Intrinsic-extrinsic protein complexes as biomimetic interfacial barriers in artificial oil body systems: 1H NMR-guided mechanistic insights into oxidation resistance.
Oct 2026· Food Research International· Vol 242 Pt 1, pp.
119816
· 0 citations· 51 references
Medicine
Abstract
Oil bodies (OBs) are native lipid storage organelles in plant seeds that form highly stable natural emulsification systems stabilized by intrinsic proteins (IPs). However, the poor water solubility of IPs limits their practical application in food systems. Herein, a stable two-protein complex was constructed by the simultaneous folding and co-assembly of IPs with extrinsic proteins (EPs). The co-assembly significantly improved the dispersibility of IPs and reduced their particle size, yielding a nanocomposite with a hydrophobic core that formed an OB-inspired interfacial barrier partially mimicking the interfacial composition and protective function of natural OBs, thereby enabling the formation of stable artificial oil body (AOB) emulsions under mechanical force. Structural analyses revealed that EP addition modulated the secondary and tertiary structures of the protein complex in a concentration-dependent manner, inducing partial unfolding and structural rearrangement, while stabilization was primarily governed by hydrogen bonding and hydrophobic interactions. Turbiscan Stability Index and microstructural analyses demonstrated that the composite rapidly adsorbed at the oil-water interface, forming a dense and robust interfacial film that effectively suppressed droplet aggregation through steric hindrance and electrostatic repulsion, thereby enhancing emulsion stability. Notably, 1H NMR results showed that the interfacial barrier formed by IPs and EPs at a 1:1 ratio markedly reduced lipid oxidation by inhibiting both primary and secondary oxidation pathways at the interface. Overall, this study establishes a facile biomimetic strategy for constructing interfacial barrier-based anti-oxidation system with promising applications in food emulsions.
Despite the advantageous functional properties of soybean protein isolate (SPI), its inherent conformation is susceptible to environmental influences, thereby limiting its utility in food systems. This work investigated the effect of mass ratio between soybean protein isolate (SPI) and citrus pectin (CP) on the structure and functionality of composite particles. Results showed that a 1:1 SPI-to-CP ratio produced the smallest particle size (280.13 nm) and the best dispersion stability. This ratio also significantly improved emulsifying activity (EAI: 54.80 m2/g) and emulsion stability (ESI: 105.91%), while enhancing the adsorption capacity of interfacial proteins. The composite particles were driven by hydrogen bonding, hydrophobic interactions, and electrostatic forces. These interactions promoted the conformational unfolding of SPI, increasing surface hydrophobicity and facilitating a structural transition from α-helix to β-sheet. This work provides fundamental insights for designing food-grade particles with enhanced interfacial activity and stability.
Yang Yang, Xiao-ning Wang, Yue Xu et al.· Food Chemistry· 0 citations
Omega-3 polyunsaturated fatty acids are highly susceptible to oxidation, limiting the shelf life and sensory quality of omega-3-fortified foods. Herein, wheat gluten peptide nanoparticles (WGPNs) with coupled emulsifying and antioxidant functions were produced by sequential pepsin-trypsin hydrolysis. LC-MS/MS showed a peptide pool (1-4 kDa) enriched in Gln/Pro, featuring hydrophobic motifs and C-terminal Lys/Arg residues that confer surfactant-like behavior. WGPNs formed spontaneously in aqueous media, mainly driven by hydrophobic association and hydrogen bonding, with concentration-dependent β-sheet formation and a critical aggregation concentration of ∼0.17 mg/mL. Above this threshold, WGPNs exhibited enhanced radical-scavenging activity and colloidal stability across a wide ionic-strength range. Interfacial measurements demonstrated rapid adsorption of WGPNs at the oil-water interface, reduced interfacial tension, and formation of a stable interfacial layer. Consequently, WGPNs effectively stabilized fish oil emulsions and markedly retarded lipid oxidation. This work establishes WGPNs as a clean-label, dual-function platform for protecting oxidation-sensitive lipids in food systems.
