Editing Flash freezing (section)

{{Short description|Quick freezing by exposure to cryogenic temperatures}}
[[File:Frozen Leaf (6886708197).jpg|thumb|Ice crystals in a frozen pond. When the water cools slowly, crystals are formed. Freezing quickly reduces crystal formation.]]

In [[physics]] and [[chemistry]], '''flash freezing''' is a process by which an object is rapidly frozen by subjecting an object to [[cryogenics|cryogenic temperatures]], or through direct contact with [[liquid nitrogen]] at {{Convert|-196|C|}}.<ref>{{cite web |title=What is Flash Freezing? (with pictures) |date=27 February 2024 |url=http://www.wisegeek.org/what-is-flash-freezing.htm}}</ref>

This process is closely related to classical [[nucleation]] theory. When water freezes slowly, [[Crystal growth|crystals grow]] from fewer nucleation sites, resulting in fewer and larger [[ice crystal]]s. This damages [[cell wall]]s and causes cell [[dehydration]]. When water freezes quickly, as in flash freezing, there are more nucleation sites, and more, smaller crystals. This results in much less damage to cell walls, proportional to the rate of freezing. This is why flash freezing is good for food and [[Tissue (biology)|tissue]] preservation.<ref name="FAO">{{Cite web |title=Freezing of fruits and vegetables |url=http://www.fao.org/3/y5979e/y5979e03.htm |access-date=2020-04-06 |website=www.fao.org}}</ref>

Flash freezing is commonly applied in the [[food industry]] and is studied in [[atmospheric science]].