Chilled spoilage is written off at the depot but starts on the quay
Updated: Oct 28
The box goes in the bin at the depot. Somebody notes the date on the pack, records the loss and moves on. The write-off is booked there, where it was noticed. The cause almost never is.
This is how spoilage is accounted for in chilled food and seafood. It is also, often, the smaller part of the cost. The larger part is product that leaves with less life than it should, and sells for less further down the line. Nobody bins it. Nobody records it either.
The sums are not small. WRAP's key facts update, published in July 2025, puts UK food manufacturing waste at around 1.4 million tonnes in 2021. Of that, 706,000 tonnes was edible food worth about £0.85 billion. WRAP's earlier study of product life sampled more than 23,000 products in 2015. It estimated that one extra day of life could prevent as much as 250,000 tonnes of food waste a year. Seafish counts 342 seafood processing sites in the UK in its 2024 figures, 43 of them in East Yorkshire and Northern Lincolnshire. For them, a day of shelf life is real money.
Life is spent by the hour, and temperature sets the rate
Chilled product has a fixed budget of life. The clearest account of how it is spent remains the FAO's technical guide to quality changes in fresh fish. It was published in 1995 and is still the standard reference. Its spoilage model shows that fish with ten days of life on ice at 0°C has about 4.4 days at 5°C, and 2.5 days at 10°C. Put the other way round, a day at 10°C uses roughly four days of shelf life on ice. In the same tables, packed cod spoils 2.3 times faster at 5°C than at 0°C, and 4.7 times faster at 10°C.
The legal line sits a long way from the commercial one. Food Standards Agency guidance says that in England, Wales and Northern Ireland cold food must be kept at 8°C or below. It advises businesses to check that fridges and display units are at 5°C or below. A chiller holding at 6°C is therefore perfectly legal. On the FAO figures, it is also spending the life of fresh fish at more than twice the rate of fish kept on ice. The law is satisfied. The margin is not.
The product thrown away at the depot was usually lost on the quay.
Follow the clock and the thermometer
The method is simple, and none the worse for that. Pick one product line. Follow several batches from landing or intake to the customer. At each handover, note the time and the product temperature:
Landing or intake, and how long product waited before it went into chill.
Processing, including time on the line and in any holding area.
The dispatch chiller, including how full it was and how often the door was opened.
Loading and transport, including time on the dock and in the wagon.
Arrival at the customer or depot, and the life left on the pack when it got there.
Most businesses already record much of this for food safety, under their HACCP plan. The records are kept and filed. They are simply never read for cost. Where time stretches or temperature drifts, that is where shelf life is being spent. In my experience it is rarely one dramatic failure. It is a slow landing, a delayed intake, a wagon that waited on the dock, or a chiller overloaded on a Friday. Each is a small thing. Together they are not.
Turn lost hours into lost money
Once you know where life is being spent, set it against what is written off, discounted or sold short-dated. A pack that arrives a day short may never appear as spoilage at all. It appears instead as a lower price, a markdown at the customer, or a smaller order next week.
A worked example, with round numbers that are illustrative only. A line ships 20 tonnes a week of chilled fish at £8 a kilo. Suppose 10% of that volume reaches the customer a day shorter than it should, and short-dated stock sells at a 30% discount. The loss is 2 tonnes at £8,000 a tonne at 30%, or £4,800 a week. Over a year that is close to £250,000. Not a single box has been binned. Set that against the cost of the dock wait or the overloaded chiller that caused it.
Mend the cause, not the write-off
The remedies are usually mundane, and they rarely need capital:
Change the intake order so the product that has waited longest goes into chill first.
Move a collection time so loads are not sitting on the dock.
Split a chiller load rather than overfilling one unit at the end of the week.
Rotate stock by life remaining, not by date of arrival.
WRAP's 2015 product-life work pointed the same way. Two of its five recommendations concerned the supply chain rather than the product. One was reviewing practices such as stock rotation, so that more usable life reaches the end customer. The other was benchmarking delivery times. Both apply as much to a fish merchant or a chilled food maker in a yard office as to a supermarket supplier.
None of these changes costs much. What makes them worth the trouble is a figure showing which handover costs the most. Then the effort goes there first, rather than everywhere at once.
What to do first
Choose one high-volume chilled line and follow five batches from intake to customer, logging time and temperature at each handover.
Pull last quarter's write-offs, credits and short-dated discounts for that line and put them on one sheet.
Set an internal chiller limit of 5°C or below and check how often it is breached.
Work out the cost of one day's lost life on that line using your own volumes and discounts.
Fix the worst handover first, then measure the same batches again.
Sources
Figures are taken from the sources listed and were correct at the time of writing. Where rules are described, check the latest official guidance and take qualified advice before acting.
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