Introduction

Volatile thiols are a family of aroma compounds that are widely known for their contribution to the fruity notes of wines. These aromas are highly characteristic of some grape varieties, such as Sauvignon Blanc, Colombard or Verdejo and represent a huge part of their typicity. They also contribute to the complexity and fruitiness of several other varieties, even in red wines. 3MH (3-sulfanyl-hexan-1-ol, also known as 3SH), its acetate 3MHA (also known as 3SH-A) and 4MMP (4-methyl-4-sulfanylpentan-2-one, also known as 4MSP) are the three most abundant compounds; 3MH is associated with the grapefruit aroma, 3MHA of passion fruit and 4MMP is responsible for the blackcurrant and boxtree aromas. Their perception threshold is very low, especially for the 4MMP (0.8 ng/L). These compounds are present in the grape must as odourless nonvolatile precursors, cysteinylated or glutathionylated conjugates. The aromatic thiols are revealed by the enzymatic action of the yeast during the alcoholic fermentation.

The Volatile Thiols Are Revealed by Wine Yeasts

Saccharomyces cerevisiae is able to take up and cleave the precursors to release the free thiols, 3MH and 4MMP (Figure 1). The 3MHA is derived from 3MH by acetylation. Wine yeast have different capacities to reveal volatile thiols depending on their genetic background and their corresponding enzymatic activities

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