What causes foods to pop and splatter when microwaved?

Question

when i heat up things, especially stews and sauces, in a microwave oven, they pop and splatter. what causes that?

Answer 1

Hi, I agree with the previous few answers to a certain extent. The heating is indeed slightly uneven, but I will attribute the main cause of 'popping and splattering' to a different reason.

Food contains little pockets of air. By ideal gas law (which is a good approximation of what happens in real life), pv = nRT where p is pressure, v is volume of the gas, n is the number of moles of the gas, R is a constant, and T is temperature.

On heating, the food try to keeps the pockets of air in. hence v is relatively constant. n is also relatively constant. Hence, pressure becomes proportional to temperature (you can see that from the above equation using maths).

As temperature increases, the pressure that the pocket of air exerts increases. Pressure is force per unit area. As pressure increases, the air exerts a higher and higher force on the food that is trapping it. Finally, the force is great enough and the air pushes through the food (e.g. pizza dough) that is blocking its way. The air escapes, causing popping.

If you would like to test this out, make a thin-walled hollow clay ball (i.e. with some air sealed up inside) and put it in the oven. It will explode. (might be messy)

Cheers.

Answer 2

The microwave acts like a very bright heat lamp.

It boils the water in your stew or sauce very quickly, and it reacts like all boiling water does: by popping and splattering as they turn into water vapor.

Answer 3

Actually the micro wave has enough energy to move the particles of the fluids inside the food. This movement it's actually    the kinetic energy of the particles that on a bigger scale is percepted as heat. This heat grows exponentially and of course the pocket of heat will make the food at some point to eiher melt or explode :D

Answer 4

Microwaves heat from the outside in, just like an oven.  Popcorn pops in an oven or on a stove top too.  I'm old enough to remember this.  But popcorn pops because the water inside turns to steam rather explosively.  Microwaves are good at heating water, because they're tuned to the resonant frequency of water.

Microwave ovens do not heat evenly.  There are high and low spots where the waves add or cancel as they bounce around in there.  So get one of those rotating things, so everything passes through the hot spots.

Answer 5

Microwaves heat the interior of the food first.  The liquid will heat unevenly, causing a 'pocket' of heat that expands until it 'pops'.