Shear emulsification condition strategy impact high internal phase Pickering emulsions stabilized by coconut globulin-tannic acid: Structure of protein at the oil-water interface

Abstract

High internal phase Pickering emulsions (HIPPEs) have gained increasing attention due to their exceptional stability. However, the stability of HIPPEs relies on specific preparation conditions. In this research, the effects of high-speed homogenization conditions on HIPPEs stabilized by coconut globulin-tannic acid (CG-TA) colloidal particles were investigated. CG-TA colloidal particles exhibited optimal wetting properties (83.5°) and created a dense interface layer (44 nm). Insufficient shearing could not effectively homogenize oil and water phases, resulting in larger droplet sizes (33 μm). Appropriately applied shearing, especially at 10000 r/min for 1 min, facilitated the reduction of α-helix content to 38% and unfolding of CG molecule, resulting in a decrease in droplet size. Meanwhile, droplet size change of HIPPEs was minimum in 28 days and profiles difference was the minimal after centrifugation. Nevertheless, excessive shearing destroyed the hydrogen bond (O–H and N–H bending vibrations shifted to 3417 cm−1) between particles, causing an increase in particle size to 369 nm and a decline in adsorbed protein percentage to 64%. Therefore, these results proved that the shear rate and time were important to the stability of protein-based HIPPEs during homogenization, thus providing theoretical basis for the application of HIPPEs, such as solid fat substitutes.