High-pressure induced structural modification of porcine myofibrillar protein and its relation to rheological and emulsifying properties

Here, we investigated the effects of high-pressure homogenization (HPH) on the physicochemical, rheological, and emulsifying properties of myofibrillar proteins (MFPs). The mean particle size of MFPs treated by HPH with different pressures (0-150 MPa) decreased from 886.0 +/- 120.2 nm to 172.6 +/- 13.7 nm with increasing HPH pressure. In addition, more uniform and homogeneous protein particles were obtained as the HPH pressure was increased. In SDS-PAGE, the band intensities of high molecular weight proteins (200 kDa) decreased and the intensities of some of the smaller molecular fractions (70-120 kDa) increased when the MFPs were subjected to HPH treatment at more than 60 MPa owing to the fragmentation of high molecular weight proteins, such as myosin heavy chains. The surface hydrophobicity of MFPs increased with increasing HPH pressure owing to the exposure of buried hydrophobic groups by protein unfolding. In the rheological study, the MFP dispersions exhibited shear thinning fluid behavior, but the MFP dispersion homogenized at high pressure (120-150 MPa) presented close to Newtonian fluid behavior with low viscosity. The emulsifying activity (EA) and emulsion stability index (ESI) of MFPs improved with increasing HPH pressures. The MFPs treated with HPH at different pressures were used for o/w emulsion preparation, and their dispersion stabilities were investigated during storage. The emulsion systems stabilized with MFPs pressurized at more than 60 MPa showed comparatively less cream formation in the top layer, indicating high dispersion stability.