November 14, 2016

Presenting Insights on Kibble Production: Extrusion & Coating

By: Kris Figge

Earlier this year, I had the opportunity to share key insights in the kibble extrusion and coating process with participants at the 15th Congress of the Colegio Brasileiro de Nutricao Animal (CBNA) conference in Campinas, Brasil. My presentation was designed to answer common questions I’m often asked in my role as AFB International technical sales manager—and to open up dialogue about those processes.

Here are some highlights from that presentation.


One way I assist customers is by offering technical guidance in the kibble manufacturing process, which includes three key aspects:


  • Achieving the desired mix and grind of ingredients: The result should be the optimal particle size for the desired pet. For example, cats have been shown to prefer food made with double-ground mix.
  • Ensuring the appropriate items and optimal time in the pre-conditioner: If the mix is in the pre-conditioner too long, it can become burnt, which affects taste and therefore palatability. Not enough time in the pre-conditioner can affect gelatinization, which holds the kibble together and could potentially cause intestinal issues for the pet. Without proper gelatinization, the kibble may crumble during shipping and handling.


  • Determining the best kibble size and shape for the desired pet audience: Our research with both dogs and cats has helped us understand what size and shape pets prefer.
  • Configuring the extrusion barrel shaft, screw and die plate: This includes optimizing to achieve the desired pressure, cook time and size/shape.


  • Identifying the right balance of time and temperature in the dryer: Too much time or too high of a temperature can burn the kibble or dry it out too much, affecting palatability. Not enough time and too low of a temperature can lead to moisture issues and the potential for microbial growth in the bag.


I also discussed the best possible application of fats and palatability enhancers. My recommendations are based on the customer’s available equipment for applying those liquids and powders—usually one of four types of coating systems:

  • Hand coating drum system: This cement mixer-style system, designed for small-scale palatability trials, is inexpensive and easy to maintain. At AFB, we use this system to evaluate our own palatants or to evaluate customer kibble using a selected palatant.
  • Spinning disc/auger system: In this continuous-flow system, two to five discs spin at high rates, evenly dispersing liquid droplets onto kibble as it falls down a cylinder. Each disc applies one coating. For example, a fat may be applied by one disc and a liquid palatant by another. Then the kibble moves to an auger system where a turning screw moves the kibble along to evenly apply the dry palatant.
  • Drum coating system: In this continuous-flow system, the kibble is introduced at the beginning of an angled, turning drum. Fats and liquid palatants are applied via a manifold that contains a nozzle for each coating. Baffles—protrusions on the drum sides—mix the kibble as it slides through the drum. Once past the manifold, dry palatants are applied in a volumetric auger channel inside the drum.
  • Vacuum coating system. In this batch system, a vacuum is used to remove the air from a kibble chamber, then fats and liquid palatants are applied through pressurized nozzles inside the chamber. When the vacuum is slowly broken, the fats and liquids are drawn deeply into the porous kibble. This system allows topical coating of high levels of fats or oils, without creating an oily or greasy residue on the kibble. This is especially helpful in manufacturing new diets that are very high in protein and/or fat.

Which system a customer chooses will depend on cost, available space, how the equipment interacts with existing equipment and access to parts and maintenance in their region. Regardless of the system a customer chooses, it’s important to perform regular system maintenance and cleaning and to check application accuracy.


To learn more about key decisions in the kibble manufacturing and coating processes, download my CBNA presentation at If you have questions, please contact me at or connect with your local AFB representative.


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