Grant: Discovery Grants Program - Individual

For this present Discovery grant, two studies involving at least two graduate students (two MSc students that could stay for their PhD) are proposed: 1) Investigation of the mechanism of protein instabilities in white wine (one MSc student and one PhD student). One problem that can arise during bottled white wine storage is the development of haze due to protein instability and visually detected by the human eyes. While there is no hazard in the consumption of such wines, the consumers tend to reject them as spoiled wines. The denaturation of white wine proteins over time involves one or several low molecular weight non-protein components (factor X) with an unknown chemical nature This study aims to isolate factor X by a series of physical and chromatographic procedures (dialysis, ultracentrifugation, HPLC-MS, ICP-MS). Some compound released during yeast autolysis (Factor Y), like the well known mannoproteins, but also new peptides and oligosaccharides, that have a stabilizing effect will also be studied. 2) Polyphenols-Aromas interactions in wine (one MSc student and one PhD student) The goal of this study will be to demonstrate the physico-chemical properties of polyphenols in relation to wine aroma. The first hypothesis examines whether polyphenols, and tannins in particular, can modify the volatility of wine volatile compounds (matrix effect). These polyphenols could then change the aroma profile of wine, especially for red wines. The second aspect will examine the chemical stability of certain wine aromas in the presence of polyphenols, and other wine antioxidants like peptides or prooxidants such as SO2 or iron. Thiols, esters, and lactones with odorant impacts and representative grape, fermentation and oak ageing origins will be targeted.