Packed foods are immersed in the pressure/cooling medium and frozen.
In high pressure assisted freezing process, water solidification is produced while pressure around the product is high. During freezing, use of high pressure facilities supercooling and promotes uniform and rapid ice nucleation throughout the product on pressure release, producing smaller ice crystals.
Phase transition occurs under constant pressure, higher than atmospheric pressure while the temperature is lowered to below the corresponding freezing point.
HPAF is based on the fact that freezing point changes with pressure and the product can be stored at normal frozen storage conditions.
High pressure assisted freezing was particularly useful for freezing large pieces of food when uniform ice crystals are requires.
In high pressure assisted freezing, product are cooled under 200 MPa to -20 ° C without ice formation, then the pressure is released and the high supercooling reached ( approx. 20 °C) promotes uniform and rapid nucleation.
High Pressure assisted Freezing (HPAF)