The typical ways to make popcorn are on the stove top or in the microwave. Both the stove top and the microwave provide the fast burst of heat that popcorn needs to pop. The oven is not the ideal tool for making popcorn. It is, however, possible if you can satisfy certain conditions.
What Makes Popcorn Pop?
Popcorn kernels are starch and moisture inside an airtight hull. When heat is applied to the kernel, the moisture inside the kernel turns to steam. The steam expands until it bursts through the hull, causing the kernel to pop. Meanwhile, the heat and moisture inside the kernel turns the starch into a liquid. As the kernel pops, the starch bubbles out like soap bubbles. When it hits the air, it changes from a bubbly mass that is more liquid than solid to a solid filled with air chambers, kind of like Styrofoam. The resulting popcorn is more than 40 percent larger by volume than the original kernel.
The Role of Heat
Popcorn pops at about 445 to 460 degrees Fahrenheit, according to The Popcorn Board. Originally, native Americans popped popcorn directly over fires or stirred it into hot sand that had been heated by a fire. The result was a tougher popcorn than the popcorn modern snackers are used to. In the early 20th century, Charles T. Manley discovered just the right combination of heat and oil needed to pop popcorn to its fluffiest. He found that oil was a better conductor of heat to the kernels than air. Oil also evened the distribution of heat, so the kernels popped before burning on one side.
The Role of Moisture
A specific level of moisture is essential in popping corn. The optimal moisture content of popcorn is 13.5 percent. Commercial popcorn makers use ovens to dry the moisture content of corn at the time of picking -- which is typically 20 to 25 percent -- to the ideal moisture content. They then vacuum seal the popcorn into jars or seal it in airtight bags to keep the moisture content from changing before the popcorn is popped.
Problems in the Oven
The problem with popping corn in the oven is that the hot air of the oven doesn't heat the kernel effectively. Air, in general, doesn't transmit heat efficiently like oil, and the still air of an oven is not the intense stream of hot air used by a hot air popper. In the oven, the kernel takes time to heat up to popping temperature. While the kernel is heating, it is also drying out.
Optimal Oven Popping
The best way to pop popcorn in an oven is to make the conditions as much like a stove top as possible. Heat a dutch oven or some other kettle that will retain heat in a 450- to 475-degree Fahrenheit oven. Add oil that has a smoke point of at least 450 degrees Fahrenheit -- like corn oil -- and heat it. Add the popcorn to the kettle, close the lid and return the kettle to the oven. The popcorn might not pop as well as stovetop popping because the oven heat is not as concentrated as the heat of the burner. It also might burn because you cannot shake the kettle with the oven door close. But at least some of the corn should pop.