Objective Evaluation of Aroma of Coffee Brew (Studies on Aroma of Coffee Part V)

Abstract

The quantitative headspace gas chromatographic (GC) analysis on a coffee brew was developed as follows. Ten grams of coffee grounds were put into a 300ml headspace vessel, on to which 100 ml of boiling water was poured. Five μl of p-anisaldehyde was added as an internal standard. Both the extraction of coffee grounds and the trapping of headspace gas were carried out water bath maintained at 75°C. The headspace voltatiles of coffee brew were trapped into Tenax-GC column (φ3.5×90mm) during the passage (50ml/min) of 400ml of nitrogen. (1) The aromagram was composed of 43 peaks regardless of the kinds of coffee beans. The reproducibilities of main components ranged from 3.6 to 9.6%. (2) The aroma potencies of coffee volatiles were evaluated by dividing peak areas on a standard aromagram by the threshold peak areas estimated by "sniff-GLC", as well as the sensory characterizations of the volatiles were performed by "sniff-GLC" of coffee cup tester. (3) The GLC data could make clear the differences between Arabica and Robusta species but could not among Arabica species. The aroma potencies and characteristics of the volatiles were more important to evaluate the aroma of coffee brew.