Skip to main content

Looking into individual coffee beans during the roasting process: direct micro-probe sampling on-line photo-ionisation mass spectrometric analysis of coffee roasting gases

Analytical and Bioanalytical Chemistry volume 405, pages 7083–7096 (2013)Cite this article

Abstract

A micro-probe (μ-probe) gas sampling device for on-line analysis of gases evolving in confined, small objects by single-photon ionisation time-of-flight mass spectrometry (SPI-TOFMS) was developed. The technique is applied for the first time in a feasibility study to record the formation of volatile and flavour compounds during the roasting process within (inside) or in the direct vicinity (outside) of individual coffee beans. A real-time on-line analysis of evolving volatile and semi-volatile organic compounds (VOC and SVOC) as they are formed under the mild pyrolytic conditions of the roasting process was performed. The soft-ionisation mass spectra depict a molecular ion signature, which is well corresponding with the existing knowledge of coffee roasting and evolving compounds. Additionally, thereby it is possible to discriminate between Coffea arabica (Arabica) and Coffea canephora (Robusta). The recognized differences in the roasting gas profiles reflect the differences in the precursor composition of the coffee cultivars very well. Furthermore, a well-known set of marker compounds for Arabica and Robusta, namely the lipids kahweol and cafestol (detected in their dehydrated form at m/z 296 and m/z 298, respectively) were observed. If the variation in time of different compounds is observed, distinctly different evolution behaviours were detected. Here, phenol (m/z 94) and caffeine (m/z 194) are exemplary chosen, whereas phenol shows very sharp emission peaks, caffeine do not have this highly transient behaviour. Finally, the changes of the chemical signature as a function of the roasting time, the influence of sampling position (inside, outside) and cultivar (Arabica, Robusta) is investigated by multivariate statistics (PCA). In summary, this pilot study demonstrates the high potential of the measurement technique to enhance the fundamental knowledge of the formation processes of volatile and semi-volatile flavour compounds inside the individual coffee bean.

This is a preview of subscription content, access via your institution.

Access options

Buy single article

Instant access to the full article PDF.

USD 39.95

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6

References

  1. Flament I (2002) Coffee Flavor chemistry. Wiley

  2. Grosch W (1998) Flavour of coffee. A review. Nahrung 42(6):344–350

    Article  CAS  Google Scholar 

  3. Mayer F, Czerny M, Grosch W (2000) Sensory study of the character impact aroma compounds of a coffee beverage. Eur Food Res Technol 211(4):272–276

    Article  CAS  Google Scholar 

  4. Nijssen LM (1996) Volatile compounds in food: qualitative and quantitative data. TNO Nutrition and Food Research Institute

  5. Vitzthum OG (1999) Thirty years of coffee chemistry research. In: Teranishi R, Wick EL, Hornstein I (eds) Flavor chemistry: thirty years of progress. Kluwer/Plenum, New York, pp 117–134

    Chapter  Google Scholar 

  6. Hashim L, Chaveron H (1996) Use of methylpyrazine ratios to monitor the coffee roasting. Food Res Int 28(6):619–623

    Article  Google Scholar 

  7. Schenker S, Heinemann C, Huber M, Pompizzi R, Perren R, Escher F (2002) Impact of roasting conditions on the formation of aroma compounds in coffee beans. J Food Sci 67(1):60–66

    Article  CAS  Google Scholar 

  8. Silwar R, Lullmann C (1993) Investigation of aroma formation in Robusta coffee during roasting. Cafe Cacao The 37(2):145–152

    CAS  Google Scholar 

  9. El-Abassy RM, Donfack P, Materny A (2011) Discrimination between Arabica and Robusta green coffee using visible micro Raman spectroscopy and chemometric analysis. Food Chem 126(3):1443–1448

    Article  CAS  Google Scholar 

  10. Esteban-Díez I, González-Sáiz JM, Pizarro C (2004) An evaluation of orthogonal signal correction methods for the characterisation of arabica and robusta coffee varieties by NIRS. Anal Chim Acta 514(1):57–67

