Short answer

A blast chiller cools cooked food from +70 °C to +3 °C (158 °F to 37 °F) in about 90 minutes using cold, fast-moving air at roughly −10 °C to 0 °C. A shock (blast) freezer continues to −18 °C (0 °F) at the core within about 240 minutes, with air at −35 °C to −40 °C.

Both machines remove heat fast. The difference is where they stop. A blast chiller brings cooked food down to fridge temperature; a shock freezer carries on until the core is frozen. Choosing between them depends on what you produce and how long it must keep.

The two cycles, side by side

Blast chillingShock freezing
Core temperature+70 °C → +3 °C+70 °C → −18 °C
Reference time≤ 90 minutes≤ 240 minutes
Cabinet airabout −10 °C to 0 °Cdown to −35 °C / −40 °C
Shelf life after cycleAbout 3–5 days chilledWeeks to months frozen
Typical usersRestaurants, central kitchens, cateringBakeries, gelato, seafood, ready meals

Why speed matters

Bacteria multiply fastest between roughly +5 °C and +60 °C. Cooked food left to cool on a bench, or loaded hot into a normal fridge, spends hours in that range and warms everything around it. A blast chiller moves the core through the danger zone in about an hour and a half, which is why HACCP plans in many countries name it as the control point for cook-chill production.

For freezing, speed changes texture. Slow freezing grows large ice crystals that pierce cell walls; when the food thaws it loses water and becomes soft. Shock freezing forms small crystals, so croissant dough, fish fillets and ice cream keep their structure.

How to size the machine

Capacity is quoted as kilograms per cycle, not cabinet volume. Start from your largest daily batch:

  1. Weigh what you need to cool in one go (for example 30 kg of cooked rice and sauces).
  2. Check the tray format you already use: GN 1/1 (530 × 325 mm) for kitchens, 600 × 400 mm for bakery.
  3. Pick a model whose rated blast chill load covers the batch with about 20% margin.
TraysBlast chill per cycleShock freeze per cycle
5 trays≈ 18 kg≈ 12 kg
10 trays≈ 35 kg≈ 25 kg
15 trays≈ 50 kg≈ 38 kg
Roll-in trolley (20 × GN 1/1)≈ 80 kg≈ 60 kg

Features worth paying for

  • Core probe. The cycle ends when the food reaches the target, not when a timer runs out. This is the only way to prove the result for HACCP records.
  • Soft and hard chill. Soft chill keeps the air just below 0 °C to protect delicate items; hard chill starts colder for dense products.
  • Automatic hold. After the cycle the cabinet switches to storage temperature until someone unloads it.
  • Stainless AISI 304 interior with rounded corners for cleaning.
  • Power supply. Small reach-ins run on 220–240 V single phase; large and roll-in models need three phase.

Which one should you buy?

Choose a blast chiller if you cook in advance and serve within a few days. Choose a shock freezer, or a combined model, if you bake frozen dough, make gelato, process seafood or sell frozen ready meals. If you are not sure, a combined cabinet gives you both cycles in one footprint.

Further reading

Quick answers

Can one machine do both blast chilling and shock freezing?
Yes. Most modern cabinets offer both programmes. Shock freezing needs a larger compressor and a colder evaporator, so a combined machine costs more than a chiller-only model.
Can I use a blast freezer as a normal freezer?
It can hold product after a cycle, but it is not efficient long-term storage. Move product to a storage freezer once the cycle ends.
How long does a shock freezing cycle take?
The common reference is +70 °C to −18 °C at the core within 240 minutes for a full rated load.
What is a shock freezer?
A shock freezer is a cabinet or room that blows air at about −35 °C to −40 °C (−31 °F to −40 °F) over food to bring its core to −18 °C (0 °F) quickly, typically within about 240 minutes. Fast freezing forms small ice crystals, which limits cell damage, drip loss and texture change when the food is thawed.
What is the difference between a shock freezer and a regular freezer?
A regular freezer is designed to store already-frozen food at about −18 °C (0 °F) and freezes warm product slowly, often over many hours. A shock freezer has far more refrigeration capacity and high-velocity air, freezing a full load to −18 °C at the core in about four hours. Use the shock freezer to freeze, then move product to storage.
How does a blast chiller shock freezer combination work?
A combined blast chiller shock freezer runs two programmes in one cabinet. The chill cycle uses air around −10 °C to 0 °C to take food to +3 °C (37 °F) in about 90 minutes without freezing the surface; the freeze cycle drops air to about −35 °C to −40 °C to reach −18 °C (0 °F) at the core. A core probe ends each cycle.
What size shock freezer do I need?
Size a shock freezer by the weight frozen per cycle, not cabinet volume. Reach-in models of 5–20 GN 1/1 or 600 × 400 mm trays suit restaurants and bakeries, typically freezing a few kilograms per tray per cycle. For whole pallets or larger batches a walk-in blast room at −35 °C is used. Share batch weight, product and pan depth for a quotation.