Moisture diffusivity in sponge cake as related to porous structure evaluation and moisture content

Water diffusivity within sponge cake was determined at 5, 20, and 25degreesC by identification from a water sorption kinetic and using a mathematical model based on Fick's 2nd law. Water diffusivity at 20degreesC within sponge cake varied from 0.5 x 10(-10) m(2)/S to 7.5 x 10(-10) m(2)/s as a function of sponge cake moisture content. Influence of temperature on the concentration-dependent diffusivity was investigated. The activation energy was found to vary with sponge cake moisture content from 84 to 128 kj/mole. Effective diffusivity variations were correlated with the changes in microstructure of the material that was observed by using environmental scanning electron microscopy. The level of porosity in the material played a dominant role in determining the effective diffusivity.