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Michelle Leus

Scientific Officer

Flavour and Analytical Chemistry

MSc (Chem)

Michelle Leus

Contact

Tel  64 3 479 7565  Ext 7565
Email michelle.leus@otago.ac.nz
Location CSB 215


About

Flavour is a very important aspect of food and by smelling something we can assess if it something we know, if it is ripe and good to eat, or if something is no longer good to consume.
The compounds responsible for flavour can be complex and at trace levels. To identify and assess the contribution of odour active compounds we use gas chromatography mass spectroscopy with concurrent odour evaluation (GC-O-MS). This means people smell the individual compounds that make up wine, beer, cheese and we have equipment that will put a name to these compounds. We also use a range of other isolation and identification techniques such as Proton Transfer Mass Spectroscopy (PTRMS).
I did an MSc in Chemistry at Otago and have worked on a variety of research projects. Since working with flavour volatiles I have a completely new respect for a human nose.

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Publications

Eyres, G., Gould, B., Ting, V., Leus, M., Richter, T., Silcock, P., & Bremer, P. (2016). Characterisation of New Zealand hop character and the impact of yeast strain on hop derived compounds in beer. Proceedings of the 34th Asia Pacific Convention of the Institute of Brewing and Distilling. Retrieved from http://convention2016.ibdasiapac.com.au/

Yao, L., Laing, R. M., Bremer, P. J., Silcock, P. J., & Leus, M. J. (2015). Measuring textile adsorption of body odor compounds using proton-transfer-reaction mass spectrometry. Textile Research Journal, 85(17), 1817-1826. doi: 10.1177/0040517515576325

Eyres, G. T., Marriott, P. J., Leus, M., & Lysaght, B. (2015). Characterisation of impact aroma compounds in hop essential oils. In A. J. Taylor & D. S. Mottram (Eds.), Flavour Science: Proceedings of the XIV Weurman Flavour Research Symposium. (pp. 19-24). Packington, UK: Context Products. [Full Paper]

Kathriarachchi, K., Leus, M., & Everett, D. W. (2014). Oxidation of aldehydes by xanthine oxidase located on the surface of emulsions and washed milk fat globules. International Dairy Journal, 37(2), 117-126. doi: 10.1016/j.idairyj.2014.03.007

Eyres, G. T., Marriott, P. J., Leus, M., & Lysaght, B. (2014, September). Characterisation of character impact aroma compounds in hop essential oils. Verbal presentation at the 14th Weurman Flavour Research Symposium, Cambridge, UK.

Chapter in Book - Research

Dufour, J. P., Leus, M., & Hayman, A. R. (2000). Chemical equilibria of beer staling: Reaction of bisulfite with unsaturated aldehydes. In P. Schieberle & K.-H. Engel (Eds.), Frontiers of Flavour Science. (pp. 579-583). Germany: Deutsche Forschungsanstalt f¿r Lebensmittelchemie.

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Journal - Research Article

Yao, L., Laing, R. M., Bremer, P. J., Silcock, P. J., & Leus, M. J. (2015). Measuring textile adsorption of body odor compounds using proton-transfer-reaction mass spectrometry. Textile Research Journal, 85(17), 1817-1826. doi: 10.1177/0040517515576325

Kathriarachchi, K., Leus, M., & Everett, D. W. (2014). Oxidation of aldehydes by xanthine oxidase located on the surface of emulsions and washed milk fat globules. International Dairy Journal, 37(2), 117-126. doi: 10.1016/j.idairyj.2014.03.007

Verachia, W., Sewell, M. A., Niven, B., Leus, M., Barker, M. F., & Bremer, P. J. (2012). Seasonal changes in the biochemical composition of Evechinus chloroticus gonads (Echinodermata: Echinoidea). New Zealand Journal of Marine & Freshwater Research, 46(3), 399-410. doi: 10.1080/00288330.2012.697070

Benjamin, O., Silcock, P., Leus, M., & Everett, D. W. (2012). Multilayer emulsions as delivery systems for controlled release of volatile compounds using pH and salt triggers. Food Hydrocolloids, 27(1), 109-118. doi: 10.1016/j.foodhyd.2011.08.008

Benjamin, O., Leus, M., & Everett, D. W. (2011). Static headspace analysis of volatile compounds released from β-lactoglobulin-stabilized emulsions determined by the phase ratio variation method. Food Research International, 44(1), 417-424. doi: 10.1016/j.foodres.2010.09.030

Niimi, J., Leus, M., Silcock, P., Hamid, N., & Bremer, P. (2010). Characterisation of odour active volatile compounds of New Zealand sea urchin (Evechinus chloroticus) roe using gas chromatography-olfactometry-finger span cross modality (GC-O-FSCM) method. Food Chemistry, 121, 601-607. doi: 10.1016/j.foodchem.2009.12.071

Shellie, R., Marriott, P., Leus, M., Dufour, J.-P., Mondello, L., Dugo, G., … Luong, J. (2003). Retention time reproducibility in comprehensive two-dimensional gas chromatography using cryogenic modulation II: An interlaboratory study. Journal of Chromatography A, 1019, 273-278.

