Refrigeration, such as walk-ins and reach-ins, holds ingredients cold and at food-safe temperatures until operators need to serve the food or assemble menu items. In contrast, blast chillers remove heat from food items, bringing them down to safe temperatures.

istock 1003976584Typically three to four times more costly than standard refrigeration units, this process forms microcrystals on products, which can keep food from becoming dehydrated.

Well-suited for large-volume applications such as catering operations and banquet halls, blast chillers allow operators to make product ahead of time and reheat the food when necessary. These units also can crank out more volume without compromising product quality and consistency.

Creative operators use blast chillers in a variety of ways. Examples of these creative applications include chilling salad plates prior to serving, cooling wine and beer glassware, refrigerating beverages quickly and reducing the temperature of hot product rapidly for easier handling.

Operators can monitor the blast-chilling process either with time and temperature or with a probe. Either way, HACCP protocol states that food must go from more than 140 degrees F to 70 degrees F in two hours and from 70 degrees F to 40 degrees F in four hours, with the total process not to exceed six hours.

By dropping food temperatures from 160 degrees F to 35 degrees F in 4 or less hours, blast chillers ensure food steers clear of the danger zone, that period of time where bacterial growth can ensue. These units expedite chilling by combining cold and moving air across the food or pulling out hot air. This happens at such a pace that the unit does not compromise food quality in the form of crystallization or freezer burn.

Choosing a Chiller

One of the biggest issues with blast chillers is that operators commonly underestimate these units’ complexity. Fortunately, with newer technology and control boards, these units have become easier to use than in the past. Still, chilling product in blast chillers is much different than simply placing food in a refrigeration unit. There needs to be an educational component for those working with this equipment about how food should be sized, shaped and packaged prior to the chilling process for optimum results and to ensure adherence to proper food safety protocol.

With blast chiller capacities ranging from 30 to 1,300 pounds, catering operators can choose the style and size that best fits their needs. When purchasing a blast chiller, operators can choose between undercounter units, countertop models that may include shelf space underneath or stand-alone systems. Roll-in and reach-in models are available, too. While reach-in blast chillers have permanent racks inside of the cabinet that can accommodate either hotel- or full-size sheet pans, roll-in units use mobile tray holders. Some models provide removable, adjustable shelving, which can provide added versatility. The majority of these units utilize 2-inch-deep pans that accommodate 10 pounds of product.

The ideal unit size will depend on the volume and application. Countertop blast chillers hold between 3 and 5 full-size pans, while roll-in units are geared for quantities of more than 200 pounds. One common mistake operators make is utilizing too big of a pan for blast chilling product. This can compromise the cooling process as the cold air won’t properly infiltrate the center of the pan. Proper container sizing plays an important role in ensuring quality results.

Also, when choosing a model, consider the type of product being chilled. For example, more delicate foods such as bakery items, rice and vegetables require a more controlled chilling method than heartier, denser food, like meat. Some blast-chilling units offer both hard and soft chill capabilities. With a hard chill, temperatures come down more quickly and bring food to an almost frozen state. Soft chill units bring product temperatures down to less than 40 degrees F gradually, making the process a little less harsh than a hard chill.

For operations with varying production levels, blast chillers that provide two independent cooling compartments can provide additional flexibility. These units can accommodate smaller amounts of food in a single compartment without cooling the entire interior, which can enhance efficiency.

This equipment utilizes large compressors, and operators can decide if a self-contained or remote condensing unit works best. Although some blast chillers require drain connections, catering operations may find a model with built-in defrost capabilities, which eliminates condensation on condenser coils, works best.

Features vary by model and may include stainless-steel interiors and exteriors, 4-inch-thick panels with CFC-free polyurethane foamed-in-place insulation, a remote refrigeration system sized to match the specific application, a door gasket heater that prevents doors from icing over, and a surface exterior-mounted control system with a digital readout of interior ambient temperature and probe temperatures, as well as automatic defrost and hold cycles.

Innovations include touch-screen controllers that can time different products, self-correcting evaporator fan motors and carbon graphite blades that change pitch to improve airflow in the event evaporator coils frost up.

The monitoring technology with these units has improved greatly in recent years. For example, in the past, operators would use handheld thermometers and a written log to track the temperature of food being blast chilled. With today’s more sophisticated technology, the majority of these units now offer data recording capabilities for HACCP documentation, with models using different methods to accomplish this.

Most blast chillers utilize a printer that records information on paper, while others have either a data port to upload reports to a computer or a USB drive for downloading temperature details on a portable storage device. Each method offers both pros and cons. For example, operators who choose a unit that prints HACCP data will need to purchase paper and designate a storage area to file these documents. Blast chillers that connect to computers may require special cables or access to hookup lines.

Cleaning and Maintenance

The average service life of a blast chiller can vary, depending on use, environment and various other factors but most last between 5 and 10 years. Unlike refrigeration equipment, blast chillers are not designed for continuous operation and should be shut off when not in use.

Keeping the interior clean represents the most important aspect of maintaining a blast chiller. Clean the interior of a blast chiller weekly using lukewarm water and detergent, per the manufacturer’s recommendations. Wash the door gasket with water and wipe it with a dry cloth.

Cleaning the condenser coil is a uniform task that applies to all refrigeration equipment. Clean the blast chiller’s condenser every 30 days, using nonmetal brushes to remove all dust and dirt from the condenser blades.

There are other steps to take that contribute to a long and productive service life for blast chillers.

  • Where drain lines are present, keep them clean of condensate water to prevent backups.
  • In addition to keeping the inside clean, keep probes in working order. These can get damaged if closed in a door.
  • Clean condensers by popping off the unit’s front panel on a weekly or monthly basis, depending on usage, environment and other factors.
  • The biggest mistake operators make is putting big sheet pans in with smaller pans on top, which can impede the cooling process.
  • Chefs and cooks tend to drop plastic on top of pans. The plastic, however, can make its way into the condensers, which impacts airflow.
  • Making sure probes are in good working condition and the wires aren’t damaged or frayed.

Unfortunately, blast chillers rarely show signs a breakdown is near. Blast chillers do, however, show some signs they may be near the end of their service lives and will soon require a replacement.

  • If the unit chills food inconsistently by either not cooling as quickly or thoroughly, operators should ensure the condenser is clean. If this is not the issue, and it is an older unit, replacement may be appropriate.
  • When repairs and service calls start adding up, it may be more cost-effective to replace the blast chiller. This typically applies for a unit that has been in service a long time and/or is part of a high-volume operation.
  • Other signs service is necessary include probes not working correctly or the condenser remaining on when the unit is turned off.
  • If the blast chiller has excessive leaks in the evaporator or refrigeration system, this may warrant replacement, depending on the unit’s age.
  • Because blast chiller evaporators can be pricey to replace, operators should consider retiring units between five and seven years old that leak.