Is an ‘isochoric freezing’ revolution really in the offing?
Comparing isochoric freezing to classical isobaric freezing and new terminology proposal based on the conclusions of a group of IIR experts.
A refrigeration technique named 'isochoric freezing', previously tested for preserving biomaterials, has recently been publicised worldwide and claimed to be a superior alternative to the classic freezing throughout the entire food cold chain. The method has been advocated as a revolution in food preservation, a 'panacea' for most problems of food storage or a breakthrough solution to both energy- and quality-related problems of global frozen food industry.
The trick is in hindering the phase transition of food’s water into ice by means of high pressures. The significant pressurisation required can occur under isochoric thermodynamic conditions by lowering the temperature inside robust constant-volume containers, where a sufficient amount of auxiliary aqueous solution, filled around foods, freezes and expands in volume.
Favourable ‘isochoric freezing’ effects on food quality are associated with reduced structural damage because of the inhibited phase-change in food. Thanks to the minimised or prevented ice crystallisation, developers report enormous potential energy savings.
Recently, a team of IIR experts assessed the actual state of play in ‘isochoric freezing’ and identified several major points which need to be scrutinised or critically re-examined.
The expert group suggested ‘isochoric pressure-aided (or pressurised) supercooling’ as a more suitable science-based term to name the technique, while ‘isochoric freezing’ might rather serve as a tradename. The method’s claimed capabilities and advantages should be verified and assessed during long-term food storage in a sufficiently representative real-life environment.
A number of thermophysical phenomena and engineering issues related to 'isochoric freezing’ require further clarification. In particular, the spectacular energy efficiency claims need to be objectivised. Determining the energy consumption per unit of useful product or useful effect is a must for any credible technology assessment.
In conclusion, the expert group points out that despite of the significant aspirations and associated claims, ‘isochoric freezing’ cannot presently be regarded as a competitive alternative to classical freezing and the frozen food cold chain at atmospheric pressure.
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