Physicochemical Changes in Pacific Whiting Muscle Proteins during Iced Storage

No changes in actomyosin Ca 2+ ‐, Mg 2+ ‐, or Mg 2+ ‐Ca 2+ ‐ATPase activities were observed during iced storage of Pacific whiting fillets, but Mg 2+ ‐EGTA‐ATPase increased with a loss of Ca 2+ ‐sensitivity. Surface hydrophobicity of actomyosin increased substantially within 2 days, but not total sulfhydryl (SH) content. During longer storage, the SH content decreased gradually, but surface hydrophobicity remained constant. Autolytic degradation products increased in fish muscle with storage time. Myosin heavy chain (MHC) was degraded by 45% within 8 days, but no noticeable difference was observed in actin. Results indicated that autolysis may be the main cause of physicochemical changes in Pacific whiting muscle proteins during iced storage.