Identification of metabolites associated with antioxidant activity in Robusta moka pot brew at different roasting degrees

Résumé

This study aims to identify compounds associated with the antioxidant activity of Robusta moka pot coffee brewed at different roasting degrees using LC-HRMS and partial least squares regression (PLS-R) analysis. Robusta Basseang coffee was used as the raw material and roasted at three degrees (light, medium, and dark), followed by brewing using a moka pot. The brewed samples were analysed to determine the content of bioactive compounds (trigonelline, caffeine, chlorogenic acid, total phenolic content), untargeted profile compounds, and antioxidant activity (FRAP and DPPH assays). The results indicated that light-roasted coffee brew had the highest concentration of bioactive compounds and antioxidant activity. LC-HRMS analysis revealed metabolite profiles across roasting degrees, with several compounds detected exclusively at specific roasting degrees. The metabolites associated with antioxidant activity differed between the FRAP and DPPH assays. Chlorogenic acid, and 4-O-Feruloylshikimic acid were associated exclusively with DPPH assay, whereas 5-O-Feruloylshikimic acid, ferulic acid, caffeic acid, D-(−)-Quinic acid, and nicotinic acid associated exclusively with FRAP assay. This study provides insights into the interaction among roasting degree, metabolite composition, and antioxidant activity, and highlights the potential of metabolite profiling for coffee quality evaluation and roasting degree differentiation.