Fluidized bed roasting of cocoa nibs speeds up processing and favors the formation of pyrazines

Roasting is an important step in cocoa processing causing water loss and generating volatile compounds responsible for chocolate aroma like nitrogen-heterocycles. In this study, the comparison of two techniques, oven roasting and fluidized bed roasting, in terms of effective water diffusivity (De) and activation energies of formation (Ea) of nitrogen-heterocycles was achieved with cocoa nibs. Fluidized bed roasting, recognized for its energy efficiency and low-footprint synthesis, was 16 times faster than oven roasting. The order of magnitude of De in fluidized-bed-roasted nibs was 8, while it was 9 in the oven-roasted nibs. Moreover, the aw was 50% higher in fluidized-bed-roasted nibs than in the oven-roasted ones. The Ea of nitrogen-heterocycles ranged roughly between 40 and 80 kJ/mol. Those values were lower under fluidized bed roasting than under oven roasting. The more effortless water mobility within fluidized-bed-roasted cocoa demanded lower Ea, and favored the formation of nitrogen-heterocyclics. Industrial relevance: This study can inspire cocoa manufacturers and equipment designers to pursue the formation of nitrogen-heterocycles during the roasting process of cocoa.