Analysis of hydroxycinnamic acids of coffee: A comparison of high performance liquid chromatography and capillary zone electrophoresis

The purpose of this work was to evaluate the heat degradation of hydroxycinnamic acids (HCAs) present in coffee by CZE and HPLC. The HCAs were obtained by alkaline hydrolysis of a coffee sample Coffea canephora var. robusta, heated at programmed temperatures and constant time, previously fixed with the limits of industrial roasting. The thermal degradation rate of each acid could apparently be explained by its specific sensitivity, which is correlated with its chemical structure. 3,4,5-Trimethoxycinnamic acid was the most resistant and caffeic acid the most sensitive of all analyzed HCAs. This study suggests that CZE, while lacking the versatility of HPLC, may be regarded as a complementary analytical technique for the evaluation of heat degradation of these compounds.