Misconceptions about microwave cooking: something else to occupy us

Misconceptions about microwave cooking: something else to occupy us

Starters (Wiki):

Another misconception is that microwave ovens cook food "from the inside out", meaning from the center of the entire mass of food outwards. This idea arises from heating behavior seen if an absorbent layer of water lies beneath a less absorbent drier layer at the surface of a food; in this case, the deposition of heat energy inside a food can exceed that on its surface. This can also occur if the inner layer has a lower heat capacity than the outer layer causing it to reach a higher temperature, or even if the inner layer is more thermally conductive than the outer layer making it feel hotter despite having a lower temperature. In most cases, however, with uniformly structured or reasonably homogenous food item, microwaves are absorbed in the outer layers of the item at a similar level to that of the inner layers. Depending on water content, the depth of initial heat deposition may be several centimetres or more with microwave ovens, in contrast to broiling/grilling (infrared) or convection heating—methods which deposit heat thinly at the food surface. Penetration depth of microwaves is dependent on food composition and the frequency, with lower microwave frequencies (longer wavelengths) penetrating further.[citation needed]

Ross1 | March 23, 2020

Use in cleaning kitchen sponges
Studies have investigated the use of the microwave to clean non-metallic domestic sponges which have been thoroughly wetted. A 2006 study found that microwaving wet sponges for two minutes (at 1000 watt power) removed 99% of coliforms, E. coli and MS2 phages. Bacillus cereus spores were killed at four minutes of microwaving.[52]

A 2017 study was less affirmative: about 60% of the germs were killed but the remaining ones quickly re-colonized the sponge.[53]

Orthopod | March 23, 2020


Does microwave cooking kill COVID-19!

rxlawdude | March 23, 2020

@Stay, I don't think that's been studied, but given existing data, the virus that causes COVID-19 DISEASE (note the difference between those terms) would not survive long on surfaces exposed to high temps

andy.connor.e | March 23, 2020

Microwave a frozen potato and tell me that a microwave cooks from the inside out.

DonS | March 23, 2020

A microwave woks on food by vibrating the water molecules causing friction at a molecular level.

I've never found an explanation of how those same microwaves act on water with the molecules locked into a rigid lattice, i.e. ice. I'm guessing the microwaves don't do much, hence the slower low power defrost modes.

mbowden | March 24, 2020

DonS They work the same on frozen water, the microwave is set to a lower power, typically cycling on and off so that it thaws the food more evenly without cooking areas.

On the physics side of things the 2.45GHz frequency 122mm matches the absorption spectrum of the water molecule.

Microwaves ovens are 2 ticks left of 10mm, the line is how much of the energy the water absorbs.

Ross1 | March 24, 2020

A story goes that in the 1920s a lab invented the MW oven, but it was not a success because when they put potatoes in to cook they exploded.

The scientist goes home, tells his wife.
Wife: Well, did you stab them with a fork first?

rxlawdude | March 24, 2020

@DonS, besides water molecules microwaves also heat fats and oils through the same mechanism.

jimglas | March 24, 2020

and in my experience, fat and oil heats up much faster than water