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Flash freezing refers to the process in various industries whereby objects are quickly frozen by subjecting them to cryogenic temperatures, or in direct contact with Liquid nitrogen at -320.8F or -196°C.
For example, flash freezing is used in the food industry to quickly freeze perishable food items (see frozen food). In this case, food items are subjected to temperatures well below water's melting/freezing point (32°F or 0°C), causing the water inside the foods to freeze in a very short period without forming large crystals, thus avoiding damage to cell membranes.
Flash freezing techniques are also used to freeze biological samples fast enough that large ice crystals cannot form and damage the sample. This rapid freezing is done by submerging the sample in liquid nitrogen or a mixture of dry ice and ethanol.
A supercooled liquid will stay in a liquid state below the normal freezing point when it has little opportunity for nucleation; that is, if it is pure enough and has a smooth enough container. Once agitated it will rapidly become a solid.
This process was further developed by American inventor Daniel Tippmann by producing a vacuum and drawing the cold air through palletized food. His process has been sold and installed under the trade name "QuickFreeze"  and enables blast freezing of palletized food in 35% less time than conventional blast freezing.