Considering that gape and heave produced during the freezing of tuna fish derive from changes in the thermophysical properties of tuna fish itself during freezing, the coefficient of linear and cubical expansion of tuna meat were measured continuously between the temperature before freezing and during freezing.
The results of measurement were shown that the coefficient of thermal expansion of tuna meat displayed special temperature dependence as sudden change at the boundary temperature of freezing beginning as summarized below: 1) the coefficient of linear expansion of tuna meat were anisotropic according to the tissue and structure of the fish body, but these properties varied according to the test temperature; and 2) the coefficient of cubical expansion during freezing assumed a maximal value when tuna meat was partially frozen.
