Flash freezing

From MedBib.com - Medicine & Nature

Flash freezing refers to the process in various industries whereby objects are quickly frozen by subjecting them to cryogenic temperatures.

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 of time without forming large crystals, thus avoiding damage to cell membranes. See also supercooling.

Flash freezing techniques are also used to freeze biological samples fast enough that large ice crystals cannot form and damage the sample.[1] This rapid freezing is done by submerging the sample in liquid nitrogen or a mixture of dry ice and ethanol.[2]

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.

See also vitrification.

American inventor Clarence Birdseye developed the quick-freezing process of food preservation in the early 20th century.

See also

References

  1. ^ "Freezing Tissue". Biotech.ufl.edu. http://www.biotech.ufl.edu/EM/data/freeze.html. Retrieved 2009-07-03. 
  2. ^ "Preparing Competent E. coli with RF1/RF2 solutions". Personal.psu.edu. http://www.personal.psu.edu/dsg11/labmanual/DNA_manipulations/Comp_bact_by_RF1_RF2.htm. Retrieved 2009-07-03. 
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