It’s now official: These foods can become toxic if reheated in the microwave

The Dangerous Side of Leftovers

• Chicken: Let’s begin with the fridge classic: leftover roast chicken. On paper, it’s as harmless as can be. But if your chicken is still a little pink and you’re hoping the microwave will cook it through—stop right there. The microwave heats unevenly, sometimes leaving cold spots where bacteria, like infamous salmonella, can thrive happily. For chicken and other white meats, go for even heating: use your oven or stove for that final touch.
• Potatoes: Another ingredient that seems totally innocent: the potato. Rich in starch, potatoes do not appreciate temperature swings. As they cool and get reheated incorrectly, they can become hard to digest, even toxic. Instead of tempting fate, turn them into a potato salad served at room temperature, add some olive oil and fresh herbs. It’s rustic, simple, and above all, safe.
• Eggs (especially hard-boiled): Speaking of risk, let’s talk eggs—specifically hard-boiled. One word: explosion. Literally. Trapped in their shells, microwaved eggs can expand and burst if you pierce them afterward. As described in research published by Science Daily, this phenomenon produces a noise comparable to a jet taking off… and if you’re too close, severe burns. To avoid this mess, simply eat them cold, perhaps in a mixed salad.

The Sneaky Risks: Rice and Mushrooms

• Rice: Rice is a takeout superstar, but it hides an unsuspected danger. If cooled improperly or left too long at room temperature, it can develop bacteria called Bacillus cereus. The result? Bloating, stomach upsets, even food poisoning. The trick: cool your rice quickly after cooking and pop it straight in the fridge.
• Mushrooms: Mushrooms are a hit sautéed or in a creamy sauce, but you really need to watch their freshness. Once cooked, don’t let them linger for more than two days. When reheated, they lose a bit of flavor and can become harder to digest. If you’ve made too much, freeze the mushrooms promptly or toss them into a quiche the next day.

How to Reheat Safely… or Not at All

You can never repeat it enough: it’s all about the “cold chain.” Hot food needs to be cooled down quickly (within two hours after cooking) and stored in the refrigerator at no more than 39°F (4°C). And when reheating, it’s best to stir halfway through or split your food into portions so the heat can spread evenly.

And sometimes, the best option is… not to reheat at all. Some dishes are just as delicious cold: a cold lentil curry with a squeeze of lemon, a vegetable tart at room temperature, or a pan of leftover quinoa transformed into salad.

Savoring Your Food, Safely

Keeping your meals tasty and safe doesn’t take much extra effort, just a bit of vigilance. Cooking is a joy, but eating well is also about being mindful of what you’re reheating. So, before sliding your leftovers into the microwave, ask yourself: is this food ready to handle a thermal shock… or would it be better off another way?

Web writer and kitchen lover, Mathilde offers accessible recipes, handy tips, and creative ideas to inspire all home cooks. Passionate about good food, she celebrates the joy of cooking and sharing.