ON THE NATURE OF THE ASSOCIATION OF PROTEIN IN FROZEN‐STORED COD MUSCLE

Abstract

SUMMARY Decrease in readily extractable protein IREPI paralleled by an increase in free fatty acid (FFA) occurred more rapidly in cod muscle during the first 8–10 wk of storage at – 12°C and ‐18°C than during subsequent storage. After 32 wk, FFA appeared to be approaching a lower maximum at –18°C. Aggregated protein was extracted during the period of decrease in REP. It was similar in extraction and sedimentation properties to altered protein obtained from frozen‐stored cod muscle in which FFA was formed largely during storage in ice. Increase in cohesiveness of the myofibrils was the only alteration in microstructure observed with phase microscopy. It was concluded that change to a more hydrophobic solvent environment due to FFA formation plays an important part in the rate change and in the level of FFA reached as a function of storage temperature. A model for the association process based on bonding potentials existing in the muscle on freezing and those developed during storage is presented.