Microwave Characterization and Modeling of the Carasau Bread Doughs During Leavening

This work deals with the electromagnetic characterization of Carasau bread doughs, in the microwave range region. The microstructure, texture, product quality and dielectric properties were investigated, jointly with a thorough thermogravimetric analysis. The goal is to link the physical properties with the product quality and to process variables. The variation of the dielectric properties during the dough leavening is studied. The dielectric properties of raw materials (water, yeast, salt and semolina) were measured from 500 MHz to 8.5 GHz. Given the heterogeneous character of bread microstructure, the possibility of predicting by using mixing formula the final characteristic of a standard Carasau bread dough, manufactured with three different semolina wheat batches, is investigated. A power law model can predict the average dough properties for frequencies higher than 2.45 GHz. This work proposes a dielectric spectroscopy model for this food material. A third order Cole-Cole model can describe the dielectric spectra of the Carasau doughs over the entire frequency range. The decrease of the complex permittivity of the dough during leavening can be modeled with a reduction of the static permittivity and a decrement of the electrical conductivity. This study can foster the development of a microwave inline system for leavening monitoring.