Post-Harvest Disinfection Monitoring in UK Fresh Produce: How PrepWorld Eliminated 12 Hours of Daily Downtime
In UK fresh produce processing, the wash stage is a Critical Control Point — and the disinfectant chemistry in that wash water needs to be right every time. Not approximately right. Not right at the start of the shift and assumed to hold. Right, verifiably, throughout every production run, across every line, on every shift.
That is a straightforward requirement to state and a significantly more complex one to deliver particularly when the produce being washed turns the wash water a colour that makes traditional testing impossible. PrepWorld, a Northfleet-based pre-packaged fruit manufacturer supplying UK grocery stores and restaurants, found themselves exactly in that position. Their solution, and the results it produced, make the case for electrochemical disinfection monitoring more clearly than any product specification could.
The Post-Harvest Disinfection Challenge
Fresh produce processing in the UK operates under significant compliance pressure. BRCGS Food Safety certification — held at AA+ level by PrepWorld — requires documented evidence of CCP monitoring throughout production. The Food Standards Agency and major UK retailers add further layers of audit expectation, with disinfection records a standard component of supplier assessment.
Peracetic acid (PAA) is the disinfectant of choice across much of the UK fresh produce sector, valued for its broad-spectrum efficacy, rapid breakdown after use, and absence of harmful residues on product. But PAA concentration in active wash water degrades with organic load, temperature, and time — which means a reading taken at the start of a wash cycle cannot be assumed to hold throughout it. Frequent, reliable monitoring is not optional. It is built into the compliance requirement.
The PrepWorld Challenge: When Testing Becomes Impossible
PrepWorld’s pomegranate processing lines presented a monitoring challenge that titration-based methods simply could not solve. Pomegranate seeds turn wash water a deep red — and titration relies on visual endpoint detection to determine PAA concentration. When the water itself is red, the endpoint disappears. The test becomes unreliable, and the result cannot be trusted.
The operational consequence was significant. To continue testing, PrepWorld had to change the wash water on the pomegranate lines approximately every two hours — purely to create conditions in which a titration test could be run. Each water change took around 30 minutes. Across an eight-hour shift, that meant up to four changes per line, totalling approximately 120 minutes of downtime. Across two pomegranate lines running three shifts a day, the avoided production time amounted to roughly 12 hours every single day.
The Palintest Kemio Range:
PrepWorld adopted the Palintest Kemio Disinfection for its pomegranate washing lines and has relied on it for three years. The electrochemical sensor technology at the heart of the Kemio range does not depend on visual endpoint detection. It measures PAA concentration directly through a sensor reaction, delivering a clear numerical result in approximately one minute — regardless of whether the water is clear, turbid, or red.
The workflow is straightforward: sample wash water from the line, insert the pre-calibrated single-use PAA sensor, close the lid, and read the result. No reagent preparation. No multi-step titration process. No dependence on water clarity. The hygiene team at PrepWorld adopted the system quickly, and the simplicity of the step-by-step process means consistent results regardless of which operator runs the test.
The Results: Uptime, Accuracy, and Audit Confidence
The impact on PrepWorld’s pomegranate lines was immediate and measurable. By eliminating the need to change wash water for testing purposes, the Kemio range removed approximately 12 hours of daily downtime across the two lines — downtime that had previously been accepted as an operational cost of running a monitoring programme in coloured wash water. Over five years of strong demand growth, that capacity has supported scaling throughput without adding complexity or cost to the testing process.
Compliance confidence improved alongside operational efficiency. Kemio’s on-device data storage automatically captures every test result with a timestamp, creating an audit-ready monitoring record that supports PrepWorld’s BRCGS Food Safety AA+ certification. The numerical output eliminates the ambiguity of visual endpoint detection, and the speed of the test — approximately one minute versus two to three for titration — means the production team can monitor as frequently as the CCP specification requires without it becoming a burden on the line.
What PrepWorld Proves for UK Fresh Produce Processing
PrepWorld’s experience is a precise illustration of what happens when the right monitoring technology meets a real operational problem. The water was coloured. The traditional method failed. The solution was not to work around the method — it was to replace it with one that works in the actual conditions of the production environment.
For UK fresh produce processors navigating the dual demands of production efficiency and BRCGS compliance, the Palintest Kemio range offers electrochemical monitoring that works where titration does not, builds the audit trail automatically, and puts reliable PAA results in the hands of the production team in under a minute. The downtime savings are real. The compliance confidence is real. The case is made.
Frequently Asked Questions
Why is peracetic acid (PAA) widely used in UK fresh produce washing?
PAA is favoured in UK fresh produce washing for its broad-spectrum antimicrobial efficacy, its ability to perform across a wide pH range, and its breakdown profile — it degrades rapidly into water, acetic acid, and oxygen, leaving no harmful residues on product or food contact surfaces. These properties make it well suited to direct product contact applications and operations supplying retailers with strict chemical residue policies.
Why does titration fail in coloured or turbid wash water?
Titration-based PAA testing relies on identifying a colour change in the sample at the endpoint of the titration reaction. When the wash water itself is significantly coloured — as occurs when washing pomegranates, red cabbage, beetroot, or other heavily pigmented produce — the endpoint colour change becomes impossible to detect reliably. The result is either an inaccurate reading or an inability to test at all, forcing facilities to change water purely to enable testing.
How does electrochemical PAA monitoring work differently from titration?
Electrochemical monitoring measures PAA concentration through a direct sensor reaction rather than a chemical titration process. The Palintest Kemio range uses pre-calibrated, single-use sensors that interact with the PAA in the sample and produce a numerical concentration reading — with no dependence on the visual clarity of the water. This makes it accurate in coloured and turbid matrices where titration cannot function reliably.
What BRCGS certification level does PrepWorld hold, and how does Kemio support it?
PrepWorld holds BRCGS Food Safety certification at AA+ level — the highest available. The Palintest Kemio range supports this by providing timestamped, operator-identified digital records of every PAA monitoring result, creating an audit-ready data trail that demonstrates consistent CCP monitoring throughout production. This documentation is a direct requirement of BRCGS Food Safety audits and is produced automatically by the Kemio range without additional administrative effort.
Can the Palintest Kemio range be used across other fresh produce applications beyond pomegranates?
Yes. The Palintest Kemio range supports PAA, chlorine, and chlorine dioxide monitoring across the full range of fresh produce washing applications — from leafy greens and salad to stone fruit, citrus, and root vegetables. Its matrix independence makes it particularly valuable wherever wash water colour or turbidity would compromise titration accuracy, but it delivers the same speed, consistency, and audit-ready data in clear water applications as well.
