Perishable foods include raw and cooked meat, poultry, and seafood products. If perishable food is left at room temperature for longer than 2 hours, bacteria can grow to harmful levels and the food may no longer be safe. The 2-hour limit includes preparation time as well as serving time. Once fruits and vegetables are cut, it is safest to limit their time at room temperature as well. One of the most common causes of food poisoning is improper cooling of cooked foods.
Bacteria are everywhere.
Even after food is cooked to a safe temperature, bacteria can be reintroduced in the cooked food from many sources and then can reproduce. Leftovers should be put in the refrigerator or freezer promptly after eating. As far as possible refrigerate perishable foods within 2 hours. Put foods in shallow containers so they cool faster. Perishable foods should always be cooked thoroughly.