From foods that go bang to items that cause sparking, there are certain products that do not react well to being microwaved. In fact, if the microwave safety instructions are not adhered to, it can lead to an electric shock, injury and even pose a fire risk. On a lighter note, there are food items that simply do not cook well and lead to a poor taste; the microwave may also be incapable of adequately heating the food items evenly, which can result in hot spots. Do you want to find out what foods should not be microwaved? Then read on to discover more.

For individuals who are new to the concept of cooking for themselves, people who batch cook meals or cook for themselves as part of adherence to their weight loss or muscle gaining food plan, or simply those individuals who worship their precious microwave, this list will help dictate what foods you can microwave as part of your food plan, and even if you’re reheating foods at a later stage, you’ll now be equipped with the knowledge of which foods to avoid for microwaving. Let’s make the world a safer and healthier place with this list so that both people and microwaves can live in harmony together.


What foods should not be microwaved? - Silver microwave oven in kitchen

Did you know? There are many misconceptions surrounding food becoming radioactive once microwaved. However, this is not the case. Additionally, no microwave energy remains within the food following cooking.

Protein

Eggs: There are numerous ways that eggs can be microwaved with excellent results. In the previous article, titled what foods can I cook in the microwave?, you were provided with 2 fool-proof recipes to make delicious scrambled egg and poached egg, without the hassle of pots and pans.

However, did you know that it is very dangerous to use a microwave to cook eggs in their shell and boiled eggs? If you do attempt to try it, you’ll be left with an exploding egg and an almighty mess to clean up. The reason for the egg exploding is attributed to excess steam generated in the egg which it cannot process through the pores; this ultimately causes it to detonate. The egg can even explode after it has been microwaved, which is even more hazardous as it may splatter hot food on you and possibly burn your skin.

Your best option is to either stick to the old reliable method of boiling eggs in the pot, or opt for scrambled eggs, poached eggs or omelette, if you do want to microwave them.

What foods should not be microwaved? - 3 eggs on table beside egg in bowl

Frozen fruit: Not only is frozen fruit cheaper than the fresh alternative, it also attains greater nutrient retention and the shelf life is much longer. The greatest inconvenience with frozen fruit is remembering to remove the portion from the freezer to thaw it overnight. Despite what you may think, it’s not advisable to defrost your fruit in the microwave. A study completed in 2010 found that microwaving frozen fruit can lead to the development of carcinogenic properties in the fruit, particularly in relation to negative immunological implications.

For this reason, it’s advised to thaw fruit overnight in the fridge or consider alternative cooking methods.

What foods should not be microwaved? - Frozen blueberries in bowl

Frozen meat: We’ve all been there, you come home in the evening ready to start cooking, only to realise that you forgot to defrost the meat and now you’ve nothing for dinner. But wait, doesn’t a microwave have a defrost function that would catapult you out of this situation in minutes? While that may be true, this method of defrosting poses a risk of food poisoning as it brings meat to the danger zone where bacteria can rapidly multiply. According to the USDA, this can be combatted by immediately cooking the meat after it has been fully thawed and removed from the microwave.

The optimal method of thawing frozen meat is to place it in the bottom shelf of the fridge for 24 hours. Never place frozen meat in hot water or leave it out on the counter at room temperature to thaw as this invites bacteria to grow exponentially in the danger zone. If you are stuck and thawing for 24 hours in the refrigerator isn’t feasible, then your last resort should be to defrost it in the microwave.

Also, don’t forget that there are many meats that are suitable to cook from frozen. Read the instructions to clarify and bear in mind that it will take up to 50% longer to cook from frozen.

What foods should not be microwaved? - Frozen meat slices on plate

Processed meats: They’re already pumped with chemicals and preservatives, but did you know that nuking your meat slices can contribute to the generation of cholesterol oxidation products, which are associated with development of heart disease? Examples of meat that were notoriously high in cholesterol oxidation products following microwave cooking included sausages, lunch meat slices and bacon. This was in comparison to alternative cooking methods; if you do need to heat such meats, opt for other methods of heating them, such as in an oven or in a grill.


What foods should not be microwaved? - Parma ham sliced on chopping board

Seafood: Some types of fish are suitable for microwaving, so much so that you can even cook some of them from raw, e.g. cod, salmon and trout. However, other seafood, such as prawns, oysters and shrimp are simply not cut out for the microwaving lifestyle. Many of them tend to develop a rubbery texture, which renders them virtually inedible. Considering the cost to purchase such food items, it would be a shame to have to throw them out, so avoid microwaving them at all costs.
What foods should not be microwaved? - Prawns on white background

Fats

Oils: If you think that you can heat up oils in the microwave, then think again. The chemical composition of oils is a poor contender for microwaving. It is primarily composed of fat as opposed to water, and as their molecules lack the polarity that is present in water, they simply don’t respond well to radiation cooking. As such, you’ll be lucky to end up with luke-warm oil at best. Microwaving oil can help if it has solidified though, otherwise, there’s no real advantage to microwaving your oil.

