Various ingredients are ground and mixed together in