A preservative is a natural or synthetic
chemical that is added to products such as foods, pharmaceuticals, paints, biological samples,wood, etc. to prevent
spoilage, whether from microbial growth or undesirable chemical changes.Preservatives may be added to
wood to prevent the growth of
fungi as well as to repel
insects and termites. Typically
copper,
borate, and
petroleum based
chemical compounds are used. For more information on wood preservatives see
timber treatment,
lumber and
creosote.Preservative
food additives can be used alone or in conjunction with other methods of
food preservation. A distinction is sometimes made between anti-microbial preservatives which function by inhibiting the growth of
bacteria and
fungi, and
antioxidants such as
oxygen absorbers, which inhibit the
oxidation of food constituents. Common anti-microbial preservatives include
calcium propionate,
sodium nitrate,
sodium nitrite,
sulphites (
sulfur dioxide,
sodium bisulfite,
potassium hydrogen sulfite, etc.) and
disodium EDTA.
Antioxidants include
BHA and
BHT. Other preservatives include
formaldehyde (usually in solution),
glutaraldehyde,
diatomaceous earth (kills insects),
ethanol and
methylchloroisothiazolinone. The benefits and safety of many artificial food additives (including preservatives) are the subject of debate among
academics and regulators specializing in
food science and
toxicology.
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