On-Line Process Control of the Roast Degree of Coffee

Wieland, Flurin; Gloess, Alexia N.; Keller, Marco; Wetzel, Andreas; Schenker, Stefan; Yeretzian, Chahan

doi:10.2533/chimia.2012.443

Cited by 8 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This study ties in with previous studies of Wieland et al, Ruosi et al, and Liberto et al about roast degree control. 9,16,17 A new concept for the identification of roasting phases for different roasting conditions together with an analysis technique for online determination of roasting phase transitions is presented. Photoionization mass spectra at four wavelengths to cover different analyte selectivity were processed in nonnegative matrix factorization (NMF) to figure out the temporal evolution of four roasting phases in score data and their associated m/z located in the factor loadings.…”

Section: ■ Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Resolving Coffee Roasting-Degree Phases Based on the Analysis of Volatile Compounds in the Roasting Off-Gas by Photoionization Time-of-Flight Mass Spectrometry (PI-TOFMS) and Statistical Data Analysis: Toward a PI-TOFMS Roasting Model

Czech

Schepler

Klingbeil

et al. 2016

J. Agric. Food Chem.

View full text Add to dashboard Cite

Coffee beans of two cultivars, Arabica (Mexico) and Robusta (Vietnam), were roasted in a small-scale drum roaster at different temperature profiles. Evolving volatile compounds out of the roasting off-gas were analyzed by photoionization mass spectrometry at four different wavelengths, either with single-photon ionization (SPI) or resonance-enhanced multiphoton ionization (REMPI). The different analyte selectivities at the four wavelengths and their relevance for the examination of the roasting process were discussed. Furthermore, intensities of observed m/z were grouped by non-negative matrix factorization (NMF) to reveal the temporal evolutions of four roasting phases ("evaporation", "early roast", "late roast", and "overroast") from NMF scores and the corresponding molecular composition from the NMF factor loadings, giving chemically sound results concerning the roasting phases. Finally, linear classifiers were constructed from real mass spectra at maximum NMF scores by linear discriminant analysis to obtain quantities which are simple to measure for real-time analysis of the roasting process.

show abstract

Section: ■ Introductionmentioning

confidence: 99%

“…Wieland et al and Gloess et al 8,9 Qualitative Detection of Volatile Species in Roasting Off-Gas at Different Wavelengths. The assignments of the m/z values are based on previous studies with photoionization 4,10−12 (and references therein) and only described briefly at this point.…”

mentioning

confidence: 99%

Resolving Coffee Roasting-Degree Phases Based on the Analysis of Volatile Compounds in the Roasting Off-Gas by Photoionization Time-of-Flight Mass Spectrometry (PI-TOFMS) and Statistical Data Analysis: Toward a PI-TOFMS Roasting Model

Czech

Schepler

Klingbeil

et al. 2016

J. Agric. Food Chem.

View full text Add to dashboard Cite

show abstract

“…Ye t, a green coffee bean has neither the typical coffee flavor, nor can it be readily ground and extracted. It is only once roasted that the precursors in the green bean react and generate the volatile [1][2][3][4][5][6][7][8] and non-volatile compounds that together form the typical flavor of coffee. [9][10][11][12][13][14][15][16][17] At the same time, the texture of the bean becomes brittle and can easily be ground and efficiently extracted.…”

Section: Introductionmentioning

confidence: 99%

Freshness Indices of Roasted Coffee: Monitoring the Loss of Freshness for Single Serve Capsules and Roasted Whole Beans in Different Packaging

Glöss

Schönbächler

Rast³

et al. 2014

Chimia

Self Cite

View full text Add to dashboard Cite

With the growing demand for high-quality coffee, it is becoming increasingly important to establish quantitative measures of the freshness of coffee, or the loss thereof, over time. Indeed, freshness has become a critical quality criterion in the specialty coffee scene, where the aim is to deliver the most pleasant flavor in the cup, from highest quality beans. A series of intensity ratios of selected volatile organic compounds (VOC) in the headspace of coffee (by gas chromatography-mass spectrometry) were revisited, with the aim to establish robust indicators of freshness of coffee - called freshness indices. Roasted whole beans in four different packaging materials and four commercial capsule systems from the Swiss market were investigated over a period of up to one year of storage time. These measurements revealed three types of insight. First, a clear link between barrier properties of the packaging material and the evolution of selected freshness indices was observed. Packaging materials that contain an aluminum layer offer better protection. Second, processing steps prior to packaging are reflected in the absolute values of freshness indices. Third, differences in the standard deviations of freshness-indices for single serve coffee capsule systems are indicative of differences in the consistency among systems, consistency being an important quality attribute of capsules.

