First evidence of the variability of varietal thiol precursors in Gewürztraminer clones

Much has been already written regarding the gluthationylate (GSH-) and cisteinylate (Cys-) precursors of 3- mercaptohexan-1-ol (3MH) since the discovery of their presence in grapes and juices. 3MH and its fermentative derivate, 3-mercaptohexyl acetate, play a remarkable role in the tropical, grapefruit-like aroma of wine, and, recently, their positive and significant contribution to the typicality of Gewürztraminer (GWT) wines was proved. The significance of varietal thiols has been investigated by several authors mainly in Sauvignon Blanc, while fewer research was focused on GWT grapes, wine ad by-products. In particular, to the best of our knowledge the only clonal variability studied until now is that of Sauvignon Blanc clones grown in a single vineyard in Australia. For this reason, we focused on the thiol precursors variability in 5 GWT clones (ISMA-AVIT 904 and 920R; ISMA 916 and 918; LB14) and 2 biotypes (906 y 1101) cultivated in Trentino (Italy) in 4 vineyards. The present work reports, for the first time in GWT, the evidence of a clonal variability regarding 3MH precursors in juice, with differences between clones up to 30%.