Application of microwave processing in the food industry

Abstract

The osmotic dehydration (OD) method is widely used for the partial removal of water from fruits and vegetables by immersion in hypertonic (osmotic) solution of sugars, polyalcohols and / or salts. Despite the reduction of the moisture content of the food favored by the process (OD), the final water activity is still very high and additional processes being necessary, such as microwave drying (MWD). In this chapter, the mechanisms for energy, mass and momentum transfer involved in osmotic and microwave dehydration processes will be analyzed. Microscopic balances of mass and energy will be raised with varying degrees of precision and description. For the first stage of dehydration by impregnation, diffusive mechanisms will be explained, as well as more complete models such as the Spiazzi-Mascheroni osmotic-diffusional model. In turn, for microwave dehydration process, energy and mass balances will be considered; internal heat generation due to the interaction of food with electromagnetic energy will be described. Mass transfer during microwave dehydration will be addressed considering the mechanistic approach. Finally, the predictions of the different models will be shown and their validation will be carried out with experimental results of osmodehydrated fruits obtained in our laboratory.