Analytical Methods Classification of brandies and wine distillates using front face fluorescence spectroscopy Jana Sádecká * , Jana Tóthová, Pavel Májek Institute of Analytical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, SK-812 37 Bratislava, Slovak Republic article info Article history: Received 18 June 2008 Received in revised form 13 January 2009 Accepted 12 April 2009 Keywords: Brandy Fluorescence Chemometry Authentication abstract This study demonstrates the use of front face fluorescence spectroscopy and multivariate data analysis for differentiating brandies from wine distillates. Owing to the low price of the wine distillates, they are sometimes used for the counterfeiting brandies. For this reason, there is a need for a rapid method for drink authentication to reassure consumers and protect regional designations. Total luminescence and synchronous scanning fluorescence spectra were recorded followed by a classification of samples using principal component analysis (PCA) and hierarchical cluster analysis (HCA). Both PCA and HCA carried out on the emission spectra (360–650 nm) recorded at excitation wavelength 350 nm and syn- chronous fluorescence spectra (200–700 nm) collected at wavelength interval 90 nm provide very good differentiation between the two spirit classes. Less good classification was obtained using excitation spectra (225–425 nm) obtained at emission wavelength 440 nm. These results indicate that the front face fluorescence spectroscopy offers a promising approach for the authentication of brandies. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Brandy is a spirit drink produced from wine spirit, whether or not blended with a wine distillate distilled at <94.8 vol.%, provided that that distillate does not exceed a maximum of 50% by volume of the finished product. This spirit is aged for at least one year in oak receptacles or for at least six months in oak casks. Wine spirit is a spirit drink produced by the distillation at <86 vol.% of wine or wine fortified for distillation or by the redistillation of a wine dis- tillate at <86 vol.%. Wine spirit shall not contain added ethanol of agricultural origin (Regulation (EC) No 110/2008). In Slovak Republic there are two types of these spirits: ‘‘wine distillates” are less expensive, and can be legally produced using wine distillates diluted with ethanol from other sources, whereas ‘‘brandy” is more expensive and should contain ethanol from grape. Brandy has to be aged for a certain period in oak casks to ob- tain characteristic taste, flavour and colour. Traditional techniques utilised to analysis of brandy, such as gas chromatography–mass spectrometry (Caldeira, Pereira, Climaco, Belchior, & Bruno de Sousa, 2004), high-performance liquid chromatography (Canas, Belchior, Spranger, & Bruno-de-Sousa, 2003) and capillary electro- phoresis (Panossian, Mamikonyan, Torosyan, Gabrielyan, & Mkh- itaryan, 2001), focus on the determination of a certain marker compounds in a test product followed by a comparison of the val- ues obtained with those previously documented for authentic product. This approach is often time-consuming, expensive, re- quires highly trained staffs and the range of compounds, which must be quantified to ensure authenticity, is continuously increas- ing. In the last few years, there has been an increasing need to de- velop rapid, inexpensive and effective analytical methods, as well as requiring low sample manipulation. These demands lead to an approach based on food matrix characterisation as a whole and spectroscopic methods combined with chemometric techniques have been studied for this purpose. While there has been a notable growth for near-infrared (Barb- oza & Poppi, 2003; Pontes et al., 2006) and Fourier transform infra- red (Lachenmeier, 2007; Palma & Barroso, 2002) spectroscopy, there has been little research carried out using either UV–VIS absorption or fluorescence spectroscopy in spirit drink authentica- tion applications. Recent work using UV–VIS absorption spectros- copy dealt with discriminating 100% agave tequilas from other types of tequila (Barbosa-García et al., 2007). A review (Christensen, Norgaard, Bro, & Engelsen, 2006) has re- vealed that the application of fluorescence spectroscopy for direct analysis of food has increased during the last decade, probably due to the wide-spread use of multivariate data analysis tools. Front face fluorescence spectroscopy has demonstrated its fea- sibility to classify Swiss honeys from seven different floral sources (Karoui, Dufour, Bosset, & De Baerdemaeker, 2007). This method has also been used for the determination of the geographical origin of milk (Karoui, Martin, & Dufour, 2005) and cheeses (Karoui, Bos- set, Mazerolles, Kulmyrzaev, & Dufour, 2005; Karoui, Dufour, et al., 2005). Within the area of cheese ripening, the studies concluded 0308-8146/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2009.04.053 * Corresponding author. Tel.: +421 2 59325722; fax: +421 2 52926043. E-mail address: jana.sadecka@stuba.sk (J. Sádecká). Food Chemistry 117 (2009) 491–498 Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem