Supercooling of Perishable Foods for Extended Freshness and Shelf Life in the Cold Chain
Department of Human Nutrition, Food and Animal Sciences, University of Hawaii(U.S.A.)
Dr. Soojin Jun
In conventional refrigerators food items are frozen among ice crystals and their quality is compromised once they are thawed. The deterioration of quality may include generation of drips, protein denaturation and changes in the cellular structure of foods. The occurrence of ice crystallization can be prevented by the phenomenon called supercooling that involves temperature reduction below the freezing point of the sample.
Supercooling involves cooling of biological samples below a phase transition temperature in a balanced state leading to prevention of their cellular activity. In this supercooled state, damage by freezing such as protein denaturation and cellular structure injuries can be avoided. The research to sustain and maintain food and biological samples in a supercooled state is drawing major attention and promises to hold great potential in the near future.
In order to enhance preservation technology over the existing art, the developed technology proposed a method and a device to preserve the quality of foods by treating them with a pulsed electric field and an oscillating magnetic field in combination. It could maintain perishable foods (such as beef and fish), in a supercooled state at around -4 ~ -6°C far below their equilibrium freezing points, and their original freshness was kept intact for transportation and storage purposes. Unlike other few supercooling methods based on the precision temperature control, the developed supercooling invention was insensitive to environmental disturbances causing ice nucleation, presumably due to ‘memory effects’ of magnetic field on water molecules. The technology may be extended to biomedical applications as well, such as preservation of cell cultures, proteins, andtissues and organs transport at subzero temperatures.