Freezing

Freezing preserves food by lowering its temperature until much of its water becomes ice, slowing microbial growth and chemical reactions.

Ice crystal: A solid crystal formed when water molecules arrange into an ordered lattice. Ice crystals form inside food as its water freezes, influencing texture.
Blast freezing: A rapid food-freezing method that uses high-velocity cold air. Fast air movement removes heat quickly, producing smaller ice crystals than slow freezing.
Food spoilage: The deterioration of food through microbial growth, chemical reactions, or physical changes. Freezing slows several spoilage processes without making food permanently stable.
Refrigeration: Food preservation by cooling without freezing most of the food’s water. Refrigeration slows deterioration but generally allows faster microbial growth than freezing.
Freezing point depression: The lowering of a liquid’s freezing point when dissolved substances are present. Sugars and salts in food lower the temperature at which its water freezes.
Cryogenic freezing: Food freezing by direct exposure to extremely cold substances such as liquid nitrogen or carbon dioxide. Cryogens freeze food rapidly when conventional mechanical refrigeration is too slow.
Microbial growth: The increase in the number of microorganisms through cell division. Low temperatures inhibit growth, but many microorganisms survive frozen storage.
Freeze-drying: A preservation process that freezes food and removes ice by sublimation under reduced pressure. Unlike ordinary freezing, freeze-drying removes most water for lightweight, shelf-stable storage.
Supercooling: The cooling of a liquid below its freezing point without formation of a solid. Food water can remain liquid briefly below its freezing point before ice nucleates.
Individual quick freezing: A process that rapidly freezes separate food pieces so they remain individually free-flowing. It keeps peas, berries, and similar pieces from freezing into one solid mass.

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