How to avoid freezer burn

Freezing is a great way to preserve many foods, but the conditions inside a freezer can have negative effects. One of these is freezer burn - the pale, discoloured areas that can develop on the surface of frozen foods, such as meat, bread and ice-cream.

Ben Dearnley

Getting colder

When a food is frozen, most of the water it contains turns to ice. However, some of the water is lost through a process called sublimation, where the ice turns directly into water vapour. Over time, sublimation causes food to become dehydrated (it's also the reason why uncovered ice cubes will gradually shrink). Freezer-burned areas of food are basically freeze-dried and are more likely to have off flavours and tough, chewy textures.

A touch of frost

Where does the water vapour go? If the food is uncovered or in a package that isn't airtight, the vapour can enter the freezer's atmosphere (which is why you get ice build-up on non-frost-free freezers). If the food is enclosed in a package with lots of unfilled space, the water vapour may solidify and form frost (snowlike ice crystals) on the inside of the package or directly on the surface of the food.

Beyond repair

What if your food is already freezer burned? Freezer-burned areas may rehydrate somewhat on thawing and cooking. However, it's probably best to discard the affected areas all together, because they're more susceptible to rancidity and textural changes can be irreversible.

How to prevent it

Sublimation is less likely to occur at lower temperatures, so try and set your freezer as low as you can.
Avoid fluctuations in freezer temperature by not putting hot food in the freezer and not opening the freezer door too often. (Unfortunately, frost-free freezers are designed to fluctuate because of their frost-free mechanism.)
Use good-quality packaging that is similar in size to the amount of food you wish to freeze (don't forget to allow some room for expansion).
When wrapping or bagging food, make sure you expel as much air as possible from the packaging. This will stop your food coming into contact with, and losing water to, dry freezer air.
Label and date your food, then use it as soon as possible - the longer something is frozen, the more opportunity there is for freezer burn to occur.