Influence of concentration, ionic strength and pH on zeta potential and mean hydrodynamic diameter of edible polysaccharide solutions envisaged for multinanolayered films production

Abstract

Polysaccharide multinanolayers are becoming a new and general means of modifying and functionalizing surfaces of several materials. This is achieved through changing the interfacial properties of those surfaces followed by sequential adsorption of e.g., polysaccharides. Knowledge of properties of polysaccharide solutions such as zeta potential (Zp) and mean hydrodynamic diameter (Z-average) is crucial to obtain stable, functional nanostructures.

In this work sodium alginate, carragennan, chitosan, and two galactomannans were characterized in terms of Zp and Z-average, as a function of polysaccharides and NaCl concentrations and pH. The most relevant effects of these factors on Zp and on Z-average were analysed using a 23 full factorial design.

With a few exceptions, the effect of independent variables on Zp and Z-average values is statistically significant. In general (except for k-carragennan solutions) higher polysaccharide concentrations lead to higher Z-average values; and higher pH values lead to higher Z-average values (except for solutions of chitosan and galactomannan of Gleditsia triacanthos). NaCl addition decreases Z-average. For the galactomannans solutions Zp values were found to be neutral (ranging from −13.7 to −2.1 mV) independently of the combinations of variables used.

This work establishes a relationship between important polysaccharides properties and the values of pH, polysaccharide and salt concentrations, thus providing insight on how to control the structure and texture of multinanolayered films in view of their potential application e.g., in the food, pharmaceutical, and cosmetic industries.