Guangxin Feng, Weiting Feng, Xiaowen Feng et al.· Journal of Agricultural and...· 0 citations
The solvent effects exerted by continuous lipid matrices on nanocarrier antioxidant efficacy remain insufficiently defined. Herein, glycated pea protein isolate-curcumin nanoparticles (gPPI-CUR NPs) were engineered to elucidate their matrix-adaptive kinetic responses across frying oils with distinct saturation profiles. Protective efficacy correlated positively with lipid unsaturation, demonstrating 55.1% relative peroxide inhibition in highly unsaturated soybean oil versus 31.7% in saturated palm oil. Concurrently, the system suppressed cytotoxic aldehydes accumulation, mitigated viscosity increments, and inhibited thermal cis-to-trans isomerization. Molecular dynamics simulations elucidated this structural adaptability. The protein shell underwent conformational expansion driven by thermodynamic compatibility with linoleic acid, while the internal core maintained hydrophobic retention for ligand stability. This structural equilibrium maximized solvent-accessible surface area, increasing interfacial collision probability for in situ lipid radical scavenging. These findings generalize the dynamic balance between interfacial flexibility and core retention as a fundamental design principle for targeted lipid protection in high-stress processing.
Macadamia protein isolate (MPI) is a promising plant-based protein but its poor emulsifying functionality limits broader applications. This study investigated the interaction mechanisms between MPI and procyanidin dimer (PA2) and their synergistic effect on the stabilization of high internal phase Pickering emulsions (HIPPEs). Spectroscopic and physicochemical analyses demonstrated that MPI and PA2 formed complexes through a spontaneous binding process mainly driven by hydrogen bonding, accompanied by hydrophobic interactions. These interactions induced notable conformational changes in MPI, leading to a reduced particle size, enhanced surface charge, and modified hydrophobicity. Moreover, MPI-PA2 complexes significantly enhanced interfacial activity by efficiently adsorbing at the oil-water interface. Consequently, HIPPEs stabilized by the complexes exhibited smaller droplet sizes, improved physical stability, and superior viscoelastic properties. Overall, this work highlights the potential of MPI-PA2 complexes as a promising bio-based emulsifier and functional delivery system, providing new insights into the value-added utilization of plant proteins in food applications.
Understanding the interaction between proteins and polysaccharides is fundamental for designing food structures, yet the potential of ultrasound to precisely modulate these interactions has not been systematically reviewed. This review critically examines the mechanistic role of acoustic cavitation and its associated physical and chemical effects in driving the formation of protein-polysaccharide complexes. We highlight how ultrasound-induced shear forces, micro-turbulence, and free radical generation not only accelerate covalent conjugation via the Maillard reaction but also reinforce non-covalent forces, such as hydrophobic interactions, hydrogen bonding, and electrostatic contacts, by inducing conformational changes in biopolymers. These ultrasound-mediated structural modifications result in significantly improved techno-functional properties, including solubility, emulsification, and foaming performance. We further discuss how these enhanced complexes are enabling innovations across emulsion stabilization, gel fabrication, bioactive compound encapsulation, and edible film formation. Finally, we identify critical research priorities, particularly the correlation between ultrasonic parameters and molecular interaction mechanisms, the structural characterization of conjugates, and the evaluation of their safety for food applications. By providing a comprehensive framework that bridges fundamental sonochemistry with food material science, this review positions ultrasound as a versatile and sustainable tool for engineering advanced food systems.
Qiufang Liang, Panpan Cao, Yunxia Du et al.· Ultrasonics sonochemistry· 0 citations
The transition toward sustainable food systems has increased interest in plant proteins as alternatives to animal-derived proteins due to their lower environmental impact, including reduced greenhouse gas emissions, land use, and resource demand. However, their broader application is constrained by structural characteristics that limit solubility, interfacial behaviour, digestibility, and sensory performance. Many plant proteins exhibit compact globular structures stabilized by strong intermolecular interactions, restricting their functionality in complex food systems. These structural constraints operate across a hierarchy of scales, from the molecular conformation of secondary and tertiary structures to the micro- and macro-structural organisation of protein aggregates, interfacial films, and gel networks, and it is this multiscale organisation that ultimately governs functional performance in complex food matrices. Non-thermal processing technologies, namely, ultrasound, pulsed electric fields (PEF), and cold plasma, together with the electro-thermal technique of ohmic heating, offer promising approaches for modifying protein structure without causing extensive thermal damage. These methods can induce partial unfolding, alter aggregation behaviour, and enhance the exposure of functional groups, thereby improving solubility, emulsification, and gelation properties. This review adopts an explicit multiscale framework to link molecular-level conformational changes to microstructural aggregation and macroscopic structure–property relationships. It summarizes the mechanisms, functional impacts, and industrial relevance of these technologies in plant protein processing. Building on this analysis, the review evaluates the principal technical bottlenecks, the economic and industrial scalability, and the priority directions for future research on non-thermal and electro-thermal processing of plant proteins.
Noorain Majeed, Kaiser Younis, Owais Yousuf· Frontiers in Soft Matter· 0 citations