Identification of Volatiles in Green Coffea Arabica and Determination of Changes Caused by the Roasting Process

Abstract

This study was aimed to understand and analyze the variability of volatile compounds in green and roasted coffee. We observed the influence and change in the profile of volatiles in samples roasted on medium roasting level, originating from different growing areas. We analyzed 9 samples, which we differentiated into three groups: Africa (Burundi, Uganda, Rwanda), Central America (Guatemala, Costa Rica, Honduras), South America (Colombia, Brazil, Bolivia). Volatiles were analyzed using GC-MS. Approximately 350 volatile compounds have been identified in green coffee. The main compounds identified in coffee samples included furan derivatives, aldehydes, alcohols, organic acids and their esters, hydrocarbons (alkanes, alkenes, alkynes, and aromatic hydrocarbons), terpenoids, heterocyclic compounds, ketones, amines, alkynes, and nitriles. Content of volatiles was expressed as concentration (%). The results show that the roasting process significantly affects the presence and concentration of volatiles, given the formation of new volatile compounds and degradation of several occurred. In our research, aldehydes, alcohols, organic acids and esters, alkanes, terpenoids, alkenes, nitriles, aromatic hydrocarbons decreased due to the roasting process. Nevertheless, only in Central America samples, aromatic hydrocarbons increase due to roasting. Furan derivates, heterocyclic compounds, ketones, amine, alkynes increased due to the roasting process. However, only in South America samples, alkynes decreased due to roasting. However, alkynes in Central America samples remained unchanged due to the roasting.