A pub group pulled its prep back into one production kitchen in east London. Braises, sauces, ragùs and stocks for the whole estate, cooked at the start of the week and delivered out over the following days. The combi ovens were specified properly. The racking, the vac-pack bench and the vans were all specified properly. The chilling step got a line on the schedule that read "existing walk-in freezer, retain".
On the first production day, hot food went into that room by the trayful. The room drifted up, the stock that had been sitting in there since Thursday drifted up with it, and by the next morning the group had a food safety problem it had built for itself. Nothing had broken. The room was being asked to do a job nobody had ever asked it to do.
Cook chill is a production method, not a piece of equipment. You cook food to a safe core temperature, chill it quickly and under control, hold it cold, distribute it, then reheat it at the point of service. The whole model stands on the chilling step, and that step needs plant built to take heat out fast rather than plant built to hold cold. Those are two different machines, and UK law defines them separately.
What cook chill is, and what it is not
Strip out the jargon and cook chill has four stages. Cook to a safe core temperature. Chill down quickly. Hold and distribute cold. Regenerate to serving temperature at the point of sale.
The cooking end is the least contested part. GOV.UK's guidance for food businesses says "Standard advice is to cook food until it has reached a core temperature of 70°C for 2 minutes" and lists equivalents including "65°C for 10 minutes" and "75°C for 30 seconds" (Cooking food safely, GOV.UK). Cook chill does not change that. What it changes is what happens in the hour after the oven door opens.
It is worth saying what cook chill is not, because these get mixed up in tender documents. It is not hot holding, where food stays above 63°C until it is served. It is not cook freeze, which takes the product below freezing and gives you a different shelf life, a different texture and a different regeneration problem. And it is not batch cooking that happens to end up in a fridge. Cook chill is a controlled process with a measured chilling step and records behind it.
Why groups move to central production
The reasons are almost always the same four, and none of them are about refrigeration.
Skill concentrates. One development chef and a small production team can hold a standard across an estate in a way that thirty separate kitchens cannot. Specification tightens, because a sauce made once to one recipe tastes the same in every site. Waste falls, because you are producing to a forecast rather than to a guess made at 8am in each kitchen. And the footprint at site level shrinks, which matters enormously if you are signing leases on high street units where every square metre of back of house is coming out of covers.
What nobody says out loud at the business case stage is that central production also concentrates risk. Thirty kitchens each losing a fridge is an inconvenience. One production kitchen losing its chilling capacity on a Monday is an estate-wide problem, because there is no longer a second place the food could have been made. That is a change in the shape of your risk, and it should change how the plant is specified and how it is maintained.
The chilling step is the part that carries the liability
Here is where the honest answer differs from what you will read on most equipment websites.
The Food Standards Agency's own safe method for this, "Chilling down hot food" in the Safer food, better business pack for caterers, states the safety point plainly: "If you have cooked food that you will not serve immediately, chill it down as quickly as possible and then put it in the fridge." The reason given is equally plain: "Harmful bacteria can grow in food that is left to chill slowly." On blast chillers specifically it says "A blast chiller is specially designed to chill down hot foods quickly and safely" and, further down, "If you chill down lots of hot food in your business you may wish to consider using a blast chiller" (Safer food, better business for caterers, Food Standards Agency).
Notice what is not in that safe method. There is no number. The regulator's instruction is "as quickly as possible".
The hard numbers sit elsewhere and they are worth knowing precisely. Chilled food in England, Wales and Northern Ireland must be held at 8°C or below, and GOV.UK is explicit that "This is a legal requirement in England, Wales and Northern Ireland. It's recommended in Scotland." The same guidance says bacteria can grow between 8°C and 63°C (Chilling and freezing, GOV.UK). On the hot side, GOV.UK states that "hot food must be kept at or above 63°C if you're not serving it straight away", and that "you can keep it below 63°C for up to 2 hours. After that, cool it as quickly as possible to 8°C or below, or throw it away" (Cooking, GOV.UK).
The legislation itself takes the same shape. Paragraph 5 of Schedule 4 to the Food Safety and Hygiene (England) Regulations 2013 gives a defence where food was above 8°C "for an unavoidable reason, such as ... to accommodate the practicalities of handling during and after processing or preparation" provided it "was kept at a temperature above 8°C ... for a limited period only and that period was consistent with food safety" (Schedule 4, paragraph 5, legislation.gov.uk). A limited period consistent with food safety. Again, no number.
