Fresh, but frozen: Sushi at -40°C?

Sushi lovers, hold onto your hats. The “fresh fish” you are getting in your sushi may alway be explicitly fresh! Fish are commonly plunged into a deep freeze immediately after being caught worldwide. Does that mean the tender and delicious salmon sashimi enjoyed at your favorite sushi bar was first frozen, before being enjoyed “fresh”? The answer is most likely yes! The majority of the fish on the market has been frozen at one point or another. 

In some locales and jurisdictions, there are even laws mandating that raw fish is frozen before serving. If that’s the case, why is freezing fresh meat and produce so stigmatized to people outside the culinary world? The answer lies in the technology used to freeze your food.

Freeze it to believe it

In the 1920s, a man named Clarence Birdseye began experimenting with freezing fish in the cold temperatures of Labrador, Canada. He discovered that by quickly freezing the fish, he was able to preserve its freshness and taste. This process caught on in the Japanese fishing market due to how it preserved the quality and flavor of fish for long periods, leading it to be one of Japan’s largest food exports.  

Flash freezing refers to rapidly cooling food to -40°F or below. Unlike conventional freezing methods, the rapid cooling of flash freezing prevents the formation of large ice crystals in the food. The lack of ice crystals allows the food to stay fresh and maintain its texture and flavor after it is thawed. Flash-freezing also slows down the growth of bacteria and microorganisms which allows the food to maintain its freshness for long periods of time. Flash-freezing is an excellent technique for exporting goods overseas, and frozen scallops from Hokkaido are Japan’s most widely exported seafood.

Locked in freshness: Japanese “fresh freezing”

As the years went by and flash freezing became standard around the world, people began to notice some flaws. Although flash freezing was leagues better than conventional freezing methods, the food was still not as good as it was before it was frozen. The Japanese man Norio Owada took note of this and began development of a new technology to revolutionize the world of flash freezing. He called his method “fresh freezing.”

Surprisingly it works similar to a microwave – with magnets. Mr. Owada found that by creating a magnetic field while rapidly cooling food it would vibrate the cells inside of food that contain liquid, causing them not to burst open and create  loss of flavor. This method effectively locks in the freshness of the food, maintaining the same overall taste and texture as before it was frozen. On top of that, food frozen with the fresh freezing method can stay frozen longer than flash freezing, making this the current go-to method for importing and exporting goods. 

Powerful applications across many industries

Mr. Owada’s fresh freezing technology is also finding its home in many other industries aside from food, most notably the medical industry. Many doctors and scientists are interested about the technology’s capability of preserving organs over a long period of time for transplants. Fresh freezing technology has the potential to save thousands of lives around the world. Scientists also have been implementing this technology to freeze and preserve medicine and vaccines, allowing for them to last longer and travel farther without their potency deteriorating.