Editing Microwave oven (section)

=== Fats and sugar ===
[[Sugar]]s and [[triglyceride]]s (fats and oils) absorb microwaves due to the dipole moments of their [[hydroxyl groups]] or [[ester|ester groups]]. Due to their [[molecular dipole moment]], however, they are heated less efficiently.{{efn|Here "efficient" means that more energy is deposited and temperature rises faster, not necessarily that the temperature rises to a higher maximum. The maximum temperature is also a function of the material's [[specific heat capacity]], which for most substances is lower than water. For a practical example, milk heats slightly faster than water in a microwave oven, but only because milk solids have less heat capacity than the water they replace.{{Citation needed|date=January 2009}}}}

Although fats and sugar typically absorb energy less efficiently than water, paradoxically their temperatures rise faster and higher than water when cooking: Fats and oils require less energy delivered per gram of material to raise their temperature by 1&nbsp;°C than does water (they have lower [[specific heat capacity]]) and they begin cooling off by "boiling" only after reaching a higher temperature than water (the temperature they require to [[vaporize]] is higher), so inside microwave ovens they normally reach higher temperatures – sometimes ''much'' higher.<ref name=Martin/> This can induce temperatures in oil or fatty foods like bacon far above the boiling point of water, and high enough to induce some browning reactions, much in the manner of conventional [[grilling|broiling (UK: grilling)]], braising, or deep fat frying.{{citation needed|date=July 2020}}

The effect is most often noticed by consumers from unexpected damage to plastic containers when microwaving foods high in sugar, starch, or fat generates higher temperatures.{{Citation needed|date=February 2025}} Foods high in water content and with little oil rarely exceed the boiling temperature of water and do not damage plastic.{{Citation needed|date=February 2025}}