So what about the figure everyone quotes? You will see "70°C to 3°C in 90 minutes" on spec sheets, in sales literature and on a great many catering websites. It is a real number with a real origin, and the origin is equipment performance. Foster Refrigerator, one of the manufacturers whose cabinets we service most often, publishes it as a rating for its own range: "Blast chill from +70°C to +3°C in 90mins with an entry temperature of up to 90°C" and "Blast freeze from +70°C to -18°C in less than 240mins" (Blast chilling range overview, Foster Refrigerator). That is a machine specification, not a statutory limit. Treat it as the yardstick your equipment is sold against, and treat the chilling time your own food safety management system sets as the thing you are actually held to. If your temperature monitoring and HACCP records show a cycle you can defend, you are on solid ground. If they show nothing, the number on the brochure will not help you.
Why ordinary refrigeration cannot do the chilling step
This is not marketing. It is in the legal definitions of the equipment.
Commission Regulation (EU) 2015/1095, retained in UK law, defines a "blast cabinet" as "an insulated refrigerating appliance primarily intended to rapidly cool hot foodstuffs to below 10 °C in the case of chilling and below – 18 °C in the case of freezing". In the same article, a "professional refrigerated storage cabinet" is defined as an appliance "capable of continuously maintaining the temperature of foodstuffs within prescribed limits at chilled or frozen operating temperature" (Article 2, Commission Regulation (EU) 2015/1095, legislation.gov.uk). Rapidly cool, against continuously maintain. One is a process. The other is a shelf.
The engineering follows from that. A walk-in room's refrigeration is sized around a steady heat load: conduction through the panels, the door openings you told the designer about, the lighting, and a modest allowance for product coming in near temperature. It is not sized to absorb a large quantity of heat in one go. Put hot trays into it and the plant does its best, but for as long as it is fighting that load the room sits above where it should be, and everything already in there sits above where it should be too. That is exactly what happened to the pub group. The freezer was fine. The specification was wrong.
A blast cabinet is sized the other way round. Its refrigeration capacity and its air movement are chosen for pull-down, so it shifts far more air across the product, at a much lower air-off temperature, than a storage room ever would. That is also why it is a poor store. It is loud, it is thirsty, and it is built for cycles.
Blast chiller, blast freezer, blast room or a walk-in
| Equipment | What it is built to do | Where it sits in cook chill | What it should not be asked to do |
|---|---|---|---|
| Blast chiller (blast cabinet) | "rapidly cool hot foodstuffs to below 10 °C in the case of chilling", per Regulation (EU) 2015/1095 | The chilling step, straight out of the oven | Storage. Its capacity is defined as a food weight per operation, not a shelf |
| Blast freezer | Same appliance class in freezing mode, "below – 18 °C" | Cook freeze, or rescuing a batch you cannot move inside its chilled life | Standing in for the chiller. A frozen ragù is a different product with a different regeneration |
| Blast room | "an enclosure, for which the doorway and internal space is large enough for a person to step inside", same rapid cooling purpose | Volume production where loaded trolleys are wheeled straight in | Doubling as a store between production runs |
| Walk-in cold room or professional cabinet | "continuously maintaining the temperature of foodstuffs within prescribed limits" | Holding chilled product after the cycle, and holding goods in | The chilling step itself, at any volume |
If you are building the chilled store as well as the production line, the two decisions interact, and it is cheaper to get them right together than to add capacity to a finished room later. That is worth raising at survey stage with whoever is handling the walk-in cold room installation rather than after the panels are up.
Reading a blast chiller specification without being sold to
Two things make comparing quotations harder than it looks.
The first is what "capacity" means. Regulation (EU) 2015/1095 defines it, for blast cabinets, as "the food weight which can be processed (by the blast cabinet) to below 10 °C in the case of chilling and below – 18 °C in the case of freezing in a single operation". A weight per cycle, not a volume. So the question that matters is not how many gastronorms fit, it is how many kilos the machine will actually pull down inside one cycle, and how many cycles you can get through in your production window.
The second is the test standard. Blast cabinets are covered by BS EN ISO 22042:2021, "Blast chiller and freezer cabinets for professional use. Classification, requirements and test conditions", published on 30 November 2021. BSI describes its scope as specifying "the requirements for the verification of performance and energy consumption of blast cabinets for professional use in commercial kitchens, hospitals, canteens, institutional catering, and similar professional areas", covering appliances "intended to rapidly cool down hot foodstuffs up to a load capacity of 300 kg". The useful part for a buyer is the exclusion list. BSI states the standard does not cover roll-in cabinets, pass-through cabinets, cabinets with a remote condensing unit, cabinets with a water-cooled condenser, blast chilling and freezing tunnels, or continuous blast-chilling equipment (BS EN ISO 22042:2021, BSI Knowledge).
