Isolation and Characterization of Polysaccharides from Grape and Yeast and their Interaction with Wine Volatile Compounds
Danye Zhu, Armando Alcazar Magana, Yongsheng
Tao, and Michael C. Qian*
*Oregon State University, 3051 SW Campus Way, Corvallis, OR,
97331 (michael.qian@oregonstate.edu)
Organoleptic properties are an important factor in wine quality. The polysaccharides from winegrapes and Saccharomyces cerevisiae yeast could be important in wine characteristics. Elucidation of structural information of grape and yeast polysaccharides is necessary to understand their interaction with other wine components and organoleptic contribution to wine quality. In this study, polysaccharide extracts from Pinot noir grapes and S. cerevisiae were purified on a DEAE Sephacel column (5.5 cm × 60 cm). After the samples were loaded on the column, the polysaccharides were sequentially eluted with 1.2 L aqueous NaCl solution (0, 0.1, 0.3, and 0.5 M) at a flow rate of 5 mL/min. The eluents were saved with a fraction collector. The polysaccharide in each tube was analyzed with the phenol-sulfuric acid method. Subsequently, the different polysaccharide fractions were obtained and concentrated by ultrafiltration with a molecular weight cut-off of 2 kDa. The purified polysaccharides were characterized by size exclusion chromatography, by ultraviolet-visible spectroscopy with a scanning range of 190 to 600 nm, and by attenuated total reflection-Fourier transform infrared spectroscopy in the wavelength range of 400 to 4000 cm-1. The nucleic acid and protein (characteristic absorption peaks at 260 nm and 280 nm) in purified polysaccharides were minimal. ATR-FT-IR spectroscopy showed different structural features of polysaccharides. Moreover, the interactions between wine volatile compounds and polysaccharides were studied.
Funding Support: American Vineyard Foundation (AVF)
