Evaluation by Flash GC Electronic Nose of the Effect of Combinations of Yeasts and Nutrients on the Aromatic Profiles of Feteasca Regala Wines after Two Years of Storage

Abstract

Feteasca regala is a semi-aromatic Romanian white grape variety, which can benefit from technological interventions aiming to modulate its aromatic profile. In this study, two specific yeast nutrients, designed to increase the esteric and thiolic aromatic potential, respectively, were added at appropriate times, before or during fermentation. The musts were inoculated with two different strains of yeast, specially selected to favour the formation of an esteric or a thiolic volatile profile. The resulting wines were bottled and analysed two years later by Heracles flash GC electronic nose (from Alpha MOS), which provided a good discrimination of the samples based on the peaks of volatile molecules identified on the two chromatographic columns. The electronic nose showed that, in the aged wines, the influence of the yeast inoculated for fermentation was more evident than the impact of the yeast nutrients added. Using the AroChemBase software module from Alpha MOS, some volatile esters and other compounds were identified, and their importance for the discrimination of the wines and for the aroma profile is discussed. However, because the GC electronic nose can identify only some volatile compounds, but not all, sensory analysis was also applied to evaluate the wine samples, showing that the yeast, as well as the nutrients, have a clear influence on the perceived aromatic profiles. As intended, samples prepared with any of the technological interventions showed different volatile/aromatic profiles than the control wine prepared by natural fermentation and were clearly separated by the electronic nose, even after two years of storage. However, due to the limitations of the chromatographic columns used, the electronic nose could not provide an overall description of the aromatic profile of the produced wines, which is why the expertise of panelists was still needed to evaluate wines.