Methoxy coffee aroma

The SPME technique has been developed by Arthur and Pawliszyn [8] and now is well known as a simple, rapid, and sensitive sampling method for liquid or gaseous volatile samples. However, the analytes adsorbed on the SPME fiber generally depend on their polarities and the SPME fiber affinity. Because coffee aroma consists of compounds having many kinds of functional groups, proper selection of the type of fiber to use is important to obtaining accurate and reproducible results [15]. In 2000, in a comparison of three fibers (PDMS, PDMS/DVB, and Carboxen/PDMS) for brewed coffee headspace volatile compounds, it was reported that PDMS/DVB gave the overall best sensitivity, especially for phenols such as 2-methoxyphenol, 4-ethyl-2-methoxyphenol, 4-ethenyl-2-methoxy-phenol, and polar compounds such as 4-hydroxy-2,5-dimethyl-3(2//)-... 

The volatile fraction of roasted coffee has a very complex composition. Dilution analyses (cf. 5.2.2) have shown that of the 850 volatile cortqtounds identified until now, only the 40 listed in Table 21.7 contribute to the aroma. Indeed, 28 aroma substances in the concentrations present in a medium roasted Arabica coffee drink (Table 21.8) can largely approximate its aroma. The correspondence becomes even better by the addition of 4-methoxy-2-methylbutan-2-thiol (cf.5.3.2.5), which has a concentration of 0.022 pg/kg in the drink. 

---