Estimating permeability and porosity of plant tissues: Evolution from raw to the processed states of potato

During the processing of water containing food materials, water transport can be driven by pressure from gas, capillarity, swelling, or gravity. To describe these various modes of pressure-driven transport using Darcy's law, permeability is a critical parameter for which few data are available, primarily as a result of measurement difficulties. Permeability in the flow of liquid water through potato tissue was estimated by approximating the plant cellular structure, measured directly using flow-through and indirectly using nuclear magnetic resonance. The data from the three approaches show the same order of magnitude 10−18 m2, and thus are in agreement with each other and results reported in the literature. The dynamics of porosity and permeability changes in fresh, water-saturated, and cooked samples were described using cellular structure changes as observed in microscopy images. Simple mechanistic equations for predicting permeability and porosity, which can include swelling and shrinkage, are proposed based on approximating the geometry of the cellular tissue. Data corroborated in three ways will provide permeability values with confidence, while the simple prediction equation will make a reasonable estimation of permeability possible for a large class of food products.