Effects of membrane alcohol reduction on key aroma compounds, including rotundone, in Austrian Grüner Veltliner

Abstract

This study examines how stepwise alcohol reduction using membrane-based processes affects the composition, aroma, and sensory properties of an Austrian Grüner Veltliner wine. Alcohol was removed with a reverse osmosis system combined with a membrane contactor, and the resulting wines were compared with blends prepared from the dealcoholised and the original wine. The analytical work included standard chemical and physical measurements, sensory evaluation, and an extensive aroma analysis. In total, around 100 volatile compounds were quantified using six complementary GC–MS or GC-MS/MS methods, covering all aroma-relevant compound classes known for Grüner Veltliner (1) Ethanol removal led to changes that stem mainly from the reduction in total volume, which resulted in higher concentrations of non-volatile constituents and, to some extent, also of individual volatile compounds such as certain monoterpenes. At the same time, thiols, esters, higher alcohols and fatty acids decreased noticeably. Rotundone—the compound responsible for the typical pepper note of Grüner Veltliner—was not affected by the treatment and remained stable throughout the process. These analytical findings were reflected in the sensory assessment. Wines with lower alcohol were described more frequently with fresher attributes, while riper notes became less prominent. The blending approach produced comparatively small differences in aroma and showed no clear preference in the ranking test. Overall, the results indicate that membrane-based alcohol reduction can be applied without compromising key aroma characteristics, including the varietal pepper note, and may therefore represent a viable option for future wine production.

References

(1) Philipp, C., Eder, P., Sari, S., Korntheuer, K., & Eder, R. (2024). The influence of prefermentation skin contact, stabulation, and skin fermentation on the aromatic behaviour and phenolic compounds of important Austrian white wine cultivars. Australian Journal of Grape and Wine Research, 2024(1), 9843225.