Edible pickering high internal phase emulsions stabilized by soy glycinin: Improvement of emulsification performance and pickering stabilization by glycation with soy polysaccharide

Abstract

There is fast increasing interest in the development of food grade high internal phase emulsions (HIPEs; with oil fractions > 0.74) stabilized by protein-based particles, due to their potential applications in food, cosmetics and biomedical fields. This work reported that soy glycinin (SG), an important soy storage globulin, exhibited a potential to act as Pickering stabilizers for HIPEs; and the glycation with soy soluble polysaccharide (SSPS) greatly improved the emulsification performance of SG, the gel network formation and stability (against heating or freeze-thawing) of the resultant HIPEs. In the work, two selected glycation incubation periods (24 and 72 h) were applied to obtain the glycated SG. The results indicated that the glycation progressively decreased the minimal concentration required for the formation of gel-like HIPEs, and droplet size, but increased the gel network strength, in an incubation period dependent manner. The improvement of emulsification performance by the glycation was mainly associated with the enhanced adsorption, as well as facilitated subunit dissociation at the interface, during the HIPE formation. All the HIPEs stabilized by untreated or glycated SG exhibited an excellent coalescence stability against a long-term storage. The structural analyses of non-adsorbed and adsorbed SG indicated that although untreated SG showed a high whole structural integrity with no distinct changes in structures after adsorption at interface, it tended to aggregate (due to its high surface hydrophobicity); in contrast, glycated SG easily dissociated into subunits at the interface, but the dissociated subunits exhibited a high structural stability at the tertiary and secondary levels. The findings would be of importance not only for the development of soy protein-based Pickering stabilizers for emulsions or HIPEs, but also for extending the knowledge about the modification of emulsifying properties of proteins by glycation with carbohydrates.