INVESTIGADORES
ZARITZKY Noemi Elisabet
congresos y reuniones científicas
Título:
Mathematical Modelling of Heat and Mass Transfer During Frying of Coated and Uncoated Products
Autor/es:
BERTOLINI SUÁREZ, R. , CAMPAÑONE, L.A. , GARCÍA, M. A. AND ZARITZKY N.E.; CAMPAÑONE, L.A.; GARCÍA, M. A.; ZARITZKY N.E.
Lugar:
Napoles , Italia
Reunión:
Simposio; CIGR Third International Symposium on FOOD AND AGRICULTURAL PRODUCTS; 2007
Institución organizadora:
CIGR International Commission of Agricultural Engineering
Resumen:
The great volume of production of fried foods enhances the study of frying process because of its strong economic and nutritional impact. An alternative to reduce oil uptake in fried foods is the use of edible films or coatings. In the present work, the effect of an edible methylcellulose coating to reduce oil uptake during frying was analyzed on a dough system. The oil uptake reduction was 30% for coated dough discs compared to uncoated ones. The coating did not modify the water content of the samples, due to the hydrophilic characteristics of the coating that led to poor water vapor barrier properties. Thermal histories and water contents of coated and uncoated samples were similar. With reference to the quality attributes (color and texture) of the fried dough discs, firmness increased as a function of frying time due to the formation of a dehydrated zone. Values of Chroma parameters and color differences (DE) also increased during this period. In all cases, the panellists could not distinguish between control and coated samples. A mathematical model of the frying process for uncoated and coated samples, based on the numerical solution of the heat and mass transfer partial differential equations under unsteady state conditions was solved using measured physical and thermal properties. The model allowed to simulate satisfactorily the experimental data of temperature and water content during the different frying stages and to predict both the position of the vaporization front and the thickness of the dehydrated zone as a function of frying time. Water content correlated linearly with the vaporization front position which corresponds to the thickness of the humidity core. Oil uptake (OU) that occurs when the sample is removed from the frying medium was correlated with the thickness of the dehydrated zone. Microstructural changes during frying were analyzed by SEM (scanning electron microscopy).The coating reduced oil uptake  becoming a mechanical barrier to lipids.