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Basically, the practical implications of microwave heating for food appear to be rather unclear to me. So, the question is whether a higher power setting for a shorter time does indeed produce, as is sometimes claimed, a worse end result than heating on a lower setting for a longer continuous period. Has anyone somewhat rigorously experimented with this, or seen credible sources?

I've found this answer that claimed that a 60 or 70% setting produced better results, and while that is helpful, no concrete reasons/sources are given, and the recommendation also seems somewhat ambiguous seeing how microwaves exist with wildly different wattages.

Marc Vaisband
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  • Related: https://cooking.stackexchange.com/questions/99008/microwave-power-settings?rq=1 – Cindy Feb 22 '20 at 16:09
  • You are correct to note that because the total power of microwaves vary, 60% on your microwave will be different than 60% on my microwave. Thus, that recommendation is completely ambiguous. – AMtwo Feb 22 '20 at 18:01
  • What's the power of your microwave? What does your reheat weigh? What container is it in? What's the fat content vs water content? How spread out is it [think pizza vs soup]? This is just not answerable. – Tetsujin Feb 22 '20 at 18:33
  • Welcome to the site! Your question is too broad at the moment, there is no single right or wrong answer as it depends on the type of food, whether it is thawed or frozen, and other factors. If you could narrow it down some it becomes more answerable. – GdD Feb 22 '20 at 21:25
  • I was not looking for a specific optimal configuration for reheating food, but rather qualitative statements that hold with some generality. As such, I'm quite happy with the accepted answer, maybe others will find it similarly helpful – Marc Vaisband Feb 23 '20 at 00:11

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Most microwaves will not reduce their power. They will reduce the percentage of time the power supply or the magnetron is active. In other words, longer rests in between shorter blasts.

The actual microwave "heat" is applied in a fairly narrow beam (about 2" in diameter). This is why some microwaves have a turn table. So, placing the food off centre is better.

When part of the food gets really hot, it starts warming up the surrounding parts as well and eventually reaches a sort of an equilibrium.

If you have a thermal imaging camera, you can place a damp paper-towel on a plate and see the heating pattern for yourself. This is where you can do the rigorous experimentation. While I did use scientific equipment in my tests, it was just for my own curiosity.

When you run the MW at 100% you're overheating parts of the food to help warm up the other parts of the food. Overheating food has a great chance of reducing flavour and breaking down some of the longer molecules. Usually, the water in the food buffers this, but it does depend on the what you're heating up.

To answer your question, yes, you are better off reducing the power. Regardless of the total wattage of your specific microwave oven

Running at lower power, reduces the peek temperature of the areas that are blasted by heat. Yes, it will take longer, but you keep the temperatures of parts of the food more even.

Again, if you're really curious, warm up food in short time intervals and take a look it with a thermal camera.

You may end up opting for a toaster oven after you see it all.

MandoMando
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    If you don't have a thermal camera handy, microwaving a bunch of ice cubes might also work to illustrate the difference. Microwaving on high will get you lots of ice chunks and hot water. Lower powers will get you more evenly melted ice. – Kat Feb 22 '20 at 23:32