Effect of grape maturity on wine sensory and chemical features: The case of Moristel wines

Among the different grape factors involved in wine quality, the present work is focused on evaluating the effect of grape maturity on wine flavour and how these sensory effects are related to wine chemical composition. Moristel grapes were collected from two vine blocks, with a priori maximum variability in terms of grape quality, at three and four different points of maturation. Wines were elaborated in triplicate yielding 21 wine samples. Sensory characterisation of samples was carried out by a trained panel following the rate-all-that-apply method. Volatiles and non-volatiles with known sensory impact were quantified. Grape maturity generated significant sensory effects on wine astringency and fruity aromas including raisin, black fruit and red fruit. Interestingly, a significant effect on oxidation nuances revealed a general pattern in the appearance of higher oxidation aromas in wines elaborated with grapes prematurely harvested. This attribute was related to concentrations of free acetaldehyde, methional, phenylacetaldehyde and isoaldehydes, and aldehyde reactive polyphenols. The presence of raisin aroma was linked to beta-darnaseenone, which was suggested to be formed during the on-vine dehydration process. Astringency was related to ethanol content, tannin activity (measured as the interaction of tannins with a hydrophobic surface), and the content in anthocyanin derived compounds.