Fast freezing of foodstuffs through hydrofluidization and pumped ice slurries

The paper is devoted to the so-called HydroFluidisation Method, recently suggested and patented by the authors to bring together the advantages and to overcome the drawbacks of both air fluidisation and immersion food freezing techniques. Two main innovative aspects can clearly be distinguished: (i) employment of unfreezable liquids as fluidising agents and (ii) use of pumpable ice slurries as fluidising media. This freezing principle provides an extremely high heat transfer rate, short freezing times, great throughput and better product quality at refrigerating temperatures maintained by a single-stage refrigeration machine. Thus, nearly two times lower investments and power costs are necessary as compared with the popular individual quick freezing methods. Moreover, such hydrofluidisation freezing systems are less hazardous from the environmental viewpoint, since the refrigerant is closed in a small isolated circuit only. Some collaborative research activities directed towards the method's development and implementation within the European Union are also outlined.