Modeling of Microbial Spoilage and Color Degradation Occurring in Convective Drying of Vegetables: A Route to Process Optimization

AbstractThe present paper was aimed at developing a rigorous methodology to optimize the performance of vegetables hot convective drying. The proposed optimization method was formulated combining a multiphase transport phenomena model, which predicted the time evolutions of temperature and water activity distributions in the food, a product decontamination model, which described the microbial inactivation kinetics of Listeria monocytogenes and a model estimating the color changes, expressed in terms of the Hunter parameters. The effects of operating conditions both on color degradation, chosen as a reference quality parameter, and on microbial population decay, chosen as a measure of food safety, were ascertained. The formulated optimization model allowed analyzing different scenarios and calculating the set of operating conditions, which were to be exploited to attain specific control objectives, represented by a trade-off between quality and safety of dried foods. By the proposed methodology, it would be possible to minimize expensive and time-consuming pilot test runs and obtain precise indications about optimization of vegetables convective drying.Practical ApplicationsThe proposed transport model allows calculating the effects of operating conditions on both microbial inactivation and color changes occurring during vegetables drying. Such a model can be exploited to develop computational tools aimed at optimizing the performance of real convective driers.