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10 Foods That You Shouldn’t Reheat in a Microwave

We already know better than to nuke plastic—or heaven forbid, aluminum foil—but certain foods can become downright toxic when blasted in the microwave. Here’s what you need to know. The post 10 Foods That You Shouldn’t Reheat in a Microwave appeared first on The Healthy.



About 30 years ago, Americans were given the microwave, which has since become an indispensable appliance in their kitchens. Today’s youth simply cannot fathom a world without it when preparing such simple treats as oatmeal, hot chocolate, and popcorn. Despite this, many of us reheat food in the microwave without following the proper protocol. We all know not to microwave anything made of metal or plastic, but there are also real dangers to nuking certain foods.

To begin with, because of the microwave’s inefficient heating, bacteria can easily multiply in previously cooked food that has been reheated in a microwave. Another issue is that microwave radiation can cause cancer by stimulating the growth of cancer-causing organisms. Ten foods should be avoided at all costs when using a microwave:

Scrambled eggs

Whether the egg is shelled or unshelled, the moisture inside generates so much steam that it can explode when cooked in a microwave. This is because the microwave acts like a miniature pressure cooker. But the scariest part is that the egg won’t crack in the microwave while it’s heating up, but rather afterward, potentially exploding in your hand, on your plate, or even in your mouth. Prevent your egg from becoming a steam bomb by cutting it into small pieces before reheating, or just don’t reheat it at all if you can help it.

Infant formula


It’s great that many new moms choose to store their breast milk in the freezer for later use, but you shouldn’t reheat it in the microwave. Similarly to how microwaves can unevenly heat plates of food, warming a bottle of breast milk in a microwave can result in “hot spots” that can burn a baby’s mouth and throat. In addition, re-heating plastic poses a carcinogen risk. Breast milk and formula should be thawed and reheated in a pot set over a stove burner or in a sink filled with hot water, as per FDA guidelines. If you need to thaw frozen breast milk quickly, you can use a microwave to heat a cup of water, and then place the bag or bottle of milk inside. Have a look at this list of additional microwave no-nos.

Cured and smoked meats

Chemicals and preservatives are commonly used in processed meats to increase their storage life. Microwaving them, alas, can make them even more harmful to your health. According to a study published in the Journal of Agricultural and Food Chemistry, microwaving processed meats may expose us to oxidized cholesterol and other chemical changes. Reheating processed meats with a burst of microwave radiation may contribute to the formation of cholesterol oxidation products (COPs), which have been linked to the development of coronary heart disease, according to research published in the journal Food Control. Microwaving processed meats is much more likely to introduce COPs into your diet than other meal-prep methods for reheating food. Here are some more summertime treats that could make you sick.


Because they heat from the outside in rather than the inside out, microwaves do not always kill bacteria with their heat. Due to the increased potential for illness, some reheated foods that are prone to the growth of harmful bacteria will have a higher survival rate of these bacteria cells. Keeping this in mind, it’s easy to see why chicken, which is susceptible to salmonella contamination, might be a risky food to microwave. Unless you want to risk eating bacteria from undercooked chicken, you should cook your chicken for at least 15 minutes. Microwaves increase the risk of ingesting bacteria like salmonella because they don’t thoroughly cook the meat. The study found that out of 30 people who reheated raw meat, all 10 who used a microwave got sick, while the other 20 who used a skillet were fine. When compared to other cooking methods, this demonstrates how much bacteria can survive in microwave-cooked meat. Here are another 50 foods that dietitians and health experts will never eat.


Vegetable greens

Plan to reheat your celery, kale, or spinach in a conventional oven, rather than a microwave, if you plan to eat them as leftovers. Natural nitrates (which are very good for you on their own) may convert to nitrosamines (which can be carcinogenic) when cooked at high temperatures in the microwave, according to studies.


Reheating nitrate-rich beets and turnips results in the same chemical conversion as that seen in reheated spinach. The fact that they taste great cold is a bonus. On the other hand, here are 16 items you probably wouldn’t have guessed were microwaveable.

Scoville scales


Capsaicin, the chemical responsible for the spicy flavor of peppers, is released into the air during microwave reheating. If inhaled, the chemical will cause severe irritation to the respiratory tract and the eyes. One apartment building in Rochester, New York, was evacuated when residents began coughing and having trouble breathing after eating pepper that had been heated in a microwave. Read on to learn the other 18 ways in which you’ve been misusing your microwave.


The grapes in the microwave won’t turn into raisins, but they will turn into plasma, a form of matter formed when gas is ionized and allows electricity to flow through it. Stephen Bosi, PhD, a physics lecturer at the University of New England, demonstrates how to create enough plasma to melt a hole through a plastic container by microwaving two pieces of a regular grape. Other fruits may not yield plasma, but you may still end up with a sticky situation. When heated, whole fruit can cause a steam explosion because the flesh traps the steam under the skin.


Lucky for us, microwaving raw potatoes is still a safe option for those times when you need a side dish fast. Reheating previously prepared potatoes poses a health risk. The botulism-causing bacteria, Clostridium botulinum, can survive cooking in aluminum foil, so long as the potato is not left out at room temperature for too long. Instead of risking food poisoning, it’s best to bake potatoes on a baking sheet instead of wrapping them in foil and store any leftover potatoes in the fridge as soon as possible. Don’t bother microwaving anything else except these dishes that even chefs recommend.


First published on The Healthy: 10 Foods You Should Never Reheat in the Microwave.