Dufour, J.-P., Wierda, R., Leus, M., Lissens, G., Delvaux, F., Derdelinckx, G., & Larsen, D. S. (2002). Quantitative analysis of beer aromatic alcohols using stable isotope dilution assay. Journal of the American Society of Brewing Chemists, 60(2), 88-96.

Dufour, J.-P., Baxter, A. J., Hayman, A. R., & Leus, M. (1999). Characterization of the reaction of bisulfite with unsaturated aldehydes in a beer model system using nuclear magnetic resonance spectroscopy. Journal of the American Society of Brewing Chemists, 57(4), 138-144.

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Conference Contribution - Published proceedings: Full paper

Eyres, G. T., Marriott, P. J., Leus, M., & Lysaght, B. (2015). Characterisation of impact aroma compounds in hop essential oils. In A. J. Taylor & D. S. Mottram (Eds.), Flavour Science: Proceedings of the XIV Weurman Flavour Research Symposium. (pp. 19-24). Packington, UK: Context Products. [Full Paper]

Dufour, J.-P., Wierda, R., Delbecq, P., Leus, M., & Silcock, P. J. (2003). Influence of ethanol on solid phase microextraction of alcoholic beverage volatile compounds. In J.-L. le Quéré & P. X. Étiévant (Eds.), Proceedings of the 10th Weurman Flavour Research Symposium: Flavour research at the dawn of the twenty-first century. (pp. 584-587). Hants, UK: Intercept. [Full Paper]

Dufour, J.-P., Wierda, R., Leus, M., Stevens, R., Silcock, P. J., & Derdelinckx, G. (2003). A novel method for the preparation of beer extracts suitable for sensory analysis and chemical characterization. Proceedings of the 29th European Brewery Convention Congress. [CD-ROM] Nürnberg, Germany: Fachverlag Hans Carl. [Full Paper]

Dufour, J.-P., Marriott, P., Reboul, E., Leus, M., & Silcock, P. J. (2003). Quantitative analysis of complex flavour mixtures using comprehensive multidimensional gas chromatography. In J.-L. le Quéré & P. X. Étiévant (Eds.), Proceedings of the 10th Weurman Flavour Research Symposium: Flavour research at the dawn of the twenty-first century. (pp. 500-505). Hants, UK: Intercept. [Full Paper]

Dufour, J.-P., Marriott, P., Reboul, E., Leus, M., Beatson, R., & Silcock, P. (2002). Application of comprehensive multidimensional gas chromatography for high resolution analysis of hop essential oil. Proceedings of the 27th Convention of the Institute and Guild of Brewing: Asia Pacific Section. (pp. 1-5). Adelaide, Australia: Institute and Guild of Brewing. [Full Paper]

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Conference Contribution - Published proceedings: Abstract

Eyres, G., Gould, B., Ting, V., Leus, M., Richter, T., Silcock, P., & Bremer, P. (2016). Characterisation of New Zealand hop character and the impact of yeast strain on hop derived compounds in beer. Proceedings of the 34th Asia Pacific Convention of the Institute of Brewing and Distilling. Retrieved from http://convention2016.ibdasiapac.com.au/

Huet, C., Niimi, J., Heenan, S., Leus, M., & Silcock, P. (2008). The effect of proton transfer mass spectrometry instrumental parameters on the headspace concentration of ethyl butyrate. Proceedings of the Institute of Food Technologists (IFT) Annual Meeting and Food Expo. Retrieved from http://www.ift.org/meetings-and-events/past-meeting-resources.aspx

Everett, D. W., Crownshaw, J., Ginestat, A., Wierda, R., Leus, M., & Dufour, J.-P. (2004). Effect of fat type and fat globule surface coating on the volatile fatty acid profile of yogurt. Journal of Dairy Science, 87(Suppl. 1), (pp. 89). [Abstract]

