title: Predictive model to describe water migration in cellular solid foods during storage.
abstract: BACKGROUND
  Water migration in cellular solid foods during storage causes loss of crispness. To improve crispness retention, physical understanding of this process is needed. Mathematical models are suitable tools to gain this physical knowledge.
  
  
  RESULTS
  Water migration in cellular solid foods involves migration through both the air cells and the solid matrix. For systems in which the water migration distance is large compared with the cell wall thickness of the solid matrix, the overall water flux through the system is dominated by the flux through the air. For these systems, water migration can be approximated well by a Fickian diffusion model. The effective diffusion coefficient can be expressed in terms of the material properties of the solid matrix (i.e. the density, sorption isotherm and diffusion coefficient of water in the solid matrix) and the morphological properties of the cellular structure (i.e. water vapour permeability and volume fraction of the solid matrix). The water vapour permeability is estimated from finite element method modelling using a simplified model for the cellular structure.
  
  
  CONCLUSIONS
  It is shown that experimentally observed dynamical water profiles of bread rolls that differ in crust permeability are predicted well by the Fickian diffusion model.
authors: TI Food and Nutrition, PO Box 557, NL-6700 AN Wageningen, The Netherlands. julien.voogt@tno.nl
authors: Juliën A
authors: JA
authors: Voogt
authors: Anita
authors: A
authors: Hirte
authors: Marcel B J
authors: MB
authors: Meinders
mesh_terms: D001939:Bread / Q000032:analysis*; D055598:Chemical Phenomena; D004058:Diffusion; D005511:Food Handling; D007700:Kinetics; D055595:Mechanical Phenomena; D008855:Microscopy, Electron, Scanning; D008956:Models, Chemical; D010539:Permeability; D013499:Surface Properties; D013696:Temperature; D014867:Water / Q000032:analysis*; D055114:X-Ray Microtomography
chemical_list: D014867:Water