    Article  Google Scholar 

  11. Keidel A, von Stetten D, Rodrigues C, Maguas C, Hildebrandt P (2010) Discrimination of green arabica and robusta coffee beans by Raman Spectroscopy. J Agric Food Chem 58(21):11187–11192. doi:10.1021/Jf101999c

    Article  CAS  Google Scholar 

  12. Rubayiza AB, Meurens M (2005) Chemical discrimination of arabica and robusta coffees by Fourier transform Raman spectroscopy. J Agric Food Chem 53(12):4654–4659. doi:10.1021/Jf0478657

    Article  CAS  Google Scholar 

  13. Gardner JW, Bartlett PN (1992) Sensors and sensory systems for an electronic nose. Kluwer

  14. Pearce TC (1997) Computational parallels between the biological olfactory pathway and its analogue ‘The Electronic Nose’: part II. Sensor-based machine olfaction. Biosystems 41(2):69–90

    Article  CAS  Google Scholar 

  15. Minor CP, Brooke H, Johnson KJ Fusion of disparate spectra for chemical identification. Proc SPIE - Int Soc Opt Eng 8064:14. doi:10.1117/12.883926

  16. Two gas atmosphere sensor system (mass spectrometer), phases 2a and 2b, June 1966-March 1969 (1970). Report number NASA-CR-1546

  17. Dorfner R (2004) Ph D Online-Techniken zur Echtzeit-Analyse von flüchtigen Verbindungen in Kaffee-Röstgasen. Technischen Universität München, München

    Google Scholar 

  18. Wieland F, Gloess AN, Keller M, Wetzel A, Schenker S, Yeretzian C (2012) 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. Anal Bioanal Chem 402(8):2531–2543. doi:10.1007/s00216-011-5401-9

    Article  CAS  Google Scholar 

  19. Lindinger C, Labbe D, Pollien P, Rytz A, Juillerat MA, Yeretzian C, Blank I (2008) When machine tastes coffee: Instrumental approach to predict the sensory profile of espresso coffee. Anal Chem 80(5):1574–1581. doi:10.1021/ac702196z

    Article  CAS  Google Scholar 

  20. Lindinger C, Pollien P, Ali S, Yeretzian C, Blank I, Mark T (2005) Unambiguous identification of volatile organic compounds by proton-transfer reaction mass spectrometry coupled with GC/MS. Anal Chem 77(13):4117–4124. doi:10.1021/ac0501240

    Article  CAS  Google Scholar 

  21. Mateus M-L, Lindinger C, Gumy J-C, Liardon R (2007) Release kinetics of volatile organic compounds from roasted and ground coffee: online measurements by PTR-MS and mathematical modeling. J Agric Food Chem 55(25):10117–10128. doi:10.1021/jf071901v

    Article  CAS  Google Scholar 

  22. Pollien P, Jordan A, Lindinger W, Yeretzian C (2003) Liquid-air partitioning of volatile compounds in coffee: dynamic measurements using proton-transfer-reaction mass spectrometry. Int J Mass Spectrom 228(1):69–80. doi:10.1016/S1387-3806(03)00197-0

    Article  CAS  Google Scholar 

  23. Yeretzian C, Jordan A, Badoud R, Lindinger W (2002) From the green bean to the cup of coffee: investigating coffee roasting by on-line monitoring of volatiles. Eur Food Res Technol 214(2):92–104. doi:10.1007/s00217-001-0424-7

    Article  CAS  Google Scholar 

  24. Yeretzian C, Jordan A, Lindinger W (2003) Analysing the headspace of coffee by proton-transfer-reaction mass-spectrometry. Int J Mass Spectrom 223(1–3):115–139

    Google Scholar 

  25. Dorfner R, Ferge T, Kettrup A, Zimmermann R, Yeretzian C (2003) Real-time monitoring of 4-vinylguaiacol, guaiacol, and phenol during coffee roasting by resonant laser ionization time-of-flight mass spectrometry. J Agric Food Chem 51(19):5768–5773

