Sterilization (microbiology)

Sterilization (British English: sterilisation) refers to any process that removes, kills, or deactivates all forms of life (particularly microorganisms such as fungi, bacteria, spores, and unicellular eukaryotic organisms) and other biological agents (such as prions or viruses) present in fluid or on a specific surface or object. Sterilization can be achieved through various means, including heat, chemicals, irradiation, high pressure, and filtration. Sterilization is distinct from disinfection, sanitization, and pasteurization, in that those methods reduce rather than eliminate all forms of life and biological agents present. After sterilization, fluid or an object is referred to as being sterile or aseptic.

Applications

Foods

One of the first steps toward modernized sterilization was made by Nicolas Appert, who discovered that application of heat over a suitable period of time slowed the decay of foods and various liquids, preserving them for safe consumption for a longer time than was typical. In the early 1900's the use of baby bottle sterilization became an important tool in the battle of infant mortality. Canning of foods is an extension of the same principle and has helped to reduce food borne illness ("food poisoning"). Other methods of sterilizing foods include ultra-high temperature processing (which uses a shorter duration of heating), food irradiation, and high pressure (pascalization).

In the context of food, sterility typically refers to commercial sterility, defined as "the absence of microorganisms capable of growing in the food at normal non-refrigerated conditions at which the food is likely to be held during distribution and storage" according to the Codex Alimentarius.

Medicine and surgery

In general, surgical instruments and medications that enter an already aseptic part of the body (such as the bloodstream, or penetrating the skin) must be sterile.