Controlling moisture transport in a cereal porous product by modification of structural or formulation parameters
2007
Roca, E. | Broyart, B. | Guillard, V. | Guilbert, S. | Gontard, N.
Equilibrium and dynamic water sorption properties of sponge cakes with varying porosity (86-52%) and fat content (0-0.30 g/g d.b.) were determined using a water vapour sorption microbalance. Contrary to porosity, addition of fat decreased equilibrium moisture contents. The effective moisture diffusivity (D(eff)) was identified from a numerical solution of Fick's second law, taking into account an external mass transfer coefficient and the swelling of the solid matrix. D(eff) increased from 1.61 to 8.67 x 10⁻¹⁰ m²/s with moisture content, reached a threshold at moisture content 0.15 g/g d.b. and then decreased until water saturation. D(eff) decreased from 8.67 to 2.97 x 10⁻¹⁰ m²/s with decreasing porosity. This effect was attributed to a change of water diffusion mechanism, from predominant vapour to liquid. D(eff) decreased from 8.67 to 2.12 x 10⁻¹⁰ m²/s with increasing fat content. Addition of fat had an effect on the water diffusion in two ways, decreasing porosity (sagging of the foam) and increasing tortuosity.
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