Aromas: thiols and terpenes

Thiols are a family of aroma compounds that are widely known for their contribution to typical notes of citrus (3MH), passion fruit (3MH-A) and gooseberry/boxwood/cassis (4MMP). These aromas are highly characteristic of some white grape varieties, such as Sauvignon Blanc, Colombard or Verdejo and represent an important part of their typicity. They also contribute to the complexity and fruitiness of several other white wines and even some red wines (Syrah, Cabernet-Sauvignon, Merlot, or Tempranillo). Thiols are very sensitive to oxidation and need to be protected throughout the whole winemaking process and beyond.

Terpenes (such as linalool, geraniol, citronellol) also actively participate in the flavour profile of wines and are responsible for floral, rose-like, citrusy, lemongrass and spicy aromas. They are characteristic of Muscat, Riesling, Gewürtztraminer, Albariño or Torrontés varietals.

Precursors of thiols and terpenes are present in the grapes in odourless form and are released to become volatile aromas during the vinification process. Certain Saccharomyces and non-Saccharomyces wine yeasts, wine bacteria and wine enzymes can release thiols or terpenes more efficiently.

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