Benzyl mercaptan, a powerful thiol imparting struck flint aromas (odor threshold 0.3 ng/L), is suspected to play a primary role in wine minerality.
On the other hand, while often not detectable in very young wines, the complex mineral, smoky and roasted coffee aroma characters associated with benzyl mercaptan and furfuryl thiol tend to develop with bottle ageing.
Indeed, it is possible (although not conclusively demonstrated) that a "bad" thiol such as [H.sub.2]S might be needed to form potentially "good" thiols such as benzyl mercaptan or furfuryl thiol, meaning that having the bad guys around for a while might eventually have some good outcomes.
With regard to what we have called smoky/mineral thiols, little is known of the factors influencing compounds such as benzyl mercaptan and furfuryl thiol during bottle ageing and on the complex smoky/empyreumatic characters that seem to be linked to these compounds.
Their sensory contribution is rather diverse, ranging from pleasant passion fruit/exotic fruit (3MH and 3MHA) to complex smoky/mineral (furfuryl thiol and benzyl mercaptan), to unpleasant reductive ([H.sub.2]S and MeSH) notes.
Thiolytic degradation of 2 with benzyl mercaptan yielded epicatechin 4-benzylthioether (2a) and epicatechin (1), which further confirmed the deduction mentioned above.
Thiolytic degradation of 4 with benzyl mercaptan yielded proanthocyanidin A2 4-benzylthioether (4a) and epicatechin (1).
Thiolytic degradation of 5 with benzyl mercaptan yielded epicatechin-(2[beta] [right arrow] O [right arrow] 7, 4[beta] [right arrow] 8)-ent-catechin 4-benzylthioether (5a) and epicatechin (1) (Fig.
Thiolytic degradation of 6 with benzyl mercaptan yielded 4, proanthocyanidin A2 4-benzylthioether (4a), epicatechin 4-benzylthioether (2a), and epicatechin (1) (Fig.
Thiolytic degradation of 7 with benzyl mercaptan yielded identical products with those of 6, which indicated that the difference between 6 and 7 lay in the interflavonoid linked position between the upper and 2nd units.