Plant protein-based antioxidant Pickering emulsions and high internal phase Pickering emulsions against broad pH range and high ionic strength: Effects of interfacial rheology and microstructure

The present work aimed to explore the stability mechanism of Pickering emulsions (PEs) and high internal phase PEs (HIPPEs) to resist environmental stresses (i.e., pH and ionic strength) via altering the interfacial rheology and microstructure. The storage, centrifugal, oxidative stabilities and interfacial properties of PEs and HIPPEs stabilized by pea protein isolate-high pectin-epigallocatechin gallate (PPI-HMP-EGCG) complex were investigated. The compact and dense viscoelastic interfacial layers, appropriate gel-like elastic network structure and apparent viscosity allowed PEs and HIPPEs to have excellent long-term storage stability, the best centrifugal and oxidative stabilities at pH 3.5 and 0 mmol/L NaCl. As PEs and HIPPEs at neutral and alkaline conditions, the centrifugal and oxidative stabilities of PEs and HIPPEs reduced, which was ascribed to the insufficient number of complexes, leading to the formation of the weak interfacial layer and the decrease of apparent viscosity and viscoelasticity. As NaCl concentration increased to 1000 mmol/L, the oil droplets were not completely surrounded by the interfacial layer with weak viscoelastic response, which resulted in the reduction of centrifugal and oxidative stabilities. These findings are useful to broaden the application of antioxidant PEs and HIPPEs in the food industry under a wide range of pH and ionic strengths.