La mise au point d’une méthode d’analyse par UPLC-MS/MS et dilution isotopique nous a permis d’identifier pour la première fois dans un moût le S-3-(hexan-1-ol)-<gamma>-glutamyl-cystéine (<gamma>GluCys-3MH). Suite à cette découverte, l’étude des interconversions entre les glutathionylés, dipeptides et cystéinylés S-conjugués au 3-mercaptohexan-1-ol (3MH) ou à la 4-mercapto-4-méthyl-pentan-2-one (4MMP), a permis de mettre en évidence deux nouvelles formes de précurseurs. Le suivi de l’évolution de ces différents composés au cours de fermentations alcooliques à l’échelle laboratoire a permis de clarifier leur rôle de précurseurs et d’établir les éventuels mécanismes d’interconversion. Par ailleurs, à travers plusieurs expérimentations viticoles et œnologiques conduites à l’échelle pilote en Languedoc et Val de Loire pendant trois années consécutives, des éléments nouveaux ont pu être apportés quant à l’impact de la maturation du raisin et son hétérogénéité, ainsi qu’à l’importance des opérations pré-fermentaires comme la macération pelliculaire ou la stabulation sur bourbes. / The development of a method using UPLC-MS/MS and stable isotope dilution assay allowed us to identify for the first time the S-3-(hexan-1-ol)-<gamma>-glutamyl-cysteine (<gamma>GluCys-3MH) in musts. Following this discovery, the study of interconversions between glutathione, dipeptides and cysteine S-conjugates to 3-mercaptohexan-1-ol (3MH) or 4-mercapto-4-methyl-pentan-2-one (4MMP) highlighted two new forms of precursors. The evolution monitoring of these compounds during alcoholic fermentations at laboratory scale allowed us to clarify their role as precursors and to establish the possible interconversion mechanisms. In addition, through several viticultural and oenological experiments carried out at pilot scale in Languedoc and Val de Loire during three consecutive years, new elements could be … about the impact of grape ripening and its heterogeneity, as well as the importance of prefermentative processes, such as skin maceration and must conservation on lees.

Purpose: To determine the effect of four postexercise beverages, differing in macronutrient content, on metabolic response to an acute resistance exercise bout. Methods: Forty male subjects performed five sets of eight repetitions at 80% 1RM for leg press and leg extension, and then consumed one of four postexercise beverages (Placebo, PL: a carbohydrate-electrolyte beverage, CE; or one of two milk-based beverages, MILK 1: 1% chocolate milk; MILK 2: a high protein milk beverage). Indicators of muscle protein synthesis (MPS) were assessed before and 1-hr after consuming a postexercise beverage. Muscle protein degradation (MPD) was examined the day before and the day of exercise. Results: No significant differences were found among groups in MPS. The resistance exercise bout increased the amount of eIF4E-eIF4G by 4.5% 1-hr postexercise (p<0.05) without affecting the amount of eIF4E-4E-BP1. One hour after beverage consumption, serum total amino acid concentration increased for MILK 1 (p=0.003) and MILK 2 (p<0.001) but decreased for CE (p=0.028) and PL (p=0.276). Consumption of MILK 1, MILK 2, and CE significantly increased circulating levels of serum insulin (p<0.001). Serum growth hormone increased 3-fold as a result of the exercise bout but fell to baseline for all groups by 60 min (p<0.001). Conclusion: The resistance exercise bout was anabolic as shown by the increase in the active eIF4E-eIF4G complex and serum growth hormone. Consumption of MILK 2 led to the most optimal environment for muscle anabolism; however, none of the experimental beverages influenced the measured indicators of muscle protein translation 1-hr after ingestion. / Master of Science