High internal phase emulsions stabilized solely by a globular protein glycated to form soft particles

Abstract

There is still a debate about the effectiveness of globular proteins of several nanometers in stabilizing oil-in-water high internal phase emulsions (HIPEs). In this work, we report that a strong internal structural integrity and high refolding ability is one requirement for globular proteins to perform as soft particles to stabilize HIPEs. Using bovine serum albumin (BSA) as the model protein, it is demonstrated that BSA glycated with galactose (Gal), possessing a much stronger structural integrity and higher refolding ability, exhibited much improved HIPE emulsification performance and subsequent Pickering stabilization than native BSA. The underlying mechanism for the improvement is largely associated with the formation of a core-shell nanostructure with a hydrophilic Gal shell surrounding the protein core in glycated BSA. The ultra-stable HIPEs (gels) were stabilized by glycated BSA at a protein concentration in the aqueous phase as low as 0.1 wt%, much lower than that reported in the literature. These HIPEs exhibited a self-supporting gel network, an extraordinary stability upon long-term storage or against drastic heating as well as good freeze-thaw reversibility. The findings are of importance for the facile fabrication of biocompatible Pickering HIPE formulations with promising applications in the food, cosmetics and pharmaceutical fields.