Here's why:

* Parasites are organisms that live in or on another organism (the host) and benefit by deriving nutrients at the host's expense. They are distinct from microorganisms that simply grow in food.

* Microorganisms are tiny living things like bacteria, yeasts, and molds. While some can cause food spoilage or illness, they are not parasites in the true sense.

* Foods that allow microorganisms to grow are called perishable foods. These foods provide the necessary conditions (moisture, nutrients, temperature) for microbial growth.

Think of it this way:

* Parasite: A tick on a dog (the parasite benefits, the dog is harmed).

* Microorganism in food: Bacteria growing on a piece of meat (the bacteria benefits, the meat spoils).

Let me know if you have any other questions!