The “food physical quality” facet covers the physical state of the food product (liquid, semiliquid, semisolid, or solid). Solid food products are further subdivided by shape or form. Terms are provided for products that have both liquid and solid components or that incorporate air or other gases. Food color and fruit ripeness facets are described separately.
An instance of a food item is connected to a a food physical quality using a “has quality” object property.
FoodOn, like many other OWL ontologies, allows some relations to implicitly be true for some time or duration, but not for all time, for simplicity’s sake. An apple instance can have (‘has quality’) some ripe quality, but making that statement doesn’t imply that it has a ripe quality during its entire existence. (A property graph database can be more easily employed to add information about the time(s) at which time a predicate holds.)