Bacteria are living organisms, too, and they prefer food that is just the right temperature, moist, and well nourished.
If these bacteria are attached to food in a warm place, they become more active and multiply rapidly. On the other hand, in a cool, dry place with no food, the bacteria are less active and fewer in number. However, even though the number of bacteria may decrease, they are rarely wiped out. Bacteria are stubborn creatures with a strong life force.
When food goes bad, it means that the bacteria take the food, eat it, increase their number, and change the food into bacterial excrement.
The stale food smells bad and has a stringy appearance. This is caused by the increase in bacteria that eat the food and the excretions produced by the bacteria.
If the food is in a dry place and the temperature is low, the growth of bacteria can be suppressed, and the food is less likely to become stale. This is the reason why food is less likely to spoil if it is kept in a refrigerator.