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This article about storing apples for the winter says:

You do not want the apples' temperature to fall below 30°F (-1.1°C), however, because that will make them freeze and turn to mush when they're thawed. Their cell walls will all collapse.

Therefore, apples are best stored somewhere around 30-35°F (-1.1 to 1.6°C), in a humid environment.

I don't understand why you should keep the apples below the freezing point of water. Why would damage only occur below 30°F (-1.1°C)?

Is the article correct?

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1 Answer 1

up vote 3 down vote accepted

This temperature range would be a compromise between a very low temperature needed to limit natural decay or decay triggered by micro-organisms (the lower the temperature, the lesser the decay) and the formation of destructive ice crystals.

Only pure water freezes at 0°C (32°F) under atmospheric pressure. But the content of apple cells and cell walls is a rather complex aqueous solution, containing many natural cryoprotectants, among which the fruit's sugars. Therefore, the freezing point of apples might be as low as 30°F.

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OK but when it says "in a humid environment" wouldn't the apple be covered in ice (damaging its skin)? –  laktak May 13 '13 at 18:50
    
They would be covered in ice if the air were saturated with water. In this case humid means that a dry environment has to be avoided. e.g. keep 80% relative humidity. –  biozic May 13 '13 at 19:50
    
Thanks for the explanation! –  laktak May 13 '13 at 19:54

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