Viscosity

“Viscosity” is a physical expression for the internal rubbing of the molecules against one another in a liquid that is flowing; that is to say, it is a statement about the material’s rheological properties. Another way to define viscosity is by the tendency of a liquid to resist flowing when a shearing force is applied to it. The viscosity of a food cannot be dissociated from its texture and mouthfeel. It may seem a little odd to talk about flow in materials other than liquids, but for the vast majority of foods there is no clear boundary between liquid and solid. This condition stems from the fact that raw ingredients and foods are mostly composed of soft materials that can have characteristics of both, depending on how quickly force is applied to them externally. And, naturally, mouthfeel is always bound up with subjecting food to the movements of the mouth, tongue, and teeth. For example, when we draw liquid from a spoon into our mouth, we notice a major difference between water and honey.