Italian Researchers Find Gewürztraminer Clones Alter Key Aroma Precursors

Researchers in Trentino, Italy, have reported what they describe as the first evidence that Gewürztraminer clones differ in the amount of key varietal thiol precursors found in grape juice, a finding that could help wine producers refine clonal selection to shape aroma and improve consistency in the cellar.

The work was published by IVES OpenScience as an extended abstract from the GiESCO 2017 conference series and was led by scientists at Fondazione Edmund Mach in San Michele all’Adige. The authors examined five Gewürztraminer clones and two biotypes grown across four vineyards in Trentino and found differences of up to 30% between clones in juice levels of precursors linked to 3-mercaptohexan-1-ol, or 3MH.

That compound, along with its fermentative derivative 3-mercaptohexyl acetate, is known for contributing tropical and grapefruit-like notes in wine. The abstract says recent research had also shown a positive and significant contribution of these varietal thiols to the typical sensory profile of Gewürztraminer wines.

The study focused on glutathionylated and cysteinylated precursors of 3MH, compounds that have been widely studied in grapes and juices since their discovery. According to the authors, most previous work on varietal thiols has centered on Sauvignon Blanc, while much less attention has been paid to Gewürztraminer grapes, wines and by-products. They also noted that, to their knowledge, the only earlier research into clonal variability of these compounds had involved Sauvignon Blanc clones grown in a single vineyard in Australia.

In the Trentino trial, the researchers evaluated clones ISMA-AVIT 904 and 920R, ISMA 916 and 918, and LB14, along with biotypes 906 and 1101. The abstract does not provide full numerical results for each clone, but it states that the variation observed in juice reached as much as 30%, enough to suggest that clone choice may influence the pool of aroma precursors available before fermentation begins.

For growers and wineries, that matters because thiol expression can affect how a finished wine presents itself in the glass. If further studies confirm the result under different vineyard and vintage conditions, clonal selection could become a more precise tool for managing aromatic typicity in Gewürztraminer and for reducing variation from one planting or production lot to another. In practical terms, that could give producers another way to align vineyard material with a desired wine style rather than relying only on harvest timing or cellar techniques.

The research comes at a time when many wine regions are paying closer attention to how plant material interacts with site and winemaking decisions. Clone selection has long been used to manage yield, disease behavior and ripening patterns. This study suggests it may also play a measurable role in compounds tied to aroma expression in Gewürztraminer, a variety whose identity often depends heavily on its aromatic profile.

The authors of the study are Tomás Román, Umberto Malossini, Roberto Larcher, Loris Tonidandel and Giorgio Nicolini, all affiliated with Fondazione Edmund Mach’s Technology Transfer Center. Their report was released on July 7 by IVES OpenScience.

Because the publication is an extended abstract rather than a full paper, it offers a concise account rather than a complete dataset or detailed methodology. Even so, the result adds an early piece of evidence to a field that has been studied far more extensively in other white varieties. For producers focused on aromatic wines, especially those seeking more predictable thiol-related character in Gewürztraminer, the finding points to clone choice as a factor that may deserve closer attention in future vineyard planning.