    Article  CAS  Google Scholar 

  26. Dorfner R, Ferge T, Yeretzian C, Kettrup A, Zimmermann R (2004) Laser mass spectrometry as on-line sensor for industrial process analysis: process control of coffee roasting. Anal Chem 76(5):1386–1402

    Article  CAS  Google Scholar 

  27. Schramm E, Kürten A, Hölzer J, Mitschke S, Mühlberger F, Sklorz M, Wieser J, Ulrich A, Pütz M, Schulte-Ladbeck R, Schultze R, Curtius J, Borrmann S, Zimmermann R (2009) Trace detection of organic compounds in complex sample matrixes by single photon ionization ion trap mass spectrometry: real-time detection of security-relevant compounds and online analysis of the coffee-roasting process. Anal Chem 81(11):4456–4467. doi:10.1021/ac900289r

    Article  CAS  Google Scholar 

  28. Zimmermann R, Heger HJ, Yeretzian C, Nagel H, Boesl U (1996) Application of laser ionization mass spectrometry for on-line monitoring of volatiles the headspace of food products: roasting and brewing of coffee. Rapid Commun Mass Spectrom 10(15):1975–1979

    Article  Google Scholar 

  29. Maier HG (1981) Kaffee. Parey

  30. Müller C, Lang R, Hofmann T (2006) Quantitative precursor studies on di- and trihydroxybenzene formation during coffee roasting using “in bean” model experiments and stable isotope dilution analysis. J Agric Food Chem 54(26):10086–10091. doi:10.1021/Jf062727y

    Article  Google Scholar 

  31. Gregg R (1978) Coffee blend comprising ground-roasted and roasted-ground coffee beans. Patent number 4.081.569

  32. Hertz R, Streibel T, Liu C, McAdam KG, Zimmermann R (2012) Microprobe sampling—photo ionization-time-of-flight mass spectrometry for in situ chemical analysis of pyrolysis and combustion gases: examination of the thermo-chemical processes within a burning cigarette. Anal Chim Acta 714:104–113. doi:10.1016/j.aca.2011.11.059

    Article  CAS  Google Scholar 

  33. Hertz R, Zimmermann R (2010) Single coffee bean roast gas measurements with microprobe single photon ionization time-of-flight mass spectrometry. ASIC Proceedings 23th Colloquium

  34. Schenker S, Handschin S, Frey B, Perren R, Escher F (2000) Pore structure of coffee beans affected by roasting conditions. J Food Sci 65(3):452–457

    Article  CAS  Google Scholar 

  35. Sutherland PW, Hallett IC, MacRae E, Fischer M, Redgwell RJ (2004) Cytochemistry and immunolocalisation of polysaccharides and proteoglycans in the endosperm of green Arabica coffee beans. Protoplasma 223(2–4):203–211. doi:10.1007/s00709-004-0036-8

    CAS  Google Scholar 

  36. Mitschke S, Adam T, Streibel T, Baker RR, Zimmermann R (2005) Application of time-of-flight mass spectrometry with laser-based photoionization methods for time-resolved on-line analysis of mainstream cigarette smoke. Anal Chem 77(8):2288–2296

    Article  CAS  Google Scholar 

  37. Mühlberger F, Hafner K, Kaesdorf S, Ferge T, Zimmermann R (2004) Comprehensive on-line characterization of complex gas mixtures by quasi-simultaneous resonance-enhanced multiphoton ionization, vacuum-UV single-photon ionization, and electron impact ionization in a time-of-flight mass spectrometer: Setup and instrument characterization. Anal Chem 76(22):6753–6764

    Article  Google Scholar 

  38. Maker PD, Terhune RW (1965) Study of optical effects due to an induced polarization third order in electric field strength. Phys Rev 137(3A):A801

    Article  Google Scholar 

  39. Adam T, McAughey J, McGrath C, Mocker C, Zimmermann R (2009) Simultaneous on-line size and chemical analysis of gas phase and particulate phase of cigarette mainstream smoke. Anal Bioanal Chem 394(4):1193–1203

    Article  CAS  Google Scholar 

  40. Aeschbacher HU, Wolleb U, Löliger J, Spadone JC, Liardon R (1989) Contribution of coffee aroma constituents to the mutagenicity of coffee. Food Chem Toxicol 27(4):227–232

