What metabolomics teaches us about wine shelf life

In grape berry pedicel, xylem hydraulic conductance can be impaired by blockage deposition in the lumen of xylem elements. However, the varietal difference of the interruptions has not yet been characterized. In this preliminary work, we utilized synchrotron x-ray computed microtomography experiments performed at MOGNO beamline (LNLS – Brazil) to identify possible blockage sites in natural grape pedicel xylem. For this, we imaged dehydrated pedicel’s stem portion from the Niagara Rosada variety in three different phenological stages (Pre-veraison (PreV), veraison (V) and post-veraison (PostV). The reconstructed tridimensional images with a voxel size of 1.16 µm were segmented for the identification of xylem vessel lumens. After analysing one pedicel stem per stage, we identified 658 vessels without occlusion throughout his axial plane and 41 in which we could identify possible interruptions.

Quantity and quality of flavonoïds in grape berries are important parts of their global quality. Several studies had shown that tannins are responsible for some major flavour properties of red wines such as colour, bitterness and astringency. Nevertheless, their synthesis and properties are still misunderstood. Some studies had suggested that the tannic pool was set before veraison. Thus, the comprehension of the relations between environment and setting of this tannic pool, up to the harvest, is not sufficient.

Esca complex is a disease affecting grapevine trunks, characterized by the colonization of the wood by xylem-residing fungi (Phaeomoniella chlamydospora, Phaeoacremonium minimum and Fomitiporia mediterranea), and posing significant risks to vineyard longevity since no efficient treatment is available. Despite its prevalence, the mechanisms beyond symptomatic manifestations like interveinal chlorosis and leaf necrosis remain unclear. Preliminary findings indicated a more pronounced metabolic reprogramming in fruits compared to vegetative organs and a putative impact on wine quality by using fruits from symptomatic grapevines.

The indigenous Greek grape varieties Assyrtiko, Malagousia, Moschofilero and Roditis are used to produce white wines that are attracting the interest of wine producers and consumers due to their aromatic characteristics [1]. In addition, the Agiorgitiko and Xinomavro varieties are Greece’s most prominent red grape varieties.

3-Sulfanylhexan-1-ol (3SH) is a key impact odorant of white wines such as Sauvignon Blanc.[1] In particular, the varietal characters of Sauvignon Blanc, especially from Marlborough New Zealand, are strongly influenced by the concentrations of 3SH.[2,3