Pressure-induced changes of silver carp (Hypophthalmichthys molitrix) myofibrillar protein structure

Silver carp (Hypophthalmichthys molitrix) is one of the major species of freshwater fish in China. Modification of myofibrillar proteins induced by high pressure processing (HPP) has been investigated at pressures ranging from 200 to 500 MPa for 10 min at 20 A degrees C. Influence of high pressure on conformational changes of myofibrils was studied by means of differential scanning calorimetry (DSC), surface hydrophobicity measurement, ultraviolet absorption spectra and second-derivative spectroscopy, intrinsic spectrofluorimetry, Raman spectroscopic analysis and circular dichroism (CD). DSC analyses revealed that the conformational stability of myofibrils is reduced to different extents when they are exposed to a pressure over 200 MPa. More sulfydryl groups as well as hydrophobic regions and amino acid residues which had ultraviolet absorbance had been found significantly after HPP (a parts per thousand yen300 MPa). Changes in the Raman spectra were interpreted as the occurrence of secondary structural changes in pressure-induced myofibrillar proteins. CD analysis results demonstrated that alpha-helix was destroyed after processed at 400 MPa for 10 min. The results implicated that HPP can be used as a possible means of improving the functional properties for growing demand for healthier fish products.