Impact of roasting conditions on the formation of aroma compounds in coffee beans

Hot air roasting of coffee beans results in a large number of aroma compounds. For a given coffee, the aroma profile is determined by the specific conditions for chemical reactions as controlled by the process parameters. Therefore, the influence of roasting temperatures on the formation of key aroma compounds was investigated. Coffee was roasted in 6 different processes to equal degrees of roast and the developing aroma compound profiles were characterized by gas chromatography, mass spectrometry, and olfactometry. A majority of aroma compounds showed the highest increase in concentration at medium stage of dehydration with bean water content from 7 to 2% (wb). Different time-temperature histories led to distinct aroma compound profiles. To reach a specific flavor profile, precise control of roasting time and temperature is required.