Spectral features of vine leaves are influenced by their mineral content

The aim of the present work was to investigate Sauternes wines aromas. The flavor profiles of two wines (vintages 2002 and 2003) were investigated. Key-odorants have been determined by AEDA applied to Amberlite XAD-2 resin extracts. Various complementary techniques were used to identify the compounds (pHMB extraction, chemical synthesis of non-commercial standards, co-injections on two capillary columns, odor description at the sniffing port, GC-MS and GC-PFPD).

Several classes of flavonoids, such as anthocyanins, flavonols, flavanols and flavones, undergo a slow H/D exchange on aromatic ring A, leading to full deuteration at positions C(6) and C(8). Within the flavanol class, H-C(6) and H-C(8) of catechin and epicatechin are slowly exchanged in D2O to the corresponding deuterated analogues; even quercetin, a relevant flavonol representative, shows the same behaviour in a D2O/DMSOd6 1:1 solution. Detailed kinetic measurements of these H/D scrambling processes are here reported by exploiting the time-dependent changes of their peak areas in the 1H-NMR spectra taken at different temperatures. A unifying reaction mechanism is also proposed based on our detailed kinetic observations, even taking into account pH and solvent effects. Molecular modelling and QM calculations were also carried out to shed more light on several molecular details of the proposed mechanism.

Wine production is a globally significant and intricate industry, characterized by diverse regions, grape varieties, and producers. Competitive advantage in wine production and marketing arises from localized natural attributes known as terroir, combined with transferable expertise in agronomic practices, winemaking methods, packaging, distribution, and marketing. Wine is a very globalized product with 40% of the total output exported. Globalization has prompted discussions on convergence of business and production practices across industries, driven by technological progress and adoption of international standards. However, persisting differences in cultural norms, institutional frameworks, and regulatory environments hinder full convergence.

Carbonic Maceration (CM) winemaking is typically used in different European regions. But It is paradoxical that being a traditional processing system and widely used in many wineries, some of the phenomena that take place and the parameters that characterize them are barely known. In this vinification system the intact grape clusters are placed in a carbon dioxide (CO2) enriched medium, and they immediately change from a respiratory metabolism to an anaerobic fermentative metabolism called intracellular fermentation, which is carried out by grape enzymes. But some grapes located in the lower zone of the tank are crushed by the weight of the ones above and release must, which is fermented by yeasts.

Le comportement de la vigne en terme de fonctionnement thermique et hydrique, influe de manière directe sur la qualité des baies de raisin. L’effet du terroir peut être perçu à travers l’étude de paramètres tels que la précocité, la mise en place de la surface foliaire ou la vigueur. Une expérimentation a été conduite en Val de Loire sur le cépage chenin dans le but de mieux comprendre le rôle des variables liées au terroir sur la croissance et le développement de la vigne et in fine sur la qualité des baies.