Water uptake by freeze-dried potato and soybean powders: experiments and simulations

In this study, the water uptake of potato and soybean powders by capillary action and magnetic resonance imaging (MRI) experiments was investigated. The potato powder exhibited higher water uptake than the soybean powder, a result which was attributed to the different powder compositions. Potato and soybean powders exhibited different wetting, swelling and dispersion behaviors in water. MRI experiments also demonstrated the difference in water uptake between the powders, and indicated the formation of air bubbles, which could hinder water uptake. Numerical simulations based on a gravity-corrected Washburn-model were further performed to elucidate the mechanism of water uptake. The simulations and experiments were in good agreement. We demonstrated that powder swelling, and a dissolution-driven viscosity increases opposed water uptake and produced an eventual plateau. Our results suggest that the model used in our simulation can explain the effects of powder swelling and viscosity changes on water up-take.