show abstract

“…The ability to separate compounds by gas chromatography (GC), to identify them by comparison with mass spectral reference libraries and to quantify them using standard compounds makes GC/MS an indispensable technique for flavor scientists. Coupled with olfactory techniques such as GC-olfactometry (GC/O), these approaches allow sensory relevant compounds to be elucidated, and their relative contributions to the flavor of the food product to be estimated. , While GC/MS is highly suitable for identifying and quantifying flavor-active compounds, it performs less well when it comes to monitoring the temporal evolution of fast dynamic processes and needs to be complemented with other analytical techniques when processes such as flavor generation − or in vivo release − need to be monitored. This has led to the introduction of new analytical technologies capable of monitoring volatiles in real-time, including electronic sensors, and direct injection mass spectrometry .…”

mentioning

confidence: 99%

“…Roasting generates around 1000 VOCs, although less than 50 might be relevant to the aroma of roasted coffee . Roasting is the most important step for the formation of the coffee aroma, and hence it is also one of the most thoroughly studied processing steps. − However, equally important to the final flavor profile in the cup is the extraction of ground coffee with water. The extraction technique and conditions used for coffee preparation strongly influence the flavor profile in the cup and is often the only parameter that can be influenced by the consumer at home.…”

mentioning

confidence: 99%

Insight into the Time-Resolved Extraction of Aroma Compounds during Espresso Coffee Preparation: Online Monitoring by PTR-ToF-MS

2014

Self Cite

View full text Add to dashboard Cite

Using proton-transfer-reaction time-of-flight mass-spectrometry (PTR-ToF-MS), we investigated the extraction dynamic of 95 ion traces in real time (time resolution = 1 s) during espresso coffee preparation. Fifty-two of these ions were tentatively identified. This was achieved by online sampling of the volatile organic compounds (VOCs) in close vicinity to the coffee flow, at the exit of the extraction hose of the espresso machine (single serve capsules). Ten replicates of six different single serve coffee types were extracted to a final weight between 20-120 g, according to the recommended cup size of the respective coffee capsule (Ristretto, Espresso, and Lungo), and analyzed. The results revealed considerable differences in the extraction kinetics between compounds, which led to a fast evolution of the volatile profiles in the extract flow and consequently to an evolution of the final aroma balance in the cup. Besides exploring the time-resolved extraction dynamics of VOCs, the dynamic data also allowed the coffees types (capsules) to be distinguished from one another. Both hierarchical cluster analysis (HCA) and principal component analysis (PCA) showed full separation between the coffees types. The methodology developed provides a fast and simple means of studying the extraction dynamics of VOCs and differentiating between different coffee types.

show abstract

On-Line Process Control of the Roast Degree of Coffee

Cited by 8 publications

References 0 publications

Resolving Coffee Roasting-Degree Phases Based on the Analysis of Volatile Compounds in the Roasting Off-Gas by Photoionization Time-of-Flight Mass Spectrometry (PI-TOFMS) and Statistical Data Analysis: Toward a PI-TOFMS Roasting Model

Resolving Coffee Roasting-Degree Phases Based on the Analysis of Volatile Compounds in the Roasting Off-Gas by Photoionization Time-of-Flight Mass Spectrometry (PI-TOFMS) and Statistical Data Analysis: Toward a PI-TOFMS Roasting Model

Freshness Indices of Roasted Coffee: Monitoring the Loss of Freshness for Single Serve Capsules and Roasted Whole Beans in Different Packaging

Insight into the Time-Resolved Extraction of Aroma Compounds during Espresso Coffee Preparation: Online Monitoring by PTR-ToF-MS

Contact Info

Product

Resources

About