Exploratory and discriminative studies of commercial processed Brazilian coffees with different degrees of roasting and decaffeinated

Abstract

The fingerprints of the volatile compounds of 21 commercial Brazilian coffee samples submitted to different industrial processing i.e. decaffeinated or different roasting degrees (traditional and dark) were studied. The volatiles were collected by headspace solid phase microextraction (HS-SPME) and analyzed by GC-FID and GC-MS. The chromatographic data matrices (fingerprints) obtained were explored by the principal component analysis (PCA) and partial least squares - discriminative analysis (PLS-DA). Initially the chromatographic profiles were aligned by the algorithm correlation optimized warping (COW). The PCA showed the discrimination of the decaffeinated coffees from the others with both the SPME fibres used. This separation probably occurred due to the loss of some volatile precursors during the decaffeination process, such as sucrose. For both the fibres tested, PDMS/DVB and CX / PDMS SPME, the PLS-DA models correctly classified 100% of the samples according to their roasting degree: (medium and dark), the main differences being the concentrations of some of the volatile compounds such as 2-methyl furan, 2-methylbutanal, 2,3-pentanedione, pyrazine, 2-carboxyaldehyde pyrrole, furfural and 2-furanmethanol.

Variability of single bean coffee volatile compounds of Arabica and robusta roasted coffees analysed by SPME-GC-MS

“…Some coffee volatile compounds were previously correlated to the roasting degree, e.g. 2,3-pentanedione, 2,5-dimethylpyrazine, 2-ethylpyrazine, 2,3-dimethylpyrazine, 3-ethyl-2,5-dimethylpyrazine, guaicol, 2-methylbutanal, 2-ethylguaicol, and 4-vinylguaiacol ( Franca et al, 2009 ; Moon & Shibamoto, 2009 ; Ribeiro, Teófilo, Salva, Augusto, & Ferreira, 2013 ; Toci & Farah, 2014 ). The concentration of total furans and generally compounds originating from chlorogenic acid degradation such as phenols and lactones is therefore expected to be higher at a more intense roasting ( Moon & Shibamoto, 2009 ).…”

Relationship Between the Different Aspects Related to Coffee Quality and Their Volatile Compounds

“…The influence of roasting on the volatile compounds and on the final quality of the coffee has been investigated in various studies (Nascimento and others ; Morais and others ; Moon and Shibamoto ; Franca and others ; Somporn and others ; Ribeiro and others ; Toci and others ). Various classes of compounds have been correlated to different degrees of roast, notably the impact compounds 2,3‐pentanedione, 2,5‐dimethylpyrazine, 2‐ethylpyrazine, 2,3‐dimethylpyrazine, 3‐ethyl‐2,5‐dimethylpyrazine, 2‐methylbutanal, 2‐ethylguaiacol, and 4‐vinylguaiacol (Table ).…”

Reliable discriminant analysis tool for controlling the roast degree of coffee samples through chemical markers approach

“…The influence of roasting on the volatiles composition and on the final quality of the coffee has been investigated and reported in various works [9,15,16,18,20,23,25]. Accordingly, several classes of compounds have been associated with different roasting degrees, being examples of it the 2,3-pentanedione, 2,5-dimethylpyrazine, 2-ethylpyrazine, 2,3-dimethylpyrazine, 3-ethyl-2,5-dimethylpyrazine, 2-methylbutanal, 2-ethylguaiacol, and 4-vinylguaiacol.…”