A seafood plant runs cold and wet all day. That is good for the product and good for everything you are trying to keep off it. Condensation on overheads, standing water in drains, biofilm in lines, and Listeria that finds a harborage point and stays for years.
The other constraint is that whatever you use has to not end up on the fillet.
Chlorine dioxide in seafood processing answers both. It is EPA registered for surfaces and equipment, and it is covered separately for direct application to the product itself at up to 10 ppm. The regulatory detail matters more here than the chemistry does.
Why does a seafood plant need two separate approvals?
Most sanitizer conversations blur these together. In a seafood plant they are different jobs under different agencies.
EPA covers surfaces and equipment
Selectrocide® is EPA registered under Reg. No. 74986-5 as a disinfectant and sanitizer for hard non-porous surfaces, including food contact surfaces and equipment, with no rinse required at sanitizer use concentrations.
FDA covers the product itself
Applying an antimicrobial directly to food is a food additive question, not a pesticide question. Selectrocide® is covered by FDA Food Contact Notifications 445, 645 and 1578, which is what permits direct application to seafood.
A vendor with one and not the other can only solve half of your plant.
What concentration do you use on seafood processing surfaces and equipment?
| Use | Concentration |
|---|---|
| Sanitizing | 20 ppm |
| Disinfection | 100 ppm |
Listed organisms include Listeria monocytogenes, Escherichia coli including O157:H7, Staphylococcus aureus and Salmonella typhimurium. Klebsiella pneumoniae is also listed, at its own use concentration.
Listeria is the one that matters in this building. It survives cold, tolerates wet, and lives in floor drains, conveyor framework, and the seams of equipment nobody breaks down nightly. It appears on both the sanitizer and the disinfectant side of the registration.
Chlorine dioxide is an oxidizer, not a detergent. Organic load consumes it.
Why use chlorine dioxide instead of chlorine in process water?
It oxidizes rather than chlorinates, so it does not form trihalomethanes or chloramine by-products. In a plant with heavy organic load, which is every seafood plant, that reaction with chlorine is constant.
It also holds effectiveness across a wider pH range than chlorine, and it keeps working in organic matter that would exhaust chlorine first. More on process water treatment.
Can chlorine dioxide be applied directly to seafood?
Yes. This is where the FDA Food Contact Notifications apply, and where the detail is worth getting right.
Direct application to seafood
Application
Up to 10 ppm
Residual in water
No more than 3 ppm
After treatment
Potable water rinse, or blanching, cooking or canning
Authority
FDA Food Contact Notifications 445, 645 and 1578
Selectrocide® reduces spoilage and pathogenic microorganisms on seafood. Spray or dip, ensuring visible wetness. Seafood that will be consumed raw requires the potable water rinse with no substitute.
The same FDA notifications also cover fresh-cut fruit and vegetables, poultry processing, meat and pork, and mushrooms.
Can you use chlorine dioxide in ice?
This is the part most operations do not know is available. Selectrocide® may be used as an agent in water and ice used to rinse, wash, thaw, transport or store seafood.
Ice is the blind spot in most seafood programs. It touches the product for longer than any wash step, it travels with the product through the plant and often out of it, and it is frequently made from water nobody is treating and held in a machine nobody is auditing. A plant can run a clean wash line and then bury the fillet in ice for eighteen hours.
Treating the ice closes that gap. The same pattern shows up outside seafood: see the chlorine dioxide in ice production write-up.
Why do clean water systems stop being clean?
Test water at the intake and it comes back fine. Test at the nozzle and it looks like a different plant.
What happens in between is biofilm. Bacteria attach to the inside of the line, build a protective matrix, and shed continuously into the water passing through, so the line reseeds the water instead of delivering it. The matrix also shields the organisms inside from treatments that only react at the surface.
Chlorine dioxide penetrates biofilm rather than reacting around it, which is why it is used to remove it rather than manage it.
Why does ultra-pure matter more in a seafood plant?
Most chlorine dioxide is made by mixing precursor chemicals on site. That leaves chlorite and chlorate in the finished solution, and whatever is in the solution goes wherever the solution goes.
Selectrocide® is generated inside a patented sealed micro-reactor. Water vapor passes in, only chlorine dioxide gas passes out, and the reactants and byproducts stay sealed in the membrane and get thrown away with the pouch. It generates greater than 99% pure chlorine dioxide in solution.
For a plant applying a solution directly to a product someone eats, that is the entire argument. What is not in the solution cannot end up on the fillet. More on how the micro-reactor works.
There is also no generation skid to buy, install, permit and maintain, and no bulk precursor chemicals in the building.
Before you build a protocol
- Decide which of the four you are treating: surfaces, process water, the product, or ice. The protocol is different for each, and most plants need more than one.
- Pre-clean heavily soiled surfaces. Organic load consumes product that should be treating the surface.
- Confirm concentration when you set up a dilution or change water source. A test strip read takes a few seconds and tells you the protocol is doing what it says.
- Treat the ice as its own line item. A plant that treats the wash step and not the ice has covered the smaller part of the product's exposure.
Talk to us about your plant
Tell us what you run, where your current program is giving you trouble, and whether you are treating surfaces, process water, product, ice, or all four. Selective Micro Technologies will help build a protocol that fits and quote it.
Every registration, notification and listing Selective Micro Technologies holds is published with the numbers, so your auditor does not have to take anyone's word for it. See the regulatory portfolio.
Email inquiry@selectivemicro.com or request wholesale pricing. For the broader application background, see chlorine dioxide in fish processing and seafood sanitation.
Frequently asked questions
Does seafood need to be rinsed after chlorine dioxide treatment?
Yes, unless the product goes on to be blanched, cooked or canned. Seafood that will be consumed raw requires a potable water rinse with no substitute.
What is the residual limit for chlorine dioxide on seafood?
Residual must not exceed 3 ppm. That is separate from the application concentration, which can run up to 10 ppm. A figure of 3 ppm is a ceiling on what is left behind, not a use rate.
Can chlorine dioxide be used in ice for seafood?
Yes. The FDA Food Contact Notifications cover water and ice used to rinse, wash, thaw, transport or store seafood. Treating the water before it is frozen is the practical way to apply it.
Does chlorine dioxide work on Listeria in a seafood plant?
Listeria monocytogenes is a listed organism on the Selectrocide® EPA registration for surfaces and equipment. Drains, conveyor framework and equipment seams are where it persists, and those are surface applications rather than product applications.