Fluorescence and infrared spectroscopies: a tool for the determination of the geographic origin of Emmental cheeses manufactured during summer

摘要

Mid-infrared (MIR) and front-face fluorescence spectroscopies, coupled with chemometric techniques, were investigated for their potential for discriminating Emmental cheeses originating from various geographic origins. A total of 74 Emmental cheeses, produced during summer, from six countries, i.e., Denmark (n = 2), Finland (n = 4), Germany (n = 6), Austria (n = 8), France (n = 27) and Switzerland (n = 27) were analysed. Within the 1500-900 cm(-1) spectral region, a good classification of samples was obtained for 83.7 and 77% of the calibration and validation data sets, respectively. Within the 3000-2800 cm(-1) the classification was considerably worse (only 57.4 and 29.7% for the calibration and validation spectra, respectively). Protein tryptophan and vitamin A fluorescence spectra were recorded directly on cheese samples. Considering tryptophan fluorescence spectra, a good classification was observed for 76.4 and 63.5% of the calibration and the validation samples, respectively. A better classification was obtained from the vitamin A fluorescence spectra since 93.9 and 90.5% of the calibration and validation spectra, respectively, were correctly classified. Cheeses from Finland and Denmark were well separated using the 1500-900 cm(-1) spectra and tryptophan or vitamin A fluorescence spectra. Considering cheeses from Germany, 100% of good classification was only obtained with vitamin A spectra. Cheeses from France and Switzerland were generally discriminated, but several samples were incorrectly classified. It was concluded that vitamin A fluorescence spectra may be considered a promising probe for the reliable evaluation of Emmental cheese origin.