Preparation and evaluation of a novel high internal phase Pickering emulsion based on whey protein isolate nanofibrils derived by hydrothermal method

Abstract The present work aimed to explore nanofibrils prepared from whey protein isolate (WPNFs) by hydrothermal to stabilize high internal phase Pickering emulsion (HIPPEs). WPNFs with well-ordered β-sheet structures and high aspect ratio were efficiently prepared by hydrothermal at 110 °C for 4 h, which is more efficiently than conventional method at 80–90 °C for 5–24 h. The characteristics of the building blocks analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with Tris-Tricine buffer system and liquid chromatography linked to tandem mass spectrometry (LC-MS/MS) proved that the formation of WPNFs is based on the hydrolysis of WPI, and hydrothermal can make WPI hydrolysis faster and more efficiently. The high internal phase Pickering emulsion (HIPPEs) stabilized by 5 wt% of WPNFs (internal phase fraction Φ up to 0.90) showed an excellent stability. The microstructure of HIPPEs illustrated by super resolution microscope and cryo-scanning electron microscopy showed that WPNFs tightly wrapped the oil droplets forming an ordered viscoelastic and dense interface layer. It can be speculated that WPNFs were flexible due to their large aspect ratio and mechanical strength, which allowed them to bend on the surface of the droplet to form a better package protection. Rheology and texture analysis showed that WPNFs stabilized HIPPEs have solid-like and tunable rheological properties. WPNFs were verified to improve the oil binding capacity and antioxidant activity. The results provided that hydrothermal is a novel and efficient method for preparing WPNFs, and the prepared WPNFs can be used to stabilize HIPPEs with tunable rheology.