Blast Chillers A Quick, Cool Approach To Food Safety

It's 'safe' to say that quick-cooling blast chillers are an efficient solution to chilling foods through microbial danger zones, and can provide other benefits to foodservice operators, as well.

Food safety issues are the best known reason for blast chilling prepared foods, but operators have discovered other benefits to blast chilling including savings on labor and food costs, as well as the consistent production of high-quality foods. Blast chillers are now available from many manufacturers in sizes that range from small under-counter units to custom walk-in chillers that are able to hold multiple rolling food carts. Because of the growing emphasis on maintaining food safety in recent years and blast chillers' ability to cool foods rapidly through microbial danger zones, the use of this equipment has expanded into a variety of operations, from those required to prepare large batches of products that are stored and served, to use in chain operations and hotel banquet prep areas. Blast chillers have notably been installed in support of cook-chill operations in the commissary kitchens of noncommercial foodservices such as healthcare institutions, colleges and universities, where their ability to chill quickly and hold bulk food products safely have contributed significantly to the efficiency of these programs.

"Food safety was the major motivation when we installed our blast chiller, but better food quality and extended shelf life are also benefits of the rapid chilling provided by these quick coolers," said Andy Allen, executive chef for Dining Services at Harvard University, Cambridge, Mass. "According to FDA regulations and for HACCP compliance, we need to get our prepared foods down to 40 °F. in four hours to stall microbial action effectively. Blast chillers are the best and most efficient equipment choice to accomplish that goal and, actually, best-case scenario, can achieve the desired cooling in 90 minutes. We work to minimize the chill-down window in our central kitchen, because the shelf life of food products is extended according to how quickly they are cooled," he explained.

The custom-built blast chiller in the central commissary kitchen at Harvard was installed during a renovation of the facility during the summer of 1999. This large blast chiller holds two full rolling racks with a capacity of 800 lbs. to 900 lbs. of product, and replaced a smaller reach-in type chiller that had been installed two years previously. "Our central kitchen and Harvard Dining Services have been undergoing an evolution that started years ago," commented Allen. "Initially, our commissary kitchen provided food to five dining halls on campus with limited kitchens. Then, we became a cook-chill operation, initially providing soups and sauces to nine different kitchens, which enhanced consistency in recipes and quality, and reduced labor needs at those facilities," he commented. "Now, with our blast-chill and cook-chill operation, we provide about 300 different food products to 24 different locations on campus, with our primary customers being 13 residence dining halls where we provide 30% to 40% of the food served. We've renamed our central kitchen operation; now we're the 'culinary support group.'

"We use our blast chiller basically for any food items that can't be stored in bags - soups and sauces go in the tumble chiller," Allen added. "When preparing protein salads for the campus, we use cold products - tuna, chicken, eggs and mayonnaise, but we lightly blanch the celery used in those salads in a steamer, as the celery is actually the most dangerous ingredient in terms of food safety. After mixing all the ingredients, the salads go into the blast chiller, which properly cools the product and also extends the shelf life to four or five days, rather than the two or three it could be kept in a traditional cooler.

"When we were envisioning how we wanted our dining program to evolve, we clearly determined that our different units should produce foods as close to service times as possible and, at the 13 residence halls, the focus is on product finishing and display cooking," continued Allen. "With the blast chiller, we can provide these locations with items such as roasted meats, which can be sliced as needed for service and rethermed in the combi ovens which are new additions at those facilities. We know now that the food we serve is safe, and that we've retained the freshness and quality that all our customers desire."

Masonic Homes, Lindenhurst, N.J., is a senior living residence with a population of 1,500 people, which includes those residing in independent living residence apartments and a nursing home, as well as a healthcare facility. Masonic Homes was built and originally opened in 1911 as an independent living facility with no on-site kitchen. Subsequent build-outs of kitchen facilities were always a challenge because of the main building's construction, according to Daphne Gulick, director of foodservice. "In considering our future growth, and our dedication to maintaining confidence in our food safety program, we reached a crossroads a few years ago. At that time, our only cooler was an old walk-in, consisting of cinderblock construction with mounted compressors, and we knew that sooner or later we would find ourselves facing a HACCP violation," explained Gulick. "So, we made the decision to go ahead and build a new, stand-alone commissary kitchen that contains a blast chiller and tumble chiller, which help us accommodate the demand arising from our growth in population and our desire for complete HACCP compliance." Gulick noted that in planning a commissary kitchen, the Society for Healthcare Foodservice Management organization was helpful, referring her to Bill Vomvoris, vice president of cook-chill operations for consultants Romano-Gatland, who designed the Masonic Home's commissary kitchen.

"Our blast chiller can accommodate a double roll-in rack, and is used mostly for conventional, 'individual portion' types of food such as our stuffed chicken breasts or other grilled food items," said Jack Dile, assistant foodservice director. "Basically, food items that can't fit into the rack's 2-in. pans are not practical for blast chilling, as their thickness would take longer to chill and defeat the quick-chill purpose," he noted. Retherming of food items that have been held after blast chilling for four to five days is accomplished in two ways at Masonic Homes, according to Dile. Portable retherm carts are used to heat individual meals in the healthcare side of the facility, while a combi retherm oven is used to support the two à la carte dining rooms that serve the independent living sector residents.

"Blast chillers are simple in one way, in their efficiency in chilling food," remarked Dile. "One problem we've experienced with our blast chillers is that we found that their monitoring features were complicated and difficult to learn. It would be great if, in the future, manufacturers could somehow simplify the blast chiller's monitoring process."

Equipment Overview
  • Blast chiller
  • 2" food pans
  • Tumble chiller
  • Food storage bags
  • Mobile rolling racks
  • Combi oven
  • Steamer
  • Walk-in freezer
  • Retherm combi oven
  • Retherm mobile cart
  • Tilting braising skillet
  • Tilting kettle
  • Charbroiler
  • Reach-in refrigerator
  • Temperature-controlled mixer
  • Blast chillers provide key support to the cook-chill kitchen that serves Worcester Medical Center (WMC), Worcester, Mass. Innovations in food safety systems and equipment led WMC to switch from cook-and-serve production to cook-to-inventory, and a state-of-the-art cook-chill production kitchen was constructed and opened along with a new medical complex building in February 2000.

    The production kitchen, responsible for providing the medical center with 1,600 meals a day for patients, off-site facilities and employees, was constructed to be completely temperature-controlled, and attention to work-flow design has resulted in enhanced efficiency. All food is prepared in the production area, which contains three large tilting braising skillets and a tilting kettle, which are used to prepare the majority of menu selections. Also located in the production area are three combi ovens, a charbroiler and a reach-in cold storage unit, as well as a temperature-controlled mixer, and all equipment was sized to support the kitchen's three blast-chiller capacity.

    Once products are ready for chilling, they are loaded into shallow pans and placed on mobile racks, which roll into the blast chillers. "Our blast chillers have pre-sets that adjust time and temperature according to the type of product being chilled," explained Ira Bernstein, director of foodservice for WMC. "They also have a tape read-out that provides us with data for our HACCP checklists and, once employees learn the steps, the blast chillers are fairly easy to use." After the blast chiller's cycles have been completed, racks are removed and food pans are labeled with the date of preparation and their intended points of distribution before they are stored. "Our production kitchen workflow is very efficient," commented Bernstein, "and, where we once required 111/2 FTEs [Full-Time Equivalent staff] in the conventional production kitchen, we now require only four."

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