Brewing-Method-Dependent Changes in the Bioactive Compound Profile and Antioxidant Potential of Coffee Beverages

Coffee is an important dietary source of bioactive antioxidant compounds contributing to the antioxidant properties of coffee beverages. While brewing affects yield of total antioxidants, it is still not really clear which individual (phenolic) compounds contribute to the antioxidant activity the most. A method combining chromatographic separation and individual antioxidant evaluation might therefore be useful. This study aimed at evaluating the antioxidant potential of the compounds in coffee beverages using a high-performance liquid chromatography approach directly coupled to the well-known trolox equivalent antioxidative capacity (TEAC) assay (HPLC-onlineTEAC). The study further evaluated the influence of different brewing methods ('Americano', 'V60', 'French press', and 'cold brew') on the bioactive compound profile and antioxidant potential of Arabica coffee beverages. The brewing method significantly affected caffeine content, chlorogenic acid composition, total phenolic content (TPC), and antioxidant activity of the analyzed beverages (p < 0.05). Cold brew samples exhibited the highest total radical scavenging activity and concentrations of major caffeoylquinic acid isomers (3-CQA, 4-CQA, and 5-CQA). In contrast, "French-pressed" beverages were characterized by the highest TPC values, while V60 samples generally showed the lowest antioxidant-related parameters. Chlorogenic acids accounted for more than 84% of the total antioxidant potential of all analyzed beverages, whereas monocaffeoylquinic acids represented the dominant fraction responsible for radical-scavenging activity. The results indicate that prolonged low-temperature extraction favors the recovery and preservation of highly reactive chlorogenic acid isomers and contributes to the enhanced antioxidant potential of coffee beverages, beyond the effect of coffee dose alone.