Wild Harenna coffee: flavour profiling from the bean to the cup

As one of the last places where coffee grows spontaneously, the Harenna forest (Ethiopia) is the origin of the coffee analysed in this study. The analysis of the volatile emission of each processing phase evaluates the chemical fingerprint of the reactions taking place at each stage, leading to the final aroma. The green beans mainly emit non-terpene esters and alkanes. Once the roasting begins, monoterpenes are the main class until 160 °C: at this point, 2,6-dimethylpyrazine prevails in the headspaces, as main product of the Maillard reactions. This compound, with its sweet and nut-like aroma, is also detected in the brewed coffee. The shed silverskins are rich in methyl chavicol and retain the monoterpenes on the beans: as these compounds are important aroma contributors, the removal of the silverskins prior to roasting seems non-advisable. The grinding of the samples breaks the matrices and leads to drastic changes in the volatile emissions.