3-Mercaptohexyl acetate

Tominaga, T., Niclass, N., Frerot, E., and Dubourdieu, D. (2006). Stereoisomeric distribution of 3-mercaptohexan-l-ol and 3-mercaptohexyl acetate in dry and swet wines made from Vitis vinifera (var. Sauvignon blanc and Semillon. ]. Agric. Food Chem. 54, 7251-7255. 

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... 

Mercaptohexyl acetate nd-0.2 Box tree, broom, passion fruit... 

The impact of a compound cannot be predicted from its OAV value, but is the result of the interaction of the odorant with the other odorants present in the mixture. In general, experience has shown that impact compounds, whenever they exist, are odorants present at concentrations higher than the threshold and showing, usually, an odor quite different from the rest of odors present in the wine and demonstrating a personal character. For instance, out of all fruity esters of wine, only isoamyl acetate and phenylethyl acetate, both of which have clear specific and differentiable aromas, have been found to be able to act as impact compounds (Van Wyk et al. 1979 Tat et al. 2007). Similarly, the three mercaptans derived from cysteine, 4-methyl-4-mercaptopentan-2-one, 3-mercaptohexanol and 3-mercaptohexyl acetate, all of which have specific aromas, have been found to be key compounds in some wines (Darriet et al. 1995 Murat et al. 2001 Ferreira et al. 2002a Campo et al. 2005). 

Fediizzi, B., Versini, G., Lavagnini, I., Nicolini, G., and Magno, F. (2007). Gas chromatography-mass spectrometry determination of 3-mercaptohexan-l-ol and 3-mercaptohexyl acetate in wine A comparison of headspace solid phase microextraction and solid phase extraction methods. Anal. Chim. Acta, 596, 291-297. 

Mateo-Vivaracho, L., Ferreira, V, and Cacho, J. (2006). Automated analysis of 2-methyl-3-furanthiol and 3-mercaptohexyl acetate at ng L-1 level by headspace solid-phase... 

HS-SPME conditions for analysis of TFSV (temperature, sampling time, pH of solution) were reported by Fedrizzi et al., (2007b). Increase of the pH matrix at a value of 7, performed in order to reduce interference in the analysis due to presence of hexanoic acid, can reduce the 3-mercaptohexyl acetate hydrolysis. Unfortunately, the antioxidant protection operated from S02 is also reduced (due to the shift of equilibrium towards the HSOj form) as a consequence phenolic acids can be easily oxidized forming the correspondent quinones (Singleton, 1987 Murat et al., 2003). They can, in their turn, oxidize thiols (Rigaud et al., 1991), even if with an opportunely delayed time as evidenced by Blancard et al. 

Tominaga, T., Darriet, P., and Dubourdieu, D. (1996). Identification of 3-mercaptohexyl acetate in Sauvignon wine, a powerful aromatic compound exhibiting box-tree odor, Vitis, 35(4), 207-210. 

The complex odor of 3-mercaptohexyl acetate is reminiscent of boxwood, as well as grapefruit zest and passion fruit. This compound was previously identified in passion fruit by other authors (Engel and Tressel, 1991). Its perception threshold is 4 ng/1 and some Sauvignon Blanc wines may contain several hundreds of ng/1. Concentrations decrease as the wine ages and 3-mercaptohexanol is formed. 

Fig. 7.9. Odoriferous volatile thiols identified in Sanvignon Blanc wine (a) 4-mercapto-4-methyl-pentan-2-one (4-MMP), (b) 4-mercapto-4-methyl-pentan-l-ol (4-MMPOH), (c) 3-mercapto-3-methyl-butan-l-ol (3-MMB) (d) 3-mercaptohexan-l-ol (3-MH), (e) 3-mercaptohexyl acetate (A3-MH)...

Numerous odour-active VSCs have been detected in beers. Examples of beer VSCs encompass methanethiol, ethanethiol, H2S, dimethyl sulphide, dimethyl disulphide, methional, methionol, 3-(methylthio)propyl aceate and 2-mercapto-3-methyl-l-buta-nol (Angelino, 1991 HiU Smith, 2000). Most VSCs cause off-odours such as rotten egg-like, cabbage-like, onion-like and garlic-like. However, some VSCs have a positive impact on beer flavour by accentuating fruitiness (e.g. 3-mercaptohexanol and 3-mercaptohexyl acetate). 

Kishimoto, T., Morimoto, M., Kobayashi, M., Tako, N., Wanikawa, A. (2008). Behaviors of 3-mercaptohexan-l-ol and 3-mercaptohexyl acetate during brewing processes. Journal of the American Society of Brewing Chemists, 66, 192-196. http //dx.doi.oig/10.1094/ ASBCJ-2008-0702-01. 

Figure 9.17 There are powerful synergies between Sauvignon Blanc grapes and yeast strains in formation of the compounds responsible for tropical fruit flavours 4-mercapto-4-methylpentan-2-one (4MMP), 3-mercaptohexan-l-ol (3MH) and 3-mercaptohexyl acetate (3MHA). Odourless cysteine and glutathione conjugates are converted to aromatic thiols by carbon-sulfur-lyase enzymes. Alcohol acetyl transferase further modifies 3MH, converting it to the more potent 3MHA.

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