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.

Impacts of fat types and myofibrillar protein on the rheological properties and thermal stability of meat emulsion systems.

Studies have shown the effects of fat or oil types and myofibrillar protein on meat emulsions. In this study, fat extracted from pork, beef, chicken, and duck, as well as corn oil, was used to emulsify the extracted porcine myofibrillar protein. We evaluated the thermal and rheological properties, emulsion stability, texture profiles, fatty acid compositions, and microstructures of these meat emulsions. Meat emulsions containing animal fat had lower emulsion stability and better thermal stability, rheological properties, and hardness than those containing oil. The ratio of polyunsaturated fatty acids in the meat emulsion containing corn oil was the highest, followed by duck, chicken, pork, and beef fat emulsions. Of the animal fat emulsions, chicken might be the best fat source when emulsifying porcine protein because of the high thermal and emulsion stability, rheological properties, and fatty acid composition of the emulsion and well-distributed fat particles in it.

The use of atmospheric pressure plasma-treated water as a source of nitrite for emulsion-type sausage.

We investigated the possible use of atmospheric pressure plasma-treated water (PTW) as a nitrite source in curing process. Emulsion-type sausages were manufactured with PTW, celery powder containing nitrite, and synthetic sodium nitrite at a concentration of nitrite ion 70mgkg(-1). In terms of sausage quality, there were no noticeable effects of PTW on the total aerobic bacterial counts, color, and peroxide values of sausages compared with those of celery powder and sodium nitrite throughout 28days of storage at 4°C. Sausage with added PTW had lower concentrations of residual nitrite compared to those of added celery powder and sodium nitrite during the storage period (P<0.05). The sensory properties of PTW-treated and sodium nitrite-treated sausages were not different, whereas the sausage with added celery powder received the lowest scores in taste and acceptability. From the results, it is concluded that PTW can be used as a nitrite source equivalent to a natural curing agent.