High-Resolution UHPLC-MS/MS Distinguishes Coffee Acidity and Polyphenols by Roasting Method and Bean Origin

Abstract Coffee is one of the most popular beverages, with ∼400 billion cups consumed annually worldwide. Thus, understanding its chemical composition is important for both sustainability and health. The primary components of coffee are melanoidins, polymers composed of sugars, proteins, phenolic acids, and alkaloids. Little is known about the precise composition of melanoidins. Coffees of various roast levels (light (L), medium (M), and dark (D)) and origins (multi-origin from the U.S. market (U) and Colombian (C)) were compared by high-resolution UHPLC-MS/MS, automatic titration, and spectrophotometric methods to determine their melanoidin concentration and total polyphenol content (TPC). Coffee melanoidin content correlated positively with pH but negatively with titratable acidity and TPC. UHPLC-MS/MS revealed that all coffee samples were chemically distinct. In the most distinct samples (CM1/CM2 and UD1), ∼60% of the total compounds detected differed in concentration (P < 0.05). In contrast, between the most similar samples (UM1 and UD1), ∼1% of the total compounds detected differed in concentration (P < 0.05). Collectively, multi-origin medium and dark roast coffee samples from the U.S. market (UM1 and UD1) were distinct from Colombian samples. For example, quinic acid and catechol were more abundant in multi-origin medium and dark roast samples, whereas chlorogenic acid and other organic acids were more abundant in Colombian samples. Principal component analysis (PC1 and PC2) accounted for 65.8% of the variability among the coffee samples. Understanding the molecular basis of coffee variability will facilitate future research on the health benefits and sustainability of coffee consumption.