How do I cool a big pot of food quickly and safely?

This is the step that quietly decides whether a batch-cooking session was a good idea or a bad one. A deep pot has very little surface area for its volume, so the middle can only lose heat through the food around it — and it does that astonishingly slowly. Splitting it is not fussiness; it is the difference between ninety minutes and eight hours.

Safety

Step by step

1. Get it out of the cooking pot straight away.A large heavy pan is designed to hold heat and it does that job perfectly while you are trying to lose it. Transfer immediately rather than leaving it on the hob to 'cool a bit first'.
2. Divide by depth, not by portion.Nothing more than about 5cm deep. Depth is the dominant variable — a 10cm depth of stew takes far more than twice as long to cool as a 5cm depth. Wide shallow containers or roasting tins beat tall tubs every time.
3. Stand the containers in a sink of cold water.Fill the sink with cold water — ice if you have it — and stand the containers in it so the water comes well up the sides but cannot get in. This is the single most effective thing you can do, and it typically halves the time.
4. Leave the lids off while cooling.A lid traps steam and heat and slows everything down. Lids go on after the food is cool, before it goes in the fridge. Cover loosely with a cloth if you are worried about the kitchen.
5. Stir every ten minutes or so.Stirring brings the hot centre to the cool surface. On a thick stew, chilli or rice dish this makes a large difference, because those are exactly the foods that conduct heat worst.
6. Break large solid items down.A whole joint, a big lasagne or a full chicken cools very slowly. Carve, portion or cut into pieces before cooling rather than after — this is the biggest single win for roast meat.
7. Change the water when it warms.The sink water heats up and stops working. Drain and refill once or twice, or add ice, and put a couple of freezer blocks in the water if you have them.
8. Refrigerate as soon as it is no longer steaming.Lids on, into the fridge, ideally within ninety minutes and no more than two hours. Spread the containers out rather than stacking them, so cold air can reach all sides — stacked warm tubs insulate each other.
9. Take rice more seriously than everything else.Cooked rice is the one to be strictest about. Spread it thin on a tray, cool it within an hour, refrigerate it, keep it one day, and reheat once until piping hot. Bacillus cereus spores survive cooking and produce a heat-stable toxin at room temperature.
10. Throw it away rather than reheating if it went wrong.A pot forgotten on the hob overnight goes in the bin. Not the fridge, not reheated, not 'boiled for ten minutes to be sure'. Time in the zone is not reversible.

Tips

• Freeze water in old plastic bottles and drop them into the sink bath — reusable, and they cool much faster than water alone.
• A metal tray or roasting tin conducts heat far better than plastic and cools food noticeably faster.
• Freezer bags laid flat cool fastest of all, because the food is a centimetre thick. Fill, seal, lay flat, and they are cold in twenty minutes.
• Plan the cooling into a batch-cooking day rather than doing it when you are tired at the end. It is the step that gets skipped.

Common mistakes

• Leaving a big pot on the hob to cool overnight — It stays warm for hours, spending the whole night in the danger zone, and it looks and smells completely normal in the morning. This is the single most common way a good batch of food becomes a bin job.
• Putting a large hot pot straight into the fridge — It raises the temperature of the whole fridge, which puts everything else in there into the danger zone, and the middle of the pot still cools slowly. Split it first, then cool it, then refrigerate.
• Cooling with the lid on to keep it clean — The lid traps steam and heat and can easily double the cooling time. Cover with a cloth if you need to, and put the lid on when it is cool.

If it doesn't work

Questions people ask