I posted this Q&A in the past, but I was reminded of it recently when a friend asked me the exact same question. It was good advice four years ago, and it’s good advice today.
Interesting question, Alex. I’m assuming you’re microwaving a watermelon purely for scientific research, because I can’t really think of any other reason to microwave a whole watermelon.
Whatever your reasons are, I’m going to say DO NOT PUT A WATERMELON IN THE MICROWAVE. It’s not a good idea, and it’s a waste of a perfectly good watermelon.
That said, let’s start with some basics about how microwaves work. The process of heating food in a microwave is actually caused by a reaction between the water molecules in the food item and the microwaves passing through it. The microwaves cause the water molecules to spin and give off heat energy. During this spinning process, the water molecules are rubbing against other water molecules, creating a chain reaction and causing things to heat up very quickly.
So, you can imagine what might happen to something like a watermelon, which is 92 percent water by weight and whose watery interior is effectively sealed off by a thick rind. You’re probably imagining lots of pressure building up inside as the watermelon heats up and something disastrous happening when the watermelon reaches its breaking point, right?
I scoured the Internet for answers and found a video that shows what happens when you microwave a sliced watermelon (nothing exciting) but no videos or testimonies of whole watermelon nuking. Similar videos showed the results of microwaving watermelon-like foods such as tomatoes (nothing), bananas (burned and charred but no explosion) and eggs (boom!).
You’re going to be disappointed with my final answer, Alex, but the truth is, I’m not really sure what would happen if you put a whole watermelon in a microwave. I thought about testing it for myself, but good sense and my love of watermelon prevented me from taking such drastic action.
My advice again is this: DO NOT PUT A WATERMELON IN THE MICROWAVE. If you have a watermelon and you really want to do something crazy with it, I’d suggest using it to make some sweet and sour watermelon chicken.
UP NEXT: My attempt at making watermelon jerky