Impacts of crosslinking conditions on Pickering emulsions stabilized by genipin-crosslinked chitosan-caseinophosphopeptides nanocomplexes

Abstract

Polysaccharide-polypeptide nanocomplexes are promising colloidal Pickering stabilizers. The resulting Pickering emulsions, however, are susceptible to pH and ionic strength changes. This phenomenon was also observed in our recently developed Pickering emulsions stabilized by the chitosan (CS)-caseinophosphopeptides (CPPs) nanocomplexes. To improve the stability of these Pickering emulsions, we herein crosslinked the CS-CPPs nanocomplexes with a natural crosslinker genipin. The genipin-crosslinked CS-CPPs nanocomplexes (GCNs) were used to prepare Pickering emulsions. The impacts of genipin concentration, crosslinking temperature, and duration on the characteristics of GCNs and the GCNs-stabilized Pickering emulsions (GPEs) were systemically investigated. GCNs showed crosslinking strength-dependent variations in their physical properties. Crosslinking at a weak or strong condition weakened the emulsification ability of GCNs at low concentrations. A strong crosslinking condition also compromised the capacity of GCNs to stabilize a high fraction of oil. GPEs were oil-in-water type and gel-like. GCNs crosslinked at a lower temperature and for a shorter crosslinking duration stabilized stronger gel-like GPEs. Moreover, GPEs had high pH and ionic strength stabilities. This work provided a feasible way to enhance the stability and regulate the physical properties of Pickering emulsions stabilized by polysaccharide-polypeptide nanocomplexes.