Profiling of coffee roasting: Integrating routine chromatography and UV/vis colorimetry to monitor key bioactives and achieve chemometric classification

Monitoring thermal degradation of key bioactives during coffee roasting is essential for quality control. While sophisticated analytical platforms offer comprehensive profiling, they are often cost-prohibitive for routine application. This study proposed an integrated approach exploiting liquid chromatography (for caffeine and chlorogenic acid), UV/vis spectrophotometry (for total phenolic contents and in vitro antioxidant capacities via various mechanisms), and multivariate analysis to monitor bioactive dynamics and achieve sample discrimination for Coffea arabica (Arabica) and Coffea canephora (Robusta) coffee under different roasting conditions (180–220 °C, 30–90 min). The results revealed that extreme thermal stress (220 °C) severely depleted moisture (∼0%), and there was an overall inverse correlation between titratable acidity and pH. While Robusta exhibited superior baseline bioactivity, both varieties underwent drastic bio-depletion during prolonged high-temperature roasting. Chlorogenic acid thermolysis followed first-order kinetics, with activation energy values of E a = 98 and 58 kJ/mol for Arabica and Robusta, respectively. In contrast, caffeine exhibited profound thermostability (1.1–2.2% w/w across all roasting conditions), serving as a reliable genetic marker. Furthermore, applying multivariate analysis successfully discriminated coffee samples by roasting temperatures and botanical origins. Ultimately, the proposed integrated platform opens an opportunity to reduce the analytical workload and dependence on high-end instrumentation for coffee quality monitoring.