Seeing as how seafood is a highly sensitive and perishable product, it presents major challenges in handling and maintenance of optimal conditions during harvesting, processing and distribution. The current cold chain, which utilizes the melting of flake or crushed ice, does not effectively meet the requirements of today, due to the fact that the chilling of seafood in ice does not lead to great results. Whereas, Deepchilling (rapid cooling to, and the ability to maintain, subzero temperatures without freezing the product) seafood can optimize the cold chain, offering increased shelf life, higher quality and bigger yields compared to traditional methods such as Refrigerated Sea Water (RSW) or flake ice.
Studies have been conducted at various stages of the cold chain (harvesting, processing to distribution) using different species of fish such as farmed salmon, trout, cobia and yellowtail. The tests analyzed cooling rates, bacterial growth, texture after maturing and freshness and evaluated the impact on the yield, shelf life, and quality of the fish.
When salmon and yellowtail are harvested before being gutted, bacteria are quickly developing inside of the fish. Deepchilling fish immediately upon harvest minimizes bacteria growth and maintains freshness from the beginning, so fish are kept safe (as in, below 0 degrees C) with an extended shelf-life. Salmon, once gutted, are typically stored overnight or additional days before filleting and pin-boning. This is a critical period where bacteria growth needs to be controlled, and firm texture must be maintained to prevent the meat from gaping. Also, to go through the filleting machine efficiently, a deepchilling process can be arranged, where fish are kept at subzero temperatures. This reduces fat accumulation on the knife, allowing better operation with cleaner cuts and less gaping. As a result, the quality of fillets is demonstrably higher and a greater filleting yield can be achieved.
Yellowtail are very sensitive fish, requiring a fast processing time to maintain the highest quality. Often shipped overseas, yellowtail requires extreme quality control. Deepchilling maintains yellowtail’s prime condition even during filleting, packaging and overseas shipping. With the extremely high cooling rate and ability to consistently maintain subzero temperature, Deepchilling enables sashimi quality fish and allows distribution from as disparate locations. Similarly, it has been observed that the deepchilling process provides an efficient method for the rapid chilling of farmed cobia from a typical tropical temperature (25-30C) to 0°C in a relatively short time period, and reducing the rate of bacteria growth which affects spoilage.
So, deepchilling has been shown to significantly improve quality, shelf life and yield as the food is kept relatively colder, fresher for longer than using other methods like flake ice. Deepchilling supports a sub-zero cold chain and is a proven, demonstrable method for keeping fish at optimal temperatures, controlling bacterial growth, maintaining freshness and extending shelf-life.