Determination of Acrylamide during Roasting of Coffee

In this study different Arabica and Robusta coffee beans from different regions of the world were analyzed for acrylamide after roasting in a laboratory roaster. Due to the complex matrix and the comparably low selectivity of the LC-MS at m/z 72, acrylamide was analyzed after derivatization with 2-mercaptobenzoic acid at m/z 226. Additionally, the potential precursors of acrylamide (3-aminopropionamide, carbohydrates, and amino acids) were studied. The highest amounts of acrylamide formed in coffee were found during the first minutes of the roasting process [3800 ng/g in Robusta (Coffea canephora robusta) and 500 ng/g in Arabica (Coffea arabica)]. When the roasting time was increased, the concentration of acrylamide decreased. It was shown that especially the roasting time and temperature, species of coffee, and amount of precursors in raw material had an influence on acrylamide formation. Robusta coffee contained significantly larger amounts of acrylamide (mean = 708 ng/g) than Arabica coffee (mean = 374 ng/g). Asparagine is the limiting factor for acrylamide formation in coffee. 3-Aminopropionamide formation was observed in a dry model system with mixtures of asparagine with sugars (sucrose, glucose). Thermal decarboxylation and elimination of the α-amino group of asparagine at high temperatures (>220 °C) led to a measurable but low formation of acrylamide.