Refrigeration: Chilling tales of technology

Thank freeze-drying, IQF and MAP for quantum leaps in the quality of foods.

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At left: A spiral freezer design from
Frigoscandia Equipment, which dramatically
improved the image of frozen food quality
when it introduced the FloFreeze IQF freezer
decades ago. Today, Frigoscandia is a unit
of FMC FoodTech.

By Mike Pehanich, Plant Operations Editor

In modern supermarkets and mass merchandising outlets, products seem to sprout from the shelves like mushrooms overnight. Nowhere is this more evident than in the frozen and refrigerated supermarket cases where attractive new products are the order of the day.

The consumer takes this horn of plenty for granted, rarely considering the technological wizardry that makes many of the most useful and exciting products possible. Old and new, big and small, following is a handful of freezing and refrigeration-related technologies that have opened the floodgates of possibility to food makers.

The fruits of freeze-drying

While freezing is a key part of the process, it turns out not to be the method of preservation in the backward world of freeze-dried foods and their three-stage metamorphosis from fresh to frozen to shelf-stable.

Freeze-dried products can be amazingly fresh-like when rehydrated. Freeze-dried shrimp plump up like a freshly cooked sea critter and look just as good as their freshly caught cousins on the rim of a cocktail bowl. Freeze-dried fruit and vegetables of comparable quality have been around even longer.

Nearly any type of fruit can be freeze dried into forms ranging from large chunks down to fine powders. Photo courtesy of Oregon Freeze Dry
A look in the supermarket might give the impression freeze-dried fruit is a new arrival in the cereal aisle. But a leader in the technology has been making freeze-dried product for two generations.

“The first freeze-dried product was a strawberry created for cereals,” says Herb Ashkenazy, president of Oregon Freeze Dry, Albany, Ore. ( “That was 41 years ago.”

Timing is everything, says Ashkenazy, and the time for freeze-dry seems to have arrived. To Ashkenazy, the wait strengthens the first principle of the food entrepreneur’s credo: The most important thing a company can do is survive the tough times and be ready when its time finally comes.

Today, new cereal products containing freeze-dried fruit seem to be arriving daily. What’s more, they are reinvigorating cereal sales. Peaches, strawberries, bananas and berries of all sorts are buried in those cereal boxes. General Mills has even employed a branded ingredient strategy with its recent fruitful offerings, listing the Oregon Freeze Dry name on products containing the freeze-dry leader’s fruit.

What’s the reason for the surge? Not necessarily improved product quality. Complaints about quality have been nearly non-existent during Ashkenazy’s 21-year tenure with Oregon Freeze Dry. What has been a factor, however, is the cost.

“We have made real strides in the output [of dried product] per unit of equipment,” says Ashkenazy. “I can’t tell you how proud I am of our people. They had been doing the same thing, and producing a great product, for decades. But then to say ‘Here’s a better way…’ ”

Freeze-drying involves sublimation, a process you learned in high school science and likely thought little about since. Product is first frozen at low temperature and then placed under vacuum. This is where the sublimation takes place. The process evaporates the ice. The ice crystals pass into the gaseous phase without first becoming liquid. Applying heat at the proper stage accelerates sublimation. Low temperature condenser plates remove the vaporized ice crystals from the vacuum chamber by converting them back to a solid.

The improved economics came by diminishing the time and energy needed to remove ice crystals from the product. Equipment is expensive, as is the cost of running it. “You have to put energy into the product in those giant vacuum chambers,” says Ashkenazy. “Accelerating drying cycles and getting more product out of a chamber without damaging the product is a big deal.”

Still, Ashkenazy insists the improved economics of processing are only a part of the success story. The economics were never as bad as they were perceived, he claims. True, it takes 12 pounds of strawberries to yield a single pound of freeze-dried strawberries. “But you get it all back when you rehydrate the product,” he says. Customers understand that message more easily today.

Of course, market success simplifies education.

“Kellogg took Special K and added elements that could have been added a half century ago and hit a home run,” says Ashkenazy. “Now, we have been able to show cereal makers what freeze-dried fruit can do for their products. Freeze-drying has the unique ability to preserve product in a dry state without loss of quality. You can dry the product for exceptional shelf life and still get the flavor, appearance and aroma of the original product with rapid rehydration. Most important is that they have enabled the creation of cereal products that are new and different and better.”

The products have helped reverse the slow decline in dry cereal usage, he says. Now they have the cereal category on an upward path.

“I have felt for the longest time that freeze drying is the most underutilized preservation method known to man,” says Ashkenazy.

Quickly frozen
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