The texture of raw fruits and vegetables can be crisp and juicy, soft and melting, mealy and dry, or flabby and chewy. These qualities are a reflection of the way the plant tissues break apart as we chew. And their breaking behavior depends on two main factors: the construction of their cell walls, and the amount of water held in by those walls.
The cell walls of our fruits and vegetables have two structural materials: tough fibers of cellulose that act as a kind of framework, and a semisolid, flexible mixture of water, carbohydrates, minerals, and proteins that cross-link the fibers and fill the space between them. We can think of the semisolid mixture as a kind of cement whose stiffness varies according to the proportions of its ingredients. The cellulose fibers act as reinforcing bars in that cement. Neighboring cells are held together by the cement where their walls meet.