The potential of multielement stable isotope analysis for regional origin assignment of butter

Regional origin assignment of highly valuable milk products such as butter, is of considerable importance for legal, fiscal and trade controls within the European Union (EU). It is also of value for ensuring fair competition and as a means of protecting consumers against fraud due to mislabelling. Conventional chemical methods of analysis are not able to determine the regional provenance of butter unambiguously. Therefore, stable isotope ratio determinations of the light elements (C,N,O,S; bioelements) and the heavy element, Sr (a trace element), have been used for this purpose. Stable isotope ratios of these elements in natural cycles, their variations due to climate and geology, the abiotic and biological fractionation of isotopes and, finally, the reasons for regional differences in multielement stable isotope ratios of butter are discussed. Results are given for butter from several European countries and from outside the EU. The results indicate that stable isotope ratios and subsequent discriminant analysis based on data for samples of certified origin can enable the reliable detection of the regional provenance of butter.