Coffee brew characterization

Structure Characterization of the Free Radical in Coffee Brew... 

Identified and characterized (MS, IR data) in roasted coffee flavor by Goldman et al. (1967) and in green coffee bean volatiles by Vitzthum et al. (1976). The concentration measured by Silwar et al. (1987) was 13.5-16.5ppm in roasted arabica. In the headspace of a brew, it represented 0.13% (GC) for Shimoda and Shibamoto (1990a). Ramos et al. (1998) extracted it from a brew as for O.2. 

Identified in roasted coffee by Sullivan et al. (1959), Heins et al. (1966), and Stoffelsma et al. (1968). Merritt et al. (1970) characterized it in roasted but not in green coffee. It is present in the headspace of roasted coffee (Cros et al., 1980 Wang et al., 1983 ), in the headspace of a brew (Shimoda and Shibamoto, 1990a) where it represents 0.67% (GC). Silwar et al. (1986) found concentrations of 0.01 ppm in arabicas and 0.10-0.12 in robustas after simultaneous distillation/extraction, capillary GC using simultaneously flame ionization or flame photometric (for sulfur-selective analysis) detectors (FID/ FPD). With a similar detection method in the GC analysis of the headspace compounds, Guyot and Vincent (1990) found 0.04-0.05 ppm in a roasted healthy arabica and 0.3-0.4 in the stinking quality (see Q.4). Procida et al. (1997) identified dimethyl disulfide in a roasted arabica but in none of the green coffees examined, contrary to their result for dimethyl sulfide (Q.ll). 

In terms of key aroma components, Czerny et al. [59] conducted sensory studies using volatiles identified in previous studies as potential contributors to coffee aroma [60] to determine the odorants truly characterizing freshly brewed Colombian coffee. They found 2-furfurylthiol, 4-vinylguaiacol, several alkyl pyrazines, furanones, acetaldehyde, propanal, methylpropanal, and 2- and 3-methylbutanal had the greatest impact on the coffee flavor. 

The GC- SNIF method has also allowed the elucidation of the process-induced modifications of the coffee aroma by comparing impact odorants of an instant coffee with the corresponding brew (29). It was applied as weU to the characterization of three Champagne wines (17), and to determine which were the impact odorants protected by the addition of an antioxidant in the wine (34). 

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