Everett, D. W., Crownshaw, J., Ginestet, A., Leus, M., & Dufour, J.-P. (2003). Gas chromatographic profile of volatiles in cheese induced by different fat globule surface coatings. Journal of Dairy Science, 81(Suppl. 1), (pp. 43). [Abstract]

Dufour, J.-P., Klein, A., Leus, M., & Silcock, P. J. (2002). How to assess the adsorption performances of SPME fibre as a function of extraction number. NZIFST Annual Conference - Thought for Food: Celebrating Innovative Food Technology. (pp. 35). Palmerston North: NZIFST. [Abstract]

Dufour, J.-P., Bulling, K., Anselme, B., Leus, M., Niven, B. E., & Hayman, A. R. (2002). Discrimination of Chardonnay and Sauvignon Blanc wines using SPME-GCMS analysis of the terpenes. Proceedings of the 25th International Symposium on Capillary Chromatography. CD-Rom. [Abstract]

Dufour, J.-P., Marriott, P., Reboul, E., Leus, M., Beatson, R., & Silcock, P. J. (2002). High-resolution hop essential oil analysis by using a comprehensive gas chromatography methodology. Brewers Digest. 77, (pp. 36). [Abstract]

Dufour, J.-P., Klein, A., Leus, M., & Silcock, P. J. (2002). A standard mixture for assessing adsorption performances of SPME fibers as a function of extraction number. Brewers Digest. 77, (pp. 36). [Abstract]

Bulling, K., Anselme, B., Leus, M., Niven, B. E., & Dufour, J.-P. (2001). Discrimination of Chardonnay and Sauvignon Blanc wines using SPME-GCMS analysis of the terpenes. NZIFST Annual Conference - 2001: A Food Odyssey. (pp. 35). Dunedin: NZIFST. [Abstract]

Dufour, J.-P., Keast, R., Wierda, R., Delbecq, P., & Leus, M. (2001). Solid phase microextraction technique for alcoholic beverage volatiles analysis: advantages and limitations. Brewers Digest. 76, (pp. 46-47). [Abstract]

Wierda, R., Dufour, J.-P., Leus, M., Lissens, G., Delvaux, F., David, L., & Larsen, D. S. (2001). Quantitative analysis of beer aromatic alcohols using stable isotope dilution assay. NZIFST Annual Conference - 2001: A Food Odyssey. (pp. 32). Dunedin: NZIFST. [Abstract]

Dufour, J.-P., Keast, R., Wierda, R., Delbecq, P., & Leus, M. (2001). Solid phase microextraction technique for alcoholic beverage volatiles analysis. NZIFST Annual Conference - 2001: A Food Odyssey. (pp. 32). Dunedin: NZIFST. [Abstract]

Dufour, J.-P., Leus, M., Lissens, G., Wierda, R., Delvaux, F., & Larsen, D. (2000). Quantitative analysis of beer aromatic alcohols using stable isotope dilution analysis. American Society of Brewing Chemists, News Letter. 60, (pp. 33). [Abstract]

Baxter, J., Dufour, J.-P., Hayman, A. R., & Leus, M. (1998). Chemical equilibria of beer staling. Conference of the American Society of Brewing Chemists. Boston, USA. [Abstract]

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Conference Contribution - Poster Presentation (not in published proceedings)

Benjamin, O., Leus, M., & Everett, D. W. (2010, November). Static headspace analysis of volatile compounds released from β-lactoglobulin-stabilized emulsions determined by the phase ratio variation method. Poster session presented at the International Dairy Federation (IDF) World Dairy Summit, Auckland, New Zealand.

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Conference Contribution - Verbal presentation and other Conference outputs

Eyres, G. T., Marriott, P. J., Leus, M., & Lysaght, B. (2014, September). Characterisation of character impact aroma compounds in hop essential oils. Verbal presentation at the 14th Weurman Flavour Research Symposium, Cambridge, UK.

Kathriarachchi, K. V., Everett, D. W., & Leus, M. (2013, September). Oxidation of aldehydes by xanthine oxidase on the surface of emulsions and washed milk fat globules. Verbal presentation at the 8th NIZO Dairy Conference: Functional Enzymes for Dairy Applications, Papendal, The Netherlands.

Benjamin, O., Silcock, P., Leus, M., & Everett, D. W. (2011, September). Multilayer emulsions as delivery systems for controlled release of volatile compounds using pH and salt triggers. Verbal presentation at the 7th NIZO Dairy Conference: Flavour and Texture: Innovations in Dairy, Papendal, The Netherlands.

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