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J. YUAN, Air Liquide, Countryside, IL 60525

In recent years, food safety has been a major concern in the United States. Fresh seafood is especially perishable because of spoilage microorganisms and may contain various pathogens. Spoilage causes high economic losses, and pathogens create potential health risks. Either situation prompts industry to look for an effective treatment to disinfect fresh seafood.

The primary objective of this study was to investigate the efficacy of ozonated water in reducing the microbial contamination on seafood surfaces.

Trout and salmon fillets were inoculated with L. monocytogenes. Shrimp, grouper, and mahi-mahi fillets represented uninoculated samples and were tested for natural spoilage microorganisms. After treatments using different exposure times and concentrations of ozonated water, the sample was individually rubbed to remove surviving bacteria, serially diluted, and plated on a selective microbiological medium.

From our preliminary results, the use of ozone as a disinfectant was effective for surface decontamination. Typically one logarithm (90%) of microorganisms could be removed using wash water, and attempts to free additional attached bacteria with increased agitation were futile. Ozonated water at the 4 ppm level reduced the microbial populations an additional log beyond that with water. For L. monocytogenes-challenged samples, up to 2.12 logs (99.4%) reduction was observed by 5 ppm of ozone for 5 min. The wash water was examined and found to be free of any microorganisms after ozone treatment. It was noted that the levels of ozone used did not affect the quality of samples other than preventing the spread of contaminants.

To enhance the effectiveness of the system, synergy of combing ozone treatment and modified atmosphere packaging will also be briefly addressed.