Modeling of Microwave Drying of Fruits. Part II: Effect of osmotic pretreatment on the microwave dehydration process

ARBALLO, JAVIER RAMIRO; CAMPAÑONE, LAURA ANALÍA; MASCHERONI, RODOLFO HORACIO

DRYING TECHNOLOGY

TAYLOR & FRANCIS INC

Año: 2012 vol. 30 p. 404 - 415

0737-3937

The heat and mass transfer during the combined process of osmotic-microwave drying (OD-MWD) of fruits was studied theoretically and experimentally through modeling and numerical simulation. With the aim to describe the transport phenomena involved during the combined dehydration process, the mass and energy microscopic balances were raised. For the first step (OD), two models with different levels of complexity were proposed, an osmotic-diffusive and a counter-current flow diffusive model. On the other hand, for MWD, the energy and mass balances were solved, using moisture and temperature-dependent properties; inner heat generation due to transformation of the electromagnetic energy was accounted for by using the approximation of Lambert?s law. The numerical solution obtained from OD was incorporated as initial values for the simulation of MWD. The model validation was satisfactorily carried out in pears, fresh and osmodehydrated during 2h in sucrose osmotic solutions and then irradiated in a microwave oven at 500W. From the results, it could be observed that higher dehydration rate, during microwave drying, was reached when the fruits were pretreated with 40 and 60ºBrix sucrose solution.