Analysis of Rotundone in Japanese Syrah Grapes and Wines using Stir Bar Sorptive Extraction (SBSE) with Heart-Cutting Two-Dimensional GC-MS

Abstract

Rotundone, an oxygenated sesquiterpene, is responsible for the peppery aroma in wines. We developed an effective and simple method to determine trace levels of rotundone in grapes and wines. The method uses stir bar sorptive extraction (SBSE) with heart-cutting two-dimensional gas chromatography/mass spectrometry without a pre-extraction process such as solid-phase extraction. The limits of detection and quantitation for rotundone were 2.1 and 6.5 ng/kg in grape and 2.4 and 7.2 ng/L in wine. The recoveries of rotundone from Cabernet Sauvignon grape and wine were 106% (spiked with 120 ng/kg for grape) and 96% (spiked with 120 ng/L for wine), respectively. We demonstrated that rotundone concentrations in Syrah grapes and wines from Ueda were higher (up to 2342 ng/kg and 232 ng/L, respectively) than the maximal rotundone concentrations in Australian Syrah grapes and wines. Findings indicate that some environmental factors in Japan may promote rotundone accumulation in Syrah grapes, and underscores the importance of studying regional characteristics of rotundone accumulation in Syrah grapes.