Thiol precursors in Vitis mould-tolerant hybrid varieties

Background Over recent years, a new wave of disease‐tolerant to mildew varieties has flooded the viticulture sector, for reasons of human safety and economic expediency. These hybrid grape cultivars are selected mainly on the basis of their intrinsic capability to counter the attack of the main fungal diseases that affect grape production, such as downy mildew and powdery mildew. However, their organoleptic and enological characteristics have not yet been studied in depth for purposes of both juice and wine production, due to the high number of newly proposed germplasm and the lack of information about their adaptability to different environments. This work examines the thiol aroma precursors concentration in 64 red and white disease‐tolerant hybrid varieties in the vine germplasm collections of CREA‐VE and FEM, both from the north‐east of Italy. Results All cultivars showed the presence of 3‐mercaptohexan‐1‐ol (3MH) precursors, ranging from 4.4 to 1141 μg/kg for S‐glutathion‐3‐mercaptohexan‐1‐ol (GSH‐3MH), and 0.3 to 136 μg/kg for S‐cysteine‐3‐mercaptohexan‐1‐ol (Cys‐3MH). The concentration of GSH‐3MH exceeded 600 μg/kg in eight varieties, with values comparable with those of the richest V. vinifera reported so far. Red grapes showed, on average, higher concentrations of 3‐mercaptohexan‐1‐ol precursors than white ones. Only two hybrids had 4‐mercapto‐4‐methylpentan‐2‐one (4MMP) precursors over the limit of quantification, albeit with a much higher concentration than those normally reported in Sauvignon Blanc. Conclusion This is the first detailed survey of 3MH and 4MMP precursors carried out taking into account a considerable number of hybrid grape varieties. The results show that some of these varieties could be interesting for the production of tropical juices or tropical‐aromatic wines and soft drinks, through the enzymatic liberation of thiol aromas, as well as for the production of aromatizing tannins to be used in the food industry