Much more than passing inspection!

Countering the Listeria threat in smoked salmon production

Not Just Passing Inspection

A major smoked salmon producer is countering the threat of Listeria contamination by washing their fish with water treated by a Scotmas Bravo WA Chlorine Dioxide generator.

Listeria is widely present in the environment, however not all listeria bacterium cause illness.  Of the 20 different species identified, only Listeria monocytogenes is a significant cause of illness, causing Listeriosis. 

Fish FarmFor most people, Listeriosis has no or mild symptoms, however for a small percentage, infection is serious.  Most affected are the elderly, pregnant women or newborn babies, diabetics, and those with compromised immune systems[1].  In 2019, 142 cases of listeriosis were recorded in England and Wales, with incidence rates highest in those aged over 80[2]

Most of the Salmon Smoker’s product is exported to the European market.  Listeria bacterium testing is extensive and product preparation is further complicated by a requirement for a 28-day shelf life.  Test sample failure will cause rejection of the entire shipment, and potentially a temporary black listing of future exports.  Financial and reputational risk are huge, making justification of the capital and operating costs of the Scotmas Bravo WA a straightforward exercise.

The Salmon Smoker investigated different options to ensure listeria control.  UV light is a recognised disinfection method but provides no residual benefit past the disinfection process.  Chlorine is a heavily used disinfectant but requires much greater disinfection strength for the same disinfection impact.  Chlorine also has the potential to leave potentially harmful disinfection by products and a residual taste or odour.

Wa StandardIn contrast, Chlorine Dioxide (ClO2), delivered through a Scotmas Bravo WA Generator, requires a very low disinfection strength compared to other oxidising biocides, does not create potentially harmful disinfection by products or residual taste or odour, and will not impact the appearance of the final product.  Once a system is clear of biofilm, ongoing control can be achieved with dose rates as low as 1.0 – 1.5ppm.

The Scotmas Bravo WA is a fully automated dosing system, delivering ClO2 in response to signals from an external water meter.  ClO2 is generated in a water jacketed reactor from two dilute precursor chemicals.  For the Salmon Smoker, there’s no handling of hazardous chemicals and the ultimate reassurance that were the reactor to malfunction, any concentrated chlorine dioxide would be instantly absorbed into the surrounding jacket of water.

On board sensors constantly monitor chemical dosing levels and combine with downstream sensors to ensure that exactly the right amount of ClO2 is being added to the water.  Alarms alert operators to any issues and the system will shut down if parameters are exceeded.

The Bravo WA is linked to Scotmas InsiteTM, an online monitoring system capable of storing full, auditable data logs for up to three years.

Scotmas have been designing and installing ClO2 water treatment systems for more than 30 years.  Our engineers have a deep understanding not just of the chemical properties of ClO2, but also how to apply the technology to maximum effect in diverse settings.

What’s the measure of success?

At the most basic level, success is passing inspection, which the Salmon Smoker’s product does every time.  Passing inspection is only part of the challenge.  It’s also vital to build and actively maintain an in-market reputation for consistency and reliability.  Ultimately, buyers face huge risk if salmon sold in their outlets is traced to an outbreak of Listeriosis, so they will only seek suppliers with the highest quality, most consistent, test and taste reputation.

So successful has the Salmon Smoker been in building their in-market reputation, their importer has now sought detailed explanation on how their results are achieved whilst maintaining the taste and appearance of their finished product.

Production Director for the Salmon Smoker said:

“Passing inspection and achieving a 28-day shelf life is a relatively simple target, achievable with several different biocides.  Passing inspection, achieving a 28-day shelf life, and not impacting the taste or appearance of our finished product is a whole new challenge.  Chlorine dioxide, delivered through the Scotmas Bravo, has ensured our salmon reaches market at its absolute peak and the feedback from  our importer is testament to the quality of the system we have.”

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Got a food processing challenge?  Concerned about keeping control of pathogens, whilst not affecting the taste or appearance of your finished product?

Talk to our experts about how Scotmas Chlorine Dioxide tablets and generators will improve your production processes.

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