Preservative
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A '''preservative''' is a natural or synthetic [[chemical compound|chemical]] that is added to products such as foods, pharmaceuticals, paints, biological samples, wood, etc. to prevent [[decomposition]] by microbial growth or by undesirable chemical changes.
==Preservatives in wood==
Preservatives may be added to [[wood]] to prevent the growth of [[fungi]] as well as to repel [[insect]]s and [[termite]]s. Typically [[arsenic]], [[copper]], [[chromium]], [[borate]], and [[petroleum]] based [[chemical compound]]s are used. For more information on wood preservatives, see [[timber treatment]], [[lumber]], and [[creosote]].
==Preservatives in foods==
Preservative [[food additive]]s can be used alone or in conjunction with other methods of [[food preservation]]. Preservatives may be ''anti-microbial preservatives'', which inhibit the growth of [[bacterium|bacteria]] and [[fungus|fungi]], or ''[[antioxidant]]s'' such as [[oxygen absorber]]s, which inhibit the [[oxidation]] of food constituents. Common anti-microbial preservatives include [[calcium propionate]], [[sodium nitrate]], [[sodium nitrite]], [[sulfite]]s ([[sulfur dioxide]], [[sodium bisulfite]], [[potassium hydrogen sulfite]], etc.) and [[EDTA|disodium EDTA]]. [[Antioxidant]]s include [[BHA]] and [[BHT]]. Other preservatives include [[formaldehyde]] (usually in solution), [[glutaraldehyde]] (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]].
===Natural food preservation===
Natural substances such as [[edible salt|salt]], [[sugar]], [[vinegar]], and [[diatomaceous earth]] are also used as traditional preservatives. Certain processes such as [[Frozen food|freezing]], [[pickling]], [[Smoking (cooking)|smoking]] and [[salting (food)|salting]] can also be used to preserve food. Another group of preservatives targets enzymes in fruits and vegetables that continue to metabolize after they are cut. For instance, [[citric acid|citric]] and [[ascorbic acid]]s from [[lemon]] or other [[citrus]] juice can inhibit the action of the enzyme [[phenolase]] which turns surfaces of cut apples and potatoes brown. Caution must be taken, however, since FDA standards do not currently require fruit and vegetable product labels to accurately reflect the type of preservative used in the products. Further, there is no current regulation requiring the inclusion of preservative chemical in labels at all; some potentially hazardous.
==Health concerns==
Some modern synthetic preservatives have become controversial because they have been shown to cause respiratory or other health problems. Some studies point to synthetic preservatives and artificial coloring agents aggravating ADD & ADHD symptoms in those affected.<ref>“Food additives and hyperactive behaviour in 3-year-old and 8/9-year-old children in the community: a randomized, double-blinded, placebo-controlled trial”, ''The Lancet'', Sept 2007</ref><ref>1997 Graduate Student Research Project conducted at the University of South Florida. Richard W. Pressinger M.Ed.</ref> Older studies were inconclusive quite possibly due to inadequate clinical methods of measuring offending behavior. Parental reports were more accurate indicators of the presence of additives than clinical tests. <ref>"Food Additives May Affect Kids' Hyperactivity", ''WebMD Medical News'', May 24, 2004</ref> Several major studies show academic performance increased and disciplinary problems decreased in large non-ADD student populations when artificial ingredients, including preservatives were eliminated from school food programs. <ref>"A different kind of school lunch", ''PURE FACTS'', October 2002</ref><ref>The impact of a low food additive and sucrose diet on academic performance in 803 New York City public schools, Schoenthaler SJ, Doraz WE, Wakefield JA, ''Int J Biosocial Res.'', 1986, 8(2); 185-195</ref> Allergenic preservatives in food or medicine can cause [[Anaphylaxis|anaphylactic shock]] in susceptible individuals, a condition which is often fatal within minutes without emergency treatment.
==References==
<references/>
==See also==
*[[Food preservation]]
[[Category:Food ingredients]]
[[Category:Chemical substances]]
[[Category:Food and drink terminology]]
[[zh-min-nan:Hông-hú-che]]
[[cs:Konzervant]]
[[da:Konserveringsmiddel]]
[[de:Konservierungsmittel]]
[[es:Conservante]]
[[fr:Conservateur alimentaire]]
[[gl:Conservante]]
[[hr:Konservansi]]
[[he:חומר משמר]]
[[lt:Konservantas]]
[[nl:Conserveermiddel]]
[[ja:防腐剤]]
[[no:Konserveringsmiddel]]
[[pl:Konserwant]]
[[pt:Conservante]]
[[ru:Консерванты]]
[[sr:Конзерванси]]
[[fi:Säilöntäaine]]
[[vi:Chất bảo quản]]
[[zh:防腐剂]]