Changes in Soluble Protein and Actomyosin during Chilled and Frozen Storage of Tilapia (Oreochromis mossambicus)

Abstract

The changes in characteristics of protein from tilapia
(Oreochromis mossambicus) as a function of storage in
ice and frozen condition were evaluated. The results
showed that actomyosin constituted about 57% of
total soluble protein which decreased by 4% after
12 days of storage in ice due to insolubilisation.
During frozen storage, however, the actomyosin
decreased by 5% after one month of storage at -20°C
and by 12% in 4 months. The Ca2+ATPase activities
decreased by 43% after 4 days of storage in ice and
by 69% after 2 months frozen storage. Mg2+ and
EDTA ATPase activities were not significantly
altered during ice storage but showed a decrease
during frozen storage. Total sulfhydryl groups of
actomyosin fraction were less (23 μM SH g-1 AM)
initially and then increased. Turbidity of total
soluble protein increased by two folds during ice
and frozen storage. SDS-PAGE pattern of protein
substantiates the insolubilisation of proteins during
storage in ice and at _20°C.