State diagram of tuna meat: freezing curve and glass transition

Abstract

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.