Role of Roasting Conditions in the Profile of Volatile Flavor Chemicals Formed from Coffee Beans

The volatile chemicals in dichloromethane extracts from green coffee beans, roasted at 230 degrees C for 12 min (light), at 240 degrees C for 14 min (medium), at 250 degrees C for 17 min (city), or at 250 degrees C for 21 min (French), were analyzed by gas chromatography and gas chromatography-mass spectrometry. Among the 52 volatile compounds identified, the major compounds were 5-hydroxymethylfurfural, furfuryl alcohol, and 6-methyl-3,5-dihydroxy-4H-pyran-4-one in light-roasted beans; furfuryl alcohol, 5-hydroxymethylfurfural, and gamma-butyrolactone in medium-roasted beans; furfuryl alcohol, gamma-butyrolactone, and 2-acetylpyrrole in city-raosted beans; and gamma-butyrolactone, furfuryl alcohol, and catechol in French-roasted beans. Furfural derivatives and furanones were yielded in relatively high concentrations under mild roasting conditions and then reduced at higher roasting intensities. More pyridines and pyrroles were formed by high roasting intensities than by mild roasting intensities. Chlorogenic acid degradation products, phenols, and a lactone were produced more by high roasting intensities than by low roasting intensities. The results of the present study suggest that controlling the roasting conditions according to the formation of particular chemicals can prepare a roasted coffee with preferable flavor.