PROPERTIES OF ACTOMYOSIN ISOLATED FROM COD (GADUS-MORHUA) AFTER VARIOUS PERIODS OF STORAGE IN ICE

Natural actomyosin was isolated from cod (Gadus morhua L) stored in ice for up to 28 days. The gelling properties, apparent viscosity, Ca2+-ATPase activity and component protein composition by sodium dodecyl sulphate (SDS) electrophoresis were determined for each preparation of natural actomyosin. Thc apparent viscosity, protease activity, trimethylamine (TMA) content and pH of the fish muscle were also determined. The results showed that the apparent viscosity and Ca2+-ATPase activity tended to decrease slightly during ageing of thc fish in ice, whereas some of the gelling properties showed a maximum between 3 and 6 days of storage. However, there was no change in the apparent viscosity of the muscle as a whole even after the fish were considered to be stale according to the TMA values. The ratio of myosin heavy chain to actin in the actomyosin changed with thc time of storage of the fish, being highest at 3 days when gelling properties were maximal and decreasing progressively thereafter.