29E-2 |
Study of diffusional phenomenon during convective drying and impregnation of b-carotene |
C. SANTACRUZ-VÁZQUEZ1, G. F. Gutiérrez2, M. E. Jaramillo-Flores3, and V. Santacruz-Vázquez1. (1) Facultad de Ingeniería Química y Alimentos, Benemérita Universidad Autónoma de Puebla, Puebla, México, 72570, Mexico, (2) Departamento de Graduados en Alimentos, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prol. Carpio y Plan de Ayala, Mexico D.F., Mexico, (3) Dept. de Graduados e Investigación en Alimentos, Escuela Nacional de Ciencias Biológicas - IPN, Carpio y Plan de Ayala, Mexico, 11340, Mexico In this work air drying, osmotic dehydration as alone process and a combination of air-drying followed by osmotic treatment (impregnation after partial dehydration instead of the more common osmo-convective drying where the osmotic treatment proceeds the air-drying) were carried out on Apple slices (var. Red Delicious) 30mm thick and 50 mm diameter. Air drying and osmotic dehydration mass transfer kinetic parameters were determined and compared with the kinetic data obtained by the coupled air drying-osmotic treatment process in order to compare the mass transfer in the studied process. The apple slices were convective dried at 70°C and drying air 2 m/s, the samples had a moisture content (0.2, 1 and 2.7 db) and were impregnated with a binary solution of b-carotene - water with concentration of 0.1 g/ml of solution. The diffusional coefficients of the water in the dried systems was found that varies in function of the time of drying. The diffusional coefficients of b-carotene and water in the impregnation process are greater when the system has moisture content (0.2 d.b.) compared with (1 and 2.7 d.b). For the use osmotic treatment with a ternary solution of water-b-carotene (0.1g/ml solution) -sucrose (20, 30, 35 °Bx) the diffusional coefficients are small, compared with the values obtained for the process of drying convective –impregnation. After treatments water and solutes (carotene and sucrose) profiles were observed. The zone of the tissue near the interface where the original concentration status has been disturbed by the osmotic process from the rest of the tissue where no changes in concentration or mass fluxes are evident. Analytical concentration profiles where also contrasted with microscopic observations.
Session 29E, Food Engineering: Transport processes and kinetics
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