Properties of beta-lactoglobulin/alginate mixtures as a function of component ratio, pH and applied shear

• Impact of processing parameters (ratio, pH, shear) on properties of alginate/β-lactoglobulin mixtures was assessed.
• Size of particles was only affected by pH.
• Surface properties of composite particles affected by main parameters and influenced viscosity
• Possible to manipulate conformation of composite particles to obtain different surface properties without changing the size

The objective of this research was to establish effects of selected process parameters (component ratio, pH, shear) on the properties of alginate (Alg)/beta lactoglobulin (βlg) mixtures. Effects were assessed by measuring apparent viscosity, particle size, ζ-potential, hydrophobicity and conformational changes (FTIR). Intrinsic viscosity and critical concentrations were also investigated. Intrinsic viscosity of individual Alg and βlg solutions increased with pH. Shearing of Alg/βlg mixtures resulted in greater apparent viscosity at pH 3 which declined proportional to increase in pH. Particle size and surface hydrophobicity were higher at pH 3 and directly related to Alg concentration. Shear induced changes were observed in the secondary structure of βlg in the βlg/Alg mixtures associated with β-sheet conformations shifting from 1635.64 to 1633.71/cm and occurred only at pH 5. Under certain conditions, application of shear could manipulate and create different structures from these two biopolymers.