How Temperatures
Affect Food

And Cause Foodborne Illness

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Have you ever left a gallon of milk or some cooked foods sitting out on your counter for too long (perhaps all night) and just put it back in the fridge to eat or drink later on?

Maybe you’re in the habit of leaving hot and cold dishes at your parties out for more than the safe maximum time of two hours. You’re thinking: What real harm is there with leaving them out one or two more hours, right?

Well, in both of those cases, the food lingering outside the fridge is NOT safe to consume. It must be thrown out. No ifs, ands, or buts.

The reason?

Hot and cold foods left out at room temperature for more than two hours are DANGEROUS.

Room temps for these foods are a veritable breeding ground for harmful (and possibly deadly) bacteria like E. coli O157:H7, Staphylococcus aureus, Campylobacter, Salmonella. Stop Foodborne Illness wants to help you understand the important role temperature plays in keeping your food safe and you free from the perils of foodborne illness. So, let’s cover some food temperature basics and specific things you need to do to stay food safe.

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Bacteria grow fastest in the range of 40 – 140°F, the “Danger Zone.” A refrigerator set at 40°F or below will protect most foods. Your fridge is one of the very best weapons you’ve got in the fight against foodborne illness. When bacteria get the nutrients, moisture, and warmer temperature it needs, rapid bacteria growth occurs and can reach levels that may cause illness. Refrigeration slows bacterial growth.


Just because your food looks done doesn’t mean it is done. The only way to know if your meat, poultry, and egg dishes are safely cooked is to use a food thermometer. For instance, many people assume that when a hamburger is brown in the middle, it’s done. But, according to research by the United States Department of Agriculture (USDA), 1 of 4 hamburgers turns brown before it reaches a safe internal temperature (SIT) of 160°F. The SIT for all ground meat and meat mixtures (meatloaf, hamburgers, turkey burgers, etc.) is 160°F; for fresh, raw, whole cuts of red meat (beef, veal, chops, and lamb), it’s 145°F. Cook all poultry to a SIT of 165°F. Not cooking your food to safe temperatures means bacteria may still be surviving inside and cause illness.


When reheating leftovers, cook them thoroughly to a minimum SIT of 165°F and use a food thermometer to check (every single time!).

Your food should be steaming hot all the way through. Cover leftovers when reheating on the stove or in the microwave, which helps retain moisture and ensures even cooking. For sauces, stews, soups, and gravies, bring them to a rolling boil. When reheating frozen leftovers, it’s best to first thaw them in the fridge.  


One of the most basic and important ways to make sure your food is safe is to set your refrigerator and freezer at safe temperatures for food storage. Per the United States Food and Drug Administration (FDA), those temps are 40°F for your fridge and 0°F for your freezer. Bacteria capable of causing foodborne illness doesn’t grow or grows very slowly at these temperatures.

This cooling of your food slows the movement of molecules, which causes bacteria to enter a dormant stage. To make sure you’ve got the right temps, check the thermometer inside your unit.  


One common cause of foodborne illness is not cooling leftovers soon enough. After foods are cooked to safe internal temperatures, bacteria can reappear and reproduce. So, be sure to get those leftovers transferred into shallow containers (for quick cooling) and into the fridge within two hours of being cooked.

And remember that your leftovers in the fridge will last safely for four days max. After that, do one of two things: Freeze ‘em or throw ‘em away.

Thanks for helping us spread the food safety word!