In this work, different thermal aggregation behaviors of soy β-conglycinin and glycinin at pH 7.0 were characterized with size exclusion chromatography and low-angle light scattering. Limited aggregation that grew via the consumption of "monomers" was detected in β-conglycinin, forming soluble aggregates. For glycinin, the association between the aggregates that led to the appearance of insoluble materials was observed. Heated with β-conglycinin, the assembly between the glycinin aggregates was terminated and its solubility was recovered. The structure of the soluble and insoluble aggregates was analyzed by small-angle X-ray scattering and dynamic light scattering. Unlike the β-conglycinin soluble aggregates that possessed limited size and less compact conformation, particles with a denser core and a less dense outer shell were found in the glycinin insoluble aggregates. Evidence is presented to reveal the transition between the soluble and insoluble aggregates and the role of β-conglycinin in the solubilization of the soy protein aggregates during heating.

This paper describes the successful preparation of a protein-based Pickering emulsion, with superior stability against both coalesence and creaming, through a novel strategy of facilitating the formation of protein particles and small molecular weight surfactant complexes; these complexes are able to overcome multiple challenges including limited solubility, poor diffusive mobility, and low interfacial loading. Soluble complexes of water-insoluble corn protein, zein colloidal particles, and surfactant sodium stearate (SS) were fabricated by simple ultrasonication. Gel trapping technology combined with SEM was applied to characterize the adsorbed particles monolayer at the oil-water interface; results revealed an enhanced adsorption and targeted accumulation of zein particles at the interface with the increase of SS concentration. Partial unfolding of zein particles modified by SS above its critical complexation concentration triggered the aggregation and close packing of particles at the oil-water interface and endowed a steric barrier against the coalescence of oil droplets. Moreover, protein-based oil gels without oil leakage were obtained by one-step freeze-drying of the zein-stabilized Pickering emulsions, which could be developed to a viable strategy for structuring liquid oils into semisolid fats without the use of saturated or trans fats.

The present investigation aimed to expand the knowledge of the in vitro bioaccessibility of fatty acids and tocopherol from natural soybean oil body emulsions stabilized with different concentrations of ι-carrageenan. Several physicochemical parameters including proteolysis of the interfacial layer, interfacial composition, and microstructure were evaluated with regard to their impact on the bioaccessibility of fatty acids and tocopherol. Results from simulated human digestion in vitro indicated that the bioaccessibility of total fatty acids and tocopherol decreased (62.7-8.3 and 59.7-19.4%, respectively) with the increasing concentration of ι-carrageenan. During the in vitro digestion procedure, ι-carrageenan affected physicochemical properties of the emulsions, thereby controlling the release of fatty acids and tocopherol. These results suggested that soybean oil body emulsions stabilized with ι-carrageenan could provide natural emulsions in foods that were digested at a relatively slow rate, the important physiological consequence of which might be increasing satiety.

A lipophilic protein nanoparticle (LPP) was fabricated by ultrasonication of the soy lipophilic protein (LP), which contains hydrophobic proteins and phospholipids. This LPP (Rh = 136 ± 0.8 nm, ζ-potential = -20 mV, pH 7.0) had an improved dispersibility and acted as an emulsifier. The oil/water (O/W) emulsion stabilized by this LPP exhibited superior physical stability over long-term storage (8 weeks), during a stress storage test (200 mM NaCl addition and heating at 90 °C), and in the presence of Tween 20 (1.0-4.0 wt %), in contrast to those emulsions stabilized by β-conglycinin and glycinin. Langmuir-Blodgett method and interface pressure determination revealed that LPP formed rigid and rough granular film at air/water interface. The excellent stability of emulsions stabilized by LPP highlights the synergic effect between hydrophobic proteins and phospholipids. These findings suggest that the complexes of hydrophobic protein aggregates and biosurfactant could form a stable interface which could be developed into a novel strategy to fabricate a stable food emulsion.

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