Sauvignon blanc thiols

Mercaptohexyl acetate (3-MHA) is another powerful thiol that contributes the passion fruit-like character of Sauvignon Blanc wines (Tominaga et al. 2000). It is... 

Masneuf-Pomarede, I., Mansour, C., Murat, M.L., Tominaga, T, Dubourdieu, D. (2006). Influence of fermentation temperature on volatile thiols concentrations in Sauvignon Blanc. Int. J. Food Microbiol, 108, 385-390. 

Tominaga, X, Murat, M.L., Dubourdieu, D. (1998a). Development of a method for analyzing the volatile thiols involved in the characteristic aroma of wines made from Vitis vinifera L. Cv. Sauvignon blanc. J. Agric. Food Chem, 46, 1044-1048. 

Several other odoriferous volatile thiols were later identified in Sauvignon blanc wines 3-sulfanylhexyl acetate (3SHA XVI) (Tominaga et al. 1996), 4-methyl-4-sulfanylpentan-2-ol (4MSPOH VI), 3-sulfanyUiexan-l-ol (3SH XVII), and... 

Table 8B.2 Assay of volatile thiols (ng/L) in four white Bordeaux wines made from Sauvignon blanc 1996 vintage (Tominaga et al. 1998a)...

Methods to measure cysteinylated aroma precursors in must were developed by Peyrot des Gachons et al. (2000) and Murat et al. (2001b). They allowed the location of thiol precursors to be determined in Sauvignon blanc grapes (Fig. 8B.7). Around 80% of P-4MSP is in the juice and 50% of P-3SH in the skin. The skin contact improves the must aromatic potential, but its main effect is on the P-3SH content (Fig. 8B.8). Similarly, in Cabernet Sauvignon and Merlot grapes, 60% of the P-3SH is located in the skins This method has been also applied to study the influence of... 

Murat, M.L., Masneuf, 1., Darriet, Ph., Lavigne, V, Tominaga, T., Dubourdieu, D. (2001c). Effect of Saccharomyces cerevisiae yeast strains on the liberation of volatile thiols in Sauvignon blanc wine. Am. J. Enol. Vitic., 52, 136-139. 

Tominaga, T, Furrer, A., Henry, R., Dubourdieu, D. (1998b). Identification of new volatile thiols in the aroma of Vitis vinifera L. var. Sauvignon blanc wines. Flav. Frag. J., 13, 159-162. 

Subileau, M., Schneider, R., Salmon, J.-M., Degryse, E. (2008) Nitrogen catabolite repression modulates the production of aromatic thiols characteristic of Sauvignon Blanc at the level of precursor transport. FFMS Yeast Research, 8, 771-780. 

More recently, some highly odoriferous sulfur compounds with thiol functions have been shown to participate in the aromas of certain grape varieties, especially Sauvignon Blanc. These compounds occur in grapes in S-cysteine conjugate form. 

Several other odoriferous volatile thiols have also been identified in Sauvignon Blanc wine (Figure 7.9) 3-mercaptohexan-l-ol acetate (Tominaga et al., 1996), 4-mercapto-4-methylpentan-... 

Research by Tominaga et al. (2000) (Table 7.8) showed that the thiols identified in Sauvignon Blanc wines also contributed to the aroma of several Alsace grape varieties, as well as Colombard, Manseng, and botrytized Semilion. 

These assay methods have made it possible to determine the location of cysteinylated thiol precursors in Sauvignon Blanc grapes (Figure 7.12). The 4-MMP and 4-MMPOH precursors are mainly located in the flesh (approximately 80%), while the skin and flesh contain equal amounts of 3-MH precursor (Peyrot des Gachons et al., 2002a). Similarly, a majority (60%) of the 3-mercaptohexan-... 

Fig. 7.11. S-cysteine conjugate precursors of volatile thiols identified in Sauvignon Blanc must...

Fig. 7.13. Formation of volatile thiols from their cysteinylated precursors in Sauvignon Blanc must during alcoholic fermentation...

Finally, it has been reported that some vine sprays may have an unexpected impact on the varietal aromas of wines. In particular, owing to the reactivity of thiols with copper, the apphcation of copper-based prodncts on Sauvignon Blanc and Cabernet Sanvignon vines results in a significant decrease in the aroma of young wines made from these grape varieties (Hatzidimitriou et al., 1996 Darriet et al, 2001). 

Some sulfur-based compounds (especially those with thiol functions) make a positive contribution to the varietal aromas of certain grape varieties. The role of 4-methyl-4-mercaptopentanone in Sauvignon Blanc aroma is well known (Section 7.4.1). However, most sulfur derivatives have a very bad smell and have detection thresholds as low as 1 p,g/l. These compounds are known as mercaptans, referring to their capacity to be precipitated by mercury salts. 

Table 8.16. Impact of barrel-aging conditions on the concentration of volatile thiols characteristic of Sauvignon Blanc varietal aroma...

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