Dsc determination of glass transition temperature on sea bass (dicentrarchus labrax) muscle: Effect of high-pressure processing

Abstract

Differential scanning calorimetric determination of glass transition temperature in the freeze-concentrated matrix (T′ g) of sea bass muscle was optimized. Conventional and modulated differential scanning calorimetry (DSC) techniques (using diverse cooling/heating rate and modulation parameters) and effect of an annealing step (-30, -20, or -15°C, 30min) were assayed. Transition was more evident using conventional DSC assays, cooling/heating rate: 10°C/min, annealing step at -20°C. A T′ g value of -15.2 ± 0.3°C was observed for sea bass fresh muscle. This method was chosen for T′ g determination on high-pressure (HP) treated and pressure shift freezing (PSF)-stored at -20°C-sea bass muscle. Thus, in both cases, transition at -15°C was less evident as a function of the pressure level applied, being very difficult to detect after treatment at 400 and 600MPa. It was observed that T′ g values were shifted to slightly higher temperatures (around 1°C higher) after HP treatment at 400 and 600MPa. The present work constituted a first approach to the study on the effect of HP on the glass transition of a complex food matrix, giving useful information about stability of the frozen food.