Descrição da secagem contínua e intermitente de pedaços de melão cortados na forma de paralelepípedos pré-tratados osmoticamente

Abstract

The technological development of the fruit drying process plays a fundamental role in minimizing food waste and reducing energy consumption used in the food processing industry. This work aimed to carry out a study of the continuous and intermittent drying processes of osmotically pretreated pieces of melon, cut in the shape of a parallelepiped, using empirical and diffusive models to describe these processes, in addition to characterizing the product obtained in terms of physicochemical, bioactive and color parameters. For this, experiments were carried out using an incubator with mechanical agitation to carry out osmotic dehydration, in order to improve sensory properties and prepare the samples for subsequent drying. Drying was carried out using an oven with forced air circulation at temperatures of 50 and 70 °C involving continuous and intermittent drying (with intermittency ratio α = 2/3) of the melon parallelepiped. As part of the study, drying was modeled using empirical equations, considering the effective operating time, with the purpose of comparing drying kinetics and analyzing the impact of intermittent drying on energy savings. Drying kinetics are also described using diffusive models that use analytical and numerical solutions of the diffusion equation, in cartesian coordinates, with first and third type boundary conditions. The results indicate a reduction in drying time and higher drying rates with the application of intermittency, providing greater energy savings. Among the empirical equations analyzed, Page's equation is the one that best describes the continuous and intermittent drying of pre-treated melon. The analytical model with boundary condition of the third type adequately describes the continuous and intermittent drying of previously dehydrated melon parallelepiped. It was found that the diffusion coefficient increases with the application of intermittency during drying. The model proposed in this work, based on the empirical equations of Page and Lewis, was able to describe the kinetics of intermittent drying, including the tempering period. According to physicochemical and bioactive analyses, intermittent drying achieved greater preservation of compounds compared to continuous drying.