Phenolic characterization, melanoidins, and antioxidant activity of some commercial coffees from Coffea arabica and Coffea canephora

Coffee phenols were identified, quantified and correlated with antioxidant activity determined by the ABTS•⁺ (2, 2'-azinobis(3-ethylbenzothiazoline-6-sulphonic acid)) and DPPH• (2, 2-diphenyl -1-picrylhydrazyl radical) assays. Melanoidins (Maillard reaction products) were determined for green and processed coffee. For green Arabica beans and its products, results suggest that roasting decreases antioxidant activity. However, torrefacto roasted coffee showed greater antioxidant activity than Caracoli beans. Instant coffee showed greater antioxidant activity than green Robusta beans by both assays. A high correlation was found between antioxidant activity and melanoidins, total phenols, caffeic acid, and caffeine.