A Frozen Food Plant Failed Its Cold Store Swabs and Lost a 6.8 Million Baht Export Order Overnight
Last updated: 6 Sep 2026 | 6 Views |
A freezing room does not kill organisms. It only slows them down.
A Frozen Food Plant Failed Its Cold Store Swabs and Lost a 6.8 Million Baht Export Order Overnight
Why washing and chemical fogging have limited use in a cold store, and why ozone is the export plant's option
Three swab points above limit in one cold store suspended an entire export consignment — and no conventional cleaning method works in a room held below freezing.
Khun Surachai is 49 and manages a frozen seafood processing plant in Mahachai, Samut Sakhon. It has two finished-goods cold stores held at minus 18 degrees and three raw material chill rooms at 0 to 4 degrees.
The plant has held GMP and HACCP certification for twelve years and exports to customers in Japan and Europe, among the most demanding inspection regimes in the world.
In July 2025 the quarterly swab results from the second finished-goods cold store showed total counts above the customer's limit at three of twelve sampling points. The Japanese customer immediately suspended a 6.8 million baht consignment due to ship the following week.
The story
Three points out of twelve that changed everything
Khun Surachai received the results on a Friday afternoon. Within two hours, an email from the Japanese customer arrived suspending acceptance of the consignment due to load the following week.
The three failing points told a very clear story between them: the wall-to-floor junction in a corner of the room, underneath the innermost pallet racking, and around the ducting of the evaporator coil.
What those three had in common was one thing only: in practical terms, nobody can reach them. A corner permanently occupied by stacked pallets, racking that requires a forklift to clear, and ducting nearly four metres up.
What he found hardest, he says, was that his team followed every point of the SSOP cleaning plan without fail and every record was complete. But even the best cleaning plan can only reach where a person can go.
Why cold stores are far harder to clean than ordinary rooms
The food safety consultant the plant brought in explained that a cold store has three constraints that severely limit conventional cleaning.
First, water. Washing in a room at minus 18 is close to impossible, because the water freezes on contact. And in a 0 to 4 degree chill room, wash water raises the humidity, which becomes ice build-up and a fresh reservoir for organisms.
Second, chemicals. Many disinfectants lose substantial efficacy at low temperature, and in food contact areas there are constraints on residue that must be rinsed away with water — which loops straight back to the first problem.
Third, shutting the system down. A deep clean means stopping refrigeration and moving stock out, which is very costly: external cold storage rental, transport, and the risk of the product's temperature changing in transit.
The real cost of a suspended order
The suspended consignment was 6.8 million baht. Khun Surachai says that is only the first number, because the product was already made and sitting in the cold store — every waiting day costs electricity and storage space.
The plant had to commission two rounds of urgent external laboratory retesting at 78,000 baht each, and submit a corrective and preventive action report to the customer within fourteen days.
The customer also cut the following quarter's order volume by 30 percent while assessing the corrective action — roughly another 9 million baht — and increased swab frequency from quarterly to monthly at the plant's expense.
The frightening thing about food export, he says, is that customers do not judge you on twelve good years. They judge you on how well you handled the most recent incident, and on whether your measures are demonstrable.
The method Japanese plants already use
The same consultant suggested he look at ozone in cold stores, saying it is long-established practice in Japanese and European food plants, particularly in areas that cannot be washed with water.
Three reasons make it suit a cold store, and they map exactly onto the three constraints. It is a gas, so it adds no water and creates no ice. It decomposes back into oxygen, so it leaves no residue on food contact surfaces. And it reaches corners, the space under racking and the area around ducting by itself, with nothing moved.
He had the team survey the following week. They assessed each cold store's air volume, adjusted the cycle for the low temperature, and carried out the work on a Sunday night when the plant was closed.
The following week's repeat swabs from all twelve original points passed. When he submitted the report together with the equipment's Department of Medical Sciences certification, the Japanese customer released the suspended consignment within five working days.
What it actually costs
A single failing point stops an entire consignment
Export customers do not assess in percentages. If any point exceeds the limit, the whole consignment is suspended. A 6.8 million baht batch already produced becomes stock consuming electricity and space every day it waits.
The knock-on damage is several times the suspended batch
The customer cut the following quarter by 30 percent — roughly another 9 million baht — and raised swab frequency from quarterly to monthly at the plant's own cost.
Even the best cleaning plan only reaches where people can go
All three failing points were a corner permanently blocked by stacked pallets, the space beneath racking that needs a forklift to clear, and ducting nearly four metres up. No SSOP puts a person there on every cycle.
