A freezing technology originally invented for the medical sector could soon be providing an alternative method of producing luxury frozen products in the UK. But whether it will ever achieve the 'Holy Grail' of enabling frozen strawberries to be thawed without product damage is not yet clear, as it is limited by the water content of the products it can handle.
The Cells Alive System (CAS), developed by ABI in Japan and now being investigated by the Grimsby Institute, ensures the retention of flavour, texture and aroma similar to that of fresh or chilled foods. And yet products can be stored for up to two years. The process avoids cell wall damage during the freezing of foods using a rotating magnetic field. And it is cell wall damage which causes loss of product quality with traditional freezing techniques.
Speaking at the annual conference of the Food Processing Knowledge Transfer Network in York last month, vice principal of research and enterprise at the Institute, professor Mike Dillon described how CAS was now being tested on foods ranging from high quality tuna, squid, oysters and langoustine to fruit, such as mangoes and avocados, and vegetables. Trials had also been carried out on red meat and poultry, he added. Dillon said the CAS retained 99.7% of the original aroma, flavour and texture of products tested.
"CAS works on the simple principle that water molecules cannot cluster and form cell-wall damaging ice crystals if they are in motion during freezing," said Dillon. "We have got a technology that allows us to control the membranes of an animal or vegetable product."
The Grimsby Institute is installing a Starfrost spiral freezer for further research into this technology in July. This will provide 25kW of refrigerator capacity, capable of freezing products down to between -18°C and -30°C. It is believed to be the first transcritical carbon dioxide system (supplied by Star Refrigeration) applied to a spiral freezer and the first CAS equipped spiral freezer in the world.
The Institute is also working with a company on the first commercial CAS installation in the UK for a 500 pallet -45°C cold store in Grimsby for high quality seafood, largely tuna.