Cost-effectively coated crispies

London – Lödige’s Ploughshare mixer has proved effective in a complex process for coating extruded cereal products - termed crispies - with chocolate and glaze, the equipment maker claims. The application, it said, shows that complex coating tasks can be implemented by relatively, cost-effective technology.

In the process, which must retain the crunchy properties of the crispies, the product to be coated has a more-or-less round shape and a porous surface. Particle size varies depending on the type, while up to ten times the amount of liquid chocolate and/or glaze is applied. The finished product is then separately wrapped as a crunchy accompaniment, e.g. as a topping for yoghurt.

At the start of the coating process the raw crispies are loaded batchwise into the mixing drum at room temperature. An expanded filling level is already taken into account when weighing, as later in the process the material requires more space than at the beginning. The peripheral speed and geometric form of the mixing tools are calculated to form a moderate, but still intensive fluidised bed.

Exactly dosed by a pump, the liquid chocolate and glaze are injected onto this fluidised bed through open pipes. Within the fluid bed the intensive product movement and resulting rubbing of the individual crispies guarantee even distribution of the liquid mass on the surface of the extruded product.

When it comes to cleaning, the machine is said to satisfy industry-specific requirements for hygienic design: the heating jacket can be heated to a temperature above the melting temperature for cleaning the inside surfaces of the drum and mixing mechanism. Remains of the coating mass simply melt off.

The sealing of the shaft passages for the mixing mechanism by mechanical seals enables sterilization of the mixer interior with hot steam process design required for a high degree of mixing and process precision.