8B Polyfunctional Thiol Compound 281
Ta b l e 8 B. 6Assay of volatile thiols (ng/L) at different stages in botrytizationyoung botrytized
wines from various appellations of the Bordeaux region. Comparison with decrease in mean grape
volume (mL/grape) (Sarrazin et al. 2007)
Variety Botrytis stage
Mean grape
volumeaVariation of
mean grape
volume (%) 3SH 3SPOH 3SHpOHSemillon Healthyb 0.85 100 195 c ± 58 d tre tr
Pourri plein 0.68 80 2326 ± 419 93 ± 14 34 ± 5
Pourri r ˆoti 0.37 44 3678 ±1765 124 ± 54 50 ± 26
Late pourri r ˆoti 0.38 45 6334 ±1267 291 ±128 118 ± 13
Sauvignon Healthy 0.78 100 161 ± 27 tr tr
Pourri plein 0.52 67 3003 ± 300 141 ± 895 ± 39
Pourri r ˆoti 0.21 27 9648 ±1544 348 ± 42 263 ± 92
Late pourri r ˆoti 0.29 37 9319 ±2050 375 ± 71 258 ± 44
aBased on the volume obtained from crushing 1000 grapes (mL/grape)
bHealthy(grapes not infected byB. cinerea),pourri plein(grapes entirely botrytized but not desic-
cated, picked two weeks after healthy grapes),pourri r ˆoti(grapes botrytized and desiccated, picked
two weeks afterpourri pleingrapes), andlate pourri rˆoti(shriveled grapes left a further 10 days
before picking)
cMean value (n=3)
dStandard deviation s (n=3)
etr: traces
botrytized wines are always well below the perception threshold (900 ng/L), while
3SHpOH rarely exceeds its perception threshold (60 ng/L). However an additive
effect of these volatile thiols combined with 3SH has been clearly demonstrated
(Sarrazin et al. 2007). Therefore, 3SPOH and 3SHpOH have a considerable impact
on overall wine aroma in the presence of other volatile thiols, such as 3SH, although
their concentrations in wines remain below the perception threshold.
The concentrations of 3SH, 3SPOH, and 3SHpOH in botrytized wines are
strongly affected by the development ofBotrytis cinerea(Table 8B.6). Wines made
from healthy grapes contain 3SH but only traces of the other two thiols. Wines pro-
duced from grapes affected by noble rot, once they reach the“pourri plein”stage
(entirely botrytized but not desiccated), have much higher thiol concentrations. The
surprisingly high concentrations of volatile thiols in botrytized wines is due to their
high cysteinylated precursor content (Thibon et al. 2008a).
8B.3 Stereoisomeric Distribution of 3-Sulfanylhexan-1-ol
and its Acetate
In dry Sauvignon and S ́emillon wines made from healthy grape must, totally unaf-
fected byBotrytis cinerea, the R and S enantiomers of 3SH are relatively uni-
formly distributed (approximately 50:50), with slight variations from one vintage to
another; e.g. there were slightly higher quantities of the R form of 3SH in wines from