Determination of must and wine polysaccharides by gas chromatography-mass spectrometry (GC-MS) and Size-Exclusion Chromatography (SEC)

Abstract

Polysaccharides are one of the major classes of macromolecules found in wines. They play a critical role in stabilizing other molecules in solution and thus are able to modify both the wine processing and organoleptic properties. Detailed analyses of these polysaccharides are essential to know their physicochemical properties and biological functions. We present analytical techniques not only to define the fine chemical structures of individual wine polysaccharides but also to estimate the overall polysaccharide composition of must and wines. The procedure covers the preparation of the sample, together with gas chromatography-mass spectrometry-based methods, for both the analysis of monosaccharides as their volatile trimethylsilyl methyl glycoside derivatives and methylation analysis to determine linkage positions between monosaccharide residues as their volatile partially methylated alditol acetate derivatives. We also provide a protocol for estimating the global content of wine polysaccharides by using size-exclusion chromatography with refractive index detector (SEC-RID). This is a rapid and simple method that can be used routinely in a reasonably equipped laboratory. Analysis complexity and time will vary depending on the method used, and the duration ranges from 2 days for a global polysaccharide estimation to 2 weeks for a carboxyl reduction/methylation linkage analysis.