We’ve all been there: The microwave beeps, you put those leftovers on a table (or in your lap), and you take a bite. The vegetable and noodles are piping hot, but the meat and beans are barely warm.
Yes, microwaves are celebrated for their convenience. Not only can they catalyze meals and reheat leftovers in minutes, but they also don’t require much effort beyond pushing a few buttons. That simplicity, however, often comes with a setback: Your food probably isn’t a uniform temperature.
How do microwaves work?
A microwave uses three components to heat food: the magnetron, the waveguide, and the chamber compartment (that holds food and contains radiation). The magnetron emits electromagnetic waves in a continuous motion to generate enough energy to heat food, says Ali Manning, food scientist and consultant. The water in our food reacts to the electromagnetic waves distributed through the waveguide, creating friction that can heat the entire mass of food simultaneously.
So, why don’t microwaves heat evenly?
There are a number of factors that may affect microwaved food’s temperature, including the type of glassware or flatware you’re using, the types of foods you’re reheating, and how you arrange the food.
You’re probably already aware that some plastics aren’t microwave-safe because they can leach chemicals into food. They’re also susceptible to melting, cracking, and burning because they’re unfit for a microwave’s temperature. This makes, say, that plastic bowl you got for $2 at Target feel hot sooner than the food inside.
The type of food you’re eating is also at play. Fatty foods, for example, heat more quickly because they have fewer water molecules for the electromagnetic waves to heat up. Various types of molecules also react to heat differently. Simpler molecules, like carbohydrates, heat up more quickly than more complex molecules, like protein.
Your microwave may also be at fault: “[Microwaves] sometimes experience uneven heating due to irregular reflections of the waves within the chamber,” Manning says.
Ways to make your microwave work for you:
First things first, be sure to use the proper container or plate. Manning recommends microwave-safe glassware and ceramic materials because they have a higher thermodynamic conductivity. These materials heat up more quickly and hold more heat—this both heats the food faster and helps it stay hot longer. Depending on the dish, you might want to use a vessel that comes with its own lid, like this for noodles or this for popcorn.
Smaller amounts of food will reheat faster, so make a point not to pile up your plate. Covering your food with a moist paper towel or microwave-safe item will keep steam from escaping and instead circulate the heat faster. You can also microwave your food in increments and stir in between, or heat your food at a lower temperature for a longer time.
Spreading food more evenly on your plate, as well as placing food closer to the edges, will help achieve a more uniform temperature. Keep things flat when possible. If all else fails, check your microwave’s settings and make sure its rotator is actually spinning.