Read that list again, because it is most of what a central production kitchen actually buys. Roll-ins and remote-condenser machines sit outside the scope of the standard, which means their published performance figures are not tested to a common method. When you are comparing two roll-in quotations, ask each supplier for the load, the product, the tray arrangement and the start and finish temperatures behind their stated cycle time. If a number arrives without those four things attached, it is a claim rather than a measurement.
Shelf life and regeneration, which is where cook chill usually comes unstuck
Two operational constraints catch groups out after they have gone live.
The first is that reheating is not warming. GOV.UK is blunt: "Reheating means cooking food again, not just warming it up. Reheat food until it is steaming hot all the way through. You can only reheat food once." That last sentence has real consequences for a satellite site running a bain-marie service off regenerated product, and it needs to be designed into the portioning at the production end rather than managed by a supervisor at 7pm.
The second is that nobody outside your business can tell you the shelf life. It comes out of your own food safety management system. GOV.UK sets out the HACCP principles you have to meet, including to "identify the critical control points (CCPs)", "set limits for the CCPs", "monitor the CCPs" and "keep records of your food safety systems, checks and how you've put things right", and warns that "If your business is involved in a food safety incident, you will need to show your records as evidence of how you keep food safe" (Food safety management systems for businesses, GOV.UK). The chilling step is a textbook critical control point. Whatever life you put on a cook chill dish has to be justified by your own validated process and evidenced by your own data, not lifted from a manufacturer's brochure or from another operator's SOP.
Which is why the refrigeration and the paperwork are the same conversation. A blast cabinet that logs every cycle, and a chilled store that logs continuously, give you the evidence. Machines that beep and forget give you nothing to show an environmental health officer. The detail on holding temperatures is covered in our guide to the legal temperature limits.
What to specify if you are moving to central production
| Specification point | The question to put in the tender |
|---|---|
| Cycle capacity against production peak | How many kilos come out of the ovens in the busiest hour, not the daily total? Size the chilling to the peak or it becomes the bottleneck on day one |
| Redundancy | If one cabinet is down, does production stop? Two smaller machines often beat one large one for an estate that cannot afford a lost production day |
| Product depth and tray arrangement | What depth of product was the quoted cycle time measured at? Deep gastronorms of dense braise behave nothing like spread trays |
| Core probes and data output | How many probes, and does the controller export cycle records in a form your food safety management system can actually keep? |
| Condensing arrangement and heat rejection | Integral or remote, and where does the heat go? A production kitchen adding blast capacity is adding a significant heat load to a plant area that was sized before you existed |
| Electrical supply | Single or three phase, and does the incoming supply have the headroom? This is the item that most often delays a fit-out |
| Chilled store capacity downstream | Where does a full cycle of chilled product go, and is that room sized for it? Chilling capacity without storage capacity just moves the queue |
| Service access and the maintenance regime | Can an engineer reach the condenser and the evaporator without emptying the kitchen, and who is servicing it at what interval? |
Most of these are decided on a drawing, not on site, which is the argument for having the refrigeration engineer in the room during design rather than at handover. We treat that as part of new refrigeration installations rather than something to sort out afterwards.
What this looks like across an estate
Once production is central, you are running two different cold chains and they need different attention.
At the production kitchen you have process plant. Blast cabinets, a chilled store sized around a production cycle, and a plant area with a real heat load. This kit runs hard in bursts, which is a different duty cycle from a shop fridge and shows up as different wear. Condenser fouling in a production kitchen happens faster than most operators expect, and a fouled condenser on a blast cabinet does not fail dramatically, it just quietly stops meeting its cycle time. Nobody notices until somebody checks the logs against the specification.
At the satellite sites you have holding and regeneration. Counter fridges, undercounters, a small store, and the delivery chain in between. GOV.UK's four-hour allowance for chilled food out of refrigeration is a useful discipline here: "You can keep chilled food out of the fridge for up to 4 hours, then you must throw it away." Cook chill moves the risk into the handover, so the goods-in process at every site becomes part of the food safety system rather than a courier's problem.
Both ends want a refrigeration maintenance plan that reflects what the equipment actually does. A blast cabinet serviced on a generic annual visit, with no cycle verification against its rated performance, is being ticked rather than checked. Ask for the cycle time to be measured and recorded at every service, on a real load. That single line in a service specification tells you more about the health of a cook chill operation than any other check on the sheet, and it turns commercial refrigeration repair across London from a reaction into something you can plan.
