Identification, quantitation and sensory evaluation of methyl 2- and methyl 3-methylbutanoate in varietal red wines

Abstract

Background and Aims: Esters are the most important class of volatile compounds contributing to fruity and berry-like aroma notes in wine. In this study, we identified aroma-active compounds in Carmenere red wine with a focus on fruity smelling compounds. Methods and Results: Application of an aroma extract dilution analysis to an aroma isolate obtained from Carmenere red wine by solvent-assisted flavour evaporation revealed, apart from well-known wine aroma compounds, two additional fruity smelling compounds, which were identified as methyl 2-methylbutanoate (M2MB) and methyl 3-methylbutanoate (M3MB). Quantitation of M2MB and M3MB in 16 different varietal red wines by stable isotope dilution assays resulted in a concentration below (M2MB) and close to or slightly above (M3MB) the respective odour threshold values. Spiking experiments based on a synthetic wine aroma model in combination with triangle tests did not result in significant sensory differences. Conclusions: Methyl 2-methylbutanoate and M3MB are two novel volatile compounds that were identified in all red varietal wines. At the concentration found, they do not contribute significantly to the fruity aroma of these red wines. Significance of the Study: This is the first report on the occurrence, concentration and sensory impact of M2MB and M3MB in red wines.