Seafood processing benefits from ozone

Ozone, long known as a protective shield between humans and the sun's rays, has a new use in the seafood industry. Researchers from the NorthCarolina State Seafood Laboratory have found that ozone may enhance the freshness of raw seafood.

The study, administered by North Carolina Sea Grant, found that treating raw fish and processing equipment with ozone significantly reduced the amount of bacteria that could potentially spoil seafood, according toresearcher Barry Nash.

"This is important because bacteria are everywhere in the environment. However, the use of ozone could greatly reduce the number of spoilage bacteria in a seafood plant and help maintain low levels of spoilage bacteria over time in air, water and on processing equipment,"​ said Nash.

Researchers also found ozone to be effective in extending the shelf life of seafood. Barbara Blakistone, one of the project investigators and a packaging consultant, said: "Ozone seemed to extend the shelf life of our treated fish by one or two days. It could help enhance product quality and lengthen the shelf life of fish so that seafood lasts longer in the retail or wholesale distribution chain."​

The results are good news for seafood dealers, who regularly lose a certain amount of fish to spoilage, said Robb Mairs, researcher andgeneral manager of Hanover Seafood Products.

"This will result in increased profitability in the seafood processing industry."​Other benefits were found when ozone was used to treat the air and waterin seafood processing facilities.

"Ozone is immediately lethal to bacteria,"​ said Nash. "Our results showed that ozone caused a marked and sustained decrease in air- and water- borne bacteria. This has important implications for minimizing bacterial cross-contamination inthe workplace environment."​

To perform the study, researchers used an ozone generator to produce and dissolve ozone into the water. Whole fish fillets were then soaked in the water, filleted and vacuum packaged. For 12 days, the fillets wererefrigerated at 41 degrees Fahrenheit and monitored for bacterial growth. Researchers found another positive result of the treatment wasthat ozone did not alter the appearance, colour or aroma of the freshfish.

"The sensory characteristics of the treated fish appeared unaffected,"​ says Nash.

Until 2001, ozone could only be used as a disinfectant to treat bottled water. But its effectiveness as an antibacterial agent allowed the FDA to extend its use last year and allow direct contact with all food.

Currently, many seafood processors use chlorine as a sanitising product. Project investigator James Yuan said that ozone "doesn't leaveany chemical residues like chlorine."​ Still, he stressed that ozone was not meant to replace cleaning agents or procedures, but to complementthem.

"Based on this research, ozone seems a promising broad-use disinfecting agent for controlling spoilage bacteria that should be considered a part of any seafood sanitation protocol,"​ said Nash.

Further studies include the incorporation of ozone into ice that is used to pack fish.

"Future projects should address the shelf life advantages for storing and distributing raw fish in ozonated ice,"​ said Blakistone.