Exploring recent innovations in ambient mass spectrometry to deliver a paradigm shift in food safety, security and authenticity

  • Nicholas Birse

Student thesis: Doctoral ThesisDoctor of Philosophy

Abstract

Food fraud has been a problem for both consumers and producers for millennia; the Roman Empire instituted some of the first legislation to protect against practices which could cause illness or death to its citizens. Governments in the years since have instituted a wide variety of safeguards to protect lives and to ensure socio-economic stability by permitting access to safe and nutritious food, concurrently, criminal entities have developed new and increasingly complex ways of defeating such safeguards.

Producers are increasingly looking to the latest analytical technologies to both demonstrate that their products are safe and nutritious, and to provide a degree of protection against criminals who could cause significant reputational harm to producers.

The aim of this thesis was to determine whether ambient mass spectrometry platforms could firstly be used to undertake the types of authenticity and quality confirmations that industry desires.

The first project was to assess whether rapid evaporative ionisation mass spectrometry could be used by a major Northern Ireland poultry producer to confirm the authenticity of each poultry product they produce, primarily to confirm that their premium product offerings such as organic and free range were correctly labelled and contained the correct product. Six different poultry production systems were analysed by means of an electrosurgical knife and a bi-polar meat probe connected to a high-resolution quadrupole-time of flight mass spectrometer, which together form the rapid evaporation ionisation mass spectrometry (REIMS) system.

Principle component analysis (PCA), linear discriminant analysis (LDA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) chemometric models were built which demonstrated clear differences between some of the different production systems, most notably allowing those using different breeds of bird to be identified.
The correct classification rates for REIMS varied from 69.22% to 100% depending on the modelling approach taken – a hierarchical approach based on separating out birds by breed then by production system was found to be much more effective than a single six class model which attempted to separate birds purely by production system first.

The REIMS project also investigated whether the age of the poultry could be assessed by means of a chemometric analysis – using the same analysis techniques as before, it was determined that REIMS could determine with 100% accuracy the age of the poultry product, taken together with the significant potential in identifying some production system characteristics and poultry breeds, REIMS shows significant potential for confirming labelling on products or in detecting relabelling frauds.

The second project was to investigate direct analysis in real time (DART) mass spectrometry as an alternative to REIMS for poultry production system identification. The analysis required a complex and lengthy sample preparation process, which would restrict the use of the system to an analytical laboratory, but it was found that DART when combined with a high-resolution Orbitrap mass spectrometer could identify poultry production systems with a 100% cross-validation accuracy when using the same PCA and OPLS-DA chemometric modelling techniques used for the REIMS analysis.

The final project was to further investigate DART mass spectrometry and assess whether it could potentially be used to detect an organic v conventional mislabelling fraud in the vegetable sector. Leeks were chosen for this analysis and three sections from each leek (leaf, stem and root) were analysed by using a DART ion source connected to a compact and potentially field deployable single quadrupole mass spectrometer. It was found that when freeze drying and extracting the samples in methanol, it was possible to identify organic and conventional leeks with a correct classification rate of between 95% and 100% depending on which section of the leek was analysed.

The work within this thesis confirms that ambient mass spectrometry could potentially be used by producers and government safety bodies to determine whether products are incorrectly labelled with regards to their quality or dates of production.
Date of AwardJul 2021
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsNorthern Ireland Department for the Economy & Waters Corporation
SupervisorChristopher Elliott (Supervisor) & Olivier Chevallier (Supervisor)

Keywords

  • mass spectrometry
  • chemometrics
  • ambient ionisation
  • direct MS
  • authenticity
  • food fraud
  • mislabeling
  • substitution

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