Use of Ultrasound in the Distilled Water Pretreament and Convective Drying of Pineapple

Abstract

Convective drying is a time-consuming process. Pretreatments in distilled water assisted with ultrasound, or the application of ultrasound during convective drying itself, could improve the mass transfer. In this work, the influence of pretreatment using distilled water (20 or 40 min at 25 °C) assisted with ultrasound (55.5 W L-1, 40 kHz) on convective drying kinetics (40 and 70 °C, 1 m s-1) of pineapple slices (2.0 cm diameter, 0.5 cm thickness) was studied. The drying was carried out with (31 kWm-3; 21.8 kHz) and without ultrasound application being the kinetics simulated using a diffusive model. The results showed that pretreatment, the use of high drying temperatures, and the application of ultrasound during drying accelerated the drying process. The effective diffusivity identified by the model allowed the quantification of the effects of each of the studied variables on the drying rate of pineapple slices.