Abstract
IntroductionProbe is a research infrastructure gathering 4 analytical platforms of INRAE and allowing multi-approach and multi-complementarity to be explored and exploited. As a proof of concept, a common study was conducted around the structure and the evolution of the skin of the grape berry and the diffusion of compounds of interest during the winemaking process.Materials and methodsIn this context, the aromatic potential on two Vitis vinifera grape varieties (Carignan and Grenache,) were studied. Berries were harvested at an average potential alcohol of 12% vol. in the vineyard of the Pech Rouge experimental unit (INRAE, Gruissan, France) and separated according to their natural heterogeneity in terms of density (degree of maturity: D), yielding two batches (D−, D+). Stir Bar Sorptive Extraction (SBSE) was used to extract the volatile compounds from the free fraction and the bound volatile fraction after acid hydrolysis. The capillary GC analysis was carried out on a DB-Wax fused silica column and the mass spectrometer detector was operated in the full scan mode (m/z 29 to 350 uma) with electron ionization at 70 eV. Identification of unknown compounds was achieved by comparing the retention times of standards, and mass spectra in the Wiley/NIST/Inramass database.ResultsDifferentiation between berries and wines was the first source of variability in the samples and was found mainly due to the presence of alcohols, esters and acids in the wines (fermentative aromas produced by yeast) while the berries were rich in aldehydes. Regarding the effect of variety, Grenache appeared to be more aromatic than Carignan (used in blended wine), even if it is considered as a neutral grape. A significant effect of hydrolysis was mainly observed for vitispirane and linalool. As they were present in grapes as glycosidic precursors, their hydrolysis led to the formation of fragrant compounds that contribute to the aroma of wine. Finally, octanol, octanoic acid and hex-2-enal were more intense in D- berries, known to be characteristic of immature berries.ConclusionThe characterization of aromatic potential of grape berry was successfully investigated, showing differences between berries and wines, varieties and hydrolyse effect. Further work will consist in relating these results to the ones obtained by the other PROBE plateforms.