Study on the gelling properties and mechanism of the grass carp surimi induced by ultra- high pressure

Effect of different pressures( 100 ~ 500 MPa /15 ~ 60min) on the gelling properties and mechanism of gels from the grass carp surimi were investigated and compared with heat- induced surimi gels. According to the results,surimi gels induced by pressure above 400 MPa possessed higher gel- strength and TPA than surimi gels induced by heat treatment.Besides,the surimi gels induced by pressure had well- distributed structure and higher whiteness and brightness,but lower hardness.The content of TCA- soluble peptide of pressure- induced gels were lower than that of heat- induced gels and the higher the pressure,the lower the content of TCA- soluble peptide,suggesting endogenous protease in surimi which could result in gel- weakening might be inactived by high pressure.Higher solubility of surimi gels treated with pressurization were observed,indicating that endogenous transglutaminase might be inactived under pressurization,which resulted in the decrease of ε-( γ- glutamyl) lysine linkage formation.The appearance of large molecule( MW > 200ku) was probably due to the formation of disulfide bond through oxidation of SH group or disulfide interchanges. The above results demonstrated that ultra- high pressure could improve the gelling properties of grass carp surimi when compared to heat- induced surimi gels,and there existed differences in mechanism of surimi induced by ultra- high pressure and heat- induced surimi gels.