Ozone in Seafood Processing

Typical applications for ozone in the seafood industry include the following:

 Direct Food Contact | Food Safety | HACCP Plan

Surface Sanitation | Conveyor Belts | Ice Machine 

 Cold Storage | Pin Bone Machine | Cutting Utensils 

 CIP | Truck Wash Down

Ozone use in seafood processing applications has proven to be a great tool in the quest for food safety as it has in many other food processing industries. There are more potential uses for ozone in the commercial seafood industry than much agricultural food based industries. Not only is ozone useful for food safety, but also for fish growing (aquaculture), storage, ozonated ice, and even odor control during processing

Traditional methods for sanitation in the seafood industry have been a wide use of chlorine dissolved in rinse and wash waters. Chlorine has been the most widely used sanitizer in the seafood industry despite the limited effect it has on killing bacteria on seafood surfaces (Augusto Goncalves). Due to the 
potential off flavor and negative health effects of chlorine by-products, improved sanitation methods have been sought. Since the acceptance of ozone use in food production and the GRAS approval granted in 2001, many uses for ozone have been researched and implemented in the commercial seafood processing industries. Ozone use in seafood processing has shown benefits in the following areas:

Aquaculture and Commercial Fish Growing Facilities

As the population of the world grows commercially, grown seafood has become more necessary to supplement wild seafood harvested from the ocean and lakes. Ozone use in aquaculture has proven effective at lowering water consumption by increasing water reuse, lowering diseases in hatcheries and growing ponds, and maintaining clean water for faster growth rates with lower feed rates.

Storage of Live Seafood
In some commercial 
applications, fish or other seafood is transported and stored live prior to processing. In these applications, ozone can be used within this storage water to reduce bacteria and virus cross-contamination and therefore lowering the bacteria plants entering the processing center.

Ozonated Ice and Fresh Fish Storage
Ozone can be dissolved into water that is then frozen in ice production. This process will essentially store the ozone within the ice creating what is commonly 
referred to as ozonated ice. This ozonated ice can be used for the storage of fish to prolong shelf-life and maintain a fresher, better-looking product to the end user.

Much of the fish that we consume is harvested in the ocean by large fishing vessels that may stay out at sea for weeks at a time. To maintain 
high-quality fish products for market, ozonated ice is commonly used on these vessels for the fish that are harvested early in the voyage and stored. Ozonated ice has gained popularity in seafood storage for many land based operations and fish farms. 

Antimicrobial Intervention in Fillet Machines and Cut Fillets 
After ozone was granted GRAS approval by both the USDA and FDA for direct contact with food, interest in antimicrobial intervention directly on food products has dominated the discussions of ozone use in food processing. Fish and seafood processing has not been immune from this shift. Ozone can be dissolved into water to provide an aqueous ozone solution that is stable, safe, and easy to control. This water containing ozone can replace chlorine as an antimicrobial agent, or be used to supplement existing water rinses and achieve improved antimicrobial intervention. 

Aqueous ozone used for processing of dressed whole fish showed a reduction of bacterial cell counts of <5,000 without ozone to <932 with ozone, and a reduction of <5,000 without ozone to <120 with ozone on fillets.

When fillets were cut from the whole ozonated fish they resulted in low cell counts of 120-190. In this cutting of the whole ozonated fish, no 
ozonated spray was done on the fillet machines, or ozonated pretreatment or ozonated ice for packing was done. Fillets without ozone treatment (but with conventional treatment) ranged from 7,500 – 5,000 cell count. 

Catfish fillets produced from implementing aqueous ozone spraying on the fillet machine showed a reduction in total plate counts of 14,906 – 2,975.

Surface Sanitation of Processing Equipment, Tables, etc.
Ozone Systems have been used in food processing applications, surface sanitation, waste water treatment, CIP applications, and 
much more!

