How to Select and Maintain a Blast Chiller

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"Really, anybody who's producing food should have a blast chiller. A lot of people don't realize that they're already doing cook-chill ... because you've always got food that you are producing in advance."

Howard Riell

Smaller, more efficient designs have helped operators improve their

standard of food safety, cut labor and food cost, increase the shelf life of

many items, improve product quality and, perhaps most important of all in 21st-century America, limit their legal liability. Blast chillers have been around for several years in various incarnations. It has only been in the last three or so years, however, that the industry has started to see larger numbers of

them moving into operations that are neither large-scale food-production facilities nor health-care related.

"We're seeing what could be called a minisystems approach," says Bill Keske, vice president of marketing for Delfield, a division of Enodis PLC. "Initially blast chillers were for large institutions doing batch cooking. They're now moving into smaller operations, combining with combi-ovens to create production systems on a much smaller scale. The systems are still in demand, but now there is also a demand for a smaller footprint."

Taking Some Stress Out of the Kitchen

"Originally, they were intended for food production, to chill food down so you could rethermalize it, giving you a longer shelf life of five days," says Robert Simmelink, executive chef for equipment manufacturer Alto-Shaam. "Also, for helping to let you produce larger quantities of food in a relatively small amount of time.

While stress is nothing new to a restaurant kitchen, the danger of liability related to foodborne illness is increasing. But now we're looking at them for food quality aspects, and for HACCP procedures [Hazard Analysis Critical

Control Point is an approach to food safety that anticipates and prevents hazards associated with ingredients]. They are a way to help take a little bit of the stress out of kitchens."

Chefs don't always cook dishes fully and chill them, Simmelink says, "but if you can stage it and chill it, it lets you handle that food and finish your production faster. Plus, it keeps it within your danger-zone tolerances, so there is no bacterial growth, which also gives you better food quality."

"You don't see [blast chillers used] too much in a lot of the QSR operations," says Mike Loprete, corporate chef for equipment maker Henny Penny Corp. in Eaton, Ohio. "They buy a lot of things [from a] commissary, or [that] may have been blast-chilled someplace else. They have very limited menus. They're doing a lot of cooking with very short hold times; not a lot of cold holding at all." On the other hand, an operation offering a buffet "would definitely do well with a blast chiller," he says. "If they have leftovers in large

quantities, they can ... rethermalize it later on."

"What we're seeing happening is that food manufacturers are starting to offer more foods prepared via sous vide, in vacuum Cryovac (plastic) bags," says Finley Lackey, facilities consultant for Bresco (Birmingham Restaurant Supply) in Alabama. "They're including product in a vacuum-sealed bag that you can basically just rethermalize. The food manufacturers have taken that step somewhat away from the restaurants and are using it to their own advantage. It's what a lot of people are doing, and they've got some excellent products out there."

Developments like this are "pretty recent," Lackey says. "I have a client we're working with right now who is tending to use some of these products. He was impressed with the quality of the food. And, of course, (restaurateurs) will typically take something like that and make it their own with individual touches."

More Controlled Surroundings

"Really," says Simmelink, "anybody who's producing food should have a blast chiller. A lot of people don't realize that they're already doing cook-chill ... because you've always got food that you are producing in advance. For instance, if you're an individual restaurant and you get an order for roast chicken, you don't put that in an oven because that takes 45 minutes to cook. You've cooked that earlier in the day. But you've then cooled it down and

staged it."

Blast chillers, he says, "are taking it to the next level, giving you much more controlled surroundings around that food. You're getting it through the danger zone very fast so there are no liabilities, no bacteria growth, no change in flavor." The units help operators with food safety, of course, as well as food quality and time management. Taking the food through the danger zone in a very short time prevents bacterial growth, which can and often will change the flavor of the food.

