Comparative investigation of three types of surfactants on the co-stabilization behavior of myofibrillar protein emulsions under low-salt conditions

This study systematically investigated the effects of three small-molecule surfactants, Tween-20, sodium dodecyl sulphate (SDS), and soy lecithin (SL), on the structure and emulsifying properties of myofibrillar protein (MP). All three surfactants altered MP conformation and reduced surface hydrophobicity via non-covalent interactions. Tween-20 acted primarily through hydrophobic interactions, whereas SDS combined electrostatic and hydrophobic binding, modifying surface charge. SL functioned through hydrogen bonding and hydrophobic interactions with charge shielding effects. With increasing surfactant concentration, the Tween-20-treated emulsion exhibited gradual reductions in particle size to 522.43 nm and ζ-potential to –2.78 mV. The SDS-treated emulsion showed an initial decrease in particle size to 1 562 nm at 0.5%, followed by an increase to 4 315 nm at 1.0%, with ζ-potential decreasing to –26.0 mV. The SL-treated emulsion displayed decreasing trends in both particle size to 2 052.33 nm and ζ-potential to –4.85 mV. Both Tween-20 and SDS produced stable emulsions at 0.1%–0.5%; at 1.0%, Tween-20 caused slight phase separation, whilst SDS caused obvious phase separation. SL exhibited phase separation at all concentrations. Molecular docking confirmed distinct binding modes: Tween-20 bound through hydrophobic interactions, whereas SDS and SL formed hydrogen bonds with specific amino acid residues. These findings clarify surfactant stabilisation mechanisms in MP emulsions, guiding surfactant selection for meat processing.