Bacteria grow most rapidly in the range of temperatures between 40 °F and 140 °F, doubling in number in as little as 20 minutes. This range of temperatures is often called the “Danger Zone.” Never leave food out of refrigeration for over 2 hours.
Bacteria can replicate at an exponential rate when they’re in a temperature range known as the danger zone, which is 40–140°F (4–60°C).
Your kitchen counter is a prime example.
If you leave food out on your kitchen counter or elsewhere in the danger zone, bacteria can double in number in as little as 20 minutes and continue to double at this rate for many hours. This leaves food highly susceptible to bacterial overgrowth that can result in illness.
On the other hand, when you store food in temperatures below 40°F (4°C), bacteria cannot replicate quickly. At temperatures of 0°F (-18°C), bacteria become dormant — sometimes referred to as “sleeping” — and will not replicate.
When food is heated to temperatures over 140°F (60°C), bacteria are unable to survive and begin to die. This is why properly cooking and reheating food to the correct temperatures is essential for reducing your risk of foodborne illness.
To find out safe minimum cooking temperatures for various contamination-prone foods, visit FoodSafety.gov.
To prevent the rapid growth of bacteria, it’s crucial to keep some foods out of the danger zone temperature range as much as possible. If contamination-prone foods have been left in the danger zone for more than 2 hours, it’s best to throw them out.
Note that putting contaminated food back in the fridge or freezer won’t kill the bacteria, and the food will remain unsafe to eat.
However, some foods are safe to store on the counter or in the pantry for a limited time. To look up food safety recommendations for particular foods, check out the FoodKeeper App from FoodSafety.gov.