Risk to GMP and HACCP certification
Repeated out-of-limit results in a food storage area weigh heavily with auditors, and the absence of a demonstrable airborne contamination control measure is the easiest weakness for an inspection to identify.
Why the usual fixes fail
Washing with water and chemicals per the SSOP
Necessary and it must continue. But at minus 18 water freezes on contact, and in a 0 to 4 degree room wash water raises humidity, which becomes ice build-up and a fresh reservoir for organisms.
Chemical fogging in the cold store
Many disinfectants lose substantial efficacy at low temperature, and food contact areas impose residue limits requiring a water rinse — which loops back to the water and ice problem.
Shutting down for a deep clean
It works, but at very high cost: moving stock to rented external cold storage, transport charges, the risk of temperature excursion in transit, and several days of stopped production.
Using UV in the cold store
UV lamps disinfect only surfaces in direct line of sight. In a cold store full of high-stacked pallets and deep racking, most of the space is in shadow — and all three failing points were places light never reaches.
Increasing cleaning frequency
The response managers usually reach for because it can start immediately. But increasing frequency where you already clean does not clean where you cannot, and it puts more water into a cold store, which makes things worse.
A cold store needs a method that uses no water, leaves no residue, and reaches where people cannot
Line up a cold store's constraints and they eliminate almost every method: no water because it freezes, no residue because it is a food contact area, no shutdown because the cost is prohibitive, and it must reach places people cannot go.
This is exactly why food plants in Japan and Europe have used ozone in these areas for years. It is the one method that satisfies all four conditions at once.
Ozone is a gas, so it fills the cold store's entire air volume: into corners blocked by stacked pallets, under the innermost racking, around ducting four metres up, and into the wall-to-floor junction. Where it meets bacteria, yeasts or mould, the third oxygen atom breaks away and destroys the cell wall. Then the ozone decomposes back into ordinary oxygen — no residue on food contact surfaces, no water rinse required, and not one percent of added humidity to form new ice.
10 reasons ozone treatment solves it
1. No water, so no ice build-up and no added humidity
This is the first and most important advantage in a cold store. Ozone is a dry gas, so it works at minus 18 without adding water that becomes ice build-up and a fresh reservoir for organisms.
2. No residue on food contact surfaces
Ozone decomposes back into ordinary oxygen after reacting, so there is no water rinse required and no chemical left on floors, walls, racking or packaging — a core requirement in food storage areas.
3. It reaches corners, under racking and around ducting
Failing swab points are almost always places that cannot be cleaned in practice. Ozone is a gas, so it reaches all of them by itself with no pallets moved and no racking dismantled.
4. No stock movement and no long refrigeration shutdown
Avoiding a move to external cold storage saves transport, rental and the risk of a temperature excursion — costs that are usually many times the service fee.
5. 99.99% removal of embedded mould
Testing confirms 99.99% removal of deep-seated mould in air conditioning systems and furnishings, with virus and bacteria kill an order of magnitude beyond that — the level export customers want to see in a report.
6. It treats the evaporator coil and ducting, a recurring risk point
Evaporator coils condense continuously and produce meltwater on every defrost cycle, making them the most common failing area in a cold store. Running the coil fans during the cycle carries ozone right through that zone.
7. The Master Ozone Generator is certified by the Department of Medical Sciences
WHD uses the Master Ozone Generator, the only ozone brand in Thailand certified by the Department of Medical Sciences, Ministry of Public Health, and tested by Intertek UK — attachable directly to a corrective and preventive action report for an export customer.
8. It can be written into a HACCP control plan as a preventive measure
Rather than an emergency fix, a scheduled ozone cycle in the control plan is a documented preventive measure — precisely what auditors and overseas customers weight most heavily.
9. It runs outside production hours with no line impact
The automatic digital timer cycle runs about thirty minutes; large areas take several consecutive cycles. The team works on a closed shift and the line runs normally the next shift.
10. It works for cold stores, packing rooms and processing areas alike
The same principle applies to raw material prep, wash rooms, packing rooms and changing rooms — the other areas where swab results commonly fail — so one method covers the whole plant.
Before and after
Before
- Swab results above limit at 3 of 12 points in the finished goods cold store
- A 6.8 million baht consignment suspended by the Japanese customer immediately
- The following quarter's orders cut by 30 percent, roughly another 9 million baht
- Two rounds of urgent external laboratory retesting at 78,000 baht each
- All failing points located where nobody can physically reach on a cleaning round
- Swab frequency raised from quarterly to monthly at the plant's own expense
After
- Repeat swabs at all 12 original points passing
- The Japanese customer releasing the suspended consignment within five working days
- No stock moved and not a single production shift lost
- No additional ice build-up and no residue on food contact surfaces
- Equipment certification attached directly to the corrective and preventive action report
- A quarterly ozone cycle written into the plant's HACCP control plan
How we get you started, in 3 steps
Survey and assessment
The team measures each cold store's air volume, notes the operating temperature, the racking layout, the evaporator and duct positions, and the historically failing points, then sets the number of machines, positions and cycles for low-temperature operation.
