Last night I left cooked roast beef on the counter to cool before refrigerating, but fell asleep and discovered it this morning. I immediately put it in the refrigerator. The U.S.Department of Agriculture's Meat and Poultry Hotline receives similar calls every day from consumers who are confused about how to keep their food safe. The answer to this caller's question is that the roast beef should be thrown out.
Bacteria exist everywhere in nature.
They are in the soil, air, water and the foods we eat. Therefore, understanding the important role temperature plays in keeping food safe is critical. Bacteria grow most rapidly in the range of temperatures between 40 and 140 F, doubling in number in as little as 20 minutes. That's why the Meat and Poultry Hotline advises consumers to never leave food out of refrigeration over two hours. If the temperature is above 90 F, food should not be left out more than one hour.