January 30, 2014

Vacuum Coating: The Pressure’s On!

Author: Courtney Loveless

AFB International’s Lovejoy Resource Center (LRC) has a pilot-sized, scalable pet food production facility where we can collaborate with our customers from around the world to experiment with new food models or processes. To make this facility even more useful, in March 2013 we added a third coating system—a vacuum coater.

Rather than simply spraying on coatings, the vacuum coater allows us to infuse palatants and/or fats deeper into kibble. The process can change kibble texture and spread flavorings more uniformly through the kibble, potentially increasing palatability.

The vacuum coating process works like this:
• We place the kibble into a chamber and draw a vacuum. Liquid palatants and fats are applied under vacuum through pressurized nozzles while mixing the kibble. 
• When the application is complete, we slowly break the vacuum. Because kibble is porous, the low-pressure environment created in the chamber reaches the subsurface pores of the kibble.
• When we break the seal to the chamber, the natural atmospheric pressure pushes the liquid palatant deep into those lower-pressure voids in the kibble.

If desired, dry palatants can be applied once the vacuum has been broken.

This approach is particularly effective with fats. With other topical application methods, the fat application ranges between about 4% and 9% on both dog and cat kibble. Beyond that level, kibble pores overflow, and excess unabsorbed fat begins to show on the kibble surface and process equipment—wasting fat and creating adverse effects. But with vacuum coating, we’ve seen up to 18% fat application with minimal residue. The fat is infused more deeply into the kibble, coating more area and boosting palatability.

The challenge of vacuum coating is that it’s a batch process rather than a continuous process. A single batch requires about four minutes from loading to unloading. However, for some plants and products, the ability to increase fat and palatant levels is well worth the modifications and extra time required.

With the vacuum coating equipment at LRC, we can process 65- to 100-pound batches. This allows us to coat several small batches of kibble using different products and application methods to test their effects on palatability, durability, texture, stability against micro-organisms and myriad other testing parameters.

Our vacuum coating testing has helped determine what combinations of fat levels and flavors yield the best palatability results on different types of kibble. In a number of cases, vacuum coating has resulted in significant improvements in palatability that would have been impossible using other coating methods.

In addition to the vacuum coater, LRC also has drum and in-line coating systems, a single screw extruder, a spray dryer, pneumatic extrudate conveyance, conveyor dryer, baking oven, fully integrated meats room, canning operation and retort. AFB welcomes customers to the LRC pilot plant to conduct their own research and development work.

Have questions about vacuum coating or how your company can use AFB’s pilot plant? We’re here to help. Email me or contact your AFB regional office.

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