    Article  CAS  Google Scholar 

  41. Carisano A, Garibold L (1964) Gas chromatographic examination of fatty acids of coffee oil. J Sci Food Agr 15(9):619

    Article  Google Scholar 

  42. Kurzrock T, Speer K (2001) Diterpenes and diterpene esters in coffee. Food Rev Int 17(4):433–450. doi:10.1081/fri-100108532

    Article  CAS  Google Scholar 

  43. Lercker G, Frega N, Bocci F, Rodriguez-Estrada M (1995) High resolution gas chromatographic determination of diterpenic alcohols and sterols in coffee lipids. Chromatographia 41(1):29–33. doi:10.1007/bf02274191

    CAS  Google Scholar 

  44. Sanz C, Maeztu L, Zapelena MJ, Bello J, Cid C (2002) Profiles of volatile compounds and sensory analysis of three blends of coffee: influence of different proportions of Arabica and Robusta and influence of roasting coffee with sugar. J Sci Food Agr 82(8):840–847

    Article  CAS  Google Scholar 

  45. Alves RC, Costa ASG, Jerez M, Casal S, Sineiro J, Núnez MJ, Oliveira B (2010) Antiradical activity, phenolics profile, and hydroxymethylfurfural in espresso coffee: influence of technological factors. J Agric Food Chem 58(23):12221–12229. doi:10.1021/jf1031229

    Article  CAS  Google Scholar 

  46. Ky CL, Louarn J, Dussert S, Guyot B, Hamon S, Noirot M (2001) Caffeine, trigonelline, chlorogenic acids and sucrose diversity in wild Coffea arabica L. and C. canephora P. accessions. Food Chem 75(2):223–230

    Article  CAS  Google Scholar 

  47. Toci A, Farah A, Trugo LC (2006) Effect of decaffeination using dichloromethane on the chemical composition of arabica and robusta raw and roasted coffees. Quim Nova 29(5):965–971

    Article  CAS  Google Scholar 

  48. Leino M, Lapveteläinen A, Menchero P, Malm H, Kaitaranta J, Kallio H (1991) Characterisation of stored Arabica and Robusta coffees by headspace-GC and sensory analyses. Food Quality Pref 3(2):115–125

    Article  Google Scholar 

  49. Mondello L, Costa R, Tranchida PQ, Dugo P, Lo Presti M, Festa S, Fazio A, Dugo G (2005) Reliable characterization of coffee bean aroma profiles by automated headspace solid phase microextraction-gas chromatography–mass spectrometry with the support of a dual-filter mass spectra library. J Sep Sci 28(9-10):1101–1109. doi:10.1002/jssc.20050026

    Article  CAS  Google Scholar 

  50. Clarke RJ, Vitzthum OG (2001) Coffee: recent developments. Blackwell

  51. Parliment TH, Stahl HD, George C (1995) Formation of furfuryl mercaptan in coffee model systems. In: Developments in food science, Volume 37. Elsevier, pp 805–813

  52. Casal S, Alves MR, Mendes EL, Oliveira MBPP, Ferreira MA (2003) Discrimination between arabica and robusta coffee species on the basis of their amino acid enantiomers. J Agric Food Chem 51(22):6495–6501. doi:10.1021/jf034354w

    Article  CAS  Google Scholar 

  53. Wold S, Esbensen K, Geladi P (1987) Principal component analysis. Chemometr Intell Lab 2(1–3):37–52

    Article  CAS  Google Scholar 

  54. Kuhnert N, Jaiswal R, Eravuchira P, El-Abassy RM, Kammer BVD, Materny A (2011) Scope and limitations of principal component analysis of high resolution LC-TOF-MS data: the analysis of the chlorogenic acid fraction in green coffee beans as a case study. Anal Methods 3(1):144–155

    Article  CAS  Google Scholar 

  55. Maeztu L, Sanz C, Andueza S, Paz De Pena M, Bello J, Cid C (2001) Characterization of espresso coffee aroma by static headspace GC-MS and sensory flavor profile. J Agric Food Chem 49(11):5437–5444. doi:10.1021/jf0107959

