A mathematical model for the numerical investigation of freeze-drying of apricot fruit

Abstract

This study proposes a mathematical model constructed in spherical coordinates to reveal the mass and temperature changes that occur during the freeze-drying of apricot fruit. A kind of polynomial approach known as the orthogonal collocation method was applied to find the solution of governing equations. The physical properties and some transport parameters that describe the freeze-drying of apricot fruit were estimated by using the Levenberg-Marquardt algorithm based on the nonlinear least-square method. The effect of product radius, drying temperature, and product shape on the length of the primary drying stage was investigated by the determined transport parameters in the model. Furthermore, the effect of the freezedrying process on product color and total phenolic content (TPC) was examined, and it was observed that the TPC value of apricot fruit increased from 295.60 +/- 16.55 to 602.63 +/- 17.74 mg GAE (Gallic acid equivalent) / 100 g DM.