Czech, H.* ; Schepler, C.* ; Klingbeil, S.* ; Ehlert, S.* ; Howell, J.* ; Zimmermann, R.
     
    
        
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.
    
    
        
    
    
        
        J. Agric. Food Chem. 64, 5223-5231 (2016)
    
    
    
      
      
	
	    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.
	
	
	    
	
       
      
	
	    
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        Publication type
        Article: Journal article
    
 
    
        Document type
        Scientific Article
    
 
    
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        Keywords
        Beverage ; Process Control ; Resonance-enhanced Multi-photon Ionization (rempi) ; Roasting Phase ; Single-photon Ionization (spi); Single-photon Ionization; Nonnegative Matrix Factorization; Flavor Formation; Online Analysis; Ms; Degradation; Cigarette; Headspace; Products; Monitor
    
 
    
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        Language
        english
    
 
    
        Publication Year
        2016
    
 
    
        Prepublished in Year
        
    
 
    
        HGF-reported in Year
        2016
    
 
    
    
        ISSN (print) / ISBN
        0021-8561
    
 
    
        e-ISSN
        1520-5118
    
 
    
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	    Volume: 64,  
	    Issue: 25,  
	    Pages: 5223-5231 
	    Article Number: ,  
	    Supplement: ,  
	
    
 
    
        
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            Publisher
            American Chemical Society (ACS)
        
 
        
            Publishing Place
            Washington
        
 
	
        
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        Reviewing status
        Peer reviewed
    
 
     
    
        POF-Topic(s)
        30202 - Environmental Health
    
 
    
        Research field(s)
        Environmental Sciences
    
 
    
        PSP Element(s)
        G-504500-001
    
 
    
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        Erfassungsdatum
        2016-07-05