Editing Antioxidant (section)

=== Food preservatives ===
{{See also|E number#E300–E399 (antioxidants, acidity regulators)}}

Antioxidants are added to food to prevent deterioration. Exposure to oxygen and sunlight are the two main factors in the oxidation of food, so food is preserved by keeping in the dark and sealing it in containers or even coating it in wax, as with cucumbers. However, as oxygen is also important for plant [[Respiration (physiology)|respiration]], storing plant materials in [[Anaerobic organism#Metabolism|anaerobic]] conditions produces unpleasant flavors and unappealing colors.<ref>{{Cite journal |vauthors=Kader AA, Zagory D, Kerbel EL |year=1989 |title=Modified atmosphere packaging of fruits and vegetables |journal=Critical Reviews in Food Science and Nutrition |volume=28 |issue=1 |pages=1–30 |doi=10.1080/10408398909527490 |pmid=2647417}}</ref> Consequently, packaging of fresh fruits and vegetables contains an ≈8% oxygen atmosphere. Antioxidants are an especially important class of preservatives as, unlike bacterial or [[fungus|fungal]] spoilage, oxidation reactions still occur relatively rapidly in frozen or refrigerated food.<ref>{{Cite journal |vauthors=Zallen EM, Hitchcock MJ, Goertz GE |date=December 1975 |title=Chilled food systems. Effects of chilled holding on quality of beef loaves |journal=Journal of the American Dietetic Association |volume=67 |issue=6 |pages=552–7 |doi=10.1016/S0002-8223(21)14836-9 |pmid=1184900}}</ref> These preservatives include natural antioxidants such as ascorbic acid (AA, E300) and tocopherols (E306), as well as synthetic antioxidants such as [[propyl gallate]] (PG, E310), [[tert-Butylhydroquinone|tertiary butylhydroquinone]] (TBHQ), [[butylated hydroxyanisole]] (BHA, E320) and [[butylated hydroxytoluene]] (BHT, E321).<ref>{{Cite journal |vauthors=Iverson F |date=June 1995 |title=Phenolic antioxidants: Health Protection Branch studies on butylated hydroxyanisole |journal=Cancer Letters |volume=93 |issue=1 |pages=49–54 |doi=10.1016/0304-3835(95)03787-W |pmid=7600543}}</ref><ref>{{Cite web |title=E number index |url=http://www.ukfoodguide.net/enumeric.htm#antioxidants |url-status=usurped |archive-url=https://web.archive.org/web/20070304151341/http://www.ukfoodguide.net/enumeric.htm |archive-date=4 March 2007 |access-date=5 March 2007 |publisher=UK food guide}}</ref>

Unsaturated fats can be highly susceptible to oxidation, causing [[rancidification]].<ref>{{Cite journal |vauthors=Robards K, Kerr AF, Patsalides E |date=February 1988 |title=Rancidity and its Measurement in Edible Oils and Snack Foods. A review |journal=The Analyst |volume=113 |issue=2 |pages=213–24 |bibcode=1988Ana...113..213R |doi=10.1039/an9881300213 |pmid=3288002}}</ref> Oxidized lipids are often discolored and can impart unpleasant tastes and flavors. Thus, these foods are rarely preserved by drying; instead, they are preserved by [[Smoking (cooking technique)|smoking]], [[salting (food)|salting]], or [[fermentation (food)|fermenting]]. Even less fatty foods such as fruits are sprayed with sulfurous antioxidants prior to air drying. Metals catalyse oxidation.{{Citation needed|date=April 2025}} Some fatty foods such as olive oil are partially protected from oxidation by their natural content of antioxidants. Fatty foods are sensitive to photooxidation,<ref>{{Cite journal |vauthors=Del Carlo M, Sacchetti G, Di Mattia C, Compagnone D, Mastrocola D, Liberatore L, Cichelli A |date=June 2004 |title=Contribution of the phenolic fraction to the antioxidant activity and oxidative stability of olive oil |journal=Journal of Agricultural and Food Chemistry |volume=52 |issue=13 |pages=4072–9 |doi=10.1021/jf049806z |pmid=15212450|bibcode=2004JAFC...52.4072D }}</ref> which forms [[hydroperoxide]]s by oxidizing unsaturated fatty acids and [[ester]].<ref name=":1">{{Citation |last=Frankel |first=Edwin N. |title=Chapter 3 - Photooxidation of unsaturated fats |date=2012-01-01 |work=Lipid Oxidation (Second Edition) |pages=51–66 |editor-last=Frankel |editor-first=Edwin N. |url=https://www.sciencedirect.com/science/article/pii/B9780953194988500047 |access-date=2023-04-15 |series=Oily Press Lipid Library Series |publisher=Woodhead Publishing |language=en |isbn=978-0-9531949-8-8}}</ref> Exposure to [[Ultraviolet|ultraviolet (UV)]] radiation can cause direct photooxidation and decompose peroxides and [[Carbonyl group|carbonyl]] molecules. These molecules undergo free radical chain reactions, but antioxidants inhibit them by preventing the oxidation processes.<ref name=":1" />