Despite its nearly century-long existence, ozone has only recently captured the attention of the food and agricultural industries as a versatile disinfectant capable of oxidizing a wide range of inorganic and organic impurities, as well as eradicating bacteria, viruses, and other pathogens.
The food-processing industries have found numerous applications for ozone, such as sanitizing seafood processing plants and processing shellfish in most European countries. Additionally, ozone is used as a wash for seafood, where it can eliminate bacteria and protein slime with greater efficiency than chlorine, by several orders of magnitude.
What is ozone?
Ozone (O3) is a gas that occurs naturally during lightning storms or as a result of ultraviolet light exposure. Alternatively, it can be produced by an ozone generator by subjecting dry air or oxygen to an electric field. Ozone’s oxidation potential surpasses that of hypochlorous acid and chlorine, which are commonly utilized in water treatment.
Following its discovery in the mid-1880s, ozone’s germicidal properties were quickly identified. By 1883, the first drinking water treatment plant utilizing ozone had been constructed and put into operation in the Netherlands. Subsequently, thousands of ozone treatment systems have been established in Europe, Russia, Japan, and the United States.
Ozone functions by breaking down the cell walls of pathogens, which is a more effective mechanism than chlorine, which relies on diffusing into the cell protoplasm and disabling enzymes. Studies have shown that exposure to an ozone concentration of 0.4 ppm for four minutes can eliminate bacteria, viruses, molds, and fungi.
Seafood Ozone Processing
Ozone’s potent oxidizing properties make it highly effective at removing soil and biofilm from surfaces, which is why it is a popular choice for seafood-processing plants. Due to its short half-life, ozone must be generated on demand, and its use produces a minimal amount of disinfection byproducts.
Shellfish Ozone Processing
Shellfish are typically processed in ozonated water in the majority of European countries. Ozone is preferred over chlorine as it provides superior elimination of bacteria and viruses, without imparting any taste on the shellfish meat.
Several oyster farms in the northwestern United States use ozonated water to eliminate pollutants and silt that oysters may have absorbed from their natural environment before being sold. The oysters are shucked and placed in tanks where they undergo multiple cycles of ozonated water to cleanse them. The residual ozone in the water prevents the growth of bacteria and other organisms in the water-packed jars. During shipping and storage at restaurants and stores, the water remains transparent and clean.
Finfish Ozone Processing
The use of ozonated water for preserving fresh fish is not a recent development. In the 1930s, LeGall and Salmon, two Frenchmen, demonstrated that the shelf life of Mediterranean fish could be increased by at least 33% by storing them under ice produced from ozonated water. The ozone in the water sterilized it, preventing the liquid water from harboring bacteria as the ice melted. As a result, bacterial growth on the surface of the fish was kept to a minimum.
Preliminary results from a recent study indicate that ozone is effective in decontaminating the surfaces of trout and salmon fillets inoculated with Listeria monocytogenes, a bacterium commonly found in soil and water that can result in severe illness. The study examined a variety of exposure times and concentrations of ozonated water.
2. Extending Shelf Life
In the early 1980s, Bill Nelson was a pioneer in the use of ozonated ice for preserving fish and demonstrated a significant extension in shelf life. Nelson and Neve’s work with Alaskan salmon involved washing the fish with ozonated freshwater and storing them under ozonated ice, which resulted in an extension of the shelf life of fresh salmon from six to 11 days.
3. Preventing Odor
Ozone has the potential to prevent odors in seafood, such as channel catfish, which has been a persistent issue for the industry in the southern United States due to the presence of 2-methylisoborneol and geosmin. Treatment with ozone is a possible solution to this problem.
Benefits of Using Ozone
Ozone can serve as an effective sanitizer for food-processing equipment and machinery, preventing the spread of pathogens into food products. It can also be used to sanitize walls, floors, and other areas within processing plants. Furthermore, ozone has a remarkable safety record, with over 100 years of use and no reported fatal accidents. It is also the reason why it can be safely used in food processing and other food-related applications.
In contrast to chlorine, which produces numerous toxic byproducts, ozone does not generate any such substances. It is produced through electrical means and does not introduce any chemicals into the treated water. When utilized as a wash for seafood, ozone proves to be 10 times more effective than chlorine at removing bacteria and protein slime. With appropriate handling, higher concentrations of ozone can be utilized without causing any toxicity or imparting any off-flavors to the seafood.
Permitted by U.S. EPA and FDA
Ozone has been approved by the U.S. Environmental Protection Agency (EPA) for treating municipal drinking water, and it has also been added to the USFDA’s list of bottled water disinfectants that are considered “generally recognized as safe.”
In 1997, an international survey of regulations and practices was conducted, and a panel of experts from the Electric Power Research Institute concluded that ozone is a safe product for use in food processing. Prior to this, the FDA had treated ozone as a food additive, but with the new declaration, ozone is approved for use in nearly all areas of food processing.
To Sum Up
The seafood processing industry can utilize ozone in several ways, such as a fumigant or by dissolving the gas in water and using it as a solution. Ozonated water is effective in equipment and facility cleaning, as well as controlling pathogens and spoilage microorganisms in both processing facilities and food materials. With its versatile applications, it is likely that seafood processors will continue to adopt ozone in their operations in the coming years.
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