Model-Based Process Control for Optimised Banana Ripening

Abstract

A dynamic model of the banana ripening process as performed in the food industry was developed. In the model, the degradation of starch to soluble sugars was described based on the carbon dioxide emission. The basis of the physico-chemical and the plant model parts were dynamic energy and mass balances. The model was evaluated by the means of experimental data produced in a pilot plant banana ripening box. The functionalities of the box follow industrial standards. The model describes the characteristic courses of the carbon dioxide concentration in the air of the process, the starch concentration in the banana pulp and the peel colour. Based on this information, the ripening state of the bananas could be estimated with the help of the model. Moreover, the model was used for an automated predictive and adaptive process control. For this purpose the Open-Loop-Feedback-Optimal (OLFO) controller was applied to the banana ripening process. Two characteristic model parameters, the starch-to-CO2 reaction rate factor and the peel colour change rate factor, were fitted to changing process courses. The control function of the banana ripening process, the set-point temperature profile, was optimised to automatically control the process to the required ripening state and the optimal storage temperature at the end of the procedure.