The "explosion" of food in a microwave typically occurs due to the rapid buildup of steam and pressure within the food. This phenomenon is known as "superheating" and can happen under certain conditions. Here's a brief explanation of the chemistry involved:
Water and heating: Microwaves work by emitting electromagnetic waves that excite water molecules within the food. As the water molecules absorb this energy, they start to vibrate rapidly, generating heat throughout the food.
Uneven heating: In some cases, the heat generated by microwaves may not be distributed uniformly throughout the food. Certain areas may become significantly hotter than others, while other regions remain cooler.
Superheating: If a liquid, such as water, is heated beyond its boiling point without any visible boiling occurring, it can become superheated. Superheating happens when the liquid's temperature exceeds its boiling point, but no bubbles form due to the absence of nucleation sites, such as impurities or rough surfaces.
Nucleation and explosion: When the superheated liquid is disturbed or encounters a nucleation site, it can undergo a rapid phase transition, causing an explosive release of steam. This sudden release of steam can cause food to "explode" or splatter within the microwave.
It's important to note that superheating is more likely to occur with certain liquids, such as distilled or purified water, as they may lack impurities or nucleation sites. Additionally, using containers with smooth surfaces or heating liquids in microwave-safe containers can contribute to superheating.
To prevent superheating and potential explosions in the microwave, you can take a few precautions:
Stir liquids: Before heating liquids in the microwave, give them a gentle stir to distribute the heat evenly and promote the formation of bubbles.
Use microwave-safe containers: Ensure that the containers you use are labeled as microwave-safe and have rough surfaces, which can provide nucleation sites for bubble formation.
Allow for standing time: After heating food or liquids in the microwave, allow them to stand for a short period. This helps to equalize the temperature throughout the food or liquid and allows any potential superheating to dissipate.
By following these guidelines and practicing microwave safety, you can minimize the risk of food "explosions" caused by superheating.