| Title: | "The cysteine reaction with diacetyl under wine-like conditions: proposed mechanisms for mixed origins of 2-methylthiazole, 2-methyl-3-thiazoline, 2-methylthiazolidine, and 2,4,5-trimethyloxazole" |
| Author(s): | Marchand S; Almy J; de Revel G; |
| Address: | "USC OEnologie-INRA-Institut polytechnique de Bordeaux-Univ. de Bordeaux, ISVV-210, Chemin de Leysotte-CS 50008, 33 882 Villenave D'Ornon cedex, France. stephanie.marchand@u-bordeaux2.fr" |
| DOI: | 10.1111/j.1750-3841.2011.02261.x |
| ISSN/ISBN: | 1750-3841 (Electronic) 0022-1147 (Linking) |
| Abstract: | "A part of the 'bouquet of wines' can be caused by the presence of odorous heterocycles produced by chemical reactions between S-amino acids and alpha-dicarbonyl compounds. Under wine ageing physic-chemical conditions (20 +/- 2 degrees C, ethanol/water 12% v/v, pH 3.5), products of the diacetyl (DI) reaction with cysteine include a number of 1,3-N,S and 1-3-N,O 5 member heterocycles having methyl groups attached at C(2). The origin of this methyl-C(2) fragment was not clear; it could be supplied from DI or from cysteine. To explore this question, a parallel reaction was run in which DI was replaced by 3,4-hexanedione. With the C(1) and C(4) carbons of DI thus marked with methyl groups, the product distribution demonstrated that in the DI and cysteine reaction, both DI and cysteine provided the methyl-C(2) to varying degrees in the formation of 2-methylthiazole, 2-methyl-3-thiazoline and 2,4,5-trimethyloxazole but only cysteine supplied this fragment for 2-methylthiazolidine. The results are interpreted in terms of reaction paths appropriate for the mild conditions. These pathways shed light on the mechanisms leading from dicarbonyls to heterocyclic compounds. Like all the chemical pathways, they anticipate the impact of other compounds and physicochemical parameters on heterocyclic generations the generation of heterocyclics. They also suggest the presence of unexplored odorous compounds" |
| Keywords: | "Acetaldehyde/chemistry Cysteine/analogs & derivatives/*chemistry Databases, Factual Diacetyl/*chemistry Gas Chromatography-Mass Spectrometry Hexanones/chemistry Methylation Models, Chemical Oxazoles/*analysis/chemistry Thiazoles/*analysis/chemistry Volati;" |
| Notes: | "MedlineMarchand, Stephanie Almy, John de Revel, Gilles eng Comparative Study Research Support, Non-U.S. Gov't 2011/07/19 J Food Sci. 2011 Aug; 76(6):C861-8. doi: 10.1111/j.1750-3841.2011.02261.x. Epub 2011 Jul 15" |
