One of the staples of the holiday season is pie and while you may have Grandma’s recipe for the perfect crust, do you really know what goes on at a molecular level? UCLA biophysicist Amy Rowat shares some of the scientific aspects of apple pie and explains how you can apply these insights in the kitchen.
1. Think of butter as a gas.
Butter is really just a bunch of teeny tiny water droplets dispersed in a matrix of fat. In the oven, these water droplets convert from liquid to gas. This means that the chunks of butter you can see in your dough are really just big pockets of air waiting to happen. More air = flakier crust! While butters with the highest butterfat content are generally synonymous with the highest quality butter, when it comes to baking pie a slightly lower fat content, and higher water content, may be a good thing.
2. Experiment with the liquids you add to your pie dough
Gluten gives structure and stability to pie dough, but can also make pie dough dense and tough when over-developed. Typically water is added to create pie dough, but you can experiment with different liquids —like vodka, rum or even carbonated water— that impede the formation of gluten protein networks.
3. Sometimes the best pie is a day-old pie.
Temperature is important for pie texture. Because molecules flow more quickly past each other at higher temperatures, hot pie filling straight from the oven will be more runny; as the pie filling cools, starchy molecules like cornstarch and flour spend more time interacting with each other. As the pie cools, the pectin molecules of your fruit also spend more time interacting with each other. This results in a more solid, gel-like filling that will take longer to seep out of the pie when it is cut and served on a plate.