State diagram of tuna meat: Freezing curve and glass transition

The state diagram of tuna meat was developed by measuring and modeling its glass transition temperatures and freezing points. Fresh tuna meat was dried in a freeze drier to vary the moisture content from 73.3% to 6.0% (wet basis). Small deformation dynamic oscillation was employed to identify changes in the viscoelastic properties of tuna as a function of solids. Cooling curve method was used to measure the freezing point and end point of freezing. The state diagram yielded maximally freeze-concentrated solutes at 61% solids with the characteristic temperature of glass formation being -54.2 °C. The freezing curve and glass transition lines were developed using the Clausius-Clapeyron equation adjusted with unfreezable water and Gordon-Taylor model, respectively.