Effets de l’application d’acide gibbérellique (GA3) sur la qualité de raisins et de vins produits en climat tropical au Nord-Est du Brésil

β-Damascenone is a key norisoprenoid in grape (Vitis vinifera L.) that imparts floral and fruity aromas to both fruits and wines. It is derived from carotenoid metabolism, with neoxanthin as a substrate.

L’objectif d’une étude sur trois années vise, pour des terroirs différents et connus pour le profil des vins qui en sont issus, à exploiter au mieux le potentiel des raisins en optimisant la date de récolte ; pour chacun des trois terroirs, les minivinifications sont réalisées à partir de trois dates de récolte . Il s’avère, grâce à un suivi analytique important (sol, précurseurs et arômes) et une caractérisation organoleptique bien encadrée (analyse sensorielle pertinente et objective), que le choix de la date de récolte, en fonction du terroir, a une incidence sur le profil du vin et devient un outil pour l’élaborateur.

The yeast Metschnikowia pulcherrima is a microorganism of great biotechnological interest, both for improving winemaking processes and for other applications outside the wine supply chain.

The aromatic quality of wines after a long aging period in bottle is one of key points for oenologists. The objective of this work is to determine the main representative aromatic compounds found in long aged wines from D.O.Ca. Rioja. This study was made by 32 wines from 1971 to 2010 vintages. Sotolon, acetaldehyde, phenylacetaldehyde, 1,1,6-trimethyl-1,2-dihydronaptalene (TDN), β-damascenone, Y-decalactone and Y-dodecalactone were determined as the most important oxidation markers by GC-MS analysis. Moreover, sensory analysis using triangular tests were performed from wines with and without the addition of the mentioned compounds. Four different concentrations of each odorant were added, as individual compounds and as mixtures. The additions were ranged from values close to the reference odour thresholds up to high level concentrations. The most identified aroma was sotolon, which is commonly associated to curry and coffee liqueur aromatic notes. Other oxidative compounds were easily detected by panellists, such as Y-decalactone (peach compote), Y-dodecalactone (ripe fruit). The mixtures of the odorants were most easily detected than the individual compounds. It should be noted that acetaldehyde and phenylacetaldehyde were rarely perceived and distinguished.

The wine industry is currently on the search for new aromas and less browning in their products. In the improvement process of wine, lower fermentation temperatures have been considered, however, the yeasts in the market cannot tolerate such temperatures