Spec Check: Blast Chillers

Using a blast chiller represents one of the safest ways to quickly reduce the temperature of hot food. That's because blast chillers pull down the temperature of hot food from 160 degrees F to 38 degrees F in 90 minutes or less.

Unlike refrigeration equipment that serves to hold cold food, such as walk-ins, reach-ins, prep tables and undercounter units, blast chillers are designed to remove heat from food.

Foodservice operators often use blast chillers along with cook tanks, stand-alone refrigeration units and large-batch production systems that may include jacketed kettles, bagging and pumping stations and tumble chillers as part of the cook-chill process, which arrests the cooking cycle. This method not only retains food quality and appearance but also preserves nutritional value and, most importantly, flavor. Rapidly reducing food temperature also enables operators to store products for up to five days.

This type of foodservice equipment also can help operators expand their menu options by allowing them to plan for production needs in advance without compromising quality. Cooking, chilling and storing food in advance also allows foodservice operators to make more efficient use of their preparation time.

Typically three to four times more costly than standard refrigeration units, blast chillers form microcrystals on products as opposed to evaporating the moisture, which can dehydrate food. Although these units continue to grow in popularity among U.S. foodservice operations of all kinds, blast chillers are more common in Europe, where back-of-house space is at a premium. This equipment can help operators expand menus in foodservice operations with limited production areas because product can be made ahead of time, blast chilled and then reheated as needed.

When choosing a blast chiller, operators need to properly estimate the amount of product that they expect to process at once to determine the size needed. These units are sized by the number of pounds that can be accommodated. Blast chillers typically house 2-inch deep pans, which hold about 10 pounds of product. Foodservice operators can use this equipment to chill as little as 30 pounds of food or up to as much as 1,300 pounds at one time.

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 is key to quality results.

When sizing a blast chiller and designating space for this unit in the kitchen, operators also need to determine if clearance is required around the unit for ventilation. If this is the case, the footprint should be taken into consideration when specifying the equipment.

Blast chillers are available in undercounter units and countertop models that may include shelf space underneath or standalone 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 are more suitable for quantities larger than 200 pounds and use mobile tray holders. Some models provide removable, adjustable shelving, which can provide added versatility. Foodservice operators can also opt to build blast chilling rooms into walk-in coolers for high-volume use.

Figuring out the production details in advance can provide added efficiencies. This is because rack blast chiller models can correlate with cooking equipment, such as combi ovens, which allows staff to transfer the same pans from the cooking unit to the chilling system.

For operations with varying production levels, blast chillers that provide two independent cooling compartments can offer added flexibility. Because these units can accommodate smaller amounts of food in a single compartment without cooling the entire interior, greater energy efficiency is achieved.

When determining size, timing needs to be taken into account for chilling and reheating. Due to food safety and quality concerns, food needs to be blast chilled immediately after it is prepared. Operators also should consider whether future menu changes will require an increased blast chiller capacity. If this is the case, it's best to size up with the initial purchase, rather than purchase another unit at a later date.

For operations with extremely high volumes, such as a commissary, a tumble chiller, rather than blast chiller, should be considered.

When choosing a model, foodservice operators should also 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, which are distinguished by how low the air temperature is inside the unit during the chilling process. 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 and the process is less harsh.

Some blast chill units also can shock freeze product to zero degrees or less. This type of system is suitable for operations that ship product to other locations or offer mail order food, like frozen pizza, for customers. This setting also can be used to extend food shelf life when products need to be held for more than five days.

Blast chillers utilize internal probes that measure and record food temperatures for HACCP documentation. Larger models may offer numerous probes that are capable of measuring the temperature of various food types simultaneously.

In the past, operators would use hand-held thermometers and a written log to track food temperatures in these units. As technology has progressed, the recording processes have become more sophisticated. Today, the majority of blast chillers offer data recording capabilities for Hazard Analysis & Critical Control Points (HACCP) documentation, with the method dependent on the model. The most common types utilize a printer that records information on paper, a data port that can be used to upload reports to a computer or a USB drive for downloading temperature details on a portable storage device. There are considerations with each type of recording method. For instance, 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 are hooked up to computers may require an Ethernet cable or other hook up lines.

Because blast chillers have large compressors, power requirements should be determined when specifying these units. By comparison, while a 27-inch undercounter refrigerator may have a ¼ or 1/5 horsepower compressor, a 27-inch blast chiller utilizes a ½ horsepower compressor.

Placement of the blast chiller's condensing unit also is a consideration, as these systems offer either self-contained or remote options. Temperature efficiency, installation cost, noise and added heat in the kitchen are factors that should be weighed. The bigger the compressor, the louder and hotter the blast chiller will be. Larger models generally come with remote systems that may be more costly to install.

One of the biggest issues with blast chillers is that operators commonly underestimate the complexity of these units. Chilling product with these systems is much different than simply

placing food in a refrigeration unit. As a result, accomplishing this process may be more challenging in foodservice operations with entry-level employees or high staff turnover. There needs to be an educational component for staff on how food should be sized, shaped and packaged prior to the chilling process.

Although training is generally necessary for optimum results and to ensure proper food safety protocol is followed, the good news is that, with newer technology and control boards, blast chillers have become easier to use than in the past.

While some models have built-in electric defrost capabilities that eliminate condensation on the condenser coils, other units must be connected to a drain. For the latter type, operators need to confirm that a drain connection is available and accessible.

Operators can choose from a variety of options and features, depending on the blast chiller model. Some types provide an ultraviolet light that sanitizes the cabinet's interior. Units with DC connections, printers, extra probes and preprogramming features also are available.

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