title: Metastable states of water and ice during pressure-supported freezing of potato tissue.
abstract: Different ice modifications were obtained during freezing processes at several pressure levels from atmospheric pressure up to 300 MPa. In the pressure range between 210 and 240 MPa, a metastable ice I modification area was observed, as the nucleation of ice I crystals in the thermodynamically stable region of ice III was reached. A significant degree of supercooling was obtained before freezing the tissue water to ice III, which has to be considered when designing pressure-supported freezing processes. The effect of supercooling phenomenon on the phase transition time is discussed using a mathematical model based on the solution of the heat transfer governing differential equations. Phase transition and freezing times for the different freezing paths experimented are compared for the processes: freezing at atmospheric pressure, pressure-assisted freezing, and pressure-shift freezing. Different metastable states of liquid water are defined according to their process-dependent stability.
authors.affiliation: Department of Food Biotechnology and Food Processing Engineering, Berlin University of Technology, Königin-Luise-Str. 22, D-14195 Berlin, Germany. oliver.schlueter@tu-berlin.de
authors.forename: O
authors.initials: O
authors.lastname: Schlüter
authors.forename: G Urrutia
authors.initials: GU
authors.lastname: Benet
authors.forename: V
authors.initials: V
authors.lastname: Heinz
authors.forename: D
authors.initials: D
authors.lastname: Knorr
mesh_terms: D003198:Computer Simulation; D004735:Energy Transfer / Q000502:physiology; D005519:Food Preservation; D005615:Freezing; D007053:Ice / Q000032:analysis; D008954:Models, Biological; D044367:Phase Transition; D011312:Pressure; D011198:Solanum tuberosum / Q000737:chemistry* / Q000502:physiology*; D013696:Temperature; D013814:Thermal Conductivity; D014867:Water / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D007053:Ice; D014867:Water