What Makes the Perfect Cookie?

Maria Corradini loves cookies. And as someone who’s being applying mathematical modeling to food for many years, she found that cookies presented an interesting challenge.

“The baking process is quite complex,” says Corradini, an associate professor in the University of Guelph’s Department of Food Science and Arrell chair in food quality at the Arrell Food Institute.

The cookie-loving food scientist wanted to better understand the baking process in order to increase food safety and sustainability. Undercooking or overcooking cookies obviously makes a bad product, but it also has safety implications, she says. In addition, finding the best model for baking would allow cookie makers to use less energy and fewer resources.

Corradini and her co-authors recently explored optimal parameters of cookie baking by examining changes in color and shape during baking. Doing so, Corradini says, is the first step in establishing a kinetic model of the baking process to help cookie makers produce consistent products.

“Our ultimate idea is to properly characterize the heat and mass transfer phenomena,” she says. The researchers’ paper was published in the Journal of Food Science.

The methodology was simple. A standard dough recipe was made, and three batches of cookies were baked at three different temperatures—185°C, 205°C, and 225°C—for up to 12 minutes. Shape, color, size, and moisture were measured while the cookies were baking. “We [were] basically mapping reaction kinetics of the different phenomena we’re interested in,” she explains.

For the duration of the baking, the researchers took two cookies out of the oven every 2 minutes to measure their moisture levels. Temperature was measured every 2 minutes using an infrared thermometer at the exterior of the oven. The changes to the cookies’ shapes—thickness and radius—were measured using an electronic caliper. The cookies were also purposely overcooked so the researchers could include overbaking in the model.

Complex Reactions

The researchers then ran a correlation analysis to find out which element of baking had more effect on which part of the cookie. Temperature, they found, had a significant effect on the shape of a cookie as the batter melted, but once an inflection point had passed, the cookie began to dehydrate and shrink.

“The ability to identify those transitions is one of most interesting parts of complicated modeling,” Corradini says.

The coupling of heat mass transfer with reaction kinetics in food is underexplored, according to Corradini. “We are assuming every reaction in food is linear,” she says. But that’s incorrect, she emphasizes. “It is a complex reaction; we have to separate each reaction into stages, and each has to be characterized.”

Corradini and her colleagues are now working on the next stage of this research, which is modeling the formation of acrylamide in cookies. She’s also involved in projects that are investigating new technologies to improve baking. One is a project that uses digital twins to model a virtual baking process. That would enable producers to experiment with different recipes and baking frameworks without wasting ingredients and other resources. “We need actual data to do that,” she says. “It’s a step forward to virtual cookies.”

She has also been involved in a project with researchers at the University of Foggia in Italy who used a very high-resolution biomedical 3D printer to produce biscuit prototypes. They found that they could design a biscuit that needed much less time baking, thereby saving energy.

Corradini maintains that the food industry could benefit from better modeling. “The food industry is not known for its amazing modeling, in my opinion,” she says. “We are a little bit behind. So we are trying to simplify [it] in order to validate the whole cookie.”ft