Influence of dietary fibers and particle size distribution on food rheology

This chapter deals with the rheology of dietary fiber (DF) suspensions and how their microstructural properties influence them. The DFs obtained from selected vegetables, namely, tomato, apple, carrot, potato, parsnip, and yacon are reported. The amount and composition of the soluble/insoluble fiber have been measured for each type of fiber. For the insoluble part, the microstructural properties such as form, degree of cell fragments and cell aggregates (light microscopy), and the particle size distribution have been registered. The rheological properties of the suspensions have been measured as the elastic modulus, G″, in the linear viscoelastic region. The pectin-rich vegetable insoluble fibers can adhere to each other and form a network that has an elastic modulus, far, much higher than the network formed by the soluble pectin in the water phase. The properties of the insoluble network are dependent on the amount of water-insoluble solids, the area of large particles, and, in the concentrated region also, the hardness of the particles.