Does It Really Matter If You Microwave Popcorn With A Certain Side Up?

It's been a while since many of us have been to the movies, but if you've tried to replicate the experience at home by turning out the lights and breaking out a bag of microwave popcorn, you might have wondered about the salty snack's peculiar cooking instructions. "Why do I have to cook the popcorn with this side up?" you might wonder.

A common misperception is that cooking popcorn wrong is a fire hazard. After all, popcorn is the only food called out by name by the National Institutes of Health's microwave safety page as a fire risk. However, as flammable as this delicious snack might be, the actual reason you are instructed to cook it with one side up is far less alarming. It's so you can have more of it to enjoy!

Microwave popcorn works like basically everything else you put in the microwave. The oven's radiation makes the water inside the corn kernels vibrate, which creates heat and pressure inside the shell until it "pops," revealing the starchy, edible snack.

So why can't the microwaves heat up the popcorn if it's cooked upside down? Technically, it can; it just won't do it as efficiently.

Reader's Digest explains that the reason for the "this side up" warning is actually the design of the bag itself. Most microwave popcorn bags — as well as packaging for other microwavable foods like personal pizzas and Hot Pockets — have a small piece of material called a susceptor in the bottom. This rectangular, metallic-looking material absorbs the microwave's radiation and heats up, which raises the temperature in the bag, helping to heat up the kernels faster and pop them by heat conduction. In order for this to work best, it needs to be underneath the kernels.

According to Yahoo, popcorn will still pop if you put the bag in upside down, much like it would if you were making popcorn in a traditional popper or with seeds in a normal brown bag, but you will end up with a lot more unpopped kernels in the bottom of your snack bowl than you would have otherwise. Additionally, the popped pieces might be bigger if cooked properly. So while following the cooking instructions isn't necessary, it will definitely get you more bang — or in this case, pop — for your buck.