Understanding Agglomeration

Understanding Agglomeration
by SteveBecker

Agglomeration,the process by which smaller particles are merged together to form largerparticles for better dispersion in liquid, is the key to success in thefast-growing functional beverage market. Not only does agglomeration lead toquick powder dispersion in liquids, it also helps with blending, filling, mixingand other functions.There are, however, multiple agglomeration processes fromwhich to choose.Which is the right one for any given product? Is it better toproduce the product inhouse or work with a contract manufacturer?

Variable ingredient properties, equipment maintenance,functionality and cost all influence which style of agglomerator is best for anapplication. Different processes yield different results. For example, milk andwhey proteins tend to form smaller particles and be less dispersible, so it isnecessary to use an emulsifier. In contrast, nonfat dry milk produces a verylarge particle when wetted with just water because it contains lactose (sugar)and tends to be very sticky. So sticky, in fact, that the lactose should beconverted to the monohydrate form or it will create clumps. Starches generally agglomerate well with good particle size.

Two different agglomeration processes to consider include thewetting chamber and the wetting tube. The wetting chamber style of agglomerationis much more versatile and allows more variables to be incorporated. Moisture, product flow, and the addition of emulsifiers andother processing aids can all be controlled and monitored closely when using awetting chamber.The system generally uses a high-pressure liquid feed system toatomize the rewet medium. Next, a holding belt is used to allow time for theparticles to react. Fluid bed driers are then used to dry the added moisture backout of the product. This creates optimal product coverage. Because of itsversatility, wetting chamber agglomerators are a reliable means for producingeither simple or complex fortified nutraceuticals. The downside is cost: awetting chamber agglomerator costs more to install than simpler agglomeratorssuch as the wetting tube.

Wetting tube agglomeration is one alternative to the wettingchamber, especially when using nonfat dry milk, a naturally sticky powder thatrequires little modification. The advantage of a wetting tube agglomerator isthat it is cheaper to install than other systems. This style uses steam as the wetting medium, a re-dry tube andthen fluid bed driers to finish the drying process. This style is not withoutits drawbacks, however. The wetting tube process allows for much lessflexibility in terms of adding processing aids. Steam tends to denatureprotein-containing ingredients, so the tubes must be changed or cleaned on aregular basis. Also, product tends to stick to the walls of the pipe, which canlead to bacterial growth.

Some powder manufacturers may use an alternative toagglomeration, called the single pass method. Single pass is done throughthe spray drying process; therefore, it is not an actual agglomeration process.Fine particles are lifted into a cyclone funnel then pushed back up through thehigh-pressure sprays of liquid coming in to the dryer chamber. This rewets theproduct to create larger particles that will disperse better when added to aliquid. While this may lead to somewhat better dispersability forcertain powders, it does not equal the functionality of true agglomeratedproduct.

Another issue to consider is whether to call on a contractmanufacturer to assist in production. There are several situations in which acontract manufacturing partner can help save time, money and headaches. Manymanufacturers do not have the expensive resources needed to produce the morecomplex agglomerates (meal replacements, fortified shakes, etc). A contractmanufacturers focus is on production, so the facility should be outfittedwith the latest equipment and capable of handling the most complex tasks. Also,if a companys production line is currently running at or near full capacity,a contract manufacturer can get new products to market quickly and efficientlywithout tying up company resources. This leaves branded manufacturers with the time and money tofocus on other core competencies, such as marketing, information management andsales. Some contract manufacturers offer custom packaging as well, from bulk toconsumer size, in order to provide turnkey solutions for customers. Qualitycontract manufacturers enforce strict quality control measures, so ask to seecertifications of compliance from outside regulatory agencies when you speakwith the company representative.

Steve Becker, director of process engineering at Century FoodsInternational, has designed and managed projects, processes and modificationsfor 10 years. Century Foods (www.centuryfoods.com) manufactures and packagesdairy proteins, whey protein concentrate, protein drinks and nutritionalingredients under private label for the food, beverage, sports and healthindustries.