Résultat de la recherche
Geographic origin of European Emmental. Use of discriminant analysis and artificial neural network for classification purposes
The goal of this work was to classify European Emmental cheeses according to their geographic origin using analytical approaches. Twenty-five analytical parameters (factors) were measured in 183 samples. Results were combined by multivariate statistical analysis. Discriminant analysis (DA) and an artificial neural network (ANN) delivered similar results when all regions and factors were included; 95% and 91%, respectively, of the samples were correctly classified in the validation procedure. To reduce the analytical costs and the risk of overfitting, a DA based on a selection of only 11 factors was calculated. In this case, the Jackknifed validation delivered 95% correct assignments. Finally, a system was optimised to discriminate between the Swiss samples and cheeses from other regions. Building a new model for each of the six pairs, Switzerland vs. another region, 100% correct classification could be achieved for the Swiss samples.
Geographic origin of European Emmental cheese: Characterisation and descriptive statistics
To survey the authenticity of Emmental cheese from some of the main European countries of origin, samples of cheeses manufactured during winter (110 samples) and summer (73 samples) were collected. From a preliminary study, a series of promising analytical methods were selected and applied: total nitrogen, water soluble nitrogen (WSN), 12% TCA soluble nitrogen (TCA-SN), pH-value, volatile short-chain acids, chloride, organic acids, enterococci, obligate heterofermentative lactobacilli (OHL), Lactobacillus helveticus, sodium, copper, zinc, magnesium and stable isotope ratios (δ2H, δ13C, δ15N, δ34S). The data were analysed by univariate statistical methods according to the geographic origin and the season of production. Significant differences between the regions of origin were found for all parameters investigated (P≤0.001). Cheeses from some regions showed very specific properties. Seasonal differences were observed in certain regions for acetate, propionate, caproate, WSN, TCA-SN, pyruvate, OHL, zinc and δ13C levels.