Supercooling Technology for Extended Shelf Life of Perishable Foods
University of Hawaii, USA
Dr. Soojin Jun
An innovative supercooling device was developed to preserve fresh quality of foods at subzero temperature by treating them with a combination of pulsed electric field and an oscillating magnetic field. The magnetic and electric fields keep water molecules vibrating to prevent the formation of ice crystals even as products drop below freezing temperatures. Therefore, under the subjected environment, supercooled foods do not need to undergo a thawing process, thus allowing them to maintain their quality, texture, and nutrients while extending their shelf life. The fabricated device successfully maintained perishable meat products and fruits in a supercooled state at around -4 ~ -7°C, and their original freshness could be kept intact for transportation and storage purposes. A microcontroller-based supercooling control unit was designed and fabricated to achieve a stable supercooled state using a combination of pulsating electric fields and oscillating magnetic fields. General performance of the supercooling unit was examined via supercooling beef steak at an ambient freezer temperature range of -8 to -10°C. An internal beef temperature of -4°C, approximately two degrees below its freezing point, was maintained for up to two weeks. Quality assessment factors such as color, lipid oxidation, drip loss and texture of supercooled beef samples were evaluated and compared with those of refrigerated (at 4°C), frozen (at -18°C) and fresh samples. Similar procedures were repeated and validated for highly perishable fish and pineapple samples.