Experimental determination of the dielectric properties of liquid and pasty foods considering the continuous heat treatment using microwave technology

Abstract

Driven by the growing demand for food products with better nutritional value and sensorial quality e by the socio-economic potential associated with the development of new processing technologies in Brazil, this project aims to determine and study the dielectric properties (DEP) of liquid foods in view of the continuous thermal processing using microwave technology. This emerging technology has great potential for the processing of liquid foods, because it promotes fast heating, avoiding quality degradation typically associated with indirect heating using heat exchangers. Moreover, the microwave energy has proven non-thermal effect on the heat-inactivation of enzymes. Therefore, the DEP are essential to study and model the response of food to the electromagnetic field with respect to the penetration depth and volumetric heat generation. The main liquid foods studied in this project will be the green coconut water, orange juice and apple juice; whereas the main pasty foods are the purees of mango and banana. Other foods will be studied, like other tropical juices of importance for the export market and milks. The DEP (dielectric constant and loss factor) will be determined for a wide range of temperature (0 to 130 ° C) and frequency (200 -3000) MHz using the coaxial probe technique with scan through a network analyzer. The depth of penetration will be calculated and all results will be correlated through non-linear estimation. Special attention will be given to the main frequencies of industrial interest in Brazil, which are (915 and 2450) MHz. (AU)