Influence of ultrasound intensity on mass transfer in apple immersed in a sucrose solution

The influence of the ultrasonic intensity in water and dry matter transport on a system constituted by apple and sucrose solution was studied in this work. Apple slices were immersed in a 30 degrees Brix sucrose solution at 30 degrees C. Three types of treatments were carried out: static (ST), with agitation (AG) and with ultrasound application (US) at five different levels of intensity, characterized using a calorimetric method. After 45 min treatment, the water losses and the increase of dry matter were significantly higher in US samples than ST samples when the ultrasonic intensity was above 10.8 W/cm(2). At 11.5 W/cm(2), the increase of dry matter was significantly higher than in samples from AG experiments. Diffusivity of water and dry matter was identified using a model based on Fick's law. Ultrasonic treatments (11.5 Wttern) supposed an increase of 117% for water diffusivity and 137% for dry matter diffusivity compared with ST experiments. (c) 2005 Elsevier Ltd. All rights reserved.