Structuring of acidic oil-in-water emulsions by controlled aggregation of nanofibrillated egg white protein in the aqueous phase using sodium hexametaphosphate

Abstract

This study investigated the mechanism behind the structuring of acidic oil-in-water emulsions made with native and nanofibrillated egg white proteins (EWP) in the presence of sodium hexametaphosphate (SHMP). Oil-in-water emulsions containing 10–70% oil content were prepared from EWP suspensions and treated with 0–500 ppm SHMP. Whereas 70% oil-in-water emulsions with both native and nanofibrillated EWP in the absence of SHMP showed a paste-like texture, the emulsions with a lower oil content (10–50% oil) had a more liquid consistency and quickly separated into two layers. No structuring effect was observed for the emulsions made with native EWP with 10–50% oil contents, however, the addition of SHMP significantly increased the creaming stability and the rheological properties of the nanofibrillated EWP emulsions containing 10–50% oil. Microstructural data suggested that nanofibrillated EWP could form a well crosslinked network in the aqueous phase of the emulsions through ion bridges with SHMP oligo anions. It resulted in the fabrication of reduced-fat emulsions with 10–50% oil content with a similar or stronger texture than that of high-fat emulsions with 70% oil content. This research provided insight into the crosslinking of nanofibrillated EWP by SHMP as a viable food grade cross-linker in designing structured acidic O/W emulsions.