Under pressure to keep food fresher
Non-thermal food processing techniques are presently regarded with an unprecedented interest by the European food industry. Among them, high pressure processing is gaining popularity because of its unique capability to preserve food while inactivating pathogenic micro-organisms. Besides promising almost complete retention of fresh foods' nutritional content without sacrificing their shelf-life, other advantages include significantly reduced process times when compared to traditional thermal processing. Within the SAFE ICE project, researchers from various fields combined their expertise to establish a sound scientific and technical basis to further improve high-pressure, low-temperature processes. Critical process parameters along with experimental data regarding the quality and safety of food products were accumulated with a view to develop and transfer equipment concepts to real food systems. For allowing semi-continuous freezing and thawing of fish blocks, a new approach was adopted by project partners at the Polish Academy of Sciences while designing a pilot high-pressure facility. Theoretical modelling of various inner geometries for the high-pressure chamber revealed that only a circular autoclave could fulfil the industrial requirements of fatigue strength. On the other hand, the thermal conductivity and low temperature stability of materials used were evaluated in a systematic way to develop their high-pressure reactor to its full potential. Furthermore, a tubular high-pressure reactor was proposed with a modular structure that permitted its length to be freely adjusted according to the results of feasibility studies. Taking into account the optimum freezing and thawing paths, the influence of high-pressure processes on enzymes responsible for food spoilage, as well as cell viability and injury were analysed. The evaluation of high-pressure processes concepts in the SAFE ICE industrial scale facilities has offered a sound basis for future improvements in the quality of processed food products.
