Question of the Week

Why does cereal go Snap, Crackle and Pop!?

Sun, 19th Jul 2009

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David Stockden asked:

Hello, Naked Scientists, could you please tell me what's happening when you hear the snap, crackle and pop with Rice Crispies? Thank you.


We put this to Paul Wheeler:

Hi my name is Paul Wheeler and I work for Kelloggs.

Rice krispiesItís actually a really simple processes itís got a lot to do with compression.  What we do is we take little grains of rice.  We soak them in water, add our secret ingredient to it and then we cook the rice at a really high temperature.  What happens then is the rice puffs up and little air pockets form inside the grains of rice.  Now also when you cook this kind of thing, rice, at such high temperature the starch molecules kind of begin to bond together and what that does is if you were to take a rice crispie out of the packet and look at it under a microscope.  You would see the actual surface of the rice becomes more brittle and actually more transparent.  So what happens is when you pour the cold liquid onto the rice crispie the small bubbles of air that weíve got, they collapse in on themselves and the rice thatís crisped up through the cooking process collapses as well and thatís where you get the sound-effect from, your listeners will hear when they pour their milk on their cereal.  Its a really, really a simple process and actually people looked at the surface of the milk when thatís happening they can actually see the air bubbles rise up and appear.


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The cereal is puffed with air. These air bubbles are then trapped when the cereal is cooked. When milk is introduced the starchy coating becomes saturated and can no longer hold in the air. The air pockets breaking through the starchy shells produce the Snap, Crackle, and Pop we love so much. bdelanghe, Fri, 17th Jul 2009

Soul Surfer, and Daveshorts previously answered a similar question
Snap, crackle and pop, Fri, 17th Jul 2009

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