High internal phase Pickering emulsions prepared by globular protein-tannic acid complexes: A hydrogen bond-based interfacial crosslinking strategy

Abstract

Native soluble globular proteins (SGPs) need to further strengthen their structural integrity to stabilize high internal phase Pickering emulsions (HIPPEs). In this study, four common SGPs in food, including ovalbumin, whey protein, bovine serum albumin (BSA), and lysozyme (LY), were used as models to form complexes with tannic acid (TA). SGPs became outstanding stabilizers for HIPPEs due to the enhanced integrity after complexing with TA. TA interacted strongly with SGPs mainly through hydrogen-bond and hydrophobic interactions. However, hydrogen-bond interaction played a key role in the SGP-TA stabilized HIPPEs. The presence of TA enhanced the wetting ability of the SGP-TA complexes at the oil–water interface, resulting in more uniform and smaller droplets of HIPPEs. These phenomena were also related to the formation of strong hydrogen bond networks among SGP-TA complexes at the interface and aqueous phase. In comparison, the BSA-TA complex had the optimal ability to stabilize HIPPEs, while LY-TA complex exhibited the lowest emulsifying activity. Notably, the gel-like network of SGP-TA stabilized HIPPEs effectively prevented droplet aggregation during storage, freeze–thaw, and heat treatment. This study developed a tangible and facile method to improve the application of SGPs in protein-based HIPPEs.