Often you'll have leftover food or takeout in an aluminium tray or container and you'll want to warm up the food. You might want to throw it in the microwave and not transfer the food to another container, but we are always told “don't put metal in the microwave”.
Is this true or can you microwave aluminium trays? What happens when you microwave aluminium trays? Will they spark and set your microwave on fire? Will they cause any damage?
Rather than trust in conventional wisdom I decided to run my own experiments as well as look at what the experts say about this and what I discovered was quite interesting:
It is actually safe to microwave aluminium trays in the microwave assuming that the tray does not touch the side of the microwave, you use only one tray at a time and that your food is not completely covered by aluminium.
This goes against the conventional wisdom that you shouldn't put metal in the microwave so let's have a closer look at my tests, and the reasons behind why this is safe (and when it might cause sparks or a fire).
What Happens When You Microwave an Aluminium Tray
I decided to run my own experiments and to risk my microwave and test this out myself.
I put an aluminium foil tray in the microwave full of food and microwaved it for 2 minutes. I then put an empty aluminium tray in the microwave and microwaved that.
When you microwave aluminium trays the microwaves bounce off the aluminium and don't pass through to the food. The food will heat up from the top opening of the tray and no sparks will be seen unless the tray touches the side of the microwave.
You can see my experiment with aluminium trays below:
When nothing exciting happened I completely scrunched up the tray and put that in the microwave. Minor sparks were seen but no damage was done to my microwave.
It was only when I scrunched up thin aluminium foil where a large quantity of sparks was created, but even still there was no fire in my microwave and only minor damage was done when I COMPLETELY filled up my microwave with alfoil.
What Do The Experts Say About Microwave Aluminium Trays?
So my experiment showed that it was fine to microwave aluminium trays. But maybe I got lucky and nothing happened in my microwave but other people might have different results.
So I had a look into it at what the experts like the USDA were saying as well as any studies on aluminium in the microwave.
The USDA states that:
It can be safe to use small amounts of aluminum foil in a microwave oven.
There was this study from the Fraunhofer Institute for Process Engineering and Packaging IVV in Freising, Germany that proved that it is safe to use aluminium foil packing in the microwave.
They stated in their critical summary:
Based on the physical insight and on empirical findings, all evaluated studies agree that there is no reason to NOT use aluminium foil packages for heating food in the microwave over – as long as some design rules and heating guidelines are followed.
They also state that “oven damage or degradation is practically no issue”
Aluminium Will Not Break Your Microwave
There is a lot of misinformation out there that the use of aluminium in a microwave can actually break your microwave.
The guiding theory is that because the metal reflects and doesn't absorb the microwaves this will somehow break the microwave.
But in this study they disprove this common myth. They state:
“No negative of destructive influence on magnetron operation was detected after a test time equivalent to 32 years average household service life”
They also state in this same study that:
“safety of microwave over operation is not affected by heating food in aluminium foil trays, if instructions are followed. If arcing occurs, it will not damage over or start a fire but may cause minor aesthetic defects in the over wall”
How To Safely Heat Food In an Aluminium Tray in the Microwave
While it's considered safe to heat food in an aluminium tray in the microwave some safety precautions should be taken to avoid sparking, fires or other potential issues:
- Trays should be placed in the center of the oven plate and should not touch the over walls
- Trays should be shallow with a deepness of less than 3cm where possible.
- Food should cover most of or all of the tray bottom
- If arcing (electric sparks) occurs turn off your microwave immediately. It will not damage the oven or start a fire but may cause cosmetic damage to the over wall.
- Be careful using a paper or cardboard lid with aluminium trays, the heated aluminium could potentially set the paper/cardboard on fire.
- If your microwave turntable is made of metal then place a glass or ceramic plate under your aluminium tray
Can Microwaving Food In Aluminium Cause Cancer or Health Issues?
Lastly I wanted to look into whether or not there are any concerns with health issues related to aluminium as I was pretty surprised when I discovered that microwaving styrofoam can leach chemicals into our food and so can microwaving paper and microwaving paper towels.
From my research it seem that using aluminium trays in the microwave to heat food poses very little health risks and is highly unlikely to lead to aluminium toxicity unless used extremely regularly. No carcinogenic effect from aluminium has been proven to date.
Aluminium is the third most abundant element in the earth's crust and occurs naturally in the environment, food and drinking water.
According to this study only about 0.1% of orally inject aluminium is absorbed and made bioavailable.
The European Food Safety Authority (EFSA) and the World Health Organization (WHO) put a tolerable weekly intake at between 1-2 mg of aluminium per kg of body weight.
There have been some news reports that aluminium is linked to Alzheimer's disease as well as some types of cancer.
However this article states:
The Alzheimer’s Society does not recognize normal daily intake of aluminum through food or cookware as a cause for the disease. Additionally, aluminum from cooking utensils has not been linked to cancer.
This study looks at a variety of studies into the negative health outcomes of aluminium and states:
No acute effects due to dietary exposure to aluminium have been observed in the general population
It also seems that links to aluminium and Alzheimer's as well as breast cancer are inconclusive with some studies showing a potential link while other studies showing no link at all.
Would I Personally Microwave Food In an Aluminium Tray?
I like to end these articles asking myself the question “do I feel comfortable microwaving my food in an aluminium tray?”
I'm more conservative that most people and from my research into paper towels and styrofoam I definitely won't be using them in the microwave anymore.
But what about aluminium? Would I microwave aluminium trays?
My answer is: yes I would
Now that I know that it is safe and is unlikely to spark or cause fires and also that health wise it is safer than plastics, styrofoam or paper I would feel quite happy to use aluminium foil trays in the microwave if I needed to.
I would still opt for using glass or ceramic bowls or plates where possible as they seem to carry even less risk, but aluminium trays to me seem fine to use in the microwave.