by Lynn Petrak

T here are a lot of people indairy plants gettingagitated about the pace ofnew technology, at least

when it comes to the function ofmixing.

Attempts at industry humoraside, there have been noteworthyrefinements to mixing and blendingsystems. Many new mixers installedin dairy processing facilities todayreflect both technological anddesign improvements.

Although shear engineeringadvances have allowed for the latestgeneration of mixing equipment, theday-to-day needs of users arealways a crucial influence. “Dairyprocessors are looking for versatilityand speed with the appropriate endproduct being produced,” says JimLeClair, regional product director,Americas, for process engineeringand automated solutions supplierInvensys APV, Lake Mills, Wis. “Thesize and power requirement of theequipment are changing, too. Nolonger is the functional-food portionof a dairy a side business, for exam-ple, so this has resulted in a demandfor more in-line systems that canproduce the volumes required forlarge processing facilities.”

Peter Leitner, vice president ofsales for sanitary mixer companyAdmix Inc., Manchester, N.H.,shares his own list of top-tier dairyindustry requirements: “ROI,

reduced energy consumption,reduced maintenance, lowercleaning chemical usage, reduc-ing BOD, elimination of fil-tered-out ingredients and truecleanability.”

The changing composition ofmany dairy-based productstoday also has a direct impacton the type of mixers thatdairies are interested in buyingfor their operations. Take, forexample, the influx of thickerproducts with more particu-lates. Bill Wade, manager forthe Kansas City, Mo.-basedBreddo Liqwifier division ofAmerican Ingredients Co., usesice cream as an example.“Customers are running higher vis-cosity ice cream mixes, whichrequire more agitation on the frontend. Those are also thicker productsso it requires more horsepower,too,” he says.

Leitner agrees that different for-mulations have caused issues withprevious equipment and notes thatdairy products are increasingly com-bined with different and sometimesmore challenging ingredients.“Today’s applications have changeddrastically. There are many moresuspended, or undissolved, particlesso the days when sweep agitatorswere sufficient to maintain a mix inthe blend tank are gone. High-effi-ciency, ultra-sanitary, low-speedaxial agitators are now required,” hesays. “Besides the suspended solids,

higher viscosities have alsocaused issues with existing

equipment causing bridgingpowder induction

systems, clog-ging of strain-ers and foul-ing in pas-teurizers,among otherthings.”

HåkanPålsson, aproduct man-ager for TetraAlfast and

Tetra Almix lines from Tetra

Pak Dairy and Beverage Systems,also points to the difficulties thatcan arise when mixing together newtypes of ingredients in traditional orold mixers, and cites the growingnumber of health-oriented dairyproducts as examples. “When youare coming into this part of newapplications, there is a demand on

the mixer. You have to be extra care-ful with products like that, becausesometimes the powders like stabiliz-ers, guar gum and others can betricky,” he explains.

Beyond product compositionchanges that are spurring enhance-ments in mixing equipment, thereare other considerations affectingmanufacturers’ choices of systems.“I think food safety is an issue inoperations. Now, with fully auto-mated machines you can keep trackof what’s going and it gives youmore control of the mixing processand that really boils down to safety,” Pålsson says.

Blending In Many mixing equipment manufac-turers have recently introduced newmodels that reflect the needs of the

mid-2000s dairy customer. Admix,for its part, debuted its Rotomaxx™mixer a couple of years ago featur-ing higher torque and larger volumeprocesses that can handle undis-solved solids and higher viscosities.Meanwhile, the Admix Rotosolver®high-shear disperser and dissolveris now being used for differenttypes of applications than in thepast, Leitner adds, including prod-ucts that are highly viscous.

“This mixer is the only in-tank,high-shear mixer to earn 3-Aapproval under the newer thirdparty verification,” he says of the

Rotosolver, noting that the unit is atop-entry, high-shear, high-flow,clean-in-place (CIP) design whichdrastically reduces energy consump-tion and once the mix is complete,its speed can be reduced to providegentle blending to maintain suspen-sion for fast settling ingredients likecarrageenan and cocoa.

The Tetra Almix line of mixingequipment is also more ergonomicin nature, notes Pålsson, and is usedfor a variety of dairy products,including reconstituted and recom-bined milk, flavored milk, yogurtdrinks, ice cream mix and otherapplications. “We are combining ahigh-shear in-line unit with a liquid-filled mixing tank on the top, withor without vacuum mixing technol-ogy. By having the vacuum mixingtechnology, it minimizes air into the

January 2007 41www.dairyfield.com

processing technology

MIGHTY MIXERSWith new product development and production pressures, dairy manufacturers take mixers to the max.

”— Bill Wade, manager, Breddo Liqwifier

COURTESY OF ADMIX INC.

COURTESY OF INVENSYS APV

“Customers are running higher viscosity ice cream mixes, which require more agitationon the front end.

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January 200742 www.dairyfield.com

final product,” he explains.At Invensys APV, meanwhile,

LeClair reports that the company’smost popular mixing equipment inthe dairy industry includes itsLiquiverter for high-shear mixing,Multiveter for high-shear mixing

with scraped interior walls andTPM Mixer for continuous incorpo-ration of powders into liquids. “Thebenefits of the Liquiverter andMultiveter are the ability to batchtogether the required componentsinto he tank and control the mixing

residence time,” he says. For prod-ucts that require extended mixingtime, an operator can place all of theingredients in the unit and let it rununtil the desire mixing is achieved,he adds.

Most recently, Invensys APV

launched two new mixers: theDARMix, an inline mixer with high-shear properties and the PowerMix,a very high-shear inline mixer. Bothwere designed based on industryinterest and feedback.

Other suppliers have unveilednew mixing systems as well. AtBreddo Liqwifier, Wade says that anew CIP seal is available for mixers,so operators don’t have to removethe impeller during cleaning.“Dairies are worried about cross con-tamination and that seal was indus-try driven, since many are lookingfor something that does not harborallergens, for example,” he says.

Paul Mueller Co., a Springfield,Mo. provider of processing equip-ment, also has upgraded its systemsused for mixing purposes. “On oursilos for raw and pasteurized milk,we use our horizontal agitatorthrough the sidewall in the alcovefor keeping a homogenous mixtureof the product. The Mueller Agitatoralso promotes cooling of the prod-uct by moving it across the coolingsurface,” explains Paul Hume,national sales manager, adding thatfor products like sour cream andyogurt, the company also offers aside- and bottom-scrape agitatorequipped to handle more viscousattributes. “The scraper will lift theproduct off of the side wall to helppromote cooling.” For blendingapplications, Hume adds, the com-pany has an offset turbine and cen-tered turbine with baffles or a sidesweep agitator for thorough mixing.

In the meantime, SPX ProcessEquipment, Delevan, Wis., recentlydeveloped a Lightinin ECL mixeravailable in both a portable andfixed-mount version that feature anaxial flow design to generate up to 70percent more flow for the same speedpower. The portability allows a userto move from one application toanother with no cross contamination.

Finally, looking ahead, Pålssonpredicts that mixers will have to bebuilt for even greater power, volumeand versatility “The demand formixers for even higher capacity iscoming,” he says, citing the possibil-ities in burgeoning markets likeChina. “I also see having mixers forspecial products and a greater needfor flexibility.” ❍

Lynn Petrak is a freelance journalistbased in the Chicago area.

processing technology

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