Emerging Technologies for Food Processing, 2nd Edition

28.2. High Pressure for Freezing: Principles and Equipment

Figure 28.1 shows the phase diagram of water. Ice I, the common ice at atmospheric pressure, is stable up to 210 MPa. Above this pressure, different ice polymorphs, from ice II to ice XV, are thermodynamically stable depending on the pressure/temperature coordinates (Bridgman, 1912; Salzmann et al., 2006, 2009).

FIGURE 28.1 Phase diagram of water.

The freezing point of water decreases with pressure up to 210 MPa. The opposite was observed above this level for ice types other than ice I (see Figure 28.1). According to the Clausius–Clapeyron equation,

ⅆTⅆP=ΔV·TkΔH

(28.1)

where T is temperature ...