Tyndallization is a process from the nineteenth century for sterilizing substances, usually food, named after its inventor

John Tyndall John Tyndall Fellow of the Royal Society, FRS (; 2 August 1820 – 4 December 1893) was a prominent 19th-century Irish physicist. His scientific fame arose in the 1850s from his study of diamagnetism. Later he made discoveries in the realms of ...

, that can be used to kill heat-resistant

endospore An endospore is a dormant, tough, and non-reproductive structure produced by some bacteria in the phylum Bacillota. The name "endospore" is suggestive of a spore or seed-like form (''endo'' means 'within'), but it is not a true spore (i.e., not ...

s. Although now considered dated, it is still occasionally used. A simple and effective sterilizing method commonly used today is autoclaving: heating the substance being sterilized to for 15 minutes in a pressured system. If autoclaving is not possible because of lack of equipment, or the need to sterilize something that will not withstand the higher temperature, unpressurized heating for a prolonged period at a temperature of up to , the boiling point of water, may be used. The heat will kill any

bacterial cells Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

; however, bacterial spores capable of later germinating into bacterial cells may survive. Tyndallization can be used to destroy the spores. Tyndallization essentially consists of heating the substance to boiling point (or just a little below boiling point) and holding it there for 15 minutes, three days in succession. After each heating, the resting period will allow spores that have survived to germinate into bacterial cells; these cells will be killed by the next day's heating. During the resting periods the substance being sterilized is kept in a moist environment at a warm room temperature, conducive to germination of the spores. When the environment is favourable for bacteria, it is conducive to the germination of cells from spores, and spores do not form from cells in this environment (see bacterial spores). The Tyndallization process is usually effective in practice. But it is not considered completely reliable — some spores may survive and later germinate and multiply. It is not often used today, but is used for sterilizing items that cannot withstand pressurized heating, such as plant seeds.

References

{{food preservation Hygiene Microbiology Food preservation Sterilization (microbiology)

See also

References