Temperature variability inside a wine production area and its effect on vine phenology and grape ripening. An example from the Saint-Emilion-Pomerol

Cyclodextrins are complex cyclic oligosaccharides of glucose units. They are produced from the breakdown of starch by the enzymatic reaction of glucosyltransferase. The result is a ring-shaped molecule with a cavity with a hydrophilic outer part and a hydrophobic inner part. As a consequence of this cavity, cyclodextrin is able to form complexes with non-polar organic molecules [1,2].

In a previous work1, it was suggested that the different contents in delphinidin and catechin of the grapes were determinant on the O2 consumption and Strecker aldehyde (SAs) accumulation rates. Higher delphinidin seemed to be related to a faster O2 consumption and a smaller SAs accumulation rate, and the opposite was observed regarding catechin.
In the present paper, these observations were fully corroborated by adding synthetic delphinidin to a wine model containing polyphenolic fractions (PFs) extracted from garnacha and synthetic catechin to a wine model containing PF extracted from tempranillo: The delphinin-containing garnacha model consumed O₂ significantly faster and accumulated significantly smaller amounts of SAs than the original garnacha model, and the catechin-containing tempranillo model, consumed O2 significantly slower and accumulated significantly higher amounts of SAs than the original tempranillo model.

Reduced off-flavour is an organoleptic defect due to an excess of volatile sulfur compounds (VSC) in wine and often happening in Shiraz wines. This off-flavour is a direct consequence of the lack of oxygen flow during winemaking and bottle storage. Therefore, wine closure could have a direct impact on the formation of VSC due to the oxygen transfer rate that can modulate their levels. Even if dimethylsulfide (DMS) contributes to reduced off-flavor, it is also a fruity note enhancer in wine and its evolution during wine ageing is not well understood.

The overall quality of fine wines is linked to the development of “bouquet” during wine bottle ageing1. Several chemical reactions, occurring in atmosphere protected from oxygen, are favourable to the formation and preservation of sulphur compounds such as dimethyl sulfide (DMS). DMS accumulate in wines thanks to hydrolysis of its precursors (DMSp) mainly constituted by S-

In white wines, Verdejo wine stands out because of its high content in total amino acids. The total content in biogenic amines was low in all wines analyzed and putrescine was the predominant biogenic amine.