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Why Should You Cover Food In A Microwave? (Explained!)

Antonio Forde
Updated: July 4, 2024
7 min read

Covering food when cooking or reheating is a microwave oven safety standard endorsed by health and food authorities worldwide.

Read on to find out why microwaving your food with a cover or a lid is essential.

Here’s Why You Should Cover Food in a Microwave:

Keeping food covered when microwaving allows heat to circulate, ensuring that it cooks evenly on all sides each time. The moist heat trapped inside the container also aids in destroying harmful bacteria in your food. With a lid on, you can prevent food splatter, making cleaning a lot easier.

Covering food in a microwave promotes uniform cooking. 

If you have been a microwave user for some time, you have probably encountered a reheated dish with some parts that are still cold. This is because microwaves are prone to the formation of cold spots.

A microwave works by using non-ionizing radiation for cooking food. When it operates, the magnetron inside releases electromagnetic waves that get absorbed in the food.

The waves cause the food molecules to vibrate then heat up. This heat cooks your food and makes it palatable.

The turntable or rotating tray turns the food in different directions for the microwaves to be consistently distributed. With other units, there are stirrers or rotating reflectors instead of turntables.

If there is an unequal heat distribution, like when the turntable is broken, cold spots can form in your food.

Putting a lid on your microwave-safe container can mitigate this setback.

When you use a cover, the steam confined inside will help heat all food portions, cooking evenly and consistently.

Of course, cutting the food into smaller sizes and arranging them properly in the container also facilitates uniform cooking.

The steaming hot vapor also helps kill harmful bacteria in your food.

Like raw foods, pre-cooked foods are also susceptible to bacteria, including E.coli and Salmonella. 

Credible studies and research have concluded that microwaving can destroy certain kinds of bacteria and some viruses.

If you use higher-powered microwaves, the disinfection rate is higher.

Covering your food when microwaving also helps keep it from drying out. 

Microwaves can heat food very fast, causing the water content to dry out. Usually, you solve this by putting a small amount of water in the oven compartment to generate more steam.

Cooking food in the microwave is actually one of the best ways to preserve the minerals and vitamins in your food, so long as you do it right.

For instance, too much heat all at once can dry up your food and zap all those nutrients. 

If you keep the food nicely covered, you can prevent this problem. The moist heat inside the container will keep the dish fresh and hydrated.

Preventing food splatter all over your oven compartment is also possible when keeping the container lid on.

Some foods, especially the greasy ones, tend to create oil splatters in the microwave. 

Eggs and potatoes, or those food with high water content, also tend to explode when cooked in the microwave. The water content turns into steam and gets trapped. 

Without a way out, the internal pressure builds quickly and causes the food to explode. Unless you have a microwave cover, the resulting splatter will be a hassle to clean.

Less or no splatters mean less cleaning time for you since you do not have to spend so much effort scrubbing stains off the oven walls.

You should note that while covering your food is an excellent practice when cooking or reheating in the microwave, you must not use an airtight container.

If the lid is completely closed, the pressure inside will be too much and causes it to explode. You should always loosen or open the cover a little to let the steam escape.

What Should You Use to Cover the Food?

Not all cover materials are microwave-safe, so you need to be cautious when choosing. You should look for safe and approved items for use in the microwave.

Plastic wraps are useful items in holding in heat and steam when microwaving. Just make sure that they are marked with a microwave-safe label. 

Since plastic wraps can get really hot and melt when they touch food, you should avoid having them in contact with the dish by leaving some space in between.

Using a sharp knife, you should also punch a few holes on the plastic wrap for the steam to escape. 

Wax and parchment papers are also excellent options. Like plastic wraps, they help retain heat for quicker cooking.

You can also cover food using paper towels to absorb extra moisture. For safety, only use white or unprinted materials.

Since paper towels can burn around the edges when overheated, you should use them only in shorter intervals and check on them frequently to see if there are scorching.

Foils covers can be safe to use in your microwave, but they must only be utilized sparingly. You have to make sure that they only certain areas of the dish. 

The microwaves will not go inside if it is fully covered, leaving your food raw. You should also only use new flat foils. Wrinkled ones can cause sparks or arcing.

Microwave cooking bags are best for retaining the maximum moisture in food. These steam bags are safe to use and do not contain chemicals that can transfer to your food when heated.

Some users are hesitant to use plastic covers, and for a good reason. Plastics contain chemicals that, when heated, are released into foods. 

However, there are plastic covers available that are certified safe for microwave use. These are cheaper and reusable replacements for plastic wraps.

When choosing the best microwave food cover, you need to consider several factors. Aside from the material having food-grade quality, you should take into account the size.

The best cover should be able to wrap the food properly and can fit in your microwave tray.

You may also prefer microwave covers with handles or made of transparent materials so you can see the food inside.

If you are still dubious about using plastic covers, glass and ceramics are excellent alternatives. They are great for foods that need steam and moisture to cook.

You should never use brown paper, newspaper, and plastic grocery bags as food covers in your microwave.

Cold storage containers, metal pans, and foam-insulation platers or trays are also a big no-no.

When using glass or ceramic, you must avoid those with metal rims.

As long as the cover you will be using is labeled microwave-safe, you should be okay. Check for the symbol of wavy lines. Those with a #5 stamp are also generally considered microwave safe.

If you cannot find the label, you can do a simple experiment to test if the cover can be used for your appliance.

You should place the cover inside the microwave alongside a cup of water. If the cover is hot after heating, it is not microwave-safe. 

If the cover is cool and the water is hot, it is safe to use.

Does Covering Your Food in the Microwave Reduce Radiation?


No. Covering your food while microwaving should not reduce radiation. Unless you use a radiation-proof container, all those electromagnetic waves emitted by your appliance will still get to your food.

You should know that microwave radiation does not make your food radioactive. It is non-ionizing, which means it is not strong enough to directly affect the structure of the food.

What non-ionizing radiation does is to cause food molecules to vibrate and heat up. This is how microwaves work.

Once your microwave starts working, the electromagnetic waves bounce off the oven walls. The heat produced is absorbed by the food’s outer layers, while the inside gets cooked mainly due to the heat conduction of the hot outer layers.

Microwave cooking does not reduce the nutritional value of the food. 

In fact, most studies agree that food cooked in the microwave tends to keep more of the vitamins and minerals compared to those cooked conventionally. 

Water-soluble vitamins like vitamin C and B are decreased by conventional cooking as they are sensitive to heat and water.

Similarly, fat-soluble vitamins like vitamins A and D and minerals like potassium and calcium are often reduced during cooking.

Since microwaves use steam for cooking your food quickly, all those nutrients are preserved.

Having said that, you only use microwave-appropriate containers and covers when cooking and reheating because they allow radiation to pass through. 

You need that radiation for the food to cook. Without it, your frozen dinner will remain stone-cold and unappetizing. 

Glass, plastic, ceramic, and paper are all materials that microwaves can travel across. While they cannot be heated by radiation, they become hot due to the heat of the food cooking inside.

Your microwave-safe cover is the same. It will not reduce radiation. What it does is ensure that the heat circulates and cooks your food evenly.

If it protects your oven walls from messy splatters, all the better.



USDA Food Safety and Inspection Service


Written by
Antonio Forde
I'm the head-writer @ Ask The Home Geek (or, in plain English, I'm the guy writing & editing the majority of the content here). Current learning project: Korean.
Have any questions? Write us a message.
Antonio Forde
I'm the head-writer @ Ask The Home Geek (or, in plain English, I'm the guy writing & editing the majority of the content here). Current learning project: Korean.