"What you have to remember is that you really don't want, at the end of the day, to take your leftover foods and sauces and just throw them into the cooler," Simmelink says. "They're not going to chill down fast, and putting that much hot mass in there means they're going to elevate the temperature of your cooler.". A lot of commercial restaurants choose to simply throw out whatever food is left over "because they don't want to have to deal with reheating it the next day and the potential liability," Simmelink says. According to his calculations, if that operator threw out $65 worth of food each day, he would have paid for his chiller in 244 days. The exact savings,

of course, vary with the size and volume of the operation.

Typically, a small operation has a small staff, and having kitchen staffers wait around to finish product, or take product out of a refrigerator or freezer is unwise. A better alternative is to be able to simply put it in a chiller and deal with it when feasible. Most chillers nowadays will also go into a "hold" mode to keep the food at a precise temperature.

Time management savings come from scheduling efficiencies. Operators can save a labor hour or two per day simply by producing extra food every day and

storing some of it in their cooler. For example, if an operator knows he is going to go through 30 pounds of rice today, he can cook 60 pounds, blast-chill 30 pounds and rethermalize it the following day. "You've actually speeded up your production, and when you start doing that with enough menu items you can start to cut back on or redistribute your labor in a much more economical way," Simmelink says. More efficient compressors, fans and evaporators have helped downsize the footprint to where the smallest models are roughly 3 feet square. Most manufacturers offer a basic three-pan (12-by-20-by-2-inches, each holding about 12 pounds of food) chiller. Loprete

says that undercounter versions that hold up to three full-size steam table pans "are about as small as you're going to see. That's pretty much adequate for most small operations.

"The latest (advance) in blast chillers has been the use of multiple probes," Loprete says. "They're used to monitor core temperatures of a variety of different products in the blast chiller at one time so that you can get them through the danger zone as quickly as possible." The first blast chillers had only a single probe because, as he says, "Most people were doing them in large operations with only one product going. Now it's a lot of small

quantities of a variety of small products going in and out all day long."

The biggest concern when using a blast chiller, Loprete says, is that the larger pieces of any product are going to take longer to chill than the smaller, less dense products. "You've got to be careful you don't freeze the smaller, delicate products before the larger ones are chilled. The units get down as cold as minus 4 degrees Fahrenheit during a chill cycle, and

that's cold enough to freeze small quantities or small products."

In addition, Loprete says, operators have to be careful. "The products that go in there should have the maximum surface area exposed in order to release the heat and chill it down properly."

Solid-state controls are reliable and secure against moisture and grease. They also will chill food in any of three different cycles: soft chilling, hard chilling and blast freezing. Soft chilling, as the name implies, uses slightly warmer air temperatures for delicate items.

Hard chilling is for denser items, like muscle meats, stews, casseroles and products that have been sealed in a bag. A valuable feature is the software that ties into today's chillers, which will record food names, times and temperatures. The hard data cannot be manipulated, making it admissible and valuable evidence in court in the case of a lawsuit. "That's your liability,

right there," says Simmelink. "I mean, you can now go into court with this data and fight your lawsuit."

Durable Units

There frankly isn't much on a blast chiller that will break under normal restaurant wear and tear. The main components are compressors and condensers. Perhaps the most common problem involves roll-in racks, but they involve the larger units used in institutional settings.

"There's not a lot to them," Loprete says. "It's [the] fans that are operating inside. You have a compressor that regulates the flow of the refrigerant through the coils, and that's what cools the food down. Blast-chilling hasn't changed much over the years; it's basically removal of heat, the same [way] as any other chilling process works."

"You've always got what I like to call 'The Kitchen Gorilla Factor,' which is that (employees) can tear up anything. You can have unskilled labor in the kitchen that doesn't really care about what they're doing. They're going to slam the doors to ovens and blast chillers, lean on them, kick them, whatever, and so manufacturers will keep it simple," Lackey says.

As with any piece of equipment, proper cleaning and sanitizing is essential. Spills should be cleaned immediately with hot soapy water. Occasional use of a mild bleach solution for wiping down is a good idea. Some units come with ultraviolet lights for sterilization.

