Ripening effect on the concentration of polyfunctional thiol precursors in 'Gewürztraminer'

The effect of ripeness on the concentration of polyfunctional thiol precursors was investigated in 'Gewürztraminer' juices in two vintages characterised by very different climate conditions. An incremental trend of glutathionyl-3-mercaptohexan-1-ol and cysteinyl-3-mercaptohexan-1-ol during ripening was observed. The increase in the last phase of maturation was noticeable in both vintages. The concentration of 4-S-glutathionyl-4-methylpentan-2-one and 4-S-cysteinyl-4-methylpentan-2-one was confirmed to be low in 'Gewürztraminer', although the latter was found at quantifiable levels in a couple of samples. The management of the harvest date appears to be highly important in order to exploit the potential grapefruit-like note related to polyfunctional thiols of little aromatic GWT wines, particularly in case of challenging vintage years.