Decoding Compositional and Interfacial Stability of Rice Bran Oil Bodies from Lipidomic Signatures to Nanomechanical Membrane Characterization

Rice bran oil bodies (OBs) represent underutilized natural carriers with unique compositional features. This study deciphered their interfacial stability mechanism through integrated lipidomics and nanomechanical characterization. Untargeted lipidomics identified 35 lipid subclasses, revealing triacylglyceride (65.91%) as the core lipid. A comparative analysis with commercial oil uncovered 287 significantly different lipid species and signature interfacial phospholipids, PA (33:0), PS (38:4), and PC (34:2). Unsaturated fatty acids, accounting for 82.49% of the total composition, enhanced interfacial membrane fluidity, while abundant bioactive components such as vitamin E (19.2 mg/100 g), γ-oryzanol (0.67%), and sterols (1153 mg/100 g) conferred oxidative stability. The predominance of hydrophilic amino acids facilitates colloidal stability and digestibility. Dominant interfacial proteins oleosin 16 and oleosin 18 kDa feature tripartite structural domains and demonstrated spontaneous C-terminal binding to PA/PS/PC via hydrogen bonding and hydrophobic interactions, forming a stable interfacial structure. The interfacial membrane consisted of a 7.47 nm phospholipid-oleosin monolayer and stable multilayers (66.98 nm). Atomic force microscopy with a colloidal probe confirmed superior mechanical properties compared to conventional oilseed OBs, with a stiffness of 0.0133 ± 0.0023 N/m and a Young's modulus of 92.09 ± 4.75 MPa. These findings establish the structural foundation for interfacial stability and position rice bran OBs as promising natural delivery systems.