Preparation and sealing
Reachable surfaces are disinfected first if needed. Gaps are opened between pallet stacks where practical, the evaporator fans are run so the gas distributes, cold store doors are sealed, and everyone leaves the area.
Ozone cycle, ventilation and check
The machine runs its automatic cycle, adjusted for the temperature and volume of the cold store. The area is then ventilated per procedure, surfaces are checked, and repeat swab sampling is recommended as documented evidence for the report.
What a customer says
“My team followed every point of the SSOP without fail. But the failing swab points were a corner blocked by stacked pallets and the area around ducting four metres up — nobody can get there on every round. Ozone is a gas, so it went there by itself with nothing moved. All twelve repeat swabs passed, and the Japanese customer released the consignment within five working days.”
Khun Surachai P. — plant manager, frozen seafood processor, Samut Sakhon
The most common misconceptions about cold stores
First: cold kills organisms. In fact cold slows growth but does not kill. Several bacteria including Listeria can grow at temperatures near zero, and many organisms simply remain dormant until conditions improve.
Second: cold stores are dry. In fact they carry a continuous moisture cycle from condensation on the evaporator and from meltwater on every defrost cycle. That water is exactly the moisture organisms need.
Third: a clean floor means a clean room. In fact failing swab points are usually not the floor — they are wall-to-floor junctions, under racking, around ducting, and in the door seals, none of which anybody scrubs daily.
Fourth: cleaning more often solves it. If the problem is where people cannot reach, increasing frequency where they can changes nothing about the results at the points they cannot.
What export customers want to see in a corrective action report
Khun Surachai says the most important lesson was not about disinfection method but about what an overseas customer wants to see in a report.
The first thing they want is a credible root cause, not an assurance that you will be more careful. Identifying that all three failing points are physically unreachable is an analysis customers accept immediately.
The second is a corrective measure that matches that root cause. If the cause is that people cannot reach, the measure must be a method that does not require a person to reach — which makes a gas the logically consistent answer.
The third is verifiable evidence: government certification for the equipment, records of the work performed, and repeat swab results from the same points. With all three, the Japanese customer released the consignment in five working days after a three-week suspension.
Frequently asked questions
Does it really work at minus 18 degrees?
Yes. The team adjusts the cycle and volume for the temperature and size of each cold store. Because ozone is a dry gas, there is none of the ice build-up that water or fogging causes.
Does stock have to be moved out?
No — a major advantage, because moving stock to external cold storage means transport, rental and temperature excursion risk. We only recommend opening gaps between pallet stacks where practical.
Is there residue on packaging or food contact surfaces?
No. Ozone decomposes back into ordinary oxygen after reacting, so no water rinse is needed and no chemical remains. This is the main reason export food plants choose it.
Can it be used as evidence in GMP and HACCP systems?
Yes. WHD uses the Master Ozone Generator, certified by the Department of Medical Sciences, Ministry of Public Health, and tested by Intertek UK. Documentation is available to attach to control plans and corrective action reports.
How often should it be done?
For export food plants, quarterly as a routine written into the control plan. Areas with a history of failing results should start with consecutive treatments and repeat swab verification before moving to the routine schedule.
Can it be used in packing and processing rooms too?
Yes, including raw material prep, wash rooms, packing rooms and changing rooms — the other areas where swab results commonly fail — so one method covers the whole plant.
Does it disrupt production?
No. The team works on a closed shift or between production runs, and the line operates normally on the next shift after ventilation per procedure.
Is anything included for factories?
For bookings of 15,000 baht and above, WHD includes free hospital-grade CHEMGENE HLD4H spray disinfection, certified by Mahidol University and NHS England — suited to contact surfaces in packing and changing rooms.
If the root cause is where people cannot reach, the fix must not require a person to reach it
If your swab results keep failing at the same points while your team follows every step of the SSOP, look carefully at where those points are. They are almost always corners, under racking and around ducting — places nobody can reach on every round.
Ozone treatment fills the cold store's whole air volume and reaches those places by itself, using no water so no ice forms, leaving no residue on food contact surfaces, requiring no stock movement, and coming with Department of Medical Sciences equipment certification you can attach to a customer report.
For bookings of 15,000 baht or more, WHD includes free hospital-grade CHEMGENE HLD4H spray disinfection.
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