Blast chillers drop food temperatures from 160 degrees F to 35 degrees F in 4 hours or quicker with some models.
Blast chillers bring food temperatures down using a combination of cold and moving air across the product, which expedites the process. However, if food temperature reduces too quickly crystallization or freezer burn can occur, thus damaging the menu item.
Operators also use blast chilling as part of cook-chill processes. A banquet hall or other operator that serves a large quantity of food all at one time can benefit from blast chilling. Culinary staff can prepare the food to roughly 85 percent cooked before blast chilling it. Before serving, staff can Reheat for the the remaining 15 percent the remaining 15 percent. Blast-chilled items not only have an extended shelf life to accommodate advanced prep needs or food availability throughout the week, but they also can cut labor time and cost when used for batch production.
Blast chillers are not just a replacement for ice baths; blast chilling/shock freezing meets HACCP protocol by processing food through the danger zone. HACCP protocol states that food must go from 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. Operators can retrieve HACCP data from these units a variety of ways, including by printer, SD card
and PC connection.
There are two ways to blast chill: by time and temperature or with a probe, which can shorten the cooling period and confirm food temperature.
Any type of blast chiller is suitable for use in prep areas, and the size depends on the application. There are countertop units that hold between three and five pans as well as larger models that look similar to reach-in units. These may have one door or be a single pass-thru unit that can be in a walk-in. Reach-in, also known as self-contained, units and stand-alone roll-in configurations also are available.
Depending on the model, standard features 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, flush-mounted polyurethane foamed doors for a dependable seal, a door gasket heater that prevents icing over on doors, 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.
Blast chiller control packages may vary. Some record, document, graph and e-mail temperature information. Touch-screen controllers may also offer timers for different products.
Blast chillers freeze quicker than freezers. For example, frosted mugs take 10 minutes to prepare and gelatin takes 20 minutes.
“This is an expensive piece of equipment, so it’s not typically used in mom-and-pop restaurants,” says John Marenic, principal at Charlotte, N.C.-based Marenic Food Service Consultants. “Like freezers, blast chillers are available in many sizes. What makes it different is the temperature and time needed to chill product. It also utilizes a different type of condenser and fan.”
Operators can use these units for almost any food item they want to freeze quickly and for a longer time period, from soup to meatballs. “It’s important to purchase a reputable brand that will be reliable,” says Marenic. “Operators can choose from blast chillers that have regular compressors or those that utilize nitrogen.”
For either type, the compressor and blower have to bring a product’s heated temperature down to frozen in 10 minutes, which ensures food stays out of the food safety danger zone. “The faster food is frozen, the better its quality will be,” says Marenic.
Operators can also tie their blast chillers to different equipment and also may utilize a swipe card for access. “This identifies anyone using the equipment, shows how they’re using it and helps reduce theft,” says Marenic.
Cleaning & Maintenance
The most important aspect of maintaining a blast chiller is keeping the interior clean using warm, soapy water.
“The biggest mistake operators make is putting big sheet pans in with smaller pans on top,” says Mike Duff, combo tech at Baltimore-based EMR. “It’s necessary to get rid of the heat, and this impedes heat transfer.”
In addition to keeping the inside clean, probes need to be in working order. These can get damaged if closed in a door.
Operators should clean condensers by popping off the unit’s front panel on a weekly or monthly basis. “Chefs and cooks tend to drop plastic on top of pans, and these can make their way into the condensers, which impacts airflow,” says Duff. “Making sure probes are in good operation and the wires aren’t torn is key. That area in the box should be kept clean.”
If the temperature isn’t going down fast enough, the blast chiller will require service. Other signs a blast chiller requires service include probes not reading correctly, the blast chiller temperature not being as cold as necessary or the condenser staying on when it is turned off.
“Many times, probes get ripped and need service,” Duff adds. “These are an expensive component.”
Excessive leaks in the blast chiller’s evaporator or refrigeration system can signal a catastrophic failure that, depending on how old the unit is, may indicate a need to replace the unit.
“Over time, the copper components of these units have been changed out or become thinner,” says Duff. “As a result, these can react to acids in the air from foods like tomatoes. This can break down the copper and cause leaks throughout the system.”
Because blast chiller evaporators are pricey to replace, operators should consider retiring units between five and seven years old that are leaking.
The average service life of a blast chiller can vary, depending on use, environment and manufacturer, but most last between 5 and 10 years. “One common mistake operators make when using this equipment is keeping them on 24-7 like a refrigerator,” says Duff. “Blast chillers are not designed for continuous operation.”
These units can be sophisticated and computerized, so it’s important to become familiar with the controls prior to chilling. “New units have so many different programs, so after purchasing, it’s best to have a factory rep do an initial startup and operations breakdown to learn how to operate the blast chiller,” says Duff.
Also, operators should note that these units must not be installed in areas by cooking equipment. Blast chillers that are situated too close to fryers run the risk of gunking up the evaporator coils with grease, which will compromise the unit’s operations.