| Title: | On-line process monitoring of coffee roasting by resonant laser ionisation time-of-flight mass spectrometry: bridging the gap from industrial batch roasting to flavour formation inside an individual coffee bean |
| Author(s): | Hertz-Schunemann R; Dorfner R; Yeretzian C; Streibel T; Zimmermann R; |
| Address: | "Joint Mass Spectrometry Centre, Chair of Analytical Chemistry, Institute of Chemistry, University of Rostock, D-18059, Rostock, Germany" |
| ISSN/ISBN: | 1096-9888 (Electronic) 1076-5174 (Linking) |
| Abstract: | "Resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOFMS) enables the fast and sensitive on-line monitoring of volatile organic compounds (VOC) formed during coffee roasting. On the one hand, REMPI-TOFMS was applied to monitor roasting gases of an industrial roaster (1500 kg/h capacity), with the aim of determining the roast degree in real-time from the transient chemical signature of VOCs. On the other hand, a previously developed mu-probe sampling device was used to analyse roasting gases from individual coffee beans. The aim was to explore fundamental processes at the individual bean level and link these to phenomena at the batch level. The pioneering single-bean experiments were conducted in two configurations: (1) VOCs formed inside a bean were sampled in situ, i.e. via a drilled mu-hole, from the interior, using a mu-probe (inside). (2) VOCs were sampled on-line in close vicinity of a single coffee bean's surface (outside). The focus was on VOCs originating from hydrolysis and pyrolytic degradation of chlorogenic acids, like feruloyl quinic acid and caffeoyl quinic acid. The single bean experiments revealed interesting phenomena. First, differences in time-intensity profiles between inside versus outside (time shift of maximum) were observed and tentatively linked to the permeability of the bean's cell walls material. Second, sharp bursts of some VOCs were observed, while others did exhibit smooth release curves. It is believed that these reflect a direct observation of bean popping during roasting. Finally, discrimination between Coffea arabica and Coffea canephora was demonstrated based on high-mass volatile markers, exclusively present in spectra of Coffea arabica" |
| Keywords: | Coffea/*chemistry Food Handling Hot Temperature Mass Spectrometry/*methods Seeds/*chemistry Volatile Organic Compounds/chemistry aroma coffee coffee roasting process monitoring resonance enhanced multiphoto-ionisation/REMPI; |
| Notes: | "MedlineHertz-Schunemann, R Dorfner, R Yeretzian, C Streibel, T Zimmermann, R eng England 2013/12/18 J Mass Spectrom. 2013 Dec; 48(12):1253-65. doi: 10.1002/jms.3299" |
