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• Study of how harvest date affects volatile compounds in two vintages of Moristel. • Earlier harvesting leads to wines with more acetaldehyde and branched fatty acids. • Volatile variations may be due to polyphenolic and yeast metabolism changes. • Relationships among aromatic buffer components change with harvesting date. • Varietal compounds and typical maturation markers do not have sensory importance. This paper presents a study of the influence of the harvesting date on concentrations of odorants in Moristel wines of two vintages. The wine made from grapes harvested early facilitated the accumulation of acetaldehyde (associated with low polyphenols concentrations) and higher concentrations of branched acids. A reason for these greater levels could be the lack of reduction factors (NADH or NADPH). Other changes with potential sensory consequences are the decrease of the branched acid/branched alcohol, branched ester/branched acid and branched ester/branched alcohol ratios that occurs as the grapes ripen. Besides, the variations of varietal or typical maturation markers did not have sensory importance. These results suggest that the characteristics of wines associated to the degree of maturity of grapes are mostly related to the changes in the profiles of fermentative compounds (especially acetaldehyde) induced by changes in the polyphenolic content and in the medium in which the yeast develops. [ABSTRACT FROM AUTHOR]

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 β-damascenone, 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. • Significant effects of grape maturity on astringency, fruity and oxidation wine aromas. • Oxidation aromas in wines elaborated with grapes prematurely harvested. • Oxidation aroma positively correlated to the concentration of Strecker aldehydes. • Lower levels of aldehyde-reactive polyphenols related to higher oxidation nuances. • Astringency positively correlated to ethanol, tannin and anthocyanin-derivatives. [ABSTRACT FROM AUTHOR]