Rheological control of pea fibre dispersions in oil: The role of particle and water volume fractions

Two distinct coarse fractions of the yellow pea, namely the pea hull (PH) and the epidermal cell wall (PCW), are investigated as rheological modifiers of an oil phase. We considered two avenues for oil structuring: (i) the increase in particle volume fraction (φ) and (ii) the addition of water to a PH and PCW-in-oil dispersion at a constant φ = 0.10. The PH and PCW-in-oil dispersions exhibited a viscosity increase as a function of the particle volume fraction, which was well captured by the Krieger-Dougherty relationship. At values close to the maximum volume fraction (φ ≃ 0.50) the PH and PCW-in-oil dispersions displayed a paste-like appearance with solid-like properties. The water addition to the PH and PCW-in-oil dispersion caused a noteworthy increase in viscosity and the development of pronounced elasticity due to the water bridges connecting neighbouring particles, rising capillary forces.