    Article  CAS  Google Scholar 

  56. Rocha S, Maeztu L, Barros A, Cid C, Coimbra MA (2004) Screening and distinction of coffee brews based on headspace solid phase microextraction/gas chromatography/principal component analysis. J Sci Food Agr 84(1):43–51. doi:10.1002/jsfa.1607

    Article  CAS  Google Scholar 

  57. Akiyama M, Murakami K, Ikeda M, Iwatsuki K, Kokubo S, Wada A, Tokuno K, Onishi M, Iwabuci H, Tanaka K (2005) Characterization of flavor compounds released during grinding of roasted robusta coffee beans. Food Sci Technol Res 11(3):298–307

    Article  CAS  Google Scholar 

  58. Freitas AMC, Parreira C, Vilas-Boas L (2001) Comparison of two SPME fibers for differentiation of coffee by analysis of volatile compounds. Chromatographia 54(9–10):647–652

    Article  CAS  Google Scholar 

  59. Freitas CAM, Mosca AI (1999) Coffee geographic origin—an aid to coffee differentiation. Food Res Int 32(8):565–573

    Article  Google Scholar 

  60. Freitas CAM, Parreira C, Vilas-Boas L (2001) The use of an electronic aroma-sensing device to assess coffee differentiation–comparison with SPME Gas chromatography–mass spectrometry aroma patterns. J Food Compos Anal 14(5):513–522

    Article  CAS  Google Scholar 

  61. Korhonová M, Hron K, Klimcíková D, Müller L, Bednár P, Barták P (2009) Coffee aroma—statistical analysis of compositional data. Talanta 80(2):710–715

    Article  Google Scholar 

  62. Risticevic S, Carasek E, Pawliszyn J (2008) Headspace solid-phase microextraction–gas chromatographic–time-of-flight mass spectrometric methodology for geographical origin verification of coffee. Anal Chim Acta 617(1–2):72–84

    Article  CAS  Google Scholar 

Download references

Acknowledgements

The authors wish to thank the Electron Microscopy Centre of the University of Rostock (EMZUniRo) for recording the electron microscopy pictures. Furthermore, the authors thank Dr. Gerhard Bytof of Tchibo GmbH, Hamburg, Germany, for his contribution to the interpretation of the REM images and S. Wohlfahrt for the preliminary SPI-HR-TOFMS data of coffee roasting gas. Additionally the authors thank Dr. Jürgen Maguhn of the Joint Mass Spectrometry Centre, Cooperation Group “Comprehensive Molecular Analytics”, Helmholtz Zentrum München—German Research Center for Environmental Health for proofreading the manuscript in orthography and grammar.

Author information

Authors and Affiliations

  1. Joint Mass Spectrometry Centre, Chair of Anal Chem, Institute of Chemistry, University of Rostock, 18059, Rostock, Germany

    Romy Hertz-Schünemann, Thorsten Streibel, Sven Ehlert & Ralf Zimmermann

  2. Joint Mass Spectrometry Centre, Cooperation Group “Comprehensive Molecular Analytics”, Helmholtz Zentrum München German Research Center for Environmental Health, 85764, Neuherberg, Germany

    Thorsten Streibel & Ralf Zimmermann

Authors
  1. Romy Hertz-Schünemann
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Thorsten Streibel
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Sven Ehlert
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Ralf Zimmermann
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Ralf Zimmermann.

Additional information

Published in the topical collection Photo Ionisation in Mass Spectrometry with guest editor Ralf Zimmermann.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Hertz-Schünemann, R., Streibel, T., Ehlert, S. et al. Looking into individual coffee beans during the roasting process: direct micro-probe sampling on-line photo-ionisation mass spectrometric analysis of coffee roasting gases. Anal Bioanal Chem 405, 7083–7096 (2013). https://doi.org/10.1007/s00216-013-7006-y

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00216-013-7006-y

Keywords

  • Coffee bean
  • Roasting
  • Micro-probe sampling
  • Single-photon ionisation mass spectrometry