Thermal Behaviour of the High-Pressure-Assisted Freezing Process and Its Effect on the Quality of Large Foodstuffs

摘要

Many different aspects are involved in a complete characterisation of the high-pressure-assisted freezing (HPAF) process. Final microstructure and temporal variation of temperature are considered in this work which employs semitendinous beef muscle and agar gel as experimental samples. The process of freezing by a conventional method generally ends with nucleation of exclusively extracellular ice, intracellular ice nucleation taking place only when a large heat gradient is applied. In the case of a HPAF process, a global nucleation is obtained in the whole sample volume. These effects are observed in the sample microstructure by scanning electron microscopy. Besides, the thermal behaviour of each process is different, as is evident from the different shape of the temperature vs. time freezing curves obtained with a food model.