TitleImpact of high hydrostatic pressure on phase transitions of foods
Publication TypeJournal Article
Year of Publication1998
AuthorsKnorr, D., O. Schlueter, and V. Heinz
Secondary TitleFood Technology
Call NumberOSU Libraries-Valley TX599.F65, Guin TX599.F65, Guin Library Seafood Technology Collection

An understanding of the phase transitions occurring in water during freeze-thaw cycles in foods can be applied to process and product development. Following an outline of recent work on pressure-assisted freezing and thawing and effects on thermodynamic properties of water in the foods examined, high-pressure freezing and thawing of potato cylinders is examined. Phase transition lines for potato cylinders were established during pressure-shift freezing and pressure thawing, and results were represented mathematically. Freezing of potato at constant pressure reduced freezing time (f.p. was reduced with increasing pressure); substantial supercooling was observed prior to freezing. In frozen samples pressure-thawed at temp. lower than those applied at atmospheric pressures, an initial phase of adiabatic heating overlapped with inward heat transfer and a reduction in temp. of the solid sample was observed during pressurization. Transitions between various forms of ice are discussed. Pressure-related phase transitions may be important for food quality, but further information is required relating to kinetic data regarding formation, size, distribution and stability of ice crystals, as affecting interactions of water and other food components, and physicochemical and physiological cellular/macromolecular effects. Developments in monitoring apparatus will be required if this is to be realised, because process inhomogeneities such as temp. gradients must be catered for.(Abstract provided by Food Science and Technology Abstacts, IFIS Publishing, 1969-2002. All rights reserved.)

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