When you put bread or other food in a microwave, it doesn't spoil as quickly as when you leave it outside because the microwave cooking process creates an environment that is not conducive to the growth of microorganisms.
Spoilage of food is primarily caused by the activity of microorganisms such as bacteria, molds, and yeasts. These microorganisms require certain conditions to grow and reproduce, including moisture, warmth, and a source of nutrients. When food is left outside, it is exposed to the natural environment where these conditions are present, allowing microorganisms to thrive and cause spoilage.
However, when you place food in a microwave, the cooking process involves heating the food with electromagnetic waves. These waves generate heat by agitating the water molecules within the food, causing them to vibrate and generate heat. The heat produced during the microwave cooking process is usually enough to kill or inactivate the microorganisms present in the food, thus slowing down the spoilage process.
Additionally, microwaves tend to heat food quickly and evenly, reducing the time that food is exposed to temperatures where microorganisms can grow rapidly. The rapid heating helps to minimize the time available for microorganisms to multiply and spoil the food.
It's important to note that while the microwave can slow down spoilage, it doesn't completely eliminate the risk of bacterial contamination or other forms of spoilage. Food should still be handled and stored properly to ensure its safety and quality.