Interfacial assembly adjusting digestion and releasing mechanism of structured fish oil emulsions

Traditional O/W emulsions are susceptible to external environment, which lowers interfacial stability as well as digestion and release of bioactives. The construction of stable gel interface is vital for their digestion and release. The interfacial stabilization and release mechanism of structured fish oil emulsions with pH-induced myofibrillar proteins (MPs) assisted by ultrasound were investigated considering spatial conformation. Results indicated that the highest levels of surface hydrophobicity, disulfide bonds and β-sheet structure at pH 7.0 contributed to film-forming and interfacial stability. pH-ultrasonic-modified MPs effectively diffused, irreversibly adsorbed and assembled to form stable protection membranes at the gel interface, in which increasing β-sheets and molecular forces enhanced interfacial adsorption capacity. In addition, final free fatty acid (FFA) releasing rates significantly increased and decreased, which was adjusted by spatial conformation. Interfacial assembly affected protein and lipid digestion. In the stomach, β-sheets were higher at the interface at pH 7.0 than at pH 3.0 and 9.0, indicating that steady-state conformation and stable gel interface reduced digestibility. For intestinal digestion, high β-sheets, hydrophobic force as well as disulfide bonds delayed FFA release. The stable spatial conformation enhanced interfacial stability and retarded intestinal digestion. Hence, the study can lay the foundation for developing low-fat and high-nutrition meat products with EPA and DHA.