Utility of Comprehensive GC×GC Gas Chromatography in Finding Varietal Markers among Volatile Compounds in Non-Aromatic Red Wines

Abstract

To investigate the utility of comprehensive GC×GC gas chromatography metabolomics in finding varietal markers among volatile compounds in non-aromatic red wines, representative samples of the two most important Croatian monovarietal red wines, Plavac mali and Teran, were subjected to analysis by both conventional gas chromatography–mass spectrometry (GC-MS) and comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOF-MS) after headspace solid-phase microextraction (HS-SPME). GC-MS was useful for the determination of the basic volatile profile composed mainly of major esters and acids, followed by terpenes and C13-norisoprenoids. GC×GC-TOF-MS allowed the identification of 209 volatiles, among which 49 were significantly different across monovarietal wines. The compounds most characteristic for Teran were two theaspirane isomers, ethyl 3-(methylsulfanyl)propanoate, ethyl methyhexanoate, and ho-trienol, whereas Plavac mali stood out with higher concentrations of tridecane and a 2,3-butanediol isomer. The two monovarietal wines were successfully differentiated between each other by multivariate statistical methods mostly based on GC×GC-TOF-MS data. The presented approach that combines conventional GC-MS and advanced GC×GC-TOF-MS showed a great potential for tracking chemical markers of varietal origin and could be practically applied in managing wine production, quality and typicity, marketing, and protection from forgery.