What foods should not be microwaved? - Glass jar of olive oil

Pizza: The primary constituents of pizza include processed meat, cheese and a crust. All three of these constituents are generally a poor combination when it comes to microwave cooking. As we discussed above, when microwaved, processed meats develop an increase in the presence of cholesterol oxidation products. Microwaved cheese and crust often tend to become soggy and chewy, which leads to a diminished texture and overall reduced enjoyment of the meal. So while there’s nothing a such stopping you microwaving it, if you can stretch yourself to wait a bit longer, then pop it in the oven and it will save on the crappy crust!
What foods should not be microwaved? - Pizza sliced on chopping board

Carbohydrates

Grapes: While this fruit possesses a high water content, you may be surprised to know that they are subject to ignition upon microwave cooking. But don’t just take my word for it, there are numerous videos available which demonstrates grapes igniting to create a microwave plasma. Fortunately, the requirement to microwave grapes isn’t exactly something people need to do, and sadly microwaving grapes won’t leave you with beautifully roasted delicacies either. In general, fruit should not be cooked in the microwave.

What foods should not be microwaved? - 3 bunches of red grapes on table

Hot peppers: If you’re thinking of making your hot peppers hotter by zapping them in the microwave, well then unless you enjoy eating flaming peppers, think again! Yes, these volatile peppers can ignite when exposed to radiation cooking. Furthermore, a chemical called capsaicin, which is the chemical responsible for the hot flavour of the peppers, is released during the microwaving process. When you open the microwave, this chemical has become airborne, so you could end up inhaling it, which causes a burning sensation in your throat. Not only that, it could also result in stinging sensations in your eyes.


What foods should not be microwaved? - Bunch of red hot peppers

Pasta sauce: You have leftover pasta sauce from last night and you want to heat it up to have a tasty quick meal. However, when you place it in the microwave, you’ll likely hear it splattering before it has been evenly heated. This is due to the thick consistency which doesn’t lend itself to allowing the built-up steam to release. For this reason, it’s best to heat it in a pan where it can be continuously stirred to avoid steam building up.

In fact, this doesn’t apply to just pasta sauce, many other sauces are also liable to splatter when heated in the microwave, so exercise caution and read the instruction before you heat it up.

Tip: Investing in a microwave cover for food helps prevent splatter and the associated mess that cleaning up splashes brings! It also allows venting of food and can be used simply to keep bugs, dust and dirt from getting onto your food!

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What foods should not be microwaved? - Red tomato sauce in pot

Water

While virtually every kitchen, no matter how small, has a kettle nowadays, there are times when boiling a kettle for one cup of water seems a bit wasteful. It’s particularly inefficient (and irritating) if the individual boils a full kettle of water knowing that they’ll only use one cup.

If you think that heating up water in the microwave is a better alternative, then you’re mistaken. Heating water by radiation can cause superheating and potentially explode. Superheating involves heating this liquid to a temperature beyond the boiling point. To put it into context, if 1 litre of water was boiled even 1°C above it’s boiling point, the unstable superheated phase could cause the water to create 3 litres of steam. This rapid steam production is what results in the water exploding.

The most concerning part is that the explosion of water can occur when you are removing the cup of water from the microwave, or even when adding an object or teabag or coffee to the mug. As a result, personal injury is increasingly likely. Fortunately this can be avoided by placing a non-metal object in the cup, such as a wooden spoon.

What foods should not be microwaved? - Tea being poured into cup

Did you know? While it’s not advisable, food can be reheated more than once, provided it is within the expiry date, thoroughly heated and piping hot throughout.

Summary

  • Always read the safety instructions on the microwave oven before using it
  • Certain foods can create dangerous conditions if placed in a microwave
  • Whole eggs and eggs in their shell are unsuitable for microwave cooking
  • Some sauces are liable to splatter when heated in the microwave
  • Food can be reheated a number of times provided it is thoroughly heated and within date
  • However, for best quality and safety results, after being cooked, food should only be reheated once
  • Some foods when reheated are subject to hot spots, so ensure food is stirred and piping hot before serving

Thankfully, the list of foods that should not be microwaved is not significantly long, it should, nevertheless, still be adhered to. While we would be lost without our microwave, there are, unfortunately, some foods that just don’t cook or reheat as well as they do in a traditional cooker.

What foods do you think don’t belong in a microwave? Have you a limit on how many times you’ll heat leftovers? Or have you ever had any incidents when cooking in the microwave? Please share your experiences, comments and queries below!

Sources

Animations.physics.unsw.edu.au. 2020. Superheating And Microwave Ovens. [online] Available at: [Accessed 7 June 2020].

Fsis.usda.gov. 2020.The Big Thaw. [online] Available at: [Accessed 7 June 2020].

