Numerical description of guava osmotic dehydration including shrinkage and variable effective mass diffusivity

- Two diffusion models were used to describe the osmotic dehydration of guava.
- Models involve numerical solution and optimization algorithm to describe mass transfer.
- One of them considers constant volume and mass diffusivities.
- Second model assumes shrinkage and variable mass diffusivity.
- Mass transfer kinetics and distribution of water and sucrose are presented and analyzed.

This article uses two diffusion models to describe osmotic dehydration of guavas cut into parallelepiped shaped pieces. A one-dimensional numerical solution of the diffusion equation with boundary condition of the first kind, obtained through the finite volume method, was proposed to describe the process. The slices were cut into the following average dimensions: 9.56 × 20.03 × 30.29 mm. Two experiments involving the dipping of the product in syrup of water and sucrose were carried out in the following conditions: (1) 40 °Brix and 30 °C, (2) 50 °Brix and 40 °C. In order to determine the process parameters, an optimizer was coupled with the proposed numerical solution. A model that considers the shrinkage and variable effective moisture diffusivity well describes osmotic dehydration for two experimental conditions, and makes it possible to predict the moisture and sucrose distributions at any stipulated time.