Editing Sulfur dioxide (section)

===Food preservative===
{{See also|Food preservation}}
Sulfur dioxide is sometimes used as a preservative for dried apricots, dried figs, and other dried fruits, owing to its [[antimicrobial]] properties and ability to prevent [[oxidation]],<ref>{{cite conference |last1=Zamboni |first1=Cibele B. |last2=Medeiros |first2=Ilca M. M. A. |last3=de Medeiros |first3=José A. G. |title=Analysis of Sulfur in Dried Fruits Using NAA |url=https://www.ipen.br/biblioteca/2011/inac/17204.pdf |conference=2011 International Nuclear Atlantic Conference – INAC 2011 |isbn=978-85-99141-03-8 |date=October 2011 |access-date=2020-06-04 |archive-date=2020-06-04 |archive-url=https://web.archive.org/web/20200604193519/https://www.ipen.br/biblioteca/2011/inac/17204.pdf |url-status=dead }}</ref> and is called [[E number|E]]220<ref>[http://www.food.gov.uk/safereating/chemsafe/additivesbranch/enumberlist#h_3 Current EU approved additives and their E Numbers], The Food Standards Agency website.</ref> when used in this way in Europe. As a preservative, it maintains the colorful appearance of the fruit and prevents [[Decomposition|rotting]]. Historically, [[molasses]] was "sulfured" as a preservative and also to lighten its color. Treatment of dried fruit was usually done outdoors, by igniting sublimed sulfur and burning in an enclosed space with the fruits.<ref name="University of Georgia">{{Citation |title=Preserving foods: Drying fruits and Vegetable |url=https://nchfp.uga.edu/publications/uga/uga_dry_fruit.pdf |publisher=University of Georgia cooperative extension service |access-date=2022-06-06 |archive-date=2022-09-27 |archive-url=https://web.archive.org/web/20220927163031/https://nchfp.uga.edu/publications/uga/uga_dry_fruit.pdf |url-status=dead }}</ref> Fruits may be sulfured by dipping them into [[sodium bisulfite]], [[sodium sulfite]] or [[sodium metabisulfite]].<ref name="University of Georgia" />

==== Winemaking ====
Sulfur dioxide was first used in [[winemaking]] by the Romans, when they discovered that burning sulfur candles inside empty wine vessels keeps them fresh and free from vinegar smell.<ref>{{cite web|url=http://www.practicalwinery.com/janfeb09/page1.htm|publisher=www.practicalwinery.com|date=February 1, 2009|title=Practical Winery & vineyard Journal Jan/Feb 2009|url-status=dead|archive-url=https://web.archive.org/web/20130928111625/http://www.practicalwinery.com/janfeb09/page1.htm|archive-date=2013-09-28}}</ref>

It is still an important compound in winemaking, and is measured in [[parts per million]] (''ppm'') in wine. It is present even in so-called unsulfurated wine at concentrations of up to 10&nbsp;mg/L.<ref>[http://www.morethanorganic.com/sulphur-in-the-bottle Sulphites in wine], MoreThanOrganic.com.</ref> It serves as an [[antibiotic]] and [[antioxidant]], protecting wine from spoilage by bacteria and oxidation – a phenomenon that leads to the browning of the wine and a loss of cultivar specific flavors.<ref name="Jackson">Jackson, R.S. (2008) Wine science: principles and applications, Amsterdam; Boston: Elsevier/Academic Press</ref><ref name="Guerrero">{{cite journal | doi = 10.1016/j.tifs.2014.11.004| title = Demonstrating the efficiency of sulphur dioxide replacements in wine: A parameter review| journal = Trends in Food Science & Technology| volume = 42| pages = 27–43| year = 2015| last1 = Guerrero| first1 = Raúl F| last2 = Cantos-Villar| first2 = Emma| issue = 1}}</ref> Its antimicrobial action also helps minimize volatile acidity. Wines containing sulfur dioxide are typically labeled with "containing [[sulfite]]s".

Sulfur dioxide exists in wine in free and bound forms, and the combinations are referred to as total SO<sub>2</sub>. Binding, for instance to the carbonyl group of [[acetaldehyde]], varies with the wine in question. The free form exists in equilibrium between molecular SO<sub>2</sub> (as a dissolved gas) and bisulfite ion, which is in turn in equilibrium with sulfite ion. These equilibria depend on the pH of the wine. Lower pH shifts the equilibrium towards molecular (gaseous) SO<sub>2</sub>, which is the active form, while at higher pH more SO<sub>2</sub> is found in the inactive sulfite and bisulfite forms. The molecular SO<sub>2</sub> is active as an antimicrobial and antioxidant, and this is also the form which may be perceived as a pungent odor at high levels. Wines with total SO<sub>2</sub> concentrations below 10 ppm do not require "contains sulfites" on the label by US and EU laws. The upper limit of total SO<sub>2</sub> allowed in wine in the US is 350 ppm; in the EU it is 160 ppm for red wines and 210 ppm for white and rosé wines. In low concentrations, SO<sub>2</sub> is mostly undetectable in wine, but at free SO<sub>2</sub> concentrations over 50 ppm, SO<sub>2</sub> becomes evident in the smell and taste of wine.{{Citation needed|date=May 2009}}

SO<sub>2</sub> is also a very important compound in winery sanitation. Wineries and equipment must be kept clean, and because bleach cannot be used in a winery due to the risk of [[cork taint]],<ref>[http://www.extension.purdue.edu/extmedia/FS/FS-50-W.pdf Chlorine Use in the Winery]. Purdue University</ref> a mixture of SO<sub>2</sub>, water, and citric acid is commonly used to clean and sanitize equipment. [[Ozone]] (O<sub>3</sub>) is now used extensively for sanitizing in wineries due to its efficacy, and because it does not affect the wine or most equipment.<ref>[https://www.practicalwinery.com/janfeb00/ozone.htm Use of ozone for winery and environmental sanitation] {{Webarchive|url=https://web.archive.org/web/20170912102459/https://www.practicalwinery.com/janfeb00/ozone.htm |date=September 12, 2017 }}, Practical Winery & Vineyard Journal.</ref>