"Just keep it clean," Lackey says. "Keep the refrigeration coils clean. Make sure the airflow is not restricted." "As you're cooling down hot product you're going to get some condensation," Loprete says. "That condensation could cling to the coils, which are very similar to a radiator's but just the opposite: You've got refrigerant going through instead of water or antifreeze. As the condensed air comes into contact with those coils -- with the refrigerant running through them they are very cold -- it could turn into ice crystals. You would want to de-ice it periodically, at least once a day." To do this, run the unit on "de-ice mode" (no refrigerant going through the coils) with the door open. "It draws warm air into the room.

That's one regular thing you should do to keep it running properly," Loprete says. Service contracts are unnecessary, Simmelink says. "Your staff can take care of all that. There is actually less maintenance on a blast chiller than there is on an oven."

The primary characteristic to look for in a unit, Lackey says, is simplicity of operation. "Most of the time, things in a restaurant that are going to be blast-chilled are going to be either in 12-inch-by-20-inch or 18-inch-by-26-inch pans. It depends what your cooking habits are."

Loprete says the life span of an average blast chiller should reach 15-20 years easily. "It depends on where it's located, how hard it's working, and whether you're maintaining it properly." Another tip: Keep dust off the air intake and the exhaust area by keeping it in a well- ventilated area.

The argument favoring blast chillers continues to gain strength. "We are starting to see a lot more sous vide, reconstituting of food, in regular restaurants," Lackey says. In addition, an increasing number of municipalities are beginning to mandate blast chillers, Simmelink says. In Las Vegas, for instance, facilities of a certain size are required to have at least one. It is also becoming more common in healthcare facilities.

That trend will almost certainly lead to chain restaurants in the months and years ahead, then to independent owner-operated restaurants. This means some initial research, at the very least, is in order.

Restaurant Startup & Growth

Cleaning and Caring For Blast Chillers

Even with such basic units as blast chillers, education can be nearly as important a product as technology. As with any piece of equipment, proper care and maintenance will extend the life span and improve the operation. Mayra Bergman, marketing manager for Victory Refrigeration in Cherry Hill, New Jersey, says her company provides detailed instructions on cleaning and otherwise caring for blast chillers. They include:

* Normal day-to-day cleaning should be done with soft cloth and soapy water. Never use abrasive materials or cleaners, or chemical cleaners, as they can damage the surface and cause corrosion. Occasionally, the exterior should be polished with a good stainless steel polish to protect the surface. Do not use abrasive cleaners, chemicals or scouring pads on the control panel. Clean the control panel only with a soft, damp cloth. Avoid excess water on the control panel, and other areas where electrical components are fitted.

* Clean the (door) gasket weekly with warm, soapy water and a soft cloth, taking care not to damage it. Do not use a sharp knife to clean or scrape the gasket. Regularly check the gasket for any damage. Damaged gaskets do not seal correctly and can increase the amount of electricity consumed, seriously affecting the efficiency and performance of the cabinet.

* To clean the condenser, which is part of the refrigeration unit, disconnect the main power supply before starting, then brush the fins vertically with a stiff brush, taking care not to damage the fins or push dirt or dust further in and vacuum away.

Among the "rules of thumb" for efficient operation that Victory provides operators:

* Pre-chill the cabinet for 30 minutes before the first load to remove interior residual heat.

* Doubling the food thickness triples the pull-down (cooling) time.

* Don't stack food and/or containers on top of or alongside one another.

* Covering the food increases pull-down time by 10 percent to 30 percent.

* The pull-down rate initially is about 2 degrees Fahrenheit per minute,and approaching the final temperature is about two minutes per degree Fahrenheit.

Several factors can affect blast chill pull-down times:

* Entering food temperatures.

* Final food temperatures.

* Food thickness, density and thermal conductivity.

* Container surface area and materials.

* Covering method and material.

* Air velocity.

* Mechanical problems with the unit.

Blast Chiller Suppliers

AGA Foodservice Group www.agafoodservice.com

Airdyne Refrigeration & Air Conditioning www.airdyne.com

Alto-Shaam Inc. www.alto-shaam.com