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Saving costs in vacuum coating in the production of aquaculture feeds Stefan Lungwitz, Amandus Kahl
For liquid addition in feed production, spraying at the end of the production line (post-pelleting application, PPA) has been established in recent years. In case a liquid quantity of greater than 7-8% has to be added to pellets, a vacuum application after pelleting or extrusion is inevitable. Compared to spraying pellets under normal atmosphere, 30-75% more liquid can be introduced into a product without it showing liquid on the surface. In the vacuum application, the liquid medium is not only bound to the surface but penetrates the core of the pellets at the porous fracture surfaces
and pores. Thus, fat additions of up to 30-40% are possible with extruded feed and 8-10% with pelleted feed. Enzymes and other active ingredients can also be added in small quantities, either directly or in a liquid mixture (blend). The vacuum coating process was developed in the 1990s for the salmon feed industry in Norway and is now, 30 years later, also used for the production of pet food, poultry feed and in the food industry. The most common types of vacuum coater to date are twin-shaft paddle mixers and conical screw mixers.
Aquafeed: Advances in Processing & Formulation Vol 13 Issue 3 2021
