Effect of l-histidine and l-lysine on the properties of oil-in-water emulsions stabilized by porcine myofibrillar proteins at low/high ionic strength

The effects of l-histidine (His) and l-lysine (Lys) on the emulsifying and interfacial properties of porcine myofibrillar proteins (MPs) at low/high ionic strength were investigated to improve physical stability of MPs emulsion at low ionic strength. Results showed that His and Lys increased emulsion stability index, and decreased creaming index at low ionic strength, but caused no significant changes in both indexes at high ionic strength. Additionaly, His and Lys increased the emulsifying activity and apparent viscosity, but decreased the droplet size at both ionic strength. His and Lys also promoted the diffusion of MPs and increased the interfacial pressure. Meanwhile, the interfacial loading of MPs was increased (p < 0.05) by 16.07% and 12.79% at low ionic strength, and by 8.85% and 8.24% at high ionic strength in the presence of Lys and His, respectively. Raman spectra revealed that the α-helix content of MPs was decreased (p < 0.05) by 5.05% and 11.79% at low ionic strength, and by 12.14% and 7.23% at high ionic strength in the presence of Lys and His, respectively. In summary, His and Lys enhanced the stability of MPs emulsion at low ionic strength via changing the structure and interfacial behaviour of MPs.