Gonella, C., 2020. 7 Foods You Should Never Microwave | Eat This Not That. [online] Eat This Not That. Available at: [Accessed 7 June 2020].

Grigoriev, Y. et al., 2010. Confirmation studies of Soviet research on immunological effects of microwaves: Russian immunology results. Bioelectromagnetics, 31(8), pp.589-602.

Schumacker, L. and Kelly, D., 2019. Foods You Should Never Put In The Microwave. [online] Mashed.com. Available at: [Accessed 7 June 2020].

Categories: Blogs

12 Comments

Rani · 08/06/2020 at 5:55 PM

Pizza and water is definitely shocking to me as these two items are the ones that are probably most commonly microwaved.

Thank you for educating us on this.

Many Thanks

Rani

    Sharon · 09/06/2020 at 7:43 PM

    Hello,

    It sure is valuable to know, hopefully nobody gets injured or sick if they are doing it.

    Thanks for visiting and posting your comments on the page, it’s much appreciated.

    Best wishes,
    Sharon

Fernanda · 08/06/2020 at 6:57 PM

Hi Sharon,

Wow thanks for this really useful information regarding microwaving! I had no idea that pizza shouldn’t really be microwaved, although I never really liked the taste of pizza when it’s not freshly baked out of the oven. I have definitely had pasta sauce explode, and as well as any fatty meat tend to “pop” in the microwave…I guess a cover can really help with that. I think microwaves are super useful, specially for people who don’t have time to cook fresh everyday, just need to be careful with the foods you have mentioned!

    Sharon · 09/06/2020 at 7:45 PM

    Hi there,

    Glad that the post has been of benefit and interest to you. True, it loses the crispness and who really wants to eat soggy pizza? True, plus the cover can be used for a multitude of other purposes too.

    Thanks for visiting and commenting on my page!
    Sharon

Michael Stevin · 08/06/2020 at 8:12 PM

Hi Sharon,

Thank you for putting this article together.

I did not know that heating up processed deli meats in the microwave could increase the amount of oxidated cholesterol, and potentially cause health issues.

I once had a room mate that cooked an egg in a tupperware container. Isn’t that potentially harmful? Do foods absorb chemical constituents when heated up in a microwave?

He said the egg tasted terrible, and he was never going to do it again, BTW. I laughed at him! He was so lazy!

Thanks once again, Sharon.

Michael

    Sharon · 09/06/2020 at 7:50 PM

    Hi Michael,

    Good to hear, I’m glad you found it valuable and educational! It is concerning that microwaving certain food instigates elevated carcinogenic risks. Possibly if the tupperware wasn’t BPA-free. There is a risk associated with chemicals leaching from food containers, such as plastic, bottles and aluminium cans. What’s also concerning is that they’re finding traces of plastic present in people, up to as much as a credit card a week! I do have intentions of migrating to glass containers, but it’s a work in progress.

    Thanks for the feedback.

    Best wishes,
    Sharon

Carla · 09/06/2020 at 11:33 PM

This is so good to know! I honestly didn’t know it wasn’t good to microwave so many things. I did know about meat and I usually put my meat in a big bowl of cool water if I need to defrost faster. I often defrost frozen fruit in the microwave, so good to know that it isn’t a good idea. Thanks for the tips!

    Sharon · 10/06/2020 at 6:11 PM

    Hi Carla,

    Thank you so much for your kind words. I hope the article was of interest and use to you and you found some tips and information to take away!

    If there’s anything I can be of assistance with, don’t hesitate to reach out!

    Best wishes,
    Sharon

Chantelle · 10/06/2020 at 4:28 AM

Hi Sharon, very interesting article. I did not know that defrosting frozen meat can cause food poisoning. But it would be common sense to use the meat after defrosting it otherwise you might as well just left it in the fridge to defrost. With the frozen fruits though, what do you mean with carcinogenic properties in the fruit, particularly in relation to negative immunological implications? Is that some form of illness that it causes?

I have microwaved coconut oil before just to melt it but not cook it since coconut oil sets at room temperature. But overall very helpful post to those people struggling to understand why some things they microwave turn on them 🙂

Thanks

    Sharon · 10/06/2020 at 6:13 PM

    Hi there,

    Thank you so much for your words and comments. What I mean by that is it can be considered to cause carcinogenic substances to form which could lead to the potential for cnancer.

    If there’s anything I can be of assistance with, don’t hesitate to reach out!

    Best wishes,
    Sharon

phil · 10/06/2020 at 7:21 AM

This is so useful, I often struggle with what I can and can’t microwave so this is a great handy guide which spilts up into section and food types. Thanks so much!

    Sharon · 10/06/2020 at 7:51 PM

    Hi Phil,

    I’m glad that the post has been of benefit to you.

    Thanks for visiting and commenting on my page!
    Sharon

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