ARTICLES Characterization of Selected South African Young Cultivar Wines Using FTMIR Spectroscopy, Gas Chromatography, and Multivariate Data Analysis LEANIE LOUW, †,§ KAROLIEN ROUX, † ANDREAS TREDOUX, † OLIVER TOMIC, # TORMOD NAES, # H´ EL ` ENE H. NIEUWOUDT, † AND PIERRE VAN RENSBURG* ,†,§ Institute for Wine Biotechnology, Department of Viticulture and Oenology, Stellenbosch University, Private Bag X1, 7602 Matieland (Stellenbosch), South Africa; Distell Ltd., P.O. Box 184, Stellenbosch 7602, South Africa; and Centre for Biospectroscopy and Data Modelling, Matforsk, Oslovegen 1, 1430 Ås, Norway The powerful combination of analytical chemistry and chemometrics and its application to wine analysis provide a way to gain knowledge and insight into the inherent chemical composition of wine and to objectively distinguish between wines. Extensive research programs are focused on the chemical characterization of wine to establish industry benchmarks and authentication systems. The aim of this study was to investigate the volatile composition and mid-infrared spectroscopic profiles of South African young cultivar wines with chemometrics to identify compositional trends and to distinguish between the different cultivars. Data were generated by gas chromatography and FTMIR spectroscopy and investigated by using analysis of variance (ANOVA), principal component analysis (PCA), and linear discriminant analysis (LDA). Significant differences were found in the volatile composition of the cultivar wines, with marked similarities in the composition of Pinotage wines and white wines, specifically for 2-phenylethanol, butyric acid, ethyl acetate, isoamyl acetate, isoamyl alcohol, and isobutyric acid. Of the 26 compounds that were analyzed, 14 had odor activity values of >1. The volatile composition and FTMIR spectra both contributed to the differentiation between the cultivar wines. The best discrimination model between the white wines was based on FTMIR spectra (98.3% correct classification), whereas a combination of spectra and volatile compounds (86.8% correct classification) was best to discriminate between the red wine cultivars. KEYWORDS: Cultivar discrimination; FTMIR spectroscopy; gas chromatography; chemometrics; clas- sification INTRODUCTION Traditionally, the only way to discriminate between wines was by sensory evaluation. Due to the subjective nature of this approach, chemical and spectroscopic analyses in combination with statistical techniques were explored and found to be robust, precise, and objective (1, 2). Many different types of analytical data have been used to investigate the chemical composition of wine in order to distinguish between wines from different cultivars, each provid- ing a unique set of information. Some examples of composi- tional information that have been used to discriminate between wine cultivars include phenolic compounds (3, 4) and volatile compounds (5, 6). Data obtained with electronic nose and electronic tongue (7, 8) detectors were used to discriminate between wines. In addition, different spectroscopic methods (9-11) have been applied successfully to discriminate between wine cultivars. The volatile composition of wines can possibly be linked the strongest to sensory analysis, the traditional method of distin- guishing wines, as these compounds are primarily responsible for the distinct flavor of wine. Higher alcohols, esters, and volatile fatty acids are especially useful for investigating differences and similarities between wines, as they appear to be generic to most wine cultivars (5). In fact, strong correlations have been found between grape variety and the main byproduct * Author to whom correspondence should be addressed [telephone (+27) 21 809 7424; fax (+27) 21 886 5414; e-mail pvanrensburg@ distell.co.za]. † Stellenbosch University. § Distell Ltd. # Matforsk. J. Agric. Food Chem. 2009, 57, 2623–2632 2623 10.1021/jf8037456 CCC: $40.75  2009 American Chemical Society Published on Web 03/12/2009