Since the accidental invention of the microwave oven in 1945, this gadget has become one of the most important appliances in modern kitchens.
The problem is, most users tend to ignore some important manufacturer instructions when using the microwave which can lead to some serious safety issues.
There are some basic microwave do’s and don’ts that you may already be aware of such as not using plastic or metallic containers.
In this article, I will be addressing one of the most asked microwave questions to unravel the facts behind it and how you should handle it moving forward.
The question is about whether to cover food while heating it in the microwave or not.
Should Food Be Covered in a Microwave?
Although not strictly necessary, it is good practice to cover all food being heated or reheated in a microwave oven.
Covering the food ensures uniformity in heat transfer in the food and also keeps the food contained thus preventing it from messing the oven by splattering.
One reason why this issue of covering food keeps coming up is the fear most people have when they hear the word “radiations” being used close to their food.
In fact, I wouldn’t be wrong if that is the reason why you thought covering the food was necessary.
That is why people make the mistake of covering food in a microwave with metallic lids with the sole purpose of avoiding the said radiations reaching their food.
To debunk this mythical idea, let me give a simple scientific explanation of how a microwave oven works.
How Food Gets Heated in a Microwave Oven
Unlike conventional stove cooking where food is heated mostly through conduction, microwave heating is a bit different.
The microwave oven does not heat the food container to transfer the heat to the food.
What happens is the electromagnetic waves generated by the oven only heat up the contents in the container through a heat transfer process called radiation.
The interesting part is what happens inside the food when it is hit by these electromagnetic waves.
Without going into too much thermodynamic physics, I will attempt a simplified explanation of the events that take place in microwave-heated food.
First, the microwave generator emits electromagnetic waves (radiations) which are absorbed by water, protein, and fat molecules in food.
For those who care to know, this process is called dielectric or radio frequency heating. You can check more about it here.
On absorbing the electromagnetic radiations, the molecules in food get excited and start moving around bumping into each other.
This kinetic motion makes them transfer their energy in form of heat throughout the food in another thermodynamic process called thermalization.
That is exactly how the food gets heated in the microwave.
It is important to note that the electromagnetic radiations do not stay inside the food as you may want to visualize.
These waves easily penetrate the food and other light materials but bounce off on other materials such as heavy metals.
This is why it is not advisable to use metallic containers and aluminum foil or leaving a spoon in the food when warming in the microwave oven.
Microwave oven manufacturers also advise against opening the top cover or putting objects on top of the oven vent because these waves need to circulate and escape out of the heated environment.
So, Why Cover Food in the Microwave Oven?
As you can see, covering food in the microwave has very little to do with radiation.
It is mainly a precaution you are advised to take to avoid the wrath of these little excited molecules in the heated food.
When water molecules in food get to some high excitement levels, they usually look for a way out.
As they forcefully find their way out of the food, they rapture everything that stands in their way causing an immense mess in the oven.
That is why you see some common occurrences in microwaving such as:
- A hard-boiled egg exploding in the oven
- Food splattering in the oven when being heated at high temperatures
- Popcorns popping in the microwave
- Food drying out due to moisture loss
- Food being unevenly heated
The above occurrences are the main reasons you need to cover food in the microwave oven.
You want to avoid everything that can mess up the microwave’s functionality and the food you are preparing.
So, forget about the thought that your food will heat faster without a cover.
You also don’t need to worry about your food being turned radioactive because of the electromagnetic waves.
What About Using Plastic Containers in Microwave Ovens?
Using plastics containers or covers is not recommended when heating food in a microwave.
With an understanding of how microwave radiations work, you can see why this can be a problem.
The heat created by the excited molecules can melt containers made of soft plastic material.
This is why you should check the plastic material you are using if it is recommended for use in microwaving food.
I am sure you have come across the much-debated issue about cancer and the use of plastics in microwaves.
According to the Centre for Food Safety, it has been confirmed that there could be possible migration of chemicals from plastics to food.
However, scientific evidence showed that the amount of chemicals migrating is too low to pose any health risks to humans.
So what does that mean?
Well, they are simply telling you to avoid plastic ware in microwaves for prolonged periods since these small doses can pile up and become lethal in the long run.
It is easier to get a proper microwave plate cover and use recommended microwave cookware to avoid these kitchen embarrassments that could even turn hazardous.
Recommended Microwave Cookware
We have already seen that soft plastics and metalware should never find their way into the microwave oven.
If I decided to give a list of what else you should not use, I might not be able to give a comprehensive list here.
This is because there are many different types of equipment in the kitchen made from different materials that I may even be unaware of.
There are also different manufacturers globally producing numerous food utensils that may be good for general kitchen tasks but not tested for use in the microwave oven.
So, other than the plastics, metals, and foils, the other common materials you shouldn’t put in the microwave are brown bags, newspapers, and those convenience food plastic containers.
But what I can confidently give you is a list of recommended utensils that you can use to cover food in the microwave and feel safe.
Check them out.
- Parchment paper for baking in the microwave oven.
- Microwave cooking bags when you want your food to retain moisture and prevent it from drying out.
- Microwave-Safe Wax paper if you are heating meat, fish or their products. Just like plastics, not all waxed papers are good. Make sure it is labelled ‘microwave safe’
- White unprinted paper towels if the food is excessively moist and you want to get rid of the excess moisture
- White unprinted microwave-safe plates for covering food in bowls.
- Glass or ceramic ware also for covering bowls and plates.
For the plate covers, it is always good when they are vented so as to allow a sizable amount of moisture to escape.
With that said, I hope you chose your microwave cookware wisely next time you are shopping for kitchen utensils.