Reheating food: 8 foods you should NEVER reheat in the microwave

Reheating food: 8 foods you should NEVER reheat in the microwave

Reheating food is always a tempting convenience, but did you know there are some foods you should never reheat in a microwave?

It's a wonder we managed in pre-microwave times. Nowadays, most kitchens have one, and we use them for almost everything, from heating up our porridge to cooking our ready meals.

Microwaves may be a wonderful invention, but that's not to say they can do everything. Discover which foods you should never put in your microwave today, or risk poisoning yourself, and family!

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1. Can I microwave celery?

celery and carrots

Although celery is usually eaten raw, it's sneaked into lots of other store-bought foods such as soup and even bolognese.

Celery contains nitrates, which, when reheated, can turn toxic, releasing carcinogenic properties. Carcinogens are substances or environments that can cause changes in a cell's DNA, and lead to cancer.

Reheating food rich in nitrates should be avoided where possible.

2. Microwave beetroot

Like celery, beetroot is also often eaten raw - this is perhaps due to it's unsuitability to being reheated. Just like celery, beetroot contains nitrates which can produce carcinogens when reheated.

Try to avoid reheating beetroot by removing it out of your meals before you zap them in the microwave.

3. Microwave spinach

healthy bean stew with spinach recipe

Spinach is also on the list of vegetables that could develop harmful carcinogens when reheated. What's more, spinach rarely tastes as good when reheated a second time.

Do your taste buds and your health a favour and leave it out of the microwave.

4. Can you reheat an omelette?

It's time for egg debate. Whilst more and more people are turning to their microwaves to scramble their eggs in the morning (and who can really blame them? It saves on mess and time), the same cannot be said for reheating.

The problem with reheating eggs in the microwave is that, often, they are not heated for long enough. If eggs are eaten at temperatures lower than 74°C, they can upset your stomach and even cause food poisoning.

If you're lucky enough to have some leftover omelette for dinner, your best bet is the frying pan. Heat it in a non-stick pan for a few minutes on each side and enjoy piping hot.

5. Can you reheat mushrooms

reheating food containing mushrooms

Linguini, stroganoff, risotto...most of us wouldn't even think twice about reheating our favourite mushroom dishes.

The problem with reheating food containing mushrooms is not the microwave itself, but the bacteria they develop between being cooked and reheated. If they are not refrigerated immediately after cooking, their complex enzymes and protein structure can be destroyed.

Once this has happened, reheated mushrooms are unsafe to eat and can cause stomach upsets.

6. How to reheat potatoes...

...the answer most definitely isn't in the microwave. Similarly to mushrooms, if stored incorrectly, potatoes can grow a bacteria called Clostridium botulinum, which can be extremely harmful when ingested.

Bacteria can be killed off at high temperatures, such as those achieved in the oven, but microwaving potatoes is always risk. To avoid tummy troubles, always store potatoes immediately at cold temperatures and do not eat below 60°C.

7. Reheating chicken

Unsurprisingly, chicken is on our list of foods you shouldn't reheat in the microwave. It's not that you can't reheat chicken, it's just not advised. Chicken contains a high-density of proteins which reheating can cause to break down, thus upsetting the stomach.

Additionally, as with eggs, there's a risk of salmonella. The problem with reheating food in the microwave is that they don't distribute heat evenly, meaning some parts of your chicken will be safe to eat, and others less so.

8. Reheating rice

reheating rice dinner

Another controversial food for reheating is rice. Similarly to mushrooms and potatoes, if left out at room temperature, rice can develop spore-forming bacteria. Spores are a sort of 'shell' that develop around harmful bacteria, and prevent them from being broken down even at high temperatures.

Reheating rice in the microwave is not enough to get rid of these poisons, which are likely to cause vomiting or diarrhoea when ingested.

Do you have an alternative method of reheating? Share your tips with us in the comments below.



Stephanie C


Lover of all things fashion & foodie...I look to satisfy my tastes without obliterating my budget. Wannabe interior designer, I'm an avid cushion cover maker and charity shop hunter.

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  1. Author Rosemary Woolard on January 17, 2018 at 9:00 am

    I have always cooked celery in the microwave, before adding to soups or stews, are you saying it should never be cooked in the microwave, or is it just reheating ?

    1. Author Stephanie C on January 23, 2018 at 9:34 am

      Hi Rosemary. It's the reheating process that's the problem, not the cooking, so you should be fine :) I hope this helps!

  2. Author John Toxteth-Riot on January 17, 2018 at 9:55 am

    Bummer! I put celery and mushrooms in my stews, so I'm not supposed to re-heat them. Even when I've had eight pints of brown ale down at the rub-a-dub and I'm home and I'm Hank Marvin. Not likely! I'm gonna whack that Looby Loo in the old nuclear oven and give it 4 mins on the 'destroy' setting. Then I'm gonna sit down in front of the telly for Family Guy and scoff it down my neck and dribble it all over my shirt. Probably wake up three hours later in the armchair with the telly still blaring out.

  3. Author LornaMM on January 17, 2018 at 10:57 am

    Wow! That's my life ruined!! Not really, but potato, mushroom and celery are all in my regularly nuked to reheat list. Stove-top it is then, thanks.

    1. Author Stephanie C on January 18, 2018 at 9:22 am

      Hi Lorna. Shocking isn't it! Reheating every now and then shouldn't do TOO much harm, it depends how strict you want to be with it.

  4. Author sarah on January 17, 2018 at 2:44 pm

    So would reheating these foods on a pan on the cooker be less harmful?

    1. Author Stephanie C on January 18, 2018 at 9:22 am

      Hi Sarah. The hob is preferable as the food reaches a hotter temperature and is also heated more evenly, which is essential to removing some of the harmful bacteria mentioned in the article. I hope this helps :)


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