starch granule, breaks then liquids will flood the cookie.
Cookie structure also depends on proteins. Cookies have protein, but not a whole lot. So, unfortunately we can’t just make cookies for dinner.
Long stretchy chains of proteins help hold the dough together, and even trap tiny air bubbles. This gives the cookie the texture you can feel when you take a bite.
At the lab, scientists test out flour that comes from either hard or soft wheat kernels. Hard wheat is great for baking bread, but doesn’t work as well for cookies.
“What makes the best cookie is soft wheat,” Engle explained. “If you bite into a wheat kernel and if it’s softer, it will make a better cookie.”
All wheat started out soft, but over centuries, hard wheat developed. Scientists aren’t totally sure why there are two kinds, but they can tell them apart when they look closely at their structures.
Some of my mice friends helped with wheat research here at WSU. They tried both kinds and preferred soft wheat to hard wheat. We don’t know exactly why or how they can tell them apart, but soft wheat is easier for them to chew. Scientists, on the other hand, can use lab equipment to measure the differences.
In the wheat lab, they measure the quality of a cookie by how it spreads in the oven. Most cookie recipes call for all-purpose flour. Usually it contains mostly hard wheat flour so to balance out the dough they call for more water and butter.
With hard wheat, the starches suck up too much of the water in the dough and the cookie shrinks when it bakes. Soft wheat makes a cookie softer and bigger.
After talking to Engle about cookies, I was getting thirsty. Thankfully, the lab of cookies was just a short walk away from a place where you can find milk courtesy of the university dairy cows.