Continuous and Intermittent Drying of Osmotically Pretreated Melon Pieces: Analysis of Energy Savings and Preservation of Bioactive Compounds

The objective of this study was to carry out a study on continuous and intermittent drying (intermittency ratio α = 2/3) of osmotically pretreated melon pieces, cut in the form of a parallelepiped. An osmotic dehydration pretreatment was performed using an incubator with mechanical shaking. Drying processes were carried out using an oven with forced air circulation at temperatures of 50 and 70 °C. The data were modeled by means of empirical equations, in order to compare the drying kinetics and analyze the impact of the intermittent process on energy savings and preservation of bioactive compounds in the final product. The experiments were also described using a diffusion model in Cartesian coordinates, with a third-kind boundary condition, in order to analyze the moisture distribution inside each piece of fruit over time. Among the empirical equations analyzed, Page’s was the one that best described the continuous and intermittent drying of osmotically pretreated melon pieces. In order to obtain dried melon, intermittent drying significantly reduced the effective processing time and, consequently, energy consumption, preserving the bioactive compounds more intensely (particularly at a temperature of 50 °C), compared to continuous drying. The diffusion model adequately described all the drying experiments, and it was found that the effective mass diffusivity increased significantly with the application of intermittency.