Effect of grape polysaccharides on the volatile composition and aromatic profile of Viura wines

Abstract

AIM: Many research studies have analyzed the effect of polysaccharides in the aromatic composition of white wines. However, it has been limited to yeast polysaccharides and commercial mannoproteins [1,2]. The aim of this research was to study the use of grape polysaccharides as finning agents and analyze their effect on the volatile composition and aromatic profile of Viura wines.

METHODS: Different fractions of grape polysaccharides were tested: polysaccharides extracted from white must (WM), red must (RM), red wine (RW), white grape skins (WGS), red grape skins (RGS), and lees from white wine (WL). A fraction of rhamnogalacturonan type II of 80% purity (RGII80%), and rhamnogalacturonan type II of 55% purity (RGII55%) were also tested. The different fractions were added as fining agents in Viura wines at bottling. Results were compared with controls and with commercial mannoproteins used for finning. The volatile composition of wines was analyzed by gas chromatography with mass detector (GC-MS) [3]. The wines were analyzed by 20 expert tasters from the D.O.Ca Rioja with a structured numerical scale according to UNE-87-020-93 Standard (ISO 4121:1987). The Geometric Mean (GM%) of the olfactory descriptors was used to classify the descriptors according to the International Organization for Standardization ISO 11035.

RESULTS: The wines treated with the RGS fraction showed the highest content of acetates, related to fruit and floral aromas. The wines treated with WL presented the highest content of total acids. Ethyl esters and C6 alcohols were found in high concentrations in most of the wines. The wines treated with the RW fraction presented the lowest content of volatile families and reduced the perception of the herbaceous descriptor.

CONCLUSIONS

This research would allow to study the effect of different fractions of grape polysaccharides as fining agents on the volatile composition and the aromatic profile of Viura wines.