Dehydration: Which Option is Best for Your Food Processing Plant?

Food manufacturers can choose from a number of developments that optimize moisture removal and minimize process cost.

By Kevin T. Higgins, Managing Editor

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Moisture removal is a fundamental process in food production, arguably second only to cooking for stabilization and preservation for both solid and, in the case of milk powder, fluid foods.

How much water is removed and the impact on what’s left behind is the job of dryers, and food processors have multiple options to attain a desired outcome. While it’s often an essential step, drying can be energy intensive and destructive of a product’s appearance and nutritional value. Stabilization at minimal cost is an ongoing R&D focus, and considerable progress is being made.

Drying with microwave energy under vacuum was first applied commercially in the 1980s. Every technical innovation experiences growing pains, and the higher cost of electricity compared to natural gas works against microwave drying. But low-pressure microwave stacks up well against freeze drying’s energy profile, and a variation called radiant energy vacuum (REV), first applied in 2008, is starting to gain industrial traction.

In August, Jack Link’s Beef Jerky became the latest food processor to sign a licensing deal with EnWave Corp., Vancouver, British Columbia. to evaluate the technology. The Minong, Wis., meat firm declined to discuss what value drying would add to products that already are shelf stable, referring instead to interest in “a variety of innovative snack products.” But two start-up companies with financial ties to EnWave are pressing ahead with shelf-stable cheese snacks that are enjoying early success at Costco, Kroger and other retailers.

Hydroelectric is a big part of the energy portfolio in the Pacific Northwest, and that helps EnWave stake a low-carbon footprint claim, at least when its machines are operating on its home turf. The vacuum level cuts the boiling point in half, and microwave energy removes moisture without collapsing the food’s cell structure.

Freeze drying also uses vacuum, but the process is longer and consumes more energy because of the multiple phase changes the food undergoes, according to Brent Charleton, EnWave vice president. REV accomplishes similar quality outcomes to freeze drying in a shorter time and at a cost closer to convective air drying. Product is loaded into carriers that tumble through the dryer, mimicking the effect that a turntable has in a home microwave oven.

NutraDried LLP, a Ferndale, Wash., processor formed last year and jointly owned by EnWave and a capital investment group controlled by an EnWave director, recently started producing Moon Cheese on a 100 kW machine, replacing a 10 kW system similar to the units used by Jack Link's and others.

“The 10 kW machine was more or less a pilot line for us until we got into about a hundred stores and could justify the bigger machine,” explains Alan Whittecker, CEO of NutraDried. The bigger unit outputs about 450 lbs. of low-moisture (typically less than 1 percent) of fresh cheese that’s shelf stable for 12 months, delivering “the fantastic taste of cheese” without preservatives or other additives, he adds. The company started shipping product from the larger dryer Dec. 2.

Air replaces moisture in the cheese as it evaporates, causing the product to puff up and resemble lunar rocks, according to Whittecker, explaining the inspiration for the product’s name. “It has a really nice crunch, unlike the spongy, almost Styrofoam mouthfeel of freeze-dried cheese,” he says.

Baking can produce shelf-stable cheese, “but with not nearly the flavor delivery and nutritiousness.” Outdoor enthusiasts are among the consumer segments targeted with the cheddar, gouda and pepperjack varieties, which typically retail at $4.99 for a 2-oz. package.

“It’s a relatively expensive snack,” concedes John Gibb, CEO of NutraDried Creations, a Blaine, Wash., copacker created to market private-label fresh cheese produced in bulk in Ferndale and packaged in Blaine. Gibb’s firm created Munchies for sale in Costco stores in the Northwest. Based on positive sales results, he expects a Kirkland version of the cheese snacks to debut in 2015.

Streamlined engineering

Sanitary design of equipment is front and center for both processors and OEMs, but considerable confusion exists, particularly when the application involves low-moisture foods. Requests for quotes often compound the problem, with food companies mixing and matching from guidelines that may or may not be appropriate for the application. The result is added cost for over-engineered equipment.

The One Voice initiative by the Alliance for Innovation and Operational Excellence is designed to address the understanding gap and move OEMs toward greater standardization that lowers equipment costs. Industrial dryers recently were addressed by One Voice’s engineering and solutions group, and the exercise helped guide development of a hygienic dryer for ready-to-eat cereals coated with sugar and other flavors.

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