Formation kinetics of neoformed compounds during the roasting stage

Coffee and cocoa roasting is a non-isothermal thermal process in which the concentrations of neoformed compounds (NFCs) evolve dynamically due to concurrent formation and degradation reactions. This chapter applies principles of chemical kinetics to quantitatively model the evolution of NFCs by integrating temperature, time, matrix properties, and precursor availability, with the aim of identifying processing conditions that balance technological quality and food safety. The case study revealed compound-specific kinetic behaviors. Acrylamide (AA) exhibited a formation–consumption profile characterized by a bell-shaped curve, reaching maximum levels near the first crack and subsequently declining due to precursor depletion and thermal degradation. In contrast, furan derivatives (HMF and FFA) tended to accumulate at later roasting stages, favored by higher thermal severity, increased acidity, and low water activity. The kinetic model (180-220°C) adequately described sucrose hydrolysis, asparagine consumption, and AA evolution (R² > 0.88), but performed poorly for glucose and fructose (R² < 0.5), suggesting the presence of parallel consumption pathways not captured by the model and thus limiting its predictive capability. Kinetic modeling, therefore, represents a useful tool for optimizing roasting profiles; however, its validity depends on underlying model assumptions and matrix heterogeneity, and it should be interpreted as an operational approximation that requires experimental validation.