Edible Pickering emulsion stabilized by protein fibrils: Part 2. Effect of dipalmitoyl phosphatidylcholine (DPPC)

Abstract

Interaction between β-lactoglobulin fibrils (BLGF) and dipalmitoyl phosphatidylcholine (DPPC) and its effect on the interfacial and emulsifying properties of BLGF were investigated at pH 7. Incorporation of a small amount of DPPC (DPPC/BLGF ratio < 1:10,000) led to the formation of brush-like complexes in which the fibrils were partially coated with a layer of DPPC. This interaction mode was favorable for the adsorption of fibrils onto the oil-water interface, resulting in a thicker and protruding interfacial layer with higher viscoelasticity. On the contrary, incorporation of excessive amount of DPPC (DPPC/BLGF ratio > 1:10) led to the formation of pearl-necklace-like complexes in which the fibrils were heavily and irregularly coated with DPPC surface micelles. This interaction mode tended to reduce the adsorption of fibrils onto the oil-water interface and thus impair the resulting interfacial viscoelasticity. Emulsifying performance of DPPC/BLGF complexes was found to be related to the different interaction modes and interfacial properties. The incorporation of a small amount of DPPC helped to reduce the particle size of BLGF-stabilized emulsions, whereas a high loading of DPPC gave coarse and unstable emulsions that destabilized within one-week storage at ambient temperature.