It's well known that the structural characteristics of food materials influence their mass transfer, especially their water transfer properties during such processes as drying, hydration, and storage. In porous cereal-based products, for example, effective water diffusivity is highly affected by the volume fraction and distribution of both solid and gas phases, while in dense food materials, such as fat-based or other edible coatings, it depends on factors that affect the "tightness" of the molecular structure (e.g., free volume, cohesive energy density, crystallinity). This Brief will review...