Effect of Mild Ozone Oxidation on Structural Changes of Silver Carp (Hypophthalmichthys molitrix) Myosin

To produce high-quality surimi, we investigated the effect of ozone-induced mild oxidation on structural changes of silver carp myosin by analyzing circular dichroism (CD), intrinsic fluorescence, the sulfhydryl group, surface hydrophobicity, SDS-PAGE, and dynamic light scattering (DLS) of myosin. Mild ozone oxidation of myosin was performed by applying gaseous ozone for a short time. Results showed that the content of sulfhydryl group decreased, and carbonyl content and surface hydrophobicity increased with an increase in ozone treatment time. A red shift in the maximum wavelength of intrinsic fluorescence indicated the unfolding of oxidized myosin. Further conformational change of myosin was illustrated by CD; α-helical content decreased significantly and β-turn, β-sheet, and random coil content increased with increased ozone treatment time, which demonstrated the rearrangement of β-structure in myosin. The results from DLS and SDS-PAGE indicated that soluble oligomers or aggregates were formed by disulfide bonds under mild ozone treatment. Therefore, ozone-induced mild oxidation did not strongly alter myosin structure but promoted myosin partial unfolding, which might result in exposing more cross-linking sites for the formation of surimi gel.