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Scientific Articles - PTR-MS Bibliography

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[1526] Gloess, A. N., A. Vietri, F. Wieland, S. Smrke, B. Schönbächler, J. A. Sanchez Lopez, S. Petrozzi, S. Bongers, T. Koziorowski, and C. Yeretzian, "Evidence of different flavour formation dynamics by roasting coffee from different origins: On-line analysis with PTR-ToF-{MS}", International Journal of Mass Spectrometry, Feb, 2014.
<p>Coffees from different origins were roasted to different roast degrees and along varying time temperature roasting profiles. The formation of volatile organic compounds (VOCs) during roasting was analyzed on-line by proton-transfer-reaction time-of-flight mass-spectrometry (PTR-ToF-MS). Coffee samples were Coffea arabica from Colombia, Guatemala (Antigua La Ceiba), Ethiopia (Yirga Cheffe, Djimmah) and Coffea canephora var. robusta from Indonesia (Malangsari). The roasting profiles ranged from high temperature short time (HTST) to low temperature long time (LTLT) roasting, and from medium to dark roast degree. The release dynamics of the on-line monitored VOCs differed for the different coffees and showed a strong modulation with the time&ndash;temperature roasting profile. While for Guatemalan coffee the formation of VOCs started relatively early in the roasting process, the VOC formation started much later in the case of Yirga Cheffe and Malangsari. Off-line analysis of the coffee brew augmented the measurements. These included headspace solid phase micro extraction gas chromatography mass spectrometry (HS SPME GC/MS), content of total solids, chlorogenic acids, caffeine, total polyphenols (Folin Ciocalteu), organic acids (ion chromatography), titratable acidity and pH. Some general trends, irrespective of the coffee origin, were observed, such as an increase in pH when going from an HTST to an LTLT profile or from a medium to dark roast degree. Furthermore, a decrease of total headspace intensity was observed from an HTST to an LTLT roasting profile. In general, the changes of the time temperature roasting profiles and/or the roast degree influenced the intensity of the respective coffee constituents as well as their relative composition differently for different coffee origins.</p>
[Gloess2013] Gloess, A. N., M. Wellinger, B. Schoenbaechler, F. Wieland, C. Lindinger, and C. Yeretzian, "Predicting the Sensory Profiles of Coffee based on PTR-ToF-MS and GC-MS Measurements", CONFERENCE SERIES, pp. 54, 2013.
[Yeretzian2013] Yeretzian, C., A. N. Gloess, B. Schoenbaechler, M. Wellinger, A. Neff, and F. Wieland, "Recent Applications of PTR-ToF-MS in Coffee Research", CONFERENCE SERIES, pp. 67, 2013.
[Wieland2012] Wieland, F., A. N. Gloess, M. Keller, A. Wetzel, S. Schenker, and C. Yeretzian, "Online monitoring of coffee roasting by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS): towards a real-time process control for a consistent roast profile", Analytical and bioanalytical chemistry, vol. 402, no. 8: Springer, pp. 2531–2543, 2012.
A real-time automated process control tool for coffee roasting is presented to consistently and accurately achieve a targeted roast degree. It is based on the online monitoring of volatile organic compounds (VOC) in the off-gas of a drum roaster by proton transfer reaction time-of-flight mass spectrometry at a high time (1 Hz) and mass resolution (5,500 m/Δm at full width at half-maximum) and high sensitivity (better than parts per billion by volume). Forty-two roasting experiments were performed with the drum roaster being operated either on a low, medium or high hot-air inlet temperature (= energy input) and the coffee (Arabica from Antigua, Guatemala) being roasted to low, medium or dark roast degrees. A principal component analysis (PCA) discriminated, for each one of the three hot-air inlet temperatures, the roast degree with a resolution of better than ±1 Colorette. The 3D space of the three first principal components was defined based on 23 mass spectral profiles of VOCs and their roast degree at the end point of roasting. This provided a very detailed picture of the evolution of the roasting process and allowed establishment of a predictive model that projects the online-monitored VOC profile of the roaster off-gas in real time onto the PCA space defined by the calibration process and, ultimately, to control the coffee roasting process so as to achieve a target roast degree and a consistent roasting.
[Yeretzian2010] Yeretzian, C., A. Glöss, S. Petrozzi, L. D'Ambrosio, K. Knöpfli-Lengweiler, F. Wieland, A. Fridolin Wild, and R. Anliker, "The smell of coffee–an analytical perspective", , 2010.
Within the last century, coffee has become one of the world’s most popular beverages and represents a major economic factor for many coffee-producing countries and a significant business sector in consuming countries. The success of this fascinating brew has been overwhelming and its future seems even more exciting1,2. The ever transforming landscape of coffee-shops and coffee-houses, the various trends and fads in the growing speciality coffee sector, the mounting awareness about origins, the steady innovations in the coffee machine sector and last but not least, the rising media-hype around the Barista-scene are all just the tip of the iceberg for a steadily growing coffee-lover community and an astonishingly recession-resistant industry

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Selected PTR-MS related Reviews

F. Biasioli, C. Yeretzian, F. Gasperi, T. D. Märk: PTR-MS monitoring of VOCs and BVOCs in food science and technology, Trends in Analytical Chemistry 30 (7) (2011).

J. de Gouw, C. Warneke, T. Karl, G. Eerdekens, C. van der Veen, R. Fall: Measurement of Volatile Organic Compounds in the Earth's Atmosphere using Proton-Transfer-Reaction Mass Spectrometry. Mass Spectrometry Reviews, 26 (2007), 223-257.

W. Lindinger, A. Hansel, A. Jordan: Proton-transfer-reaction mass spectrometry (PTR–MS): on-line monitoring of volatile organic compounds at pptv levels, Chem. Soc. Rev. 27 (1998), 347-375.


Lists with PTR-MS relevant publications of the University of Innsbruck can be found here: Atmospheric and indoor air chemistry, IMR, Environmental Physics and Nano-Bio-Physics


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