Abstract: To investigate the effects of ultra-high pressure (UHP) treatment and vegetable oil addition on its heat-induced gel properties, rabbit myosin was subjected to UHP treatments (10 ℃/2 min) at different pressure levels (100, 150 and 200 MPa), and then mixed with different amounts (0%, 10%, 20% and 30%) of soybean oil and phosphate buffer to prepare emulsion systems, whose heat-induced gelation was carried out at a programmed heating rate of 1 ℃/min. Myosin not treated by UHP served as control. The storage modulus G’, loss modulus G”, gel strength, water-holding capacity (WHC), microstructure and relaxation time spectra of heat-induced myosin gels were measured by rheometer, texture analyzer, scanning electron microscope (SEM) and low-field nuclear magnetic resonance spectroscopy (NMR). The results showed that compared with the control group, the storage modulus, loss modulus, gel strength and WHC of heat-induced myosin gels were increased significantly by high pressure treatment and the addition of soybean oil. SEM revealed that the three-dimensional network structure became denser and more compact. The NMR analysis showed that the relative content of free water in the gel matrix gradually decreased with an increase in pressure, and the degree of proton binding of immobilized water and the relative content of bound water significantly increased. Under the same pressure, the G’, G”, gel strength and WHC increased with increasing addition of soybean oil, showing significant differences among addition levels (P < 0.05). The 200 MPa + 30% soybean oil group had the best heat-induced gel properties. Therefore, appropriate high-pressure treatment combined with the addition of soybean oil enhanced the interaction between protein and fat, and changed the microstructure and water distribution state and consequently gel properties such as rheological properties, texture and WHC of heat-induced myosin gels, which played a positive role in improving the functional properties of heat-induced rabbit myosin gels.

Key words: ultra-high pressure; myosin; vegetable oil; gel; water-holding capacity