While food safety is certainly one of the most important reasons to install a blast chiller, the benefits extend well beyond safe cooling to better food quality, higher yield, and lower food and labor costs, as well. Yet many operators still consider these units an “extra” or luxury when their value should be weighed across this broad spectrum of benefits.
Safety first: The latest FDA Model Food Code (the 2013 version) says you have to cool cooked foods from 135°F to 70°F within two hours, and from 70°F to 41°F within another four (a total of six hours) to ensure food gets through the “temperature danger zone” between 135°F and 41°F. That’s the range in which bacteria grow quickly. If your employees are putting whole hot roasts, deep pans of lasagna or big pots of steaming soup into the cooler, you have problems. If they’re cooling foods with ice baths, ice paddles and using other means to cool foods safely, kudos, but cooling is likely still taking longer than it needs to and your employees need to stick around to see the cooling process through.
The FDA puts a lot of emphasis on HACCP as a way to mitigate risks of foodborne illness, and it’s likely that upcoming Food Code revisions will continue to push more operators to adopt a HACCP food safety plan. So employees might be diligent about cooling foods safely, but they’ll need to be recording their efforts too. Blast chillers report temperatures automatically and keep your records for you.
Blast chillers are designed to bring the core temperature of food from around 160°F or more down to 41°F or less in about 90 minutes. Most units will freeze food in four hours or less. Cutting the time needed to cool food by 75% is a great benefit to any operation. And cooling foods faster means employees go home sooner at the end of their shifts.
The food safety benefit of blast chilling also helps preserve food quality. Chilling foods fast means there’s little time for the bacterial growth that also degrades food quality. And, because foods cool so quickly, blast chillers prevent moisture from evaporating the way it does when foods are cooled more slowly in a cooler or freezer. Food that retains its moisture tastes fresher, maintains aroma and is essentially just the quality it was before you put it in to chill.
With a blast chiller, your kitchen professionals can buy foods in volume (reducing per unit costs), buy foods at the peak of their seasonal flavor and availability (freeze berries or oysters), or take advantage of foods on sale, because they can blast chill the items and substantially extend shelf life, by weeks in some cases.
Blast chilling can help your kitchen optimize labor schedules and simultaneously help ensure good food quality on a consistent basis. You can schedule your most skilled, most highly-compensated staffers to oversee volume production of myriad dishes (including soups, sauces, gravies, even center-plate items) a few days a week, say during off-peak production times, rather than every day. Chill the items and they’re ready to retherm and serve anytime. Cooks can par-cook and chill a wide assortment of dishes and, because of the way blast chilling holds the foods in “stasis,” they can be finished off days later, in half the time, and with the same quality outcome as if the staff had cooked and served the item immediately. Think half-grilled tenderloin fillets for a wedding banquet; they can be finished off and served all at once.
Blast freezing or shock freezing quickly freezes fresh and cooked food, transforming the liquid in the food to micro-crystals of ice (vs. macro-crystals, which would develop during a slow freeze in a regular freezer). Micro-crystals don’t damage the cellular structure of the food, macro-crystals do. That’s why when you freeze fresh berries in a regular freezer and then thaw them later, they turn into a pulpy mess with a lot of seeping berry juice; the macro-crystals expand and burst the cell walls. Not so with microcrystals; thawed berries look, taste and feel the same as they did when they were fresh, and they retain all their nutrients.
When you’re ready to specify a blast chiller, you want to think about the size you need, the size and number of pans it fits, the type of chilling modes it offers and how the manufacturer has engineered air flow.
Blast chillers come in huge roll-in versions for high-volume production kitchens, reach-in models and half-size undercounter and countertop units; any size or style of operation from a hotel to a quick-service restaurant can find a suitably-sized unit.
Pan capacity on reach-ins are typically in the 10-13 sheet-pan and 20-26 hotel-pan range, or anywhere from about 85 to 200 lb. of food. Undercounter and countertop units will typically accommodate anywhere from four to six full-size pans. Figure out what capacity you need by looking at the proportion of your menu that you’ll want to prepare and chill in advance. For example, take your most popular item and figure out what your highest volume of that item is per week. That will give you an idea of the maximum number of pans the chiller should hold at one time.
Be aware that models made in European Union countries will likely be designed to hold hotel pans that measure just 12 in. x 20 in. x 2 in. The same hotel pan in the U.S. is actually 2½-in. deep, which may mean you’ll fit fewer in the cabinet than the specs indicate. Match your pans to the units to ensure you get an accurate fit and capacity. In some makes, pan slides are adjustable.
The way manufacturers engineer their units’ airflow is a point of differentiation that you should investigate. The larger the amount of air moved, the faster it will strip heat away from the hot food product. Some designs introduce cold air by blowing air over the evaporator coil, into the cabinet and over the product. Others draw the heat from the product, circulate it to the evaporator and then send it through the cavity and over the food. The methods may sound similar but the difference, makers say, is blowing cold air over the food to push heat out or drawing heat off of the food and then replacing it with cold air.
Almost all blast chillers have at least two cycles—hard chill and soft chill. Hard chill is designed to bring down temperatures of any type of food as quickly as possible with high-volume and velocity air circulation at often sub-freezing temps. If you intend to chill more delicate items—fish fillets, seafood, rice, vegetables, desserts, etc.—soft-chill cycles protect quality by moving 38°F or 39°F air a little more slowly through the cabinet.
Models also designed to shock freeze product will have a third cycle that circulates air at temps as low as -40°F to bring food temps down to 0°F in less than four hours. (In fact, shock freezers that don’t produce internal air temps of at least -25°F may not get the job done in that time.) Even more, and more precise, cycles are available on some models including soft and hard chill, soft and hard freeze, hold, proof, thaw and even low-cook (for a full blast chiller equipment comparison, see “Just Chillin’” FER, Feb. 2016, http://bit.ly/2o77bGK).
Blast chillers have followed a similar evolutionary path as combi ovens. Manufacturers have worked hard to make them easier and more intuitive to operate. Practically all models let you set a cycle by time or end temperature. Set the time or insert a temperature probe into the product, and the unit will automatically shut off at the end point, and usually hold the product at temperature until you remove it.
All models come with temperature probes, and some with as many as three, giving you even greater automatic control over the cooling cycle depending on the food in the cabinet. The probes constantly monitor the core temperature of the food and adjust cooling accordingly, so a thinner product doesn’t freeze while a thicker product is cooling, for example.
Even more impressive are units that use probes that accept multiple inputs. These probes are able to measure both internal and surface temperature of food, giving the unit even more accurate data on the cooling process, so it can automatically adjust both air temperature and circulation in the cavity. This kind of fine-tuning helps maintain food quality. Probes for shock freezers are typically heated so they can be removed from the frozen product.
There are 18 blast chiller manufacturers whose lines are available in the U.S. today, so you have a good number of possible providers. Based on all the benefits a blast chiller can bring to your kitchen, it’s a good bet that you may be asking yourself not if you need one, but whose model you need.
Blast Chiller Makers
Angelo Po America/Marmon-Berkshire Hathaway
Victory Refrigeration/Ali Group
Williams By Beverage-Air/Ali Group
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