Mass transfer analysis in vacuum impregnation of fruits
J. WELTI-CHANES1, M. S. Tapia2, A. López-Malo3, E. Palou1, H. Mújica-Paz4, and A. Valdez-Fragoso4. (1) Depto. de Ingeniería Química y Alimentos, Univ. de las Americas-Puebla, Sta. Catarina Mártir, Cholula, Puebla, 72820, Mexico, (2) Instituto de Ciencia y Tecnología de Alimentos, Univ. Central de Venezuela, PO Box 47097, Caracas, 1041-A, Venezuela, (3) Departamento de Ingeniería Química y Alimentos, Universidad de las Américas-Puebla, Sta. Catarina Mártir, Cholula, Puebla, 72820, Mexico, (4) Facultad de Ciencias Químicas, Universidad Autónoma de Chihuahua, Ciudad Universitaria, Chihuahua, 31170, Mexico
Vacuum Impregnation (VI) can be considered as a good alternative to modify the composition of high porosity foods. Through VI is possible to incorporate minerals, vitamins and other nutrients in isotonic or osmotic syrups into fruits and transform them in functional foods. Information about the analysis of mass transfer phenomena in this type of process in which impregnation of the food structure as well as osmotic dehydration (OD) occur, is scarce. The objective of this work was to analyze VI of apple slabs with sugar syrups at different calcium and zinc concentrations and model the mass transfer of both minerals in OD or VI process. Apple slabs were placed in sucrose syrup (50 Brix) containing different concentration of calcium (0-1000 ppm) or zinc (0-375 ppm) and vacuum pressures of 50 cm Hg were applied. Impregnation and relaxation times varied between 3 and 45 min. Atmospheric pressure process (APP) were performed for reference purpose. Final concentrations of calcium and zinc in the impregnated fruit were in the range of 113-314 ppm and 20.4-114 ppm respectively. Average errors of 47.7% and 27.3% were obtained in the calcium composition predictions using the OD or the VI mathematics principles respectively and were 45.5% and 38.3% for the change of zinc concentrations. A result showed that a mass transfer processes (OD or VI) predominates depending on the impregnation and relaxation times. A mathematical model is proposed to consider the combined phenomena of IV and OD and improve the predictions.
Session 58, Food Engineering: Transport processes and kinetics