Rice Krispies has been known for its famous catchphrase—and the three mascots named for this catchphrase—for almost as long as it’s been available (and given that the cereal is about a century old, that’s saying something). But have you ever wondered precisely why Rice Krispies snap, crackle, and pop? What is it about puffed rice that causes it to make such bizarre sounds when you add milk to it?
It turns out that there is some science behind Rice Krispies’ tendency to snap, crackle, and pop. It has to do with the method used to make this breakfast favorite, and what happens to it when liquid is introduced to the equation. Curious? Read on; there’s more going on here than just breakfast.
A Brief History of Puffed Rice Cereal
Puffed rice has, of course, been around for a long time—much longer than puffed rice breakfast cereals have been. In India, for example, puffed rice has long been a staple, traditionally made using the hot salt frying or hot sand frying techniques: Salt or sand is first heated in a pan over a fire; then parboiled rice is added to the pan. The high heat and salt or sand cause any remaining water in the rice to evaporate immediately—and as it does so, the rice grains expand due to their starch content and the pressure created by the rapid evaporation. The grains then dry out quickly and harden, thus creating puffed rice. In China, meanwhile, puffed rice was made in a pressurized iron cauldron, and can be found in records dating back to the Song dynasty (960 to 1279 C.E.).
Breakfast cereals like Rice Krispies, however, are made a little differently—and the technique used in their creation is much more recent. The method is usually credited to Minnesota native Alexander P. Anderson, who, in 1901, discovered that starch granules heated in a sealed glass tube until browned puffed up when the tube was smashed. The puffing action occurred as a result of the tube pressurizing as it heated up inside, combined with the fact that the seal kept the water in the starch from boiling. The rapid drop in pressure caused by the smashing of the tube caused the water still present in the starch to vaporize immediately and expand the starch grains.
Anderson kept experimenting with his pressurized puffed grain-making method, and by 1904, he had created a sort of cannon that took care of the whole process. He brought his operation to the World’s Fair in St. Louis and used it to make and sell puffed rice as a snack. By the fair’s conclusion, Anderson had puffed 20,000 pounds of rice—and the Quaker Oats Company took notice. Working with Anderson, the company introduced Puffed Rice and Puffed Wheat breakfast cereals to the market in 1905 to huge success.
When Kelloggs introduced its puffed rice cereal, Rice Krispies, to the market in 1928, the ad campaign immediately drew attention to some of the cereal’s more unique qualities. For one thing, it didn’t get mushy in milk as quickly as many flaked cereals did—and for another, it made some fascinating sounds when milk was added to a bowl. According to Smithsonian Magazine, radio commercials for Rice Krispies boasted about the way they “merrily snap, crackle, and pop.” When artist Vernon Grant heard this ad, he drew a trio of elves, one for each sound, and sent them off to the ad agency in charge of Kelloggs’ marketing. By the early 1930s, Snap, Crackle, and Pop had become the cereal’s mascots, cementing Rice Krispies, the cartoon faces that represent them, and the noise they made in the public imagination.
The Science of Cereal Sounds
But why does puffed rice cereal make that distinctive sound? What causes Rice Krispies to snap, crackle, and pop in the first place? Unfortunately, the truth is that we don’t entirely know— mainly because there’s just not a lot of money available for research focusing on cereal sounds. As food scientist Ted Labuza of the University of Minnesota put it to Live Science in 2006, “I have not seen anyone fund this. It’s not rocket science.”
Lack of official funding hasn’t stopped scientists from looking into it anyway, though; it’s a topic that has long fascinated many—including Labuza himself, along with a handful of other food scientists. And they’ve come up with a possible explanation that seems reasonably likely to be the case.
As Live Science explains, the cooking process for puffed rice cereal does two things to the rice: It creates incredibly strong, glass-like bonds in each piece to hold the starch molecules together; and it causes “a network of air-filled caves and tunnels” to form inside the pieces, as well. When you add milk to a bowl of the stuff, the cereal begins to absorb the milk, which then puts additional pressure on the air pockets inside the cereal pieces. The pressure forces the air against the walls of each little pocket—and when there’s enough pressure, those walls eventually snap, with the sound being a result of the glass-like bonds holding the starch molecules together shattering. When you lean in close and listen to your breakfast, all of those little walls inside all of those pieces of cereal snap together in chorus, thus creating the now-famous snap, crackle, and pop sound forever associated with a bowl of Rice Krispies.
The effect doesn’t last forever, of course; per Scientific American, the cereal does eventually become saturated with milk, at which point the snapping, crackling, and popping pipes down, turning your cacophonous breakfast into a quieter affair. But hey, it was fun while it lasted, right?
The Practical Application of Snapping, Crackling, and Popping
Interestingly, puffed rice has recently served a very different purpose in scientific research: As a stand-in for snow and rock for the study of “collapse events” occurring in nature. Termed “brittle, porous media,” but often referred to by scientists as merely “crunchy material,” both things like snow and rock and puffed rice cereal have been found to deform in similar ways depending on the velocity of whatever might be compacting them. According to one study published in the journal Nature Physics in 2015, this observation could have some valuable implications assessing the safety of snow following an avalanche.
What’s more, puffed rice is particularly useful when studying collapse events that involve water. As Atlas Obscura reported in 2018, puffed rice, like snow and rock, “breaks under pressure and degrades in fluid,” making it ideal for creating lab simulations of events like avalanches, earthquakes, sinkholes, and more in which water is a component. Researchers have lovingly dubbed these lab simulations “ricequakes”; research involving these ricequakes is ongoing.
It’s clear to see that there’s a lot more to a bowl of puffed rice cereal than meets the eye—so the next time you pour yourself a bowl of Rice Krispies, remember: It’s more than just breakfast.