Quick Answer
A blast chiller takes cooked food from 70°C to 3°C within 90 minutes, and a shock freezer takes it to −18°C within 240 minutes. That speed carries food through the 8–63°C danger zone fast enough to satisfy UK cook-chill guidance. Expect £3,200 for a 5 x 1/1GN cabinet, rising to £8,500 for 15 x 1/1GN.
Caterzone supplies blast chillers and shock freezers to UK restaurants, gastropubs, bakeries, and central production kitchens, and a blast chiller is the piece of equipment that turns a kitchen from cook-to-order into cook-ahead. It is also the one most often bought at the wrong capacity, because operators size it on cabinet volume rather than on kilograms per cycle.
This guide covers what blast chilling actually does to food, the UK 90-minute and 240-minute standards, how to size a cabinet against your production, probe versus time cycles, running costs, what an EHO will want to see in your records, and the price you should expect to pay. Browse the commercial refrigeration range as you read.
What does a blast chiller actually do?
A blast chiller drives cold air across food at high velocity to remove heat far faster than a standard fridge can, and the speed is the whole point.
A conventional walk-in or upright fridge is designed to hold food that is already cold. Put a 6cm-deep gastronorm of hot bolognese into a walk-in and two things happen: the food sits in the bacterial growth zone for three or four hours while its core slowly falls, and the warm mass raises the temperature of everything else in the cabinet. Both are food safety failures, and the second one is why EHOs look for a blast chiller in any kitchen doing volume batch cookery.
A blast chiller instead pushes air at around 4–8 metres per second across the product at an evaporator temperature well below zero — typically −10°C to −25°C depending on the cycle. High air velocity strips the insulating boundary layer off the surface of the food, so heat leaves the core several times faster. A 5cm-deep tray of rice that would take four hours to reach 3°C in a fridge reaches it in 60–80 minutes in a blast chiller.
A shock freezer is the same machine running a colder, longer cycle. It drives the product through the −1°C to −5°C zone quickly, so ice crystals stay small. Small crystals do not rupture cell walls, which is why shock-frozen food thaws without the drip loss and mushy texture you get from slow freezing in a standard freezer.
What are the UK blast chilling standards?
UK cook-chill practice, derived from Food Standards Agency guidance and reflected in most HACCP plans, sets two clear targets that your equipment must be able to hit.
Blast chilling: cooked food must go from 70°C to 3°C or below within 90 minutes. Once chilled, hold at 0–3°C. Chilled food produced this way is generally given a shelf life of up to five days including the day of production, provided the cold chain is unbroken and your HACCP plan supports it.
Shock freezing: cooked food must go from 70°C to −18°C or below within 240 minutes, then be held at −18°C or colder.
These sit alongside the general legal requirement in England, Wales, and Northern Ireland that chilled food be held at 8°C or below, with 5°C or below recommended as good practice and 0–3°C used for cook-chill. Hot holding remains 63°C or above. The purpose of blast chilling is simply to cross the gap between those two numbers as quickly as possible.
The other standard that matters is F-gas. Blast chillers are sealed refrigeration systems, and units with a charge above 5 tonnes CO₂ equivalent must be leak-checked at least annually by an F-gas certified engineer, with records kept. Most cabinets in this class now use R290 or R452A; check the data plate and keep the logbook with your maintenance file.
How do you size a blast chiller for your kitchen?
Size on kilograms per cycle, not on cabinet volume, because the compressor sets the limit long before the shelves do.
Every blast chiller carries two ratings: a chilling capacity in kilograms per 90-minute cycle, and a lower freezing capacity in kilograms per 240-minute cycle. A cabinet rated 20kg/15kg will chill 20kg of cooked product to 3°C in 90 minutes, or freeze 15kg to −18°C in 240 minutes. Load it with 30kg and it will simply take longer and miss the standard — which is exactly the failure an EHO finds when they read your temperature logs.
