Hydrophobic interaction at the O/W interface: Impacts on the interfacial stability, encapsulation and bioaccessibility of polyphenols

The interfacial complexation of modified goose liver protein (M-GLP) and hydrophobic polyphenols (curcumin, resveratrol, rutin and quercetin) and its role on gastrointestinal fate of polyphenols have been investigated. Results of fluorescence quenching suggested that the type and structural specificity of polyphenols (within oil phase) influenced their capacity to form interfacial complexation with M-GLP (within aqueous phase), which was hydrophobic interaction dominated. Raman spectroscopy and interfacial dilatational analysis revealed that the diketone structure and high hydrophobicity of curcumin caused the pronounced M-GLP-curcumin hydrophobic interaction and then enhanced the protein conformational flexibility. This conduced to the improved steric stability of the emulsion through strengthened interfacial loading and lateral association. Via the mechanism, there were improved physical stability and higher photo and storage stability of curcumin than resveratrol, rutin and quercetin. Moreover, emulsion droplets size distribution and in vitro digestion results revealed that, compared with other polyphenols, the stronger interfacial complexation between M-GLP and curcumin caused higher droplet stability during gastric environment and more sufficient intestinal lipolysis with O/W interface wreckage and related micelllization, finally yielding higher bioaccessibility for curcumin. This study may put further insight into the active role of hydrophobic compounds encapsulated on the emulsion system with delivery potency.