What Is Blast Chilling? Why Use A Blast Freezer?

A guide on how to use a blast chiller and blast freezer, and why the cook chill process is important in commercial kitchens.

What is Blast Chilling and Blast Freezing?

The principle feature of Blast Chillers, Blast Freezers or Blast Chiller Freezers is that they are capable of rapidly reducing the temperature of hot foods (+90°C) to low, safe temperatures (+3°C or -18°C). This means it passes through the 'food danger zone' quickly eliminating the opportunity for harmful bacteria to develop and multiply (bacteria multiplies fastest between 8˚C and 68˚C).

A blast chiller rapidly lowers the temperature of hot food from +70°C to +3°C in just 90 minutes. Williams blast chillers can accomodate higher starting temperatures of +90°C, offering the same cycle performance, down to +3°C in just 90 minutes.

The advanced 'Airsmart' system in a Williams product blast chills in three directions simultaneously, ensuring even chilling and eliminating dehydration time after time. Even delicate foods are cooled without damage and maintained in the best possible condition.

A blast freezer rapidly reduces the temperature of hot foods from +70ºC down to –18ºC in 240 minutes. Williams blast freezers can accomodate higher starting temperatures of +90ºC, offering the same cycle performance, down to –18ºC in 240 minutes.

The process makes it easier for caterers to comply with Food Safety and Temperature Control Legislation too. In fact, many caterers are using them solely for that purpose, and in doing so are performing a very simple cook-chill operation.

What is Cook-Chill?

Cook-Chill is a simple, controlled system of advanced food preparation designed to provide more flexibility in foodservice. The technique involves the full cooking of food, followed by rapid chilling and storage at controlled temperatures (for up to five days). When required, the food must be regenerated before service. The production system itself is simple to operate if well managed, and completely safe provided the Department of Health Guidelines on temperature/time controls are followed. Read more about the cook-chill process here

WTBC70 blast chiller is perfect for cook chill process

When to use a Blast Chiller or Blast Freezer?

Blast chillers and blast freezers are the perfect choice for caterers within every sector who cook and then chill food such as hospitals, pubs, airlines, schools, restaurants and events, to name but a few.

They also provide a great solution to help reduce food waste in kitchens. Having to dispose of ingredients or meals before they get used can be a significant issue for businesses, both on sustainability and costs. Implementing a blast chill or blast freeze approach can deliver production and operational benefits.

At Williams, we supply a range of sizes from 10kg under counter blast chillers and blast freezers to modular roll in blast chillers that are able to handle up to 320kg of food. Typically, reach-in blast chillers range in capacity from 10kg to 50kg whilst the roll-in blast chillers range from 90kg to 320kg. More on our chiller freezer ranges can be found here.

Blast chiller and blast freezer temperature range

Blast Chilling and Blast Freezing: Energy Efficient Tips

Historically, blast chillers and freezers were previously seen as energy hungry units that were only suitable for large institutions. This has changed with units now available to offer easy, energy efficient blast chill or blast freeze cycles.

Food safety is vital 

HACCAP compliance is a must with blast chilling. Before buying a unit that uses less power ensure it’s able to blast chill food in an acceptable time. Regulations state that the core of the food must be chilled in 90 minutes and frozen in 240 minutes. For added flexibility consider a unit that can chill from +90°C rather than the standard +70°C.

The right size for the job: An easy way to reduce energy use is to have a unit designed to blast chill just the amount of food you need. If you are producing low volumes of food a small undercounter blast chiller will be more efficient.

Before you begin: Ensure that the blast chiller or freezer is switched on and is at the correct temperature (3°C for chilling / -18°C for freezing) before hot food is loaded, otherwise the refrigeration system will be overworked. As well as being less efficient to run there’s the risk that the cycle may not complete correctly.

Half loads: When blast chilling or blast freezing less than a full load, space the trays out evenly throughout the cabinet. This will speed up the process and ensure the food is uniformly chilled. If possible, use a food probe to control the cycle, as this will save energy by stopping the cycle as soon as the correct temperature is reached.

Use a food probe: Using a food probe to control the blast chill cycle can save energy. To ensure the most accurate temperature readings, position the probe in the middle of the tray on the middle shelf, in the densest part of the food.

Air distribution: Having even, all round air flow not only ensures uniform chilling and minimises the risk of damaging the food but also reduces energy use. 

Self-diagnostics: With any unit maintenance is key to ensuring your product runs efficiently for the life of the unit. Blast Chillers are available with self diagnostics, which mean service engineers can quickly find a fault and correct it. Maintenance reminders such as condenser cleaning lights are also invaluable in keeping your refrigeration running smoothly.   

Keep it closed: Once the blast cycle has started, do not open the door, for example to add more trays of product. The food already in the unit will be subjected to warm air, while the food that is added won’t get the full blast cycle. This not only reduces the efficiency of the unit but, food safety will be compromised. 

Don’t cover food: Don’t cover food in trays in the blast chiller or freezer, it will compromise the efficiency of the blast cycle. Modern blast chillers and freezers have special airflow designs, such as Williams’ AirSmart, which protect even delicate food, so there is no need to cover it.

High performance insulation: increased thermal efficiency can be achieved with improved insulation. By maintaining a constant temperature more easily, and reducing heat ingress, the refrigeration unit will have to work less, reducing its energy use.

Storage mode: Many blast chillers and freezers now come with a storage mode. The energy savings available for this can be sizeable as it negates the need for a separate unit to hold products at the appropriate temperature. This is especially true for high volume modular units.

View our range of Blast Chillers and Blast Freezers here.