Effect of Pressure Assisted Thawing on sea bass (Dicentrarchus labrax L.) quality

TIRONI, V., DE LAMBALLERIE, M. AND LE BAIL, A

Cordoba

Congreso; Congreso Internacional de Ciencia y Tecnología de los Alimentos 2006; 2006

Agencia Cordoba Ciencia

The influence of a pressure assisted thawing process PAT (200 MPa, 20 °C, 20 min) on sea bass muscle was evaluated, in comparison with a conventional thawing process AT (air-blast, 4 °C, air speed: 4 m/sec). Sea bass muscle was air-blast frozen (-30 °C, air speed: 4 m/sec) and thawed after storage at -15 °C (0, 1, 3 and 5 months). Muscle proteins alterations (differential scanning calorimetry DSC, sarcoplasmic and myofibrillar proteins extractability –SPE and MPE, respectively); water holding capacity WHC of raw and cooked muscle, and color, were analyzed. PAT process produced a partial denaturation of myosin and sarcoplasmic proteins, as well as extractability loss of the sarcoplasmic and myofibrillar fractions in the non stored samples (t = 0); meanwhile, the conventional thawing process had not effects on the protein structures. However, after frozen storage, air-blast thawed muscle presented denaturation of myosin and sarcoplasmic proteins as a function of the storage time, while PAT muscle presented only small modifications at 5 months respect to t = 0, being comparable the myosin denaturation entalphy values of both system after 3 months of storage. In the same way, MPE showed comparable values for both systems after 1 and 3 months of storage due to a diminution in the case of the conventional thawed muscle, which experienced an increase at 5 months. WHC of the raw muscle decreased because of the PAT process, but differences between PAT and AT samples disappeared after cooking; this behavior was constant during the overall storage time.  PAT caused color modifications –increasing of L* and b*- showing differences with the conventionally treated muscle at all times of storage. In conclusion, PAT permits a very more rapid thawing process; although protein modifications are produced by the high-pressure treatment, differences between AT and PAT muscles decreased after frozen storage. The facts that some properties -such as the water holding capacity and the color- became similar for both systems after cooking, and that PAT permits a very more rapid thawed, support the application of this process.