Investigation of effective parameters on particle size, zeta potential and steady rheological properties of colloidal system based on carrageenan-caseinate nanoparticles

Biopolymer-based nanocomplexes could be produced by electrostatic interactions between opposite-charge-groups on two types of biopolymers. In this research, the production method and properties of the kappa carageenan-caseinate based nanocomplex were investigated. The particle sizes of carageenan-caseinate complexes were vigorously dependent to pH and biopolymers concentrations and optimum level was observed for both of these factors. The sizes of the smallest particles were 74 and 75 nanometers which were obtained at pH=4.9 and concentrations of 1% caseinate-0.03% carageenan and 0.5% caseinate-0.02% carageenan, respectively. Reduction of pH from 5.3 to 5.1, caused decrease of particle size in all samples and continuing pH reduction to 4.9 caused more reduction of particle size at low concentration of caseinate. The zeta potential data showed that the amount of negative charges in complexes were higher than sum of charges in both biopolymers. All pure and complex samples showed Newtonian behavior and increasing both biopolymer concentrations enhanced viscosity of complex.