A Comparative Study of the Volatile Constituents of Southeast AsianCoffea arabica,Coffea libericaandCoffea robustaGreen Beans and their Antioxidant Activities

A comparative study on the volatile constituents of green beans of three commercially grown coffees in Southeast Asia, namely Coffea arabica, Coffea robusta and Coffea liberica, and their antioxidant properties was carried out. Volatile constituents of the green beans were isolated by hydrodistillation followed by extraction of the distillates with dichloromethane. These compounds were analysed using capillary gas chromatography and gas chromatography-mass spectrometry. The volatile compositions of the green beans of these three species were remarkably similar, being characterized by high levels of phenolic compounds, principally p-vinylguaiacol, and carboxylic acids. The volatile extracts were examined for antioxidant activity using total phenols, DPPH radical scavenging and FRAP assays which showed that the volatile extract from C. liberica possessed the highest antioxidant capacity, followed by those of C. arabica and C. robusta, respectively.