Fresh fish for poke, sushi and sashimi is highly prized and usually in great demand in Hawaii, especially around the holidays.
The fresher the fish, the better.
Now researchers at the University of Hawaii have figured out how to keep an ahi filet “fresh” for at least 10 days without any deterioration or compromise in quality.
The scientists have
developed a “supercooling” technology that preserves perishable materials at below-freezing temperatures without the formation of ice crystals that rake over food tissues like a glacier scouring a mountainside.
The process involves the deployment of combined, pulsed electric and magnetic fields that work to
realign and reorient water molecules and keep them in a balanced state to prevent ice crystals from forming during the freezing process.
“This has the potential to be a radically new food preservation method for consumers and the commercial food industries,” said project lead Soojin Jun, an associate professor at UH. “Food could be maintained in their natural state with the same taste, texture, nutrition and moisture content they had before being supercooled.”
Jun is working on the supercooling project with colleagues Kacie Ho and Yong Li in the College of Tropical Agriculture and Human
Resources’ Department of Human Nutrition, Food and Animal Sciences.
The effort began in 2014 with a $500,000 grant from the U.S. Department of Agriculture.
“We first started with beef, fruits and vegetables. It works on anything that has a good water content,” he said.
But they were small items.
With another USDA grant, this time for nearly $482,000, the team will begin work to scale up the technology over the next several years to handle
bigger items.
The eventual goal is to make the technology work for warehouses, distribution centers, trucks, air cargo services, fishing vessels, grocery stores, restaurants and more.
“Right now we have a 20-liter capacity, but we’d like to get it to a 50- to 100-liter capacity,” he said.
Jun said fish is the most difficult of all the foods to preserve using this method.
“If it can work with fish, it can work for everything because fish is the hardest one,” he said.
Seafood is one of the most perishable of all foods since it is easily spoiled by bacteria and falls victim to oxidation fairly quickly.
Freshly caught fish is generally put on ice while at sea and must be consumed in fairly quick order or preserved to reduce the risk of spoiling.
The USDA recommends that raw fish and shellfish be kept in the refrigerator
for only a day or two before cooking or freezing. After cooking, seafood can be kept in the fridge for three to four days. While frozen fish is safe indefinitely, the
flavor and texture lessens over time.
“Frozen fish can be stored longer, but texture and overall quality is diminished by the freezing and thawing processes,” Jun said.
At the store, the difference in price between fresh fish and frozen can be huge:
at least double and often more.
Guy Tamashiro, vice president of
popular Honolulu fish retailer Tamashiro
Market, said he would welcome a technology that could help extend the life of fish as fresh.
“It would be great,” he said. “You could keep fish longer if you have to. If bad weather was coming, you could keep it longer. It sure can make a difference.”
Beyond the food industry, the supercooling technology offers possibilities for use in medical applications such as organ and tissue transplantation, Jun said.
UH holds the U.S. patent for the process, and Jun has a startup company that owns an exclusive license to the technology that requires it to pay back everything the university spent on the effort.
The project, he said, is working with
LG Electronics about the possibility of
creating a supercooling box that could go in any refrigerator.
Such a box — which might one day be a staple of every refrigerator — might cost only about $1,000 to produce and doesn’t require much energy to run, he said.
