Interfacial properties of plant protein-flavonoid hybrid particles: towards influencing in vitro gastric digestion of emulsions.

Effect of Gelation pH on the Entrapment and In Vitro Gastrointestinal Digestion of Plant Proteins in Alginate Beads

The development of plant protein-based delivery systems is often limited by poor stability and low retention efficiency under gastrointestinal conditions. This study investigated how pH (4 and 7) during external gelation influences the physicochemical properties, entrapment efficiency (EE), and in vitro gastrointestinal behaviour of alginate beads loaded with hemp protein concentrate (HPC), pea protein concentrate (PPC), or soy protein isolate (SPI). Zeta potential and Fourier transform infrared (FTIR) analyses suggested that at pH 4, the charge profiles of plant proteins favoured electrostatic association with anionic alginate, which was associated with higher EE values, with HPC achieving the maximum of 89.5% at pH 4. Conversely, at pH 7, electrostatic repulsion between biopolymers was associated with reduced EE. During in vitro digestion, beads formulated at pH 4 exhibited greater protein release than those prepared at pH 7, consistent with the expansion of the polymeric network under intestinal conditions. Size exclusion chromatography showed that released proteins underwent extensive proteolysis, generating low-molecular-weight fractions smaller than 300 Da. These results indicate that gelation pH is a relevant processing parameter for modulating protein retention and the extent of protein release of simulated digestion in alginate-based systems, with potential applications in protein-enriched food formulations.

Lutein-loaded Pickering high internal phase emulsions stabilized by protein-polyphenol-polysaccharide self-assembled particles: Interfacial behavior, in vitro/in vivo stability and release.

This study aimed to encapsulate lutein in high internal phase emulsions (HIPEs) stabilized by quinoa protein isolate (QPI), tannic acid (TA), and high-methoxy pectin (HMP) particles at varying concentrations to address its low delivery efficiency and bioavailability. High concentrations (3%-4%) of QPI-TA-HMP particles demonstrated strong interfacial adsorption, forming thick viscoelastic films around oil droplets. These interfacial properties imparted controllable rheological behaviors, textural characteristics, and stable 3D-printing scaffolds to the lutein-loaded HIPEs, achieving an encapsulation efficiency of 81.65 ± 2.36%. In vitro tests indicated that HIPEs enhanced lutein's resistance to storage, heat, and UV exposure while facilitating sustained intestinal release, resulting in a lutein bioaccessibility of 43.73 ± 1.44%. In vivo experiments further demonstrated that the HIPEs delivery system maintained high lutein concentrations in the small intestine, cecum, and colon, thereby significantly enhancing lutein accumulation in systemic circulation. These findings provide new insights into enhancing lutein's stability, delivery performance, and bioavailability.

Reconstituted soybean protein isolate emulsion gel induced by transglutaminase: structure, stability, and application in quercetin delivery.

The reconstituted soybean protein isolate (SPI) was constructed by adjusting the ratios of its main components, namely lipophilic protein (LP), glycinin (11S), and β-conglycinin (7S). The effects of different LP/11S/7S ratios on stability and delivery function of transglutaminase-induced emulsion gel were investigated. The reconstituted SPI with a high proportion of LP had lower particle size, higher surface charge and excellent interface affinity, which helped to strengthen microstructure of emulsion gel. The reconstituted SPI emulsion gels exhibited higher viscoelasticity and water holding capacity, and the freeze-thaw, thermal and pH stability were enhanced. Furthermore, reconstituted SPI emulsion gels increased encapsulation efficiency of quercetin to 92.2%, which facilitated its chemical stability and promoted bioaccessibility to 61.78%. Therefore, reconstituted SPI emulsion gel can be improved by regulating ratios of LP, 7S and 11S, thus promoting quercetin delivery, which provides a theoretical basis for construction and application of stable SPI-based emulsion gel carriers.

Enzymatic Construction of Whey Protein-Arabinoxylan Conjugate Particles and Their Regulation on the Stability and Curcumin Delivery Property of High Internal Phase Pickering Emulsions

Kinetic and Oxidative Stability of Oil-in-Water Pickering Emulsions Stabilized by Lysozyme-Ferulic Acid Conjugates

The demand for ingredients with natural appeal has driven the development of multifunctional natural emulsifiers. This study aimed to synthesize covalent conjugates of lysozyme (LYS) and ferulic acid (FA) via a free radical reaction and investigate their application in stabilizing soybean oil Pickering emulsions. Conjugate formation was confirmed by SDS-PAGE and FTIR and UV-Vis spectroscopy, indicating alterations in the protein’s tertiary structure. The LYS-FA conjugate exhibited techno-functional properties superior to native lysozyme, including higher emulsifying capacity and antioxidant activity, with inhibition values above 74% for both DPPH and ABTS. Furthermore, in vitro digestion studies demonstrated that conjugation protected FA from degradation in the gastric phase. Oil-in-water Pickering emulsions were prepared with different conjugate concentrations from 2 to 4% w/w in the aqueous phase. The formulation with 4% LYS-FA resulted in an excellent kinetic stability, showing no creaming for 8 days. Rheology revealed pseudoplastic behavior with a predominantly elastic character, where G’ was higher than G’’, suggesting the formation of a robust network at the interface. In addition to physical stability, the Pickering emulsions significantly retarded the primary and secondary lipid oxidation of the encapsulated soybean oil compared to the control, attributed to the interfacial barrier and antioxidant action formed by the conjugate. These results suggest that LYS-FA conjugates are promising candidates as emulsifiers with good techno-functional properties and antioxidant capacity for applications in the food industry.

Enhancing composite emulsion stability through electrostatic modulation of polysaccharides-whey protein isolate interactions for probiotic encapsulation.

This study investigates how electrostatic interactions between whey protein isolate (WPI) and polysaccharides (konjac glucomannan, guar gum, pectin, sodium alginate, chitosan) affect the stability and encapsulation of high-internal-phase emulsions (HIPEs, oil fraction >74%), revealing charge-driven structural and network stabilization mechanisms. The findings demonstrate that anionic WPI (pH 7.0) alone was more effective than cationic WPI (pH 4.0) in stabilizing oil-in-water HIPEs. Neutral polysaccharides enhanced emulsifying performance through viscosity-induced stabilization. While electrostatic repulsion increased ζ-potential of the complexes, thereby synergistically strengthening hydrophobic interaction-driven emulsifying activity. In contrast, excessive attraction (pectin, ζ-potential -17.0 mV) destabilized structural network through bridging or depletion flocculation, whereas moderate attraction (sodium alginate, ζ-potential -11.5 mV), facilitated the formation of stable emulsion systems. Notably, sodium alginate-WPI systems demonstrated robust stability (for 4 months) across all electrostatic conditions and offered excellent biocompatibility (<5%) and probiotic protection (>9.05 log CFU/mL). Collectively, these findings elucidate the mechanism of electrostatic tuning in stabilization of HIPEs, providing a promising approach for probiotics delivery.