An optimized approach to recovering O/W interfacial myofibrillar protein: Emphasizing on interface-induced structural changes

Abstract

The structures of proteins on the interface of oil-in-water emulsions that influence the interfacial film strength are significant to the emulsions stabilization. It is expected that the interfacial protein could be fully recovered based on the competitive displacement of low-molecular surfactant, when the recovery approach and relative parameters are optimized, so that the structural properties of interfacial proteins can be evaluated to clarify their adsorption behaviour and film forming mechanism. In the present study, an optimized and efficient approach to fully recovering interfacial myofibrillar protein (MP) was established by optimizing protein concentration, Tween-20 concentration and different accelerating treatments (agitation or freeze-thawing), for interface-induced structural changes analysis. It was found that the interfacial MP in 2.5 mg/ml protein-stabilized emulsion could be fully recovered in 96 h with 4% (v/v) Tween-20 under agitation treatment. Freeze-thawing treatment could accelerate the desorption process by which interfacial MP in the above emulsion could be fully recovered in 3 cycles with 2% or 3% (v/v) Tween-20 but might cause damage to the MP structure. Based on the established recovery approach, it was concluded that the tertiary structure of interfacial MP unfolded to expose hydrophobic residue branch for interfacial adsorption and film formation, which further caused aggregation of desorbed MP through hydrophobic interaction. While the α-helix decreased due to interface-induced denaturation and the β-sheet increased to improve protein-protein interaction on the interface. These results provided an optimized strategy to analyze interfacial protein structure.