Refrigerated leftovers typically last up to four days if your leftovers are sealed and stored correctly. For most people, covering a plate with foil and tossing it in the fridge is a quick, easy way to store food. However, wrapping your food in a sheet of aluminum foil is also an easy way to put yourself at risk for health hazards.
Much like we need air to breathe, bacteria need air to thrive. Some bacteria like staph and Bacillus cereus, which causes foodborne illnesses, produce toxins that aren’t destroyed by high cooking temperatures. When a hot meal is left out at room temperature for more than two hours, the bacteria grow rapidly, according to the Washington State Department of Health.
Using aluminum foil to cover food poses the same risk, since it doesn’t completely seal your food off from the air. “When air is present, that allows the bacteria to grow faster, so you really want to get the right containers and pack things appropriately,” says Lindsay Malone, a registered dietitian at the Cleveland Clinic. “Otherwise, your food isn’t going to last.”