Ludwig Ring, Elizabeth Tomasino, James Osborne, and Michael Qian*
*Oregon Wine Research Institute, 100 Wiegand Hall, Corvallis, OR 97331 (michael.qian@oregonstate.edu)

The chemical nature of red wine mouthfeel has been addressed in multiple recent studies. However, most focused on polyphenols such as tannins, which have been shown to account for the astringency of red wine. In contrast, the compounds contributing to mouthfeel and body remain unclear. This ongoing study investigates red wine polysaccharides, since they might affect the textural sensation, and thus the mouthfeel properties, of red wine. A procedure including precipitation, hydrolysis, and derivatization (silylation with TMSI) was developed to analyze the total carbohydrate composition by means of their per-O-trimethylsilylated methyl glycoside derivatives via GC-FID. Variations in the total carbohydrate composition of several red wines were observed. Although all samples comprised the same monomers (mannose, arabinose, galactose, rhamnose, galacturonic acid, glucose, and xylose), the ratios differed. Depending on the monomer, this can give insights into the winemaking process. For instance, a high-mannose portion could result from a longer yeast contact, since mannoproteins originate from yeast cell walls. However, it remains to be investigated which parameters most influence the composition at most (e.g., winemaking process, grape variety, or age), and to what extent this affects mouthfeel. Additional sensory studies will examine the organoleptic impact of red wine polymers to elucidate potential correlations between analytical and sensory data and gain a better understanding of the non-volatile sensory active compounds in red wine.

Funding Support: Oregon Wine Research Institute