Soy glycinin as food-grade Pickering stabilizers: Part. III. Fabrication of gel-like emulsions and their potential as sustained-release delivery systems for β-carotene

Formulation of food-grade Pickering emulsions has attracted growing attention in the food and drug fields, due to their promising potential as novel delivery systems for lipophilic bioactive ingredients. The present work reported that a kind of gel-like Pickering emulsions stabilized by heat (at 100 °C)-treated soy glycinin (SG; a major globulin in soy proteins), fabricated by modulating protein concentration (c) and/or oil fraction (ϕ), can perform as sustained release delivery systems for β-carotene. Rheological measurements and microstructural observations indicated that increasing c and/or ϕ resulted in a progressive strengthening of gel-like network in the emulsions stabilized by heated SG, which was closely related to a high percentage of proteins adsorbed at the interface, or entrapped within the network. In contrast, no distinct gel formation was observed for the emulsions stabilized by unheated SG. In vitro intestinal digestion experiments showed that for the emulsions (stabilized by unheated or heated SG) without distinct gel formation, the release behavior of β-carotene was mainly determined by droplet size, while in the case of gel-like emulsions by heated SG, the gel-like network formation greatly slowed down the β-carotene release (irrespective of the applied c and/or ϕ). All the test emulsions did not suffer a distinct degradation of β-carotene over the whole digestion process. The findings are of great interest for the development of novel sustained delivery systems for lipophilic components, based on Pickering emulsions stabilized by a kind of protein-based particle stabilizers.