Property and structure changes of myofibril protein in pork treated by high pressure combined with heat

The effects of myofibril protein in pork treated by high hydrostatic pressure combined with heat were investigated. The solubility of myofibril protein significantly increased up to 400 MPa but since then began to decrease up to 600 MPa. The best solubility was shown under all pressure at 35 ℃ and the lowest solubility was observed at 55 ℃. The carbonyl group value, disulfide bond and surface hydrophobicity exhibited pressure-dependent increase in the same manner. Particle size decreased up to 400 MPa and then increased up to 600 MPa, but the turbidity always reduced. The increase of intrinsic fluorescence intensity with red shift and decrease of absorbance around 278 nm with blue shift indicated that protein unfolding and exposure of hydrophobic amino acid occurred with increase of pressure. The second derivative infrared spectra and curve fittings suggested that high pressure induced reduction of β-sheet structures, enhancement of α-helix and random coil and β-turns segments, which was opposite to the effects of temperature. Emission scanning electron microscope assay further demonstrated protein unfolding and aggregation process induced by different pressure and temperature. The data suggested that cooperative effect of moderate pressure and temperature could improve physical-chemical and processing properties of meat.