Determination of Caffeine, Chlorogenic Acid, Total Phenolic Contents, and Antioxidant Capacities for Arabica and Robusta Coffee from Vietnam

In Vietnam, the cultivation and production of coffee have been expanding over the past few decades and are known as an important part of the national economy. However, the scientific data regarding the internal compositions of coffee have still been limited, especially the changes during the processing, typically the roasting period. The present study aimed to demonstrate an insight into the variations in chlorogenic acid, caffeine, total phenolic contents (TPCs), and trolox equivalent antioxidant capacities for two common coffee species, that is, Robusta and Arabica, and three roasting levels, that is, light, medium, and dark. Generally, Robusta coffee performed higher chlorogenic acid, caffeine, and TPCs, resulting in dominant antioxidant capacities compared to Arabica. High Pearson correlation coefficients (calculated by SPSS) were found for most pairs of parameters, r > 0.80. Regarding roasting levels, a descending order was highlighted for most analytical parameters: light > medium > dark. Two parallel processes in the roasting period were revealed by observing the antioxidant capacities, that is, thermal degradation and formation of other antioxidants by the Maillard reaction. Principal component analysis (SIMCA-P 11) was attempted to discriminate the available coffee samples by their species and roasting levels, indicating proper classification (the cumulative variance is 95.3%).