Effects of polyphosphates on dispersion state of protein in Alaska pollack [Theragra chalcogramma] frozen surimi [minced fish meat]

For clarifying what dispersion state the proteins assume in Alaska pollack frozen surimis, effects of polyphosphates and of pH, ionic strength and Mg2+ on dispersion state of proteins were examined by phase contrast microscopy and electron microscopy. Frozen surimi and carp myofibril were homogenized with various dispersion media, and the dispersion states of proteins in the resultant homogenates were compared with respect to the effects of the medium composition. The pH of the dispersion media was found to affect the dispersion state of proteins, while ionic strength of polyphosphates did not affect the dispersion significantly. The ionic strength of polyphosphates, low or high, was not found to increase the effect of polyphosphates to cause dissociation of actin and myosin, resulting in occurrence of myosin-poor actomyosin filaments and myosin free F-actin filaments. Based on the facts obtained, it was estimated that actin and myosin in the frozen surimi exist in the state of myofibrillar structure.