Frequently asked questions
What is the difference between cook chill and cook freeze?
The end temperature and everything that follows from it. Cook chill takes cooked food down to chilled holding, which GOV.UK confirms must be 8°C or below as a legal requirement in England, Wales and Northern Ireland. Cook freeze takes it below freezing, and Regulation (EU) 2015/1095 puts the blast freezing target at "below – 18 °C". Freezing buys you far more time but changes texture on sauces, emulsions and anything with a high starch content, and it adds a controlled thaw step you have to plan and evidence. Most multi-site operators use chilling as the default and freezing selectively.
Can we use the blast chiller as extra cold storage between production runs?
It will hold product, because most cabinets drop into a hold mode after the cycle, but it is the wrong machine for it. The retained EU definition describes a blast cabinet as an appliance "primarily intended to rapidly cool hot foodstuffs", and its capacity is defined as a weight processed in a single operation. Using it as a shelf means the machine is unavailable when the next batch comes out of the oven, and running a process cabinet as a store is expensive in energy and hard on the plant. Size the chilled store properly instead.
Do we need a blast freezer as well as a blast chiller?
Only if the menu needs it. Many production kitchens buy multi-use cabinets that will do either, which is sensible flexibility, but the freeze cycle takes considerably longer than the chill cycle on the same machine. Foster, for example, rates its chill cycle at 90 minutes and its freeze cycle at under 240 minutes. If you plan to freeze a meaningful share of production, work out what that does to your cycles per shift before you commit to a cabinet count.
How do we set the shelf life for a cook chill dish?
Through your own food safety management system, validated for your own process and your own products. GOV.UK requires you to identify and set limits for your critical control points and to keep records that show the system works, and the chilling step is one of those points. In practice that means microbiological validation on your actual recipes, chilling data from your actual equipment, and a documented rationale. It is the one part of cook chill that cannot be bought in with the plant, and it is worth taking specialist food safety advice on rather than copying a figure.
Is cook chill worth it for a single site?
Rapid chilling is worth it for almost any kitchen doing volume prep in advance, because it is the only sensible way to get cooked food out of the growth range quickly. Cook chill as a production model is a different question, and it usually only pays once you have enough sites to justify concentrating skilled labour and enough distribution to move the product. A single busy restaurant normally wants a blast cabinet. A group of ten wants a conversation about central production.
What goes wrong most often once cook chill is running?
Load discipline, in our experience. The cabinet was specified on a certain load, at a certain depth, with air able to move between the trays, and six months later it is being packed to the roof with deep containers because production has grown. The cycle time goes out, the controller reports a longer cycle or an aborted one, and somebody concludes the machine is failing. Occasionally it is. More often the machine is being asked to chill twice what it was bought to chill, and the fix is a production schedule change or a second cabinet rather than a repair.
Get the chilling step right and the rest of the model works
Cook chill is not a complicated idea. It is cook, chill fast, hold cold, reheat once, and keep the records that prove you did. The bit that decides whether it works is the chilling step, and that is a refrigeration decision made on a drawing months before the first batch is produced. Every cook chill operation I have seen struggle has struggled there: the wrong machine, the right machine sized to the wrong load, or the right machine with no chilled store behind it.
Groups planning central production usually get the ovens and the vans right and leave the chilling to the end. Bring it forward. If you are sizing blast chiller installation for a new production kitchen, or you already have cabinets that are not meeting their cycle times, it is worth going through the load and the plant with an engineer before anyone writes a specification. We will tell you honestly whether you need more capacity, a different machine, or just a different way of loading the one you have. If you want the mechanics of the cycle itself, our explainer on how blast chilling works covers the equipment side in more detail.
About the author: Ali Elm runs Be Cool Refrigeration & Air Conditioning, a family-run London firm that has been installing, servicing and repairing commercial refrigeration and air conditioning since 2004. His F-Gas certified team has delivered more than 2,000 projects across London and the South East.
Last updated: 18 September 2026
Written by
Ali Elm
Ali is the Head of Operations at Be Cool Refrigeration with over a decade of hands-on experience in HVAC and commercial refrigeration. He oversees every installation, repair, and maintenance project, making sure the work meets the highest standards. Ali holds full F-Gas certification and has worked across residential, commercial, and industrial refrigeration systems throughout London and the South East. When he is not on site, he writes these guides to help business owners and homeowners understand their cooling systems better.