|MadSci Network: Chemistry|
Microwaves heat thru two simple mechanisms. For molecules with a dipole moment, rotational energy is imparted. For free ions, a vibrational pattern is set up. The energy of microwave generated by home cooking units is not adequate to break bonds, just to spin up the molecules and allow them to collide, producing heat. For instance the energy of microwaves at the standard frequency of 2.45 GHz is only 0.0016 ev. This is not even strong enough to break the weak hydrogen bond (bond energy of 0.21 ev), much less a real bond such as the carbon-carbon single bond in ethane with has a bond energy of 3.8 ev. Free radicals can still be produced by spontaneous decomposition or other processes. But the fact that the heating is done by microwave vs convection heating will have no impact on the generation of free radicals per se. There is one other consideration. With microwave heating of a food in a microwave transparent container, the food is always hotter than the container since the container is only heated by heat transfer from the food. But in conventional heating, the container may be much hotter than the food leading to superheating, burning, etc. This might be more likely to produce free radicals and other dangerous compounds. Consider a outdoor cooking grill as well for excessive heating. Hope this helps. --Rick (some information provided by CEM Corp, laboratory microwaves)
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