Physicochemical evaluation of chitosan-xanthan gum nanoemulsions as polyunsaturated enriched lipid-carrier

Polyunsaturated enriched lipid-carriers have been drawn attention due to their health benefits. This work aimed to develop new delivery carriers based on chitosan-xanthan gum nanoemulsions with tuna oil, which is rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Therefore, it was intended to elucidate the physicochemical interactions within chitosan-xanthan gum-polyunsaturated fatty acids nanoemulsions. The droplets size, zeta potential, rheological and thermal characteristics, as well as the kinetic, thermodynamic and oxidative studies of the nanoemulsions were performed. All emulsions presented droplet sizes in the nanoscale range (around 224-289 nm) and a pseudoplastic rheological behavior. Thermodynamic parameters showed that the viscous flows of all nanoemulsions were nonspontaneous and exothermic, presenting a more orderly state. However, increased xanthan gum concentration resulted in endothermic viscous flow. Based on the results, protonated amino groups from chitosan improved electrostatic stability due to an increase in zeta potential values, while the enhanced viscosity led to by xanthan gum reduced the diffusivity of dissolved oxygen and increased oxidative stability. Moreover, electrostatic interactions between chitosan and xanthan gum increased the steric and oxidative stabilities of nanoemulsions.