Modulation of ovalbumin gel properties via liposome incorporation: Structural and mechanistic insights

The study investigated the enhancement of ovalbumin (OVA) gel properties through the incorporation of liposomes (Lip) and clarified the mechanisms responsible for these improvements, with the aim of addressing limitations in water-holding capacity (WHC), gel strength, and stability commonly observed in native OVA systems. Lip was incorporated into OVA gels at various Lip-to-OVA ratios, and Lip-OVA gel properties were evaluated and analyzed. Results demonstrated that Lip-OVA gel WHC, strength and freeze-thaw stability were significantly improved with the Lip-to-OVA ratio increasing. SEM micrographs revealed a denser and more homogenous network structure in Lip-OVA gels compared to native OVA gels. FTIR and fluorescence spectroscopy indicated that hydrogen bonding, hydrophobic interactions, and protein conformational rearrangements were pivotal to gel enhancement. Surface hydrophobicity and contact angle measurements further confirmed increased exposure of hydrophobic groups and supported conformational rearrangement. The increase in free sulfhydryl content and the change in CD spectra indicated that OVA structure shifted towards a decrease in α-helix content and an increase in β-sheet content, leading to the unfolding of OVA and promoting intermolecular cross-linkage. The primary forces contributing to the improved gel structure were identified as hydrophobic interactions and disulfide bonding, with ionic and hydrogen bonds playing a supportive role. Furthermore, it was observed that the gel stabilization shifted toward hydrophobic interactions over disulfide bonding after incorporation with Lip. These findings provide mechanistic insight into how Lips modulate protein gel structure and function, offering a strategy to design protein-based gels with enhanced texture, stability, and potential for advanced food applications.