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russell_frewPhD BSc(Hons) (Otago)

Tel: 03 479 7913
Location: Science II 3n12

Main research interests

  • Trace metals in natural waters
  • Stable isotope geochemistry
  • Paleo-chemistry
  • Geochemical provenancing

Current research projects

Determining the geographical origin of food and other commodities of interest:
The geochemical composition of a natural product provides a inherent signature that can be related to its point of origin. We are currently working on developing robust tools encompassing analyses (light isotopes, trace metals and heavy isotopes), databasing and statistical interpretation. Projects on whole foods (e.g. honey, coffee, edible oils) are on-going and attention is now on deciphering the signal within complex mixtures.

Nitrogen in the oceans, fate and fluxes:
Nitrogen compounds i the ocean play an important role in sustaining primary productivity and some are implicated as potential climate modifiers. However the the controls of the rates and pathways of the cycling of nitrogen from the relatively inert N2(g) through the essential nutrients NO3 and NH4, amino acids and various gaseous oxides is not well understood. The potential of climate change underlines the importance of understanding the marine biogeochemistry of nitrogen. For example, the regions of nitrogen fixation will increase with global warming thereby enhancing the marine fixed nitrogen pool. On the other hand nitrous oxide is a significant greenhouse gas with a global warming potential 300 times that of CO2 on a molecular basis. This project applies isotopic tools to unravel the complexities of the marine nitrogen systematics.


Sim, J., McGoverin, C., Oey, I., Frew, R., & Kebede, B. (2024). Optimisation of vibrational spectroscopy instruments and pre-processing for classification problems across various decision parameters. Food Innovation & Advances, 3(1), 52-63. doi: 10.48130/fia-0024-0004 Journal - Research Article

Green, S., Fanning, E., Sim, J., Eyres, G. T., Frew, R., & Kebede, B. (2024). The potential of NIR spectroscopy and chemometrics to discriminate roast degrees and predict volatiles in coffee. Molecules, 29, 318. doi: 10.3390/molecules29020318 Journal - Research Article

Sim, J., Dixit, Y., McGoverin, C., Oey, I., Frew, R., Reis, M. M., & Kebede, B. (2024). Machine learning-driven hyperspectral imaging for non-destructive origin verification of green coffee beans across continents, countries, and regions. Food Control, 156, 110159. doi: 10.1016/j.foodcont.2023.110159 Journal - Research Article

Li, A., Abrahim, A., Islam, M., Mejías, E., Hafizati Abdul Halim, N., Frew, R., … Kelly, S. D. (2024). A new approach to detecting sugar syrup addition to honey: Stable isotope analysis of hexamethylenetetramine synthesised from honey monosaccharides (fructose and glucose). Food Chemistry, 434, 137451. doi: 10.1016/j.foodchem.2023.137451 Journal - Research Article

Soni, K., Kebede, B., & Frew, R. (2023). Employing stable isotopes and trace elements to trace soybean origin sourced from deforestation hot stops. Proceedings of the New Zealand Institute of Food Science & Technology (NZIFST) Conference: Food in a Changing World. S20. Retrieved from Conference Contribution - Published proceedings: Abstract

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