Determination of the Geographical Origin of Cheese Using Multi-Element Stable Isotope Ratio Analysis.

摘要

Determining the regional origin of cheese provides an important tool that can be utilized in fighting commercial fraud, bioterrorism, and food-born illnesses. The stable isotope ratios (13C/12C and 15N/14N) of casein in sample cheeses from around the world were determined by isotope ratio mass spectrometry (IRMS). In addition, a probe into the fatty acid profile of ten cheddar cheeses from various countries was performed using Gas Chromatography Isotope Ratio Mass Spectrometry (GC-IRMS). The data were processed using multivariate statistical analyses including principle component analysis (PCA) and linear discriminant analysis (LDA) in order to challenge research hypothesis suggesting that the analytical approaches used can allow distinguishing between U.S. domestic cheeses and foreign ones and that the regional origin (state) of domestic cheeses can be identified. Results indicated that domestic cheeses were distinguished from Australian, Chinese, Israeli, and Colombian cheeses as well as from some European cheeses. Results also indicated that domestic cheeses could be discriminated based on specific regions, particularly the Northwestern region (New York, Maine, Vermont), which had deltaC values ranging from -19.95 ‰ to -17.82 ‰ and deltaN values ranging from 5.37 ‰ to 6.04 ‰, and the Midwestern region (Indiana, Minnesota) with some of the most negative deltaC values ranging from -26.22 ‰ to -24.73 ‰. Data (13C/ 12C isotope ratios) established with domestic cheeses allowed separating the cheeses into those prepared from milk of grass-fed cows (with deltaC lower than -23.5 ‰) and those from maize fed cows. The latter may allow distinguishing between organic and non-organic cheeses.