Everyone knows popcorn is a great tasting snack, but it is also a fascinating food and great subject for your science fair or school project. Take a look through these sections for helpful information.
What Makes Popcorn Pop?
People have been fascinated by popcorn for centuries. Native Americans believed that a spirit lived inside each kernel of popcorn. When heated, the spirit grew angry and would eventually burst out of its home and into the air as a disgruntled puff of steam. A less charming but more scientific explanation exists for why popcorn pops.
Popcorn is scientifically known as Zea mays everta. It’s a type of maize, or corn, and is a member of the grass family. Popcorn is a whole grain and is made up of three components: the germ, endosperm, and pericarp (or hull). Of the 4 most common types of corn—sweet, dent (also known as field), flint (also known as Indian corn), and popcorn—only popcorn pops! Popcorn differs from other types of corn in that its hull has just the right thickness to allow it to burst open.
Each kernel of popcorn contains a small drop of water stored inside a circle of soft starch. Popcorn needs between 13.5-14% moisture to pop. The soft starch is surrounded by the kernel's hard outer surface.
As the kernel heats up, the water begins to expand. Around 212 degrees the water turns into steam and changes the starch inside each kernel into a superhot gelatinous goop. The kernel continues to heat to about 347 degrees. The pressure inside the grain will reach 135 pounds per square inch before finally bursting the hull open.
As it explodes, steam inside the kernel is released. The soft starch inside the popcorn becomes inflated and spills out, cooling immediately and forming into the odd shape we know and love. A kernel will swell 40-50 times its original size!
Where to Begin an Experiment?
There are a lot of experiments you can try using popcorn. First, you need to figure out what you want to compare and what you can measure. For example:
Variables: What is it that you want to compare?
- Brands
- White vs. yellow
- Flavor vs. plain
- Methods of popping: microwave, stovetop, or air popper
- Size/amount of kernels
- Storage temperature for kernels
- Storage conditions (moisture, dryness) for kernels
- Popping time
Outcome: What is it you actually want to find out? What is it you can measure?
- Total number of kernels popped or unpopped
- Percentage of popped kernels
- Volume of popcorn produced
- Weight of popcorn produced
- Average size of popped corn
- Time it takes to pop popcorn
Once you have decided what you want to look at, start thinking of questions you can ask and hopefully answer.
For example:
- How does moisture affect popability?
- Which brand of microwave popcorn pops fastest?
- Which brand leaves the most unpopped kernels?
Avoid questions like “Which brand tastes best?” because it is a subjective question and difficult to measure.
Make sure you replicate your experiment. It’s important to repeat your test at least three times. That means, if you’re comparing microwave popcorn for the number of unpopped kernels left after popping, you need to test 3 of the same type of bag per brand. Sure, that’s a lot of popcorn, but that just means you get to eat a lot of popcorn. Be smart: plan ahead and conduct your experiment over several nights.
Which Brand of Microwave Popcorn Pops Fastest?
If we had a dollar for every time we have been asked this question, we would be very, very wealthy. And if we had a dollar for every time we’ve answered it, we would be very, very poor.
First, we don’t mention or talk about brands. You might have a favorite popcorn brand, but we don’t. We love ALL American processed popcorn! But we appreciate that you’re doing a science fair project and you want a quick answer, which brings us to our second point: It’s your science fair project; you have to do your own experimenting and see what happens. The bad news is there’s no quick answer. The good news is that you get to eat lots of popcorn along the way.
General Measuring Rules
- 2 tablespoons of unpopped popcorn kernels will make about a quart popped
- 2 tablespoons = 1/8 cup = 1 ounce
- 8 ounces in a cup
- 4 ounces in ½ cup
- 4 cups in a quart
- 4 tablespoons = 1/4 cup which would yield about 2 quarts popped
Sample Experiments
The following are just a few of the experiments you can do using popcorn.