Never Reheat Food in a Plastic Container That Isn’t Microwave-Safe

The leftovers kept in the fridge are naturally placed in the microwave in the same container. Something that is acceptable for keeping food cold isn’t necessarily recommended for heating food as well. The leftovers are in the container they went into the fridge in. 

Not All Plastic Containers Are Made for Heat

Food-contact plastics are designed for specific uses, and temperature is one of the conditions considered. A container might be suitable for refrigerated storage, but not for reheating.

As we all know, plastic behaves differently when it’s heated, it can relase chemicals into your food, so pay attention to that! Substances can migrate from food-contact packaging into food, depending on the material, food type, temperature, and contact time. Not all plastic containers are a problem, but not all of them belong in the microwave either. 

A Common Mistake: Reheating in Takeout Containers

Take extra care with takeout containers, foam containers, and other single-use packaging that are not labeled or intended for microwave use. Do not use a container that isn’t marked to be safe for the microwave. Especially for foods that contain oil or are acidic.

Some studies have reported that when heated under certain conditions, plastic containers release microplastics or nanoplastics. Research is still underway on the potential health implications of such exposures, so follow the manufacturer’s instructions and use only plastic containers intended for microwave heating. 

Yogurt or margarine containers are fine for use in the refrigerator, but they should not be used to heat food.

What to Use Instead

The best options are glass or ceramic, as they are generally safe for the microwave. Don’t take a glass dish from the fridge and put it straight in the microwave, the sudden temperature change can crack it. Give it few minutes on the counter first.

What Does Microwave-Safe Mean? 

Before using plastic containers, ensure that they have the microwave-safe label on them. Such containers are usually marked with wavy lines or the words “microwave-safe.” Don’t rely on the recycling number alone. The resin identification code indicates the type of plastic used to make the container, but it does not, by itself, indicate that the container is suitable for microwave heating. 

Three Questions Before You Microwave Food

• Is there a microwave-safe mark?

• Did the food arrive in the same container as it did from the shop?

• Is the container damaged from heating previously? 

Separate Storage From Reheating 

At Cooking Office, we think kitchen habits shouldn’t make cooking riskier than it needs to be. One easy tip: separate storage and reheating; use plastic containers for what they’re meant for, and transfer food to a suitable microwave-safe container when it’s time to reheat. 

You don’t have to get rid of all plastic containers in the kitchen simply because they are plastic. The idea is to use each container for what it’s designed for.

A Simple Rule to Remember

Don’t reheat food in a plastic container unless it is clearly marked as microwave-safe. Glass or ceramic are better alternatives than other materials. 

FAQs

Can I microwave takeout containers?

Only if they’re marked microwave-safe, and most aren’t. The clear plastic clamshells and the foam ones are designed to hold food, not to heat it. Tip the food onto a plate — it takes ten seconds and it’s the single most common version of this mistake.

Can I cover food with plastic wrap in the microwave?

FSIS says plastic wrap shouldn’t touch the food while it heats. If you use it, leave a gap and vent one corner — or use a paper towel or an upturned plate instead.