A S-cysteine conjugate, precursor of aroma of White Sauvignon

• Main Authors: Takatoshi Tominaga, Isabelle Masneuf-Pomarède, Denis Dubourdieu
• Format: Article
• Language: English
• Published: International Viticulture and Enology Society 1995-12-01
• Series: OENO One
• Subjects: White Sauvignon; aroma; aroma precursor; 4-methyl-4-mercaptopentan-2-one; cysteine-S-conjugate; β -lyase
• Online Access: https://oeno-one.eu/article/view/1123

4-mercapto-4-methylpentan-2-one (4-MMP), a strongly odorant compound responsible for the « boxtree » or « broom plant » odour of the Sauvignon wines, can be enzymaticaly released in vitro from an odourless must extract. The enzyme source used is a cell-free extract of the gastrointestinal bacterium Eubacterium limosum. This crude preparation exhibits a cysteine β-lyase activity which requires the presence of pyridoxal phosphate. The release of 4-MMP is inhibited when the substrate is previously treated with N-hydroxysuccimide acetate which reacts with a primary amine. The same bacterial extract is also able to release 4-MMP, pyruvic acid and ammonium, from S-(4-méthylpentan-2-one)-L-cysteine. On the other hand, the cleavage of S-(4-méthylpentan-2-one)D,L-homocysteine and S-(4-méthylpentan-2-one)- glutathione is very limited. These results suggest that the precursor of 4-MMP in Sauvignon must is a S-cysteine conjugate. Such an aroma precursor in grapes or in other fruits has never been round berore.