How do I freeze meals properly?

What freezes well, what does not, and the packing and labelling that stops the freezer becoming an archive.

Difficulty: beginner
Time: 30 min
Read: 2 min
Safety: caution

Short answer

Cool it fast, portion it, get the air out, and label it with what it is and the date. Freeze flat in bags — they stack, they defrost far quicker and they use half the space of a box.

Freezing is not what damages food; ice crystals are. Fast freezing makes small crystals and slow freezing makes large ones that rupture the cell walls, which is why texture suffers. Everything below is about freezing fast and keeping air out.

Safety

Cool food quickly before freezing — within two hours — and never refreeze anything that has been thawed, unless you have cooked it in between. Defrost in the fridge rather than on the counter, and reheat until piping hot throughout.

Step by step

Cool it quickly first.Shallow containers, within two hours. Putting hot food in the freezer both raises the temperature of everything else and freezes slowly, which is the worst combination.
Portion before freezing, not after.You cannot subdivide a frozen block. Meal-sized portions mean you defrost what you need.
Freeze flat in bags where you can.Bags laid flat freeze faster, stack neatly, defrost in a fraction of the time and take much less space than tubs.
Get the air out.Air causes freezer burn — dehydrated grey patches. Press it out of bags, or leave minimal headspace in containers.
Leave room for expansion in liquids.Soups and sauces expand as they freeze. A couple of centimetres of headspace stops containers splitting.
Label with contents and date, always.Everything looks identical frozen. An unlabelled container becomes a mystery and then waste. Most things are good for three to six months.
Know what does not freeze well.Salad leaves, cucumber, raw potato, cream sauces, egg-based sauces, yoghurt and fried food. They go watery, grainy or limp.
Defrost in the fridge, and reheat thoroughly.Overnight in the fridge. Reheat until piping hot all the way through, and only once.

Tips

Freeze on a tray first for anything you want to stay separate — berries, meatballs, blanched vegetables. Then bag them once solid.
Undercook pasta and vegetables slightly in a dish you intend to freeze. They cook a little more on reheating.
Keep a list on the freezer door. It is the difference between a stocked freezer and an archaeological site.

Common mistakes

Freezing a big pot as one block — It freezes slowly, forming large ice crystals, and you cannot take out a single portion later.
Not labelling — Everything is unidentifiable when frozen. Unlabelled food gets left until it is thrown away.

Questions people ask

How long can I keep food in the freezer?

Most cooked dishes are good for three to six months for quality. They stay safe longer at a steady -18°C, but texture and flavour decline.

Can I refreeze defrosted food?

Not raw food that has thawed. You can freeze it again once it has been cooked — for example, defrosted raw mince made into a bolognese.