Determining the geographic origin of Emmental cheeses produced during winter and summer using a technique based on the concatenation of MIR and fluorescence spectroscopic data

Byline: Romdhane Karoui (1), Eric Dufour (1), Laurent Pillonel (2), Daniel Picque (3), Thomas Cattenoz (3), Jacques-Olivier Bosset (2) Keywords: Emmental cheese; Authenticity; Geographic origin; Infrared; Fluorescence; Chemometry; Concatenation Abstract: A technique that used multivariate data analysis to combine mid-infrared (MIR) spectroscopy with front-face fluorescence spectroscopy was used to discriminate between Emmental cheeses originating from different European countries: Austria (n=12), Finland (n=10), Germany (n=19), France (n=57), and Switzerland (n=65). In total, 163 Emmental cheeses produced in winter (n=91) and summer (n=72) periods were investigated. When Factorial Discriminant Analysis was applied to either the infrared or fluorescence spectral data the classifications were not satisfactory. Therefore, the first twenty principal components (PCs) of the PCA extracted from each data set (MIR and tryptophan fluorescence spectra) were pooled (concatenated) into a single matrix and analysed by Factorial Discriminant Analysis. Correct classifications were obtained for the samples for 89% of the calibration spectra and 76.7% of the validation spectra. The discrimination for cheeses from Finland was excellent, while Austrian, German, French and Swiss cheeses were also discriminated well although a few samples were misclassified. It was concluded that concatenation of the data from the two spectroscopic techniques is an efficient technique for authenticating Emmental cheeses independently of their manufacturing period. Author Affiliation: (1) U.R. 'Typicite des Produits Alimentaires', ENITA de Clermont Ferrand, 63370, Lempdes, France (2) Station Federale de Recherches Laitieres de Liebefeld (FAM), CH-3003, Berne, Switzerland (3) Laboratoire de Genie et Microbiologie des Procedes Alimentaires, Institut National de la Recherche Agronomique, 78850, Thiverval Grignon, France Article History: Registration Date: 22/04/2004 Received Date: 16/01/2004 Online Date: 08/06/2004