DYNAMIC RHEOLOGICAL MEASUREMENTS ON HEAT-INDUCED PRESSURIZED ACTOMYOSIN GELS

The heat-induced gelation of actomyosin (or natural actomyosin) treated with high pressure was investigated by dynamic rheological measurements. When actomyosin at 0.6 M KCl and pH 6.0 was subjected to a pressure of 150 MPa for 5 min, the dynamic rheological behavior during heat gelation showed a pattern similar to that of myosin. That is, the rheological transition in the 46-53-degrees-C range induced by the presence of F-actin disappeared. The storage modulus (G') of pressurized actomyosin at 80-degrees-C was almost double that observed in unpressurized actomyosin. In 0.2 M KCl at pH 6.0, where unpressurized actomyosin forms a very weak heat-induced gel, pressurized actomyosin formed a firm heat-induced gel having higher G' value than either pressurized or unpressurized actomyosin at 0.6 M KCl. The gel of pressurized actomyosin at 0.2 M KCl also resembled that of pressurized myosin at 0.2 MKCl in the dynamic rheological behavior. The remarkable increase in the storage modulus of pressurized actomyosin at low and high KCl concentrations seemed to arise from pressure-induced denaturation of actin in actomyosin. These results suggest that high hydrostatic pressure technology is potentially useful for improvement in the functional property (e.g., gel-forming ability) of muscle proteins.