Sunday, 19 July 2015

Using the Microwave Oven: Boiling Water, and Eggs

For a while now I have driven around with the Microwave in the back. I had tested it right after Christmas, when I cooked one of those meals specifically made for microwave cooking. It had worked fine, but now I wanted to do a more thorough testing.

So I decided to heat 0.5l of water and observe the boiling process. The microwave oven is specifically manufactured for use in a motorhome and therefore does have less power than any usual household microwave oven. This is because campsites often only provide limited electric power, sometimes only 4A at 240V, which is around 1kW. The heating power of this microwave oven is 425W, compared to 700W or more for a small household oven. Therefore, it is to be expected that the boiling duration would take longer. Also, this has to be considered when cooking meals: the times given for certain microwave powers need to be extended for use with this oven.

0.5l is quite a large amount. This is about 3 cups of coffee/tea and is sufficient for any soup that I would want to cook. I measured 0.5l, then used a microwaveable cup to heat the water.

Then I heated the water in intervals and measured the surface temperature with a remote infrared thermometer. The plot of the temperature rise is shown here:

The graphs seems not to show that the water is brought to a boil - but actually the water was boiling in the end, blubbering, even though the surface temperature seemed not to increase beyond 87 C.

The next experiment was to boil eggs. Usually eggs are very difficult to boil in a microwave oven: the power needs to be deliberately reduced to achieve a slow cooking. Here is where the reduced power of this oven becomes really useful. I used a plastic egg boiling container specifically made for microwave cooking.

To avoid that an explosion would throw egg around in the oven I affixed the top cover with a rubber band.

After about 45 seconds of heating I heard an explosion. Nothing really happened, just the egg cracked a bit. I took it out after 1 minute, and here is how it looked:

Not yet fully hard-cooked, the egg white was still partially transparent. So I boiled it for another minute. Here is how it looked then:

Well done, a hard-boiled egg in 2 minutes!

The next experiment was to boil 2 eggs in the special microwave cooking device which my friend Falk had given me a few years ago (knowing my cooking style). This is a plastic container in which one can either cook 2 eggs or one slice of bacon.

I opened 2 eggs, one in each of the compartments, as shown in the picture above. After 45 seconds there was again an explosion. Here is how they looked after 1 minute:

Only the right one seemed to be done, whereas the left one remained uncooked. After another minute the result was this:

Clearly there was an issue with the internal distribution of the microwaves: apparently the power was stronger in the right part of the oven. I ate the well-done egg and boiled again the not-yet-boiled one, for 1:30 min. Perfectly done then!

My final experiment for the day was to boil again two eggs, this time just switching sides after 1 minute. Did this, and after the rotation I did cook them for another minute.

They tasted excellent!

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