In The Mix
by Lynn Petrak
Dairy manufacturers upgrade mixing and blending equipment to enhance consistency and efficiency.
Giving new meaning to the term “whipped into a frenzy,” dairy processors facing internal and external pressures for consistent product quality and enhanced efficiency are taking a new look at mixing and blending equipment.
Whether updating worn-out machines that have surpassed their average 15-year life span or investing in the latest equipment as part of new construction, dairy manufacturers might be surprised at how mixers, blenders and agitators have become increasingly sophisticated.
The latest systems, like other equipment used in dairy environments, are constructed to be durable, quick, flexible and sanitary, developments that are due as much to the demands of today’s users as they are to technological advances. That is true for units used for straightforward liquid-to-liquid blends and tank agitation as well as for more complicated powder-to-liquid combinations, products with particulates and purees.
According to suppliers who regularly field calls from dairy customers, effectiveness is a constant issue because it relates directly to the quality of the finished product. “The big thing is when they get to a point where they don’t feel they are getting as good of a mixture with their current system,” says Randy Verges, senior applications manager for Fristam Pumps, Middleton, Wis. “We started getting into mixing and blending equipment after realizing that everyone has mixing applications in a plant but a lot of people are doing it the old fashioned way, trying to stir it up. We saw a need for better, more efficient incorporation.”
New Needs
Successful mixing and blending is especially important in today’s processing environments, as dairies continue to diversify their product lines and develop formulations that are more complicated.
Lou Beaudette, president of equipment supplier Admix Inc., Manchester, N.H., cites some examples. “The increasing use of stabilizers used for ice cream, yogurt, cheese and flavored milk drinks has presented new challenges to processors to find a way to of quickly dispersing and hydrating them,” he says, “especially some of the new natural stabilizers used for organic dairy products, a growing market segment.”
In response to such processing challenges, Admix went to the drawing board and came up with a new bottom-entry blender called the LiquiShear for rapid introduction of milk powders, sugars, sweeteners, stabilizers, cocoa powder starches and gums. “The LiquiShear has a unique integrated powder conveying and feed system to quickly and ergonomically feed the above powders at waist height,” Beaudette says. “This approach increases the safety factor in handling and processing all of the powders used for dairy processing, while increasing the efficiency and effectiveness of blending, dispersing and hydrating.”
Fristam also has engineered new mixers and accompanying pumps to work with today’s powder and liquid blends. Nearly two years ago, the company introduced a powder-mixer unit that features a liquid ring pump used in combination with a shear blender. “It works to pull the liquid and the powder out of the tank and feeds them into a shear blender unit. It’s economically a very effective way to shear and mix powders and liquids,” Verges says, adding that common dairy applications include the incorporation of powders like cocoa flavorings and those used for nutrient fortification.
Beyond effective blending of powders and liquids, viscosity is another emerging issue that affects mixing and blending machines. The development of more viscous dairy products, such as drinkable yogurts and shake-style milk drinks, has caused suppliers to provide new mixing and blending solutions to their industry customers.
Verges, for example, says Fristam’s liquid ring pump that incorporates and feeds powders and liquids into a blender can handle highly viscous products. “Otherwise, you’d have to put in a special pump which is more expensive,” he says.
Another equipment supplier, Hauppauge, N.Y.-based Charles Ross & Son Co. (Ross), recently rolled out a new model of its Double Planetary Mixer, used for a thorough mixing of ingredients under low-shear conditions. Ideal for bench-top development of highly viscous materials, the unit features a vacuum, sight/charge port, jacketed mix vessel and a thermocouple to sense batch temperature, along with a complete control panel with a frequency inverter to control blade speeds.
“It’s been out for a while, but we have new stirrer blades that are being used,” says product manager Bill Alhofen. “The improvement is for flow characteristics within the mix, particularly for highly viscous materials, it prevents problems that were associated with rectangular blades.”
Meanwhile, Delavan, Wis.-based SPX Process Equipment has worked with more large companies that have expanded product lines to include thicker products. “We typically sell agitators on heavier new products, like sauces,” says Tracy Breneman, sales manager for the nation’s central region. Among its various models for high-viscosity products used by a range of dairy processors is a series of double planetary mixers engineered to result in de-aeration of finished products, fast homogenous dispersions and smoother finished products.
Another equipment maker that has tweaked its mixer design for flexibility and effectiveness is APV/Invensys, Lake Mills, Wis. APV/Invensys has upgraded its Flex-Mix™ Liquiverter mixing system, which can be used for a wide range of mixing and dispersion applications. The unit includes a recirculation pump as an option, a dispersion head for fast operation and improved quality and a direct drive created to reduce spare parts and cut down on wear and tear. The Flex-Mix Liquiverter can be tailored to meet specific customer requirements for a particular function.
Designs on Speed
In addition to performance related to effective ingredient combinations, particularly for new products, there are other issues spurring suppliers to mix it up with designs for new mixers, blenders and agitators. Speed is one of them. “Usually, processors want volume but they want to make sure they pass it through in a certain amount of time. In some cases, we are cutting down blending time by a half or third,” Verges says of Fristam’s capabilities. “For example, if someone is incorporating 100 pounds of chocolate sugar slurry a minute, now we can do it in 15 minutes.”
Beaudette, for his part, agrees that volume is a key driver. “In addition to the processing side, we have seen a substantial rise in inquiries for a more operator friendly and ergonomic method of adding or ‘feeding’ a high volume of powders into mixing and blending tanks,” he says. “Admix is addressing this issue with a new series of powder feed systems, our Fastfeed and Optifeed products, that use vacuum technology to both move and disperse powders in line directly to a mix tank, reducing dusting, aeration of the product, and processing speed, while substantially improving operator safety.”
Finally, sanitation and clean-in-place (CIP) options have been added to the list of processor requests for new mixing and blending equipment, given that dairy plants require frequent washdowns with harsh cleansers in cold temperatures.
Verges, for instance, is quick to note that Fristam’s new liquid ring pump and shear mixer units are “CIP-able.”  Alhofen, too, says that Ross’s sanitary mixer is easy to clean for traditional and high viscosity dairy products and is available in CIP-able models with an incorporated spray nozzle. Admix also offers stainless-steel construction and easy-to-clean elements in its various mixing and blending machines.
Rugged, stainless construction that can withstand frequent cleanings has other benefits as well, as Alhofen notes. “Maintenance is always a big thing,” he says. “Processors want low-maintenance equipment that will keep running.”
Lynn Petrak is a freelance journalist based in the Chicago area.
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