Physical pre-treatment of plums (Prunus domestica). Part 1. Modelling the kinetics of drying

An alternative physical method for enhancing the drying rate of plums is proposed. It consists of the superficial abrasion of the plums’ peel using an inert abrasive material to remove the cuticular waxy layer, the limiting factor for moisture loss. The physical pre-treatment was compared with a chemical treatment in which the plums were dipped into a solution of ethyl oleate. The drying kinetics of the above samples, including the untreated one, were reconstructed by using a mathematical model. The drying process, carried out at 60 °C to reduce the prunes’ quality loss, showed the great capability of both pre-treatments to enhance water diffusivity in the plum peel with respect to the untreated samples. Moreover, it was found that the physical treatment was more effective than the chemical one.