Differential model of the kinetics of water vapour adsorption on maize starch particles

. An understanding of the kinetics of water vapour sorption allows for the prediction of the stability of food in the management of transport and storage processes, it also facilitates the optimization of drying processes, and the rationalization of the methods of studying sorption statics. The present study aimed to determine an appropriate model of the kinetics of water vapour sorption on the surface of maize starch particles, which could prove useful in describing kinetic curves as well as allowing for the determination of the time required to reach a state of equilibrium. Experimental data was obtained through the continuous measurement of the increase in sample mass. The model was developed by matching the simulation results to the experimental results. Its parameters were identified by minimizing the mean square error between the time courses of the simulation and the experimental results, which allowed for the avoidance of problems concerning data processing and the loss of information. Two methods were deployed in order to minimize the occurrence of error: multi-start and gradient ones. The proposed model provided an appropriate description of the kinetics of water vapour adsorption by maize starch, regardless of the mass of the samples used and the physical state of their particles. The time required for a state of equilibrium to be attained was significantly shorter than the usually assumed period of 30 days.