Experts' Experts: What should you do with hot leftovers — let them sit, or refrigerate immediately?

Mom always said to leave them out to cool to room temperature before sticking them in the fridge.

Mom also said that reading in bad light would hurt your eyes.

Mom was wrong both times.

Maybe more — but let's not be haters: after all, look how well you turned out.

Erm... maybe it's time to move on.

Okay, then, on to Anahad O'Connor's "Really?" feature in the New York Times Science section, which addressed the very question raised in the headline up top.

The Claim: Hot Leftovers Should Cool at Room Temperature

The Facts: What to do with leftovers? One common bromide is that leftovers stored in the refrigerator must be allowed to cool first at room temperature.

The reasoning behind the claim varies. One theory is that allowing food to cool at a slower rate reduces the likelihood that it will spoil. Another suggests that hot food can somehow interfere with the circulation of cold air in the refrigerator. The notion may have originated back when food was stored in iceboxes, and thus could not be too hot when put away.

Whatever the rationale, the claim is wrong. According to the Food and Drug Administration, leftover food (particularly meat) should be refrigerated immediately after serving, and certainly within two hours of cooking.

Food bacteria can double every 30 or 40 minutes, and several outbreaks of food poisoning have been linked to meat cooked and left to cool at room temperature for too long.

Generally, the bacteria that contaminate food thrive at temperatures between 40 and 140 degrees Fahrenheit, so leftovers should always be stored in a refrigerator set at 40 degrees or below.

When the quantity of food is large, it should be separated into small containers for quicker cooling, and reheated no more than once.

The Bottom Line: It’s a bad idea to let food sit at room temperature before refrigerating.