Different Mixers for Different Food Blending Applications

Mixing and blending are fundamental to many food processes, and matching the machine to the application is the first step in ensuring consistent results and quality outcomes.

By Kevin T. Higgins, Managing Editor

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For all the 3-A certified components and stainless steel sensors, the real star of the blending system is the controls architecture, suggests Derek Deubel, TechniBlend vice president.

"Static mixers are great, but they are designed specifically for the ingredients you use and the flow rate you set to the mixer," he says. In reality, flow rates accelerate and slow down,  forcing a system to cycle on and off and resulting in premature wear for pumps and valves and increased energy consumption.

"We use variable speed mixing and stay in tighter process control," he says. Two check valves open and close, depending on flow, and ensure the two streams are deflected at a 90-degree angle for optimal mixing.

The spirits business exemplifies the shift to in-line mixing. Instead of traditional distilling, companies bring in raw alcohol and create a base, then blend flavors and fragrances to produce ready-to-drink cocktails, cordials and other beverages. The change has unfolded in recent years. When Diageo completed a major expansion of its Plainfield, Ill., facility in 2009, two gin mills from the 1960s still were fired occasionally. Those mills were rendered obsolete and sold off, and the facility now is a blending and bottling operation only.

TechniBlend helped Jim Beam make the blending transition in 2009, when the spirits company shuttered a Cincinnati distillery and shifted production to Frankfort, Ky. Deubel's firm engineered an 11-stream blending system for cordials, obsolescing the old process in which an individual would dump each ingredient in turn into a blending vat.

"Instead of tankfuls of bad product, we put instrumentation as far up in the process as possible to measure product quality 3 feet after blending at 160 gallons a minute," Deubel recalls. Flavor oils replaced some dry ingredients, and the order in which tartaric and citric acids were introduced was shuffled, depending on how well they dissolved in a given chemistry.

When it was time to throw the switch on the new process, senior managers traveled to Kentucky to bear witness. The trepidation was palpable, Deubel recalls. "They asked, 'What if it doesn't taste the same? We're concerned that the process is art, not science.' We said, 'Well, then you change it until it tastes right.'"

That's not an answer the process industry is eager to hear, but it highlights the need to consider factors beyond mechanical motion. Silverson's Smith relates an experience early this year involving a Dutch manufacturer of ready-made refrigerated pancakes. The firm trialed the Silverson mixer in a 230-gal. vessel, improving yield and resolving nozzle-clogging issues the manufacturer experienced with a bottom-entry mixer. However, small lumps remained in the mix.

Drawing on experience with a similar process, Silverson technicians recommended reshuffling the order in which ingredients were added. By dispersing flour and buckwheat flour first, they prevented the fat in milk powder from encapsulating those solids, resulting in a lump-free batter.

"Mixing isn't rocket science: it's a spinning rotor inside a stream," concludes Smith. "Application knowledge also is important."

So, too, is the particular mixer for the work at hand. SPX's APV Flex-Mix series for dairy numbers no fewer than seven different machines. "The technology ranges from simple static and venturi mixers to innovative vacuum mixing," according to Bent Oestergaard, director-global marketing, food and beverage for SPX Flow Technology, Charlotte, N.C.

Depending on whether the application involves mixing liquid and air, liquid and liquid, liquid and particles or liquid and powder, a different machine is recommended for best results, not only in the blend but also in downstream homogenizers and other equipment.

Mixing and blending are fundamental to many processed foods. Far from being commodities, the particular machine selected for the job and the way it is used has a profound impact on a food manufacturer's finished goods.

This article originally appeared in our June issue of Food Processing magazine.

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