Microwave ovens have made our lives easier: we can cook, reheat and, in some cases, even bake and brown food. They also allow us to defrost food in just a few minutes and, in general, make our work easier if we are cooks without much time to cook.
But if we don’t use them properly, we might end up cursing that appliance because we have to clean up the spaghetti sauce splatters or leftover eggs we cooked in the microwave. When certain foods are introduced, they begin to burst and leave the entire inside splattered with food. What is it about this device that makes some foods more prone to this than others? Why is this happening? Is there any way to avoid it?
Pressure, responsible for the explosion of certain foods
To understand why some foods explode, it’s important to first understand how microwaves work. These use microwave radiation, a form of electromagnetic radiation, to heat food. But unlike a conventional oven, which heats the ambient air, that is, transfers heat from the outside to the inside of the food, microwaves penetrate deeper inside.
Microwaves cause molecules to spin and collide with each other, creating heat. Water is one of these polar molecules and we find a good part of the explanation here. Although heat can escape, it is usually trapped inside, allowing for faster cooking. But if the food contains a lot of water, it expands and turns into steam. What happens if the food is wrapped in a shell, like an egg, or in a skin, like grapes? This will cause as the water inside evaporates, the amount of water vapor inside will increase and, as it cannot escape because it meets a barrier, it will exert pressure on the coating and will eventually burst.
Another similar explanation is given by the United States Department of Agriculture (USDA), according to which the main culprit is water, which explodes if it exceeds its boiling point. Therefore, if we want to heat water, we must do it carefully. In the case of eggs, steam cannot escape from the whites, so pressure is generated. What happens is that the microwaves set the moisture particles in the egg into motion; The friction heats the egg from the inside and releases steam that cannot escape through the shell. If it hasn’t exploded before, when you cut it or, even worse, bite it, the steam is released instantly and the explosion can burn you.
What other foods can burst? We are talking about tomatoes and tomato sauce, lemons, potatoes (unless holes are made in them before cooking) or eggplants, as well as whole, unpeeled fruits such as peas or corn. Thicker soups are also more likely to splatter than thinner liquids, because heat concentrates more easily in a viscous liquid, allowing steam bubbles to expand until a pop forms.
In the case of tomato sauce, what happens is that the mixture of water and fiber it contains tends to retain the heated water molecules, preventing evaporation to the point where the steam ends by escaping and exploding towards the walls of the microwave pan. This can also happen with any type of puree.
It is also not recommended to reheat mussels or clams in their shells, as they will burst within a short time. Even without the shell, shellfish are not very suitable for this type of cooking, not only because they can explode but also because, being rich in collagen, a protein that requires gentle cooking, they risk becoming sticky.
What to do to prevent food from exploding in the microwave
Even if finding our microwave full of soup or tomato sauce is something that we do not like, it is, as we have seen, a purely physical phenomenon which is nota priori, dangerous. Even if there are tips to limit the risks. Some ways to achieve this are more obvious than others, but no less important:
- Place food in the center of the microwave so that the heat is distributed evenly. It should be kept in mind that the edges contain hot spots which are more likely to transform the water in preparations such as soups into explosive steam bubbles.
- Cook thick soups or stews on lower power, stirring occasionally. Using lower powers allows us to extend the cooking time, ensuring that the heat has a chance to transfer to the internal parts of foods like sausages without overcooking the exterior or causing a steam explosion.
- Make a small cut in the skin of tomatoes, grapes or peas to prevent heat from concentrating inside and being able to escape.
- It is not advisable to cover the container with a tight-fitting lid, as steam will accumulate underneath and be violently expelled. Yes, you can cover the bowl with a small plate, which will not prevent the explosion, but it will avoid having to clean the walls of the microwave.
- Pierce the plastic lids when we put them in the microwave. This way we give the steam a path and an exit route so that it can escape and the container does not explode.
- Stir the sauces frequently to prevent them from bursting because this way the steam dissipates and we will avoid splashing.
We need to keep in mind that the more food we put in the microwave, the more likely it is that there will be cold spots that don’t heat as well. We can avoid this by cutting food into smaller pieces, dividing it into smaller, flatter portions, or heating it at regular intervals, stirring occasionally to heat evenly. For example, in the case of spaghetti, it is best to make a circle in the center of the plate.
