Why can microwave ovens “brown” food?
Microwaves interact most efficiently (that is, more energy is transferred) with water molecules rather than the “solid” molecules. When you cook food in a microwave, you are actually cooking it by heating or boiling the water molecules inside it. The solid particles at the surface of food are usually dry compared to the interior, as they lose water to the atmosphere — so microwaves start having an effect a few micrometers below the surface (this is probably what gives rise to the urban legend that microwaves cook “from the inside out”). However, this does not lend itself well to heating the particles at the very surface enough to brown them. In conventional ovens, heat is transferred first to the particles at the surface, which heat more compared to the particles in the interior — lending itself to “browning” the surface before the inside burns.
