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Scientific Articles - PTR-MS Bibliography

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Publications

Found 2 results
Title [ Year(Asc)]
Filters: Author is Ali, Santo  [Clear All Filters]
2011
[Dold2011] Dold, S., C. Lindinger, E. Kolodziejczyk, P. Pollien, S. Ali, J. Carlos Germain, S. Garcia Perin, N. Pineau, B. Folmer, K-H. Engel, et al., "Influence of foam structure on the release kinetics of volatiles from espresso coffee prior to consumption.", J Agric Food Chem, vol. 59, no. 20: Nestlé Research Center, P.O. Box 44, 1000 Lausanne 26, Switzerland., pp. 11196–11203, Oct, 2011.
Link: http://dx.doi.org/10.1021/jf201758h
Abstract
The relationship between the physical structure of espresso coffee foam, called crema, and the above-the-cup aroma release was studied. Espresso coffee samples were produced using the Nespresso extraction system. The samples were extracted with water with different levels of mineral content, which resulted in liquid phases with similar volatile profiles but foams with different structure properties. The structure parameters foam volume, foam drainage, and lamella film thickness at the foam surface were quantified using computer-assisted microscopic image analysis and a digital caliper. The above-the-cup volatile concentration was measured online by using PTR-MS and headspace sampling. A correlation study was done between crema structure parameters and above-the-cup volatile concentration. In the first 2.5 min after the start of the coffee extraction, the presence of foam induced an increase of concentration of selected volatile markers, independently if the crema was of high or low stability. At times longer than 2.5 min, the aroma marker concentration depends on both the stability of the crema and the volatility of the specific aroma compounds. Mechanisms of above-the-cup volatile release involved gas bubble stability, evaporation, and diffusion. It was concluded that after the initial aroma burst (during the first 2-3 min after the beginning of extraction), for the present sample space a crema of high stability provides a stronger aroma barrier over several minutes.
2005
[Lindinger2005] Lindinger, C., P. Pollien, S. Ali, C. Yeretzian, I. Blank, and T. Maerk, "Unambiguous identification of volatile organic compounds by proton-transfer reaction mass spectrometry coupled with GC/MS.", Anal Chem, vol. 77, no. 13: Nestlé Research Center, Vers-chez-les-Blanc, 1000 Lausanne 26, Switzerland., pp. 4117–4124, Jul, 2005.
Link: http://pubs.acs.org/doi/abs/10.1021/ac0501240
Abstract
Interest in on-line measurements of volatile organic compounds (VOCs) is increasing, as sensitive, compact, and affordable direct inlet mass spectrometers are becoming available. Proton-transfer reaction mass spectrometry (PTR-MS) distinguishes itself by its high sensitivity (low ppt range), high time resolution (200 ms), little ionization-induced fragmentation, and ionization efficiency independent of the compound to be analyzed. Yet, PTR-MS has a shortcoming. It is a one-dimensional technique that characterizes compounds only via their mass, which is not sufficient for positive identification. Here, we introduce a technical and analytical extension of PTR-MS, which removes this shortcoming, while preserving its salient and unique features. Combining separation of VOCs by gas chromatography (GC) with simultaneous and parallel detection of the GC effluent by PTR-MS and electron impact MS, an unambiguous interpretation of complex PTR-MS spectra becomes feasible. This novel development is discussed on the basis of characteristic performance parameters, such as resolution, linear range, and detection limit. The recently developed drift tube with a reduced reaction volume is crucial to exploit the full potential of the setup. We illustrate the performance of the novel setup by analyzing a complex food system.

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Download Contributions to the International Conference on Proton Transfer Reaction Mass Spectrometry and Its Applications:

 

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).
Link

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.
Link

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.
Link

 

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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