We became curious about our microwave as we worked through how to reheat various things we made. This curiosity led to a lot of questions. For example, knowing how a microwave works, why does it have a pizza setting when pizzas are better reheated via dry heat? Due to this curiosity, we decided to dig in a bit to see if we could use the microwave with a little more finesse. Like anything, it can be a great tool once you understand its strengths and limitations. This post is about understanding both of those.
Just Nuke It!
When at work I have never seen anyone in the company kitchen use anything but 100% power to nuke to oblivion whatever it was they were heating. This was my standard operation of a microwave as well. You select Add a Minute, or whatever time you need, hit go, and wait. After the time elapses, it beeps, and you open the door. If it is hot enough you pull it out and if not you repeat the steps until done. There isn’t a lot of magic there.
Time and multiple attempts have convinced me that the popcorn setting on microwaves never produces good popcorn. In my opinion, the button needs to be labeled Destroy Popcorn. Let’s face it, you would think there wasn’t that much variation between companies in a standard bag of microwave popcorn but there is. For us using the bag’s advice of listening until popping slows was a far better method than the popcorn button.
The Basics
Just a quick review of the basics of how a microwave works. If you want to get into the details of how a microwave works you can read about that in depth on other sites. A microwave uses a magnetron to excite water molecules. The more agitated the water gets, the more the heat it produces. The thermal limit of water at sea level is 212℉ before it turns into steam. This upper limit is why microwaves can’t brown food via the Maillard Reaction.
The key technology used here is the magnetron. The microwave is rated by its power. It is simple enough to understand, that the more power, the faster it can heat food. How fast it heats food has positives and surprisingly some negatives. More power is fine, however, too much power isn’t great at times. It turns out too much power can lead to some overheating with messy results.
Last, no matter what a manufacturer tells you, a microwave can’t roast or air fry. If the manufacturer states it can do those things, you are buying a hybrid with two separate machines built in. If you do some homework you will see it is simply a traditional oven with a microwave. A magnetron can only excite water not create convection or conduction via the dry heat needed for those cooking types. It is not simply not possible for a magnetron to roast or air fry.
Popcorn, Defrost and Vegetables, Oh My!
If you are like us, then you probably have only played around with all the presets, like popcorn. Let’s face it: We use a microwave to save time. What saves time? Full power!! True as that is, it is generally at the cost of something else. But first, about those preset buttons.
In an attempt to apply the right power and time to provide the proper heating of your food, manufacturers create those preset buttons. Most microwaves do this through a set of mathematical equations by approximating how much water and mass the food has. With that approximation, the microwave then decides, based on its power output, how much time and power to use. Great because we all know exactly how much our frozen leftover lasagna weighs! No, most of us probably don’t unless we are dialed into how it was made, for what calorie budget, and the portion sizes we cut it into.
Higher-end microwaves may use humidity, infrared, and sound to monitor cooking. Oddly enough, popcorn seems to have driven a lot of this innovation. If you have ever overcooked popcorn in a microwave, you understand why it is so critical not to have that happen. When popcorn is cooked too long in a microwave it will turn to a tar-like material and also produce an acrid smoke and smell. It can be so bad that you may need to replace your microwave. I know this from personal experience.
It’s Not Just About Water, Power, and Time
All presets and management of cooking in a microwave is still about balancing power and time to increase the temperature of the food through the excitement of water. You will also read that they excite the molecules of fat and sugar. Realize those are mostly composed of water hence why we say water not all three. The last important key is the mass of the food. This is why you will see presets such as defrost by weight or bag size for popcorn.
In these cases, the microwave adjusts the power and time to make sure it slowly raises the temperature of the food. Why slowly? If you have melted cold butter in a microwave and had it explode you know the reason. The cooking of the food is based on how deep the microwaves penetrate the food, where the water is in the food, and how much water is in the food.
Microwaves actually can only penetrate from one to one and a half inches. That means in small pieces of food they cook from the inside out whereas in large they cook from the outside in. In the case of outside in, the interior is done by conduction from the hot part of the food, not the microwave. This is why it is easy to overcook the outside of food and still have a cold center.
A Pair of Examples
For example, butter has a lot of water and is small. The microwave cooks the melted butter inside out. As the butter superheats the water flashes to steam at 212F which expands rapidly creating an explosion. If you have made this mistake then you know what it is like to clean butter out of every nook and cranny in your microwave.
My nemesis, Lasagna, is on the opposite side of the reheating problem. For us, frozen lasagna is a block of high-moisture frozen food usually stored in a plastic container. It is large enough that it cooks from the outside in. In the past, we would nuke this at high power. As a result of that reheating process, the outside bits got hot enough to destroy plastic containers.
Back to the Presets
We still shy away from presets and here is why. I want to understand how my food is being cooked so I can use that in other places. If you have a microwave at work that is 800 watts it is not going to behave like your home microwave of 1000 watts. Our guesses and experiences were the ones in our work environment that didn’t have all the bells and whistles as well.
When we started to understand how to use the microwave more effectively, we wanted to be able to use that knowledge and adapt to other microwaves. Since nothing is standardized we can’t hope the two machines are the same including their presets. Overall though, I am pretty sure we can get close to home if we simply use the same power settings and only change the amount of time we cook.
All Things in Moderation
Since moderation of power and time was key we started our experiments. As with the article on reheating, it doesn’t mean there is going to be an easy button or simple answer. After researching a bit we found Whirlpool puts out a pretty good list to explain power levels, foods, and how they go together.
But turning down the power means cooking longer, correct? It can, however, be more of a trade-off. By turning down the power, and increasing time, we get more predictable cooking times. This leads to being able to walk away from the machine rather than babysit it. For example, for our serving size of Lasagna, we can put it on for 10 minutes at 50% power and walk away. In our previous cooking style, we would microwave for a minute, wait 30 seconds, and repeat until cooked through. That left us babysitting our food for 7 or 8 minutes.
This is not the case in popcorn which I don’t trust. For me, no matter the preset, sensor, or other dark arts, I babysit it. There are some items like this where full power and babysitting are needed. I will wait until I hear that popping slow down before I stop it.
Wrapping Up
In this post, we discussed some ways to use a microwave more successfully. By moderating power and temp you can achieve better cooking and reheating of food. By not using presets you also learn how to adapt to other microwaves that you use. These two points make the microwave an even more powerful tool in the kitchen.