抄録
We developed a mid-infrared (MIR) spectroscopic evaluation method of brewed coffee, whose quality and taste highly depend on the properties such as the geographical origin and the roasting, grinding, blending and extraction conditions, using an FT-IR spectrometer equipped with an attenuated total reflectance (ATR) accessory. The objective and stable method to evaluate the brewed coffee characteristics is desirable, since the determination of coffee process conditions and the grasp of the characteristics of coffee varieties are very empirical in coffee manufacturing. Then we studied the influences of the coffee varieties and the roasting degree on the MIR spectral characteristics of brewed coffee and examined to determine the caffeine and chlorogenic acid contents in brewed coffee using the FT-IR/ATR method. Arabica (Colombia, Brazil and Guatemala) and Robusta (Indonesia) coffees roasted to City were prepared as the sample. Indonesian coffees roasted to Full City were also used. All roasted beans were ground to a standard cupping grind and brewed by adding hot water. As the results, the differences between the second derivatives of the ATR spectra of the brewed Arabica and Robusta coffees were observed around the several peaks. In addition, the brewed coffee from the Brazil variety had the different spectral features from those of the other Arabica coffees. Moreover, the roasting conditions of the Indonesian beans reflected the spectral features of the brewed coffee. Furthermore, the caffeine and chlorogenic acid contents in brewed coffee would be determined by the spectroscopic method as well as those in the aqueous solutions.
