Changes of volatile compounds by the addicion of yeast autolysated in white sparkling wine elaboration

Abstract

Natural sparkling wines are obtained after a second fermentation in closed bottles, and they remain in contact with the yeast lees for at least 9 months. During sparkling wine aging, different compounds such as polysaccharides can be released due to yeast autolysis that can cause important changes in wine composition, affecting the quality of sparkling wines. Yeast autolysis is a slow natural process that takes long time, and the addition of some products could improve the quality characteristics of these wines.Therefore, the aim of this work was to study the effect of the addition of several commercial yeast autolysated on the volatile composition of white sparkling wines elaborated from two white grape varieties (Godello and Verdejo), and aged on lees for 9 months.The base wines were elaborated following the traditional white winemaking process. The studied varieties were: Verdejo from the Rueda Designation of Origin (DO), and Godello from the Bierzo DO. The sparkling wines were elaborated following the traditional or “champenoise” method, and after the tirage phase, the bottles were kept in a cellar at temperature and relative humidity controlled for 9 months.The volatile compounds were analysed by gas chromatography coupled to a mass detector, after a previous liquid-liquid extraction. The polysaccharide and monosaccharide composition of the commercial preparations was determined by GC-MS of their trimethylsilyl-ester O-methyl glycosyl residues.The percentage of mannoproteins of the different commercial products, estimated by the mannose concentrations, was between 53-83%. The percentage of glucans, estimated by the concentrations of glucose, was between 14-47%. Therefore these results indicate that these products presented in general higher amounts of mannoproteins than of glucans.The statistical analysis of the data was carried out by the discriminant analysis, which indicated that the sparkling wines treated with PCP2 in the tirage phase showed the highest differences in the volatile composition of both sparkling wines studied, being the ethyl esters, alcohol acetates and terpenes the compounds that were affected in a greater extent. This fact could be due to the commercial product, PCP2, presented the highest percentage of mannoproteins that can interact with volatile compounds, modulating their volatility and perception.