Grapes to wine: The nexus between berry ripening, composition and wine style

Grape ripening is a process driven by the interactions between grapevine genotype and environmental factors. Grape composition is largely responsible for the production and final concentrations of most wine aroma compounds even though many compounds in wines (aromatic and non-aromatic) are substantially transformed during the complex process of fermentation and wine ageing. The aim of this study was to investigate if a common pattern in grape/wine flavour plasticity related to ripening exists irrespective of a grape growing region. A further aim was to identify and highlight compounds present in grapes and wines in which plasticity is directly related to grape ripening and is consistent over several vintages. Irrespective of the region, a clear separation of samples was noted according to the harvest stage based on the grape and wine chemical analyses and wine sensory description. ‘Shiraz’ wines from the first harvest (H1) were associated with red fruit descriptors and higher acidity. Wines from the third harvest (H3) were correlated with dark fruit characters and a higher perception of alcohol. Later harvest dates resulted in higher concentrations of some amino acids in grapes, higher alcohol acetates and dimethyl sulphide in wines, whereas concentrations of Z-3-hexenol, ethyl isobutyrate and ethyl leucate were lower in these wines compared to earlier harvest dates. Trends described were significant and consistent across two distinct regions and two vintages. Irrespective of the environment, this study demonstrated that for Shiraz, a common evolution of grape flavours exists, influencing the final wine chemical and sensory properties. Furthermore, during the late ripening stage, no direct nexus was observed between sugar concentration and grape and wine flavour evolution.