Compression and Expanded Pellets

Compression Pellets (P)

The conventional compression pellet is still used widely within the research industry. It is manufactured using the simple procedure of pushing the meal through a cylindrical die where knives cut the pellets to a specified length. Minimum temperatures reached are 80°C.

Compression pellets have a higher bulk density than expanded pellet so they take up less space and in storage and in the hopper (therefore require less “topping up”). This can be an advantage where storage space or labour is an issue.

Expanded Pellets (E)

SDS has been manufacturing ‘expanded diets’ since 1976. There is a fundamental difference in the way in which the pellets are manufactured. The meal is formed in exactly the same way as the compression pellet however it is then subject to an injection of steam under very high pressure. The meal is then forced through a die. As the pellets are pushed out into ambient temperature, the steam expands and evaporates forming the classic expanded “honeycomb” type pellet. Average temperature is 120°C to 150°C.

We have found that, in most cases, expanded pellets give a number of significant improvements when compared to traditional, compression pellets.

These include:

high levels of palatability

wastage reduction – by the animal and in the bag

a microbiologically cleaner pellet due to high temperatures and pressures during processing

better food conversion efficiency

a more homogeneous pellet providing a standardised diet across a single batch