Effect of Time Temperature History on Coffee Aroma during Roasting with Heat Conduction

The objective of this research is to determine the effect of time temperature history on coffee aroma. Four levels of temperature (160, 180, 200, and 220oC) were used for roasting temperature with heat conduction. The dried mature of coffee beans (12% MC w.b.) was used as samples. About 100 gram of Robusta coffee was subjected on each pan temperatures during 12 minutes. The surface of pan temperature was automatically controlled and the coffee was stirred manually during roasting. During roasting aroma observation was conducted with an own made electronic nose using four gas sensors (TG S880, TGS 826, TGS 825, and TGS 822). Air delivery time is 90 seconds and it is repeated five times. Temperature was measured every 2 minutes with thermo logger. The weight loss and moisture content were determined every 2 minutes. Coffee aroma was measured by two method