Ethane-1,1-dithiol explained

Ethane-1,1-dithiol is an organosulfur compound with formula CH3CH(SH)2. It is a colourless smelly liquid that is added to or found in some foods. The compound is an example of a geminal dithiol.

Use

Flavouring uses of ethane-1,1-dithiol may include drinks, oil, gravy, soup, meat, fruit, seasonings, and snacks. Maximum concentrations in use that are generally recognised as safe (GRAS) is five parts per million (ppm) but typical uses are around 0.2 ppm.[1] It is supplied as a 1% solution in ethanol, due to its strong offensive smell. In the diluted form with 4% ethyl acetate and ethanol the CAS number is 69382-62-3.[2] Toxicity may be due to metabolism products hydrogen sulfide and acetaldehyde, however as used it has a margin of safety of over 10,000,000.[3] Other ways that it is modified in the body apart from hydrolysis is methylation to 1-methylsulfanyl-ethanethiol, oxidation of the sulfur to an ethyl sulfonate, glucuronidation of the sulfur, or combination with cysteine by way of a disulfide bridge.[3]

Identifiers

Since it is used in the food industry there are codes issued by various authorities. It is identified as JECFA number 1660. The Flavor and Extract Manufacturers Association (FEMA) id is 4111.[1] The European designation for the flavouring is Fl 12.293.[4]

Natural occurrence

It can be produced during fermentation of grapes.[5] It is used as a food flavouring.[6]

It is found naturally in the scent of durian.[7] [8]

Properties

The nuclear magnetic resonance spectrum shows three environments for protons, in the ratio of 3:2:1 corresponding to CH3 SH and CH.[9] [10]

Reactions

Ethane-1,1-dithiol has several reactions known that are important in white wine flavours. In the presence of oxygen, ethane-1,1-dithiol is converted to cis/trans-3,6-dimethyl-1,2,4,5-tetrathiane which has a rubbery aroma. This molecule has a ring with four sulfur atoms and two carbons, two ethane-1,1-dithiol molecules become linked at their sulfur atoms with the loss of hydrogen.[11] This can further oxidise to cis/trans-3,5-dimethyl-1,2,4-trithiolane which has a meat-like odour.[11]

Ethane-1,1-dithiol reacts with hydrogen sulfide to form cis/trans-4,7-dimethyl-1,2,3,5,6-pentathiepane, a ring containing five sulfur atoms and two carbons. This has a meaty smell.[11]

Formation

Ethane-1,1-dithiol can be formed in the reaction of acetaldehyde with hydrogen sulfide. 1-Hydroxyethanethiol is formed as an intermediary.[11]

See also

References

  1. Web site: GRAS Flavoring Substances 22. Smith. R. L.. S. M.. Cohen. J.. Doull. V. J.. Feron. J. I.. Goodman. L. J.. Marnett. P. S.. Portoghese. W. J.. Waddell. B. M.. Wagner. T. B.. Adams. August 2005. Food Technology. Institute of Food Technologists . 47. 1 December 2012.
  2. Web site: 1,1-ethane dithiol 1% in ethanol 94.5% / ethyl acetate 4% fragrance 69382-62-3. 1 December 2012. 2018-04-15.
  3. Book: Meeting. Joint FAO/WHO Expert Committee on Food Additives.. Organization. World Health. Evaluation of Certain Food Additives and Contaminants: Sixty-eighth Report of the Joint FAO/WHO Expert Committee on Food Additives Geneva from 19 to 28 June 2007. 1 December 2012. 2007. World Health Organization. 9789241209472. 108, 214–218.
  4. European Food Safety Authority. Scientific Opinion on Flavouring Group Evaluation 91, Revision 1. EFSA Journal . 2011 . 9. 12 . 2459. 10.2903/j.efsa.2011.2459. free.
  5. Book: Fedrizzi, Bruno. Giuseppe Versini. Roberto Ferrarini. Fabio Finato. Giorgio Nicolini. Franco Magno. 2011. 1068. 215–228. 0097-6156. 10.1021/bk-2011-1068.ch010. Sulfur Compounds in Still and Sparkling Wines and in Grappa: Analytical and Technological Aspects. Volatile Sulfur Compounds in Food. ACS Symposium Series. 978-0-8412-2616-6.
  6. Web site: List of Codex Specification for Food Additives. Joint FAO/WHO Expert Committee on Food Additives. 2012. CAC/MISC 6. 90. 1 December 2012.
  7. Web site: Scientists sniff out the substances behind the aroma in the 'king of fruits'. American Chemical Society. 28 November 2012. 1 December 2012.
  8. Li. Jia-Xiao. Peter Schieberle. Martin Steinhaus. 2012. Characterization of the Major Odor-Active Compounds in Thai Durian (Durio zibethinus L. 'Monthong') by Aroma Extract Dilution Analysis and Headspace Gas Chromatography–Olfactometry. Journal of Agricultural and Food Chemistry. 60. 45. 11253–11262. 0021-8561. 10.1021/jf303881k. 23088286.
  9. Web site: No 1660 Ethane-1,1-dithiol HNMR. 2 December 2012.
  10. Book: Joint FAO/WHO Expert Committee on Food Additives Meeting . Food and Agriculture Organization of the United Nations . Compendium of Food Additive Specifications . 2007 . Food & Agriculture Org. . 978-92-5-105866-4 . 112 . en.
  11. Book: Moreno-Arribas. M. Victoria. Polo. Carmen. Wine Chemistry and Biochemistry. 2 December 2012. 2008-11-14. Springer. 9780387741161. 604–.

External links

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