Understanding Agglomeration

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Understanding Agglomeration
by Steve Becker

Agglomeration, the process by which smaller particles are merged together to form larger particles for better dispersion in liquid, is the key to success in the fast-growing functional beverage market. Not only does agglomeration lead to quick powder dispersion in liquids, it also helps with blending, filling, mixing and other functions.There are, however, multiple agglomeration processes from which to choose.Which is the right one for any given product? Is it better to produce 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 an application. Different processes yield different results. For example, milk and whey proteins tend to form smaller particles and be less dispersible, so it is necessary to use an emulsifier. In contrast, nonfat dry milk produces a very large 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 be converted to the monohydrate form or it will create clumps. Starches generally agglomerate well with good particle size.

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

Wetting tube agglomeration is one alternative to the wetting chamber, especially when using nonfat dry milk, a naturally sticky powder that requires little modification. The advantage of a wetting tube agglomerator is that it is cheaper to install than other systems. This style uses steam as the wetting medium, a re-dry tube and then fluid bed driers to finish the drying process. This style is not without its drawbacks, however. The wetting tube process allows for much less flexibility in terms of adding processing aids. Steam tends to denature protein-containing ingredients, so the tubes must be changed or cleaned on a regular basis. Also, product tends to stick to the walls of the pipe, which can lead to bacterial growth.

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

Another issue to consider is whether to call on a contract manufacturer to assist in production. There are several situations in which a contract manufacturing partner can help save time, money and headaches. Many manufacturers do not have the expensive resources needed to produce the more complex agglomerates (meal replacements, fortified shakes, etc). A contract manufacturer’s focus is on production, so the facility should be outfitted with the latest equipment and capable of handling the most complex tasks. Also, if a company’s production line is currently running at or near full capacity, a contract manufacturer can get new products to market quickly and efficiently without tying up company resources. This leaves branded manufacturers with the time and money to focus on other core competencies, such as marketing, information management and sales. Some contract manufacturers offer custom packaging as well, from bulk to consumer size, in order to provide turnkey solutions for customers. Quality contract manufacturers enforce strict quality control measures, so ask to see certifications of compliance from outside regulatory agencies when you speak with the company representative.

Steve Becker, director of process engineering at Century Foods International, has designed and managed projects, processes and modifications for 10 years. Century Foods (www.centuryfoods.com) manufactures and packages dairy proteins, whey protein concentrate, protein drinks and nutritional ingredients under private label for the food, beverage, sports and health industries.

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