Identification of adducts between an odoriferous volatile thiol and oxidized grape phenolic compounds: kinetic study of adduct formation under chemical and enzymatic oxidation conditions.
HPLC-MS and (1)H, (13)C, and 2D NMR analyses were used to identify new addition products between 3-sulfanylhexan-1-ol (3SH) and o-quinones derived from (+)-catechin, (-)-epicatechin, and caftaric acid. The kinetics of formation of these adducts were monitored in a wine model solution and in a must-like medium by HPLC-UV-MS with the aim of understanding the chemical mechanism involved in reactions between volatile thiols and o-quinones. One o-quinone-caftaric acid/3SH adduct, three o-quinone-(+)-catechin/3SH adducts, and three o-quinone-(-)-epicatechin/3SH adducts were characterized. Caftaric acid was oxidized faster than (-)-epicatechin and (+)-catechin when these phenolic compounds were incubated in a one-component mixture with polyphenoloxidase (PPO) in the presence of 3SH. Consequently, o-quinone-caftaric acid formed adducts with 3SH more rapidly than o-quinone-(+)-catechin and o-quinone-(-)-epicatechin in the absence of other nucleophilic species. Furthermore, o-quinone-(-)-epicatechin reacted faster than o-quinone-(+)-catechin with 3SH. Sulfur dioxide decreased the yield of adduct formation to a significant extent. Under chemical oxidation conditions, the rates and yields of adduct formation were lower than those observed in the presence of PPO, and o-quinone-caftaric acid was slightly less reactive with 3SH, compared to oxidized flavan-3-ols. The identification of o-quinone-caftaric acid/3SH and o-quinone-(+)-catechin/3SH adducts in a must matrix suggests that the proposed reaction mechanism is responsible for 3SH loss in dry wines during their vinification and aging process.
Unité de recherche Oenologie, EA 4577, USC INRA 1219, Institut de Sciences de la Vigne et du Vin, Université Bordeaux Segalen, Villenave d'Ornon, France.
Maria
M
Nikolantonaki
Michael
M
Jourdes
Kentaro
K
Shinoda
Pierre-Louis
PL
Teissedre
Stéphane
S
Quideau
Philippe
P
Darriet
D004156:Catechol Oxidase / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry / Q000378:metabolism*; D010936:Plant Extracts / Q000737:chemistry / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000737:chemistry / Q000378:metabolism*; D027843:Vitis / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D055549:Volatile Organic Compounds / Q000737:chemistry*
D010636:Phenols; D010936:Plant Extracts; D010940:Plant Proteins; D013438:Sulfhydryl Compounds; D055549:Volatile Organic Compounds; D004156:Catechol Oxidase; C515101:caftaric acid