How to Freeze Food So It Tastes Good Later

This guide is for anyone who has pulled a frosty, flavourless lump out of the freezer and wondered what went wrong. You will learn how freezing affects food, how to prepare, wrap and label it, which foods freeze well and which do not, and how to thaw and use it safely. Storage times and safety advice vary by country, so check your national food-safety agency for the official figures. General information, not professional advice.

What Freezing Does to Food

Freezing does not kill most bacteria. It pauses them. At the standard home-freezer temperature of -18 C (0 F) or colder, bacteria cannot grow, which is why frozen food stays safe for a long time. When the food thaws, any bacteria present can become active again, so food that goes in the freezer should be fresh and handled hygienically.

What changes with time is quality, not safety. Two things cause most of the damage. The first is ice crystals: water in food expands as it freezes, and large crystals break cell walls, which is why some foods turn mushy when thawed. Fast freezing makes smaller crystals and less damage. The second is freezer burn: dry, greyish-white patches where air has reached the food's surface and moisture has evaporated. Freezer-burned food is safe to eat but tough and bland in those spots.

Prepare Food the Right Way Before It Goes In

Good freezing starts before anything goes near the freezer. The quality of what comes out depends on the quality of what goes in, plus a few simple preparation steps.

1. Freeze food at its best Freeze fresh produce, meat and bread while they are still in good condition, not on their last day. Freezing will not improve food that is already tired.
2. Cool cooked food quickly Divide hot food into shallow containers so it cools fast, then refrigerate or freeze it within the time your local guidance recommends, often within one to two hours of cooking. Do not put a large hot pot straight into the freezer, as it warms everything around it.
3. Portion it Freeze in the amounts you will actually use, such as single meals, two-person portions or cups of stock. Smaller portions freeze and thaw faster and reduce waste.
4. Remove as much air as possible Air causes freezer burn. Press air out of bags, or use the water-displacement trick: lower an open zip bag into a bowl of water so the pressure pushes air out, then seal.
5. Leave headspace for liquids Soups, sauces and stocks expand as they freeze. Leave about 2 cm (1 inch) at the top of rigid containers so the lid does not pop off.
6. Flat-freeze bags Lay bags of soup, mince or sauce flat on a tray until solid, then stand them up like files. They freeze faster, stack neatly and thaw quickly.

For items that clump together, such as berries, sliced fruit, meatballs, dumplings or cookie dough balls, use open freezing. Spread them in a single layer on a lined tray, freeze until firm, then tip them into a bag. You can then take out exactly the number you need.