|MadSci Network: Other|
Hi, Nicole! Popcorn "pops" by the pressure of steam building up inside the enclosed kernel. The steam forms by heating the small amount of water remaining in the kernel. The amount of water in the kernel is important for good "popping". If there is too much water, the kernel is too soft and gives way slowly instead of exploding. If there is too little water, the steam pressure may not be great enough to cause the explosion. The reason that popping loose kernels of popcorn in the microwave is difficult is that the absorption of microwave energy is only due to the residual moisture in the corn. Commercial popcorn bags have metallized film to capture a much larger amount of energy, and oil to conduct it to the popcorn. Higher energy per unit time means a higher temperature and a much higher steam pressure. Without the rapid rise in temperature coming from the metallized film, the kernels may give way slowly instead of exploding. I hope this answers your question!
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