Ozone dissolved in the 
water can be used throughout a seafood processing plant for surface sanitation. This is a common application to sanitize fillet machines, cutting tables, knives, and all equipment that may be used in the seafood processing areas. Ozone is used throughout the food processing industry for surface satiation of shipment. This application is certainly not limited to the seafood industry. 

Odor Control in Offal Rooms and Other Processing Areas
Seafood processing can create foul odors in certain processes. The offal processing can create a foul odor that is less than ideal for the employees working within that specific room. In some 
applications, seafood is dried to create a final product. The drying process releases the moisture and odor to the outdoors. Foul odors from this process or other processes can cause potential odor issues surrounding a seafood processing plant, causing complaints from neighbors in the community. Ozone is commonly used in industrial odor control for many applications. There are a variety of methods to implement ozone safely. The main goal is to maintain worker safety while improving indoor and outdoor air quality. 

Ozonated Ice and Fish Storage
Ozone gas can be dissolved into water with an Ozone Injection System, then fed into an ice making machine that will then freeze that ozone dissolved into the water to produce ozonated ice. This process will essentially store the ozone within the ice, creating what is commonly referred to as ozonated ice. This ozonated ice can be used for the storage of fish to prolong shelf-life and maintain a fresher, better-looking product to the end user.

Ozone used to produce ozonated ice is not a new concept. In 1936, research in the commercial fish industry was conducted in France that showed a 33% extension in shelf-life of fresh fish stored on the ozonated ice when compared with ice produced from regular water in the holes of fishing vessels. Ozone can also be dissolved into water and used to wash seafood and fish fillet's to reduce bacteria and extend shelf-life in fresh fish.

Historically, fresh fish has commanded a premium in price over frozen fish products. The appearance of this fish will affect the market price of fresh fish. Ozone use in ice for storage in fishing vessels has been used to maintain the highest quality fish and garner the highest possible price for fresh fish products. While fishing vessels are at sea it is imperative that the fish and seafood harvested early in the voyage are as fresh and comparable in quality as the fish caught near the end of the voyage. As these vessels can at times stay out to sea for weeks at a time, ozonated ice was seen as a great solution to the storage issues experienced in this unique industry.

The use of ozonated ice in fish storage has expanded beyond the fishing vessel to fish farming and processing throughout the industry. Today, many fish processors and fish farms will use ozonated ice for all their seafood storage needs. Ozonated ice offers a convenient method of prolonging the shelf-life of seafood products.

References and Case Studies:
Use of ozone and ozonated ice increased 
shelf life of good quality sardines from 5 days to 8 days, and acceptable quality sardines from 15 days to 19 days (Campos, et al).

Salmon iced with ozonated ice extended shelf-life from 4 days to 6 days when compared to non-ozonated ice, this data led to full scale implemented of ozone at the same plant in 
full-scale application shelf-life extension of 33-50% was realized (Blogoslawski, et al).

Catfish fillets treated with aqueous ozone showed a shelf-life of 14 days, compared to 4-6 days for conventional treatments of iced fillets. 
In this case, ozone provided greater than a 100% extension of shelf-life (Brooks and Pierce).

Squid stored on ozonated ice extended shelf-life by 12% and had a 2 log reduction in aerobic bacterial plate count vs. squid stored on conventional flake ice with no ozone (Blogoslawski, et al).
Walter Blogoslawski stated in his paper Some Ozone Applications in Seafood that in his research, a plastic milk bottle filled with triple-distilled super-ozonized water (2-4 mg O3/ml water) frozen at -80-deg C could retain a residual of 1-2 mg of ozone for up to 6-months.

Sease (1976) has stated that the half-life of ozone at 0-deg C, under sterile conditions, is on the order of 2,000 years. Thus, freezing water which contains residual ozone will produce ice containing ozone, which will reform water containing dissolved ozone when it melts. Ozone sterilized ice can normally be expected to be used within a few hours of 
its manufacture, certainly within a few days. Under this 
scenario, there should be little, if any, loss of ozone in the ice due to decomposition back to oxygen (Rice, et al).