To size, work out your largest single production batch, not your daily total:
- Restaurant, 60–80 covers, some prep-ahead: typically 15–20kg per batch → a 5 x 1/1GN cabinet rated around 20kg/15kg
- Gastropub or hotel, batch sauces and stocks: 20–25kg → a 7 x 1/1GN cabinet at around 25kg/20kg
- Bakery or patisserie, tray production: 25–30kg → a 10 x 1/1GN cabinet at around 30kg/25kg
- Central production or contract catering: 35kg+ → a 15 x 1/1GN cabinet at 35kg/30kg or a roll-in unit
Two rules save money here. First, product depth matters more than weight: never load gastronorms deeper than 50mm for chilling or 30mm for freezing, because the cycle time is governed by the distance heat has to travel out of the core. A 65mm pan of stew will fail the 90-minute target even in an oversized cabinet. Second, leave 20–25mm of clear air between trays; blocking airflow is the most common reason a correctly sized machine underperforms.
Blast chiller capacity comparison
| Capacity | Chill / freeze rating | Typical footprint | Best for | Price guide |
|---|---|---|---|---|
| 5 x 1/1 GN | 20kg / 15kg | 750 x 740 x 850mm (undercounter) | Restaurant to 80 covers, small bakery | £3,200–£3,900 |
| 7 x 1/1 GN | 25kg / 20kg | 790 x 800 x 1,290mm | Gastropub, hotel kitchen, deli production | £4,000–£4,700 |
| 10 x 1/1 GN | 30kg / 25kg | 790 x 800 x 1,700mm | Bakery, patisserie, 150+ cover site | £4,600–£5,500 |
| 15 x 1/1 GN | 35kg / 30kg | 850 x 900 x 1,900mm | Central production, contract catering | £6,600–£8,500 |
| Refurbished / B-grade | Varies by model | Varies | Budget-constrained sites, second unit | £3,300 upwards |
Probe cycle or time cycle — which should you use?
Use the core probe for anything you are logging for HACCP, and the timed cycle only for repeatable products you have already validated.
A timed cycle runs the compressor for a set period regardless of what is inside. It is simple, but it assumes the load is identical every time. Vary the depth, the starting temperature, or the quantity and the timed cycle will either overshoot — freezing the surface of a chilled product — or stop short of 3°C.
A core probe cycle uses a needle probe inserted into the thickest part of the largest piece. The machine runs until the probe reads the target temperature, then automatically switches to a holding mode at 0–3°C (or −18°C after a freeze cycle) so the product is safe if nobody is there to unload it. This is the correct method for mixed production and the one that produces a defensible record.
Insertion matters. Put the probe in the geometric centre of the densest item, not touching the pan base, and not in a sauce that will chill faster than the meat sitting in it. A probe touching metal will read the pan temperature and end the cycle early — the most common cause of a "chilled" product that is still 12°C in the middle.
Sanitise the probe between cycles. It penetrates cooked product directly, so it is a genuine cross-contamination route and should appear in your cleaning schedule.
What does a blast chiller cost to run?
A blast chiller is intermittent-load equipment, so annual running cost is far lower than the compressor rating suggests.
Take a 7 x 1/1GN cabinet with a nominal 1.6kW compressor. A full 90-minute chill cycle draws heavily for the first 30–40 minutes and then tapers, averaging roughly 1.1kW across the cycle — about 1.65 kWh per cycle. At 26p per kWh that is 43p per full chill cycle. Run two cycles a day, six days a week, and you are looking at roughly £270 a year in electricity.
Set that against what it earns. A kitchen that can safely cook ahead buys back chef hours at the busiest point of the day, cuts waste by extending the safe life of batch production from same-day to five days, and can buy proteins in whole primals rather than portioned. In most sites the labour saving alone repays a £4,000 cabinet inside eighteen months.
Two running-cost details worth knowing. Blast chillers reject a lot of heat — a 1.6kW unit dumps roughly 2.5kW into the room — so site it away from your walk-in condenser and make sure the kitchen extraction can cope, or your other refrigeration will work harder. And condenser cleaning is the single biggest efficiency variable: a dust-blocked condenser can add 20–30% to energy use and will eventually trip the unit on high pressure. Brush it monthly.
What records does an EHO expect?
An environmental health officer will not usually inspect the machine itself; they will ask to see the evidence that it works.
Keep a chilling log recording, for each cycle: the product, the batch date, the start temperature, the finish temperature, the cycle time, and the initials of the person who ran it. Most modern cabinets have an HACCP printout or USB export — use it, because a machine-generated record carries far more weight than a handwritten one.
Label every chilled or frozen item with the production date and the use-by date the moment it comes out of the cabinet. Five days from production for cook-chill at 0–3°C is the usual maximum, but your own HACCP plan sets the number and you must be able to justify it.
Hold the F-gas leak-check certificates, the service records, and a calibration record for your probes — probes should be verified against an ice slurry at 0°C and boiling water at 100°C, typically monthly, with the check written down. Finally, keep a written procedure covering what happens when a cycle fails to reach 3°C in 90 minutes. "Discard and record" is a perfectly acceptable answer; having no answer is not.
Frequently asked questions
How fast should a blast chiller cool food?
A blast chiller must take cooked food from 70°C to 3°C or below within 90 minutes to meet UK cook-chill guidance. A shock freezer must reach −18°C within 240 minutes. Product depth is the limiting factor — keep gastronorms under 50mm deep for chilling and 30mm for freezing.
What size blast chiller do I need?
Size on your largest single batch in kilograms, not cabinet volume. A restaurant to 80 covers usually needs a 5 x 1/1GN cabinet rated around 20kg per 90-minute cycle; a bakery or 150-cover site needs 10 x 1/1GN at around 30kg. Freezing capacity is always lower than chilling capacity.
Can I put hot food straight into a normal fridge?
No. Hot food in a standard fridge takes three to four hours to reach 3°C, leaving it in the bacterial growth zone far too long, and it raises the temperature of everything else in the cabinet. If you cook in batches and chill for later service, a blast chiller is effectively a requirement rather than an upgrade.
How long does blast-chilled food last?
Cook-chill food blast chilled to 3°C within 90 minutes and held at 0–3°C is normally given a shelf life of up to five days including the production day. Shock-frozen food held at −18°C typically keeps for three to six months depending on product. Your HACCP plan must justify whichever figure you use.
Do blast chillers need F-gas servicing?
Yes. Blast chillers are sealed refrigeration systems and any unit with a refrigerant charge above 5 tonnes CO₂ equivalent must be leak-checked at least annually by an F-gas certified engineer, with records retained. Check the data plate for the refrigerant type and charge, and keep the logbook with your maintenance file.
Is a refurbished blast chiller worth buying?
A refurbished Williams or Foster cabinet from a reputable supplier can be sound value at around £3,300, particularly as a second unit or for a site with modest throughput. Insist on a refrigeration service record, a verified chill cycle against a probe, and a warranty on the compressor and gas circuit specifically.
Where to buy blast chillers and shock freezers in the UK
Caterzone stocks blast chillers and shock freezers from 5 x 1/1GN undercounter cabinets to 15 x 1/1GN production units, plus refurbished Williams and Foster machines. Browse the commercial refrigeration collection, or start with the 5 x 1/1GN blast chiller and shock freezer rated 20kg/15kg at £3,222.90 for a restaurant line, step up to the 10 x 1/1GN unit at 30kg/25kg for £4,692.90 for bakery or high-cover production, or take a refurbished Williams blast chiller freezer at £3,325.95 if budget is tight and you want a UK-serviceable brand.
For the cold chain either side of the chiller, read our commercial chest freezer buyer's guide and our refrigerated prep counter and saladette guide. To size a cabinet against your batch production, call Caterzone on +44 7787 069044 or email info@thecaterzone.co.uk.
