Isotopic analysis of eggs: evaluating sample collection and preparation

Egg traceability/authenticity is a worldwide concern. Stable isotope techniques have been suggested as a tool to address this issue. To further validate the use of these techniques, a research project was undertaken to evaluate what effect sample collection and preparation have on the measured isotopic composition of egg components. The timing of egg collection, the timing of egg preparation after collection, and the use of pasteurisation were investigated. The C, N, O, and S isotopic compositions of egg components from 7 different production systems were measured. Two sets of eggs were collected (4 months apart). It was found that the 'isotopic fingerprint' of a particular production system was maintained over time, and that it may be possible to trace liquid egg products based on isotopic data from fresh eggs. The findings from this study support the integration of stable isotope techniques in egg traceability/authenticity systems.