Powerful aromatic volatile thiols in wines made from several Vitis vinifera grape varieties and their releasing mechanism

By extracting specific volatile thiols using p-hydroxymercuribenzoate, 4-mercapto-4-methylpentan-2-one (4MMP), 4-mercapto-4-methylpentan-2-ol (4MMPOH), 3-mercapto-3-methylbutan-1-ol (3MMB), 3-mercaptohexan-1-ol (3MH), 3-mercaptohexyle acetate (3MHA), and furanmethanethiol (2FM) were identified in wines made from several Vitis vinifera white and red grape varieties. The assay of volatile thiols in certain wines made from Sauvignon blanc, Gewurztraminer, Riesling, Colombard, Petit Manseng and botrytized Semillon confirmed the contribution of 4MMP, A3MH and 3MH to their characteristic aromas reminiscent of box tree, grapefruit, and passion fruit. 2FM, exhibiting a strong roasted coffee aroma, is present in white and red wines elaborated in new oak barrel at much higher concentrations than the perception threshold. 4MMP, 4MMPOH and 3MH can be released during alcoholic fermentation from their S-cysteine conjugate precursors. 2FM is generated in white wines during barrel fermentation. The formation is due to yeast transformation of furfural released from toasted staves. (C) 2004 American Chemical Society.