Papers by Author: Francisco Chenlo

Paper TitlePage

Authors: Ramón Moreira, Francisco Chenlo, L. Chaguri, Christiana Fernandes
Abstract: Many food materials must be dried in order to decrease its water activity and to increase the shelf-life. Also, rehydration operation must be carried out as previous step before consumption. Both operations are commonly employed in some industrial chestnut processing. These processes can be carried out at different temperatures and in all cases the quality of the final product can be affected. In this work, convective drying with hot air is the employed method for water removal and rehydration is carried out by immersion of chestnut in water. In both cases, mass transfer processes are governed by water diffusion in the bulk of the solid. The aim of this work is to determine experimentally the drying and rehydration kinetics of chestnut samples at different conditions of temperature and moisture content. Obtained data are modeled with a diffusional model taking into account volume variations and the corresponding values of the coefficients of diffusion of water are obtained. Analysis of the results indicates that drying/rehydration rates increase with temperature and rehydration kinetics are also depending on the initial moisture content of chestnut. Finally, leaching flow during rehydration is only important at high temperature due to starch gelatinization processes.
758
Authors: Luis Mayor, Ramón Moreira, Francisco Chenlo, Alberto M. Sereno
Abstract: Chesnut and pumpkin fruits were dehydrated with osmotic solutions of sucrose and NaCl at 25°C. These food materials have different structure, composition and porosity. Water loss and solids gain kinetics were experimentally determined and modeled using a diffusional model. In spite of the several mass transfer mechanisms taking place along with diffusion during osmotic dehydration, the modeling was satisfactory and involved effective coefficients of diffusion useful to quantify the different mass transfer fluxes. Water and sucrose transfer rates during osmotic dehydration with sucrose solutions are independent on the initial food material characteristics; however they seem to be related with the permeability of these components to a sucrose layer formed in the surface of the samples. In the case of osmotic dehydration with sodium chloride solutions, the coefficients of diffusion show a dependence on food material characteristic and higher values of these coefficients for pumpkin (more porous material) were found.
575
Authors: Ramón Moreira, Francisco Chenlo, N. Vallejo, Lionel Gerbet
Abstract: Osmotic dehydration of eggplant slices in sucrose and sodium chloride solutions at different solution concentrations, stirring levels and time of process is studied. Water loss and solids gain kinetics were experimentally determined and modelled using a diffusional model and equilibrium values were predicted by means of Azuara model. Modelling was satisfactory and involved effective coefficients of diffusion useful to quantify the different mass transfer fluxes.
413
Authors: Luis Mayor, Ramón Moreira, Francisco Chenlo, Alberto M. Sereno
Abstract: Osmotic dehydration experiments of pumpkin with binary aqueous solutions of sucrose, sodium chloride and ternary solutions with both solutes at 298 K were carried out. Weight reduction, water loss and solute acquisition kinetics were determined. Experimental data were fitted employing a diffusional model considering samples as spheres and the external resistance to the mass transfer negligible. The model gave as parameter of fitting an effective diffusion coefficient for each component transferred (water, sucrose and sodium chloride) for each experimental condition assayed. Correlations between the effective diffusivity and solute concentration were established for binary and ternary systems.
213
Showing 1 to 4 of 4 Paper Titles