Effects of high pressure processing on the thermal gelling properties of chicken breast myosin containing κ-carrageenan

The effects of high pressure processing (HPP) (0–400 MPa for 10 min, 0–20 min under 300 MPa) on the water holding capacity (WHC) and gel strength of chicken breast myosin containing 0.225% κ-carrageenan (W/V, 2.25 g/L relative to myosin solution) (myosin-K) and the thermal gelling mechanism were investigated. The results revealed that HPP at 100–400 MPa could significantly increase the WHC of myosin-K gels while decreasing the gel strength (P < 0.05). The turbidity, surface hydrophobicity and reactive sulfhydryl contents of the pressurized myosin-K increased significantly at 200–400 MPa (P < 0.05). Dynamic rheological measurements indicated that the thermal gelling ability of the pressurized myosin-K matrix gradually decreased as the pressure increased (100–400 MPa). Low-field nuclear magnetic resonance data suggested that HPP at 100–400 MPa might shorten the water relaxation time of the gel. The Fourier transform infrared spectroscopy data revealed that the hydrogen bonding interactions in the gels might weaken when subjected to 100–300 MPa but could be enhanced at 400 MPa. The scanning electron microscopy images revealed that HPP (300 MPa, 10 min) produced a dense, networked myosin-K gel structure with small cavities and thin cross-linked strands. Moreover, pressure levels were responsible for the above results. The protein in myosin-K could denature, unfold and aggregate under HPP (100–400 MPa), thus decreasing the thermal gelling ability of myosin-K matrix. The high WHC of the pressurized myosin-K gel was attributed to the enhanced hydrogen bonding and hydrophobic interactions, as well as the uniform and dense networked structure; the low gel strength might be ascribed to the low thermal gelling ability of pressurized myosin-K.