Determining the geographic origin of milk in Australasia using multi-element stable isotope ratio analysis

A pilot study was conducted to evaluate the suitability of multi-element isotope ratio analysis for determining the origin of cows' milk produced within Australasia. A milk sample from pasture-fed cows was obtained from seven dairying regions in Australia and New Zealand and analysed for the ratios of (13)C/(12)C, (15)N/(14)N, (18)O/(16)O, (34)S/(32)S, and (87)Sr/(86)Sr. Each milk sample displayed a distinct isotopic fingerprint. Isotope ratios for (18)O/(16)O and (13)C/(12)C, in particular, conformed to predicted isotope fractionation patterns based on the latitude and climate of each region. Relative to skim milk, casein was enriched in (13)C and (15)N, and depleted of (34)S, whereas, predictably, (87)Sr/(86)Sr ratios remained equivalent in both skim milk and casein. The milk samples from Australasia were considerably enriched in (18)O and (34)S compared with reported values for most European dairy products. Overall, multi-element isotopic analysis has good potential for determining the geographic origin of dairy products produced within Australasia. Crown Copyright (c) 2006 Published by Elsevier Ltd. All rights reserved.