Ice leaving without melting
What Is Freezer Burn?
Ice can turn straight into vapour, and over months it walks out of your food.
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Step 1 of 5
Ice can skip the liquid stage.
Which is how food dries out in a freezer that never once goes above zero. Water molecules at the surface of ice sometimes have enough energy to leave directly as vapour. No melting is needed at all.
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Step 2 of 5
Freezer air is extremely dry.
Cold air holds almost no vapour, and the freezer's cooling coils are constantly stripping out what little there is. Water always leaves the food.
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Step 3 of 5
The lost water reappears as frost.
The escaped vapour refreezes on the coldest thing nearby — the packet or the freezer wall. The frost in the bag is your dinner.
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Step 4 of 5
What is left is dry and oxidised.
Two damages at once: the water gone, and the fat going stale The dried patches are grey and leathery, and with no water shielding it the fat there reacts with oxygen and turns stale-tasting.
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Step 5 of 5
Air is the enemy, so squeeze it out.
Vapour needs a gap to cross. Wrapping tightly against the surface, or vacuum sealing, leaves it nowhere to travel.
Freezer-burnt food is still safe to eat. It has lost texture and flavour, not safety.
The short version
Freezer burn is ice turning straight to vapour and refreezing on the packet, leaving the food dry and stale.
Try it yourself
Leave an ice cube uncovered in the freezer for a fortnight. It gets visibly smaller without ever melting.