DSC Determination of Glass Transition Temperature on Sea Bass (Dicentrarchus labrax) Muscle: Effect of High-Pressure Processing

Differential scanning calorimetric determination of glass transition temperature in the freeze-concentrated matrix ( $$ T_{\text{g}}^{\text{'}} $$ ) 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 $$ T_{\text{g}}^{\text{'}} $$ value of –15.2 ± 0.3°C was observed for sea bass fresh muscle. This method was chosen for $$ T_{\text{g}}^{\text{'}} $$ 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 $$T_{\text{g}}^{\text{'}} $$ 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.