Towards improved understanding of the viscoelastic properties of functionalized lemon peel fibers in suspension based on microstructure, hydration value and swelling volume

Abstract

Lemon peel fibers were obtained using different processing conditions (pH, addition of salts, mechanical processing and storage), they showed distinctly different viscoelastic properties when dispersed in an aqueous solution. In order to gain insight in the mechanism underlying their texturizing properties, the volume occupation in dispersion was determined through small molecule diffusion experiments and the swelling volume was measured by a conventional method. Based on the diffusion coefficient of glucose as a function of fiber concentration, the hydration value and volume occupancy of differently functionalized fibers were calculated. The diffusion based volume occupancy and the swelling volume were related with the fiber suspension microstructure and its rheological properties. High pressure homogenization (HPH) improved the viscoelastic properties, mainly due to an increase of the swelling volume. Salt addition and pH influenced the hydration value, the swelling volume and viscoelastic properties. These results show that the texturizing properties of lemon peel fibers induced by HPH, are mainly determined by the extent of swelling and network formation rather than an increased fiber hydration value.