How do I cool a large pot of food safely?

A big pot of stew is the most common food safety failure in a home kitchen, and it is entirely about physics rather than hygiene.

Safety

Step by step

1. Understand why volume matters.Heat leaves through the surface. A deep pot has a small surface relative to its volume, so the centre can stay above 40°C for hours while the outside feels cool. That centre is where bacteria multiply.
2. Divide it immediately.Into several shallow containers, ideally no more than about 5cm deep. This is the single most effective step and it needs no equipment.
3. Aim for two hours.From cooked to refrigerated. That is the practical target and it is achievable with shallow containers and a little help.
4. Use a cold water bath.Stand the containers in a sink of cold water, changing it as it warms. It moves heat out far faster than air, and stirring speeds it further.
5. Stir it.Moving the food brings the hot centre to the surface. An occasional stir in a water bath roughly halves the cooling time.
6. Add ice to the food where it suits.For soups and stocks, a few ice cubes cool it instantly and dilute it slightly. Better still, freeze some of the stock in advance and use that.
7. Do not put a large hot pot in the fridge.It raises the temperature of everything else in there, putting the rest of the contents at risk while the pot itself still cools slowly.
8. Do put small warm containers in.Once divided and no longer steaming, small containers go in safely. The old advice to wait until fully cold leaves food in the danger zone longer than necessary.
9. Leave them uncovered until cold.A lid traps heat and steam. Cover once cold, or leave a gap. In a fridge, cover as soon as it is cold to avoid drying and cross-contamination.
10. Treat rice and pulses as high-risk.They carry spores that survive cooking and produce toxin as the food sits warm. Cool fast, refrigerate within an hour if you can, and use within a day.
11. Cool meat joints by carving.A whole joint holds heat for a very long time. Slicing it and spreading it out cools it in a fraction of the time.
12. Never cool food outdoors.It is not reliably cold, and it attracts animals and insects. A sink of cold water is faster and safer.
13. Label with the date.Cooked food keeps two to three days refrigerated, and less for rice. Guessing tends towards optimism.

Tips

• Shallow containers. It is most of the answer and it needs nothing you do not already own.
• A sink of cold water with an occasional stir roughly halves the time.
• Small warm containers can go in the fridge. Waiting for fully cold keeps food in the danger zone longer.

Common mistakes

• Leaving a large pot out to cool overnight — The centre stays in the bacterial growth range for hours, and some of what grows produces toxins that reheating does not destroy.
• Putting a whole hot pot straight into the fridge — It raises the temperature of everything else in the fridge while still cooling slowly itself, so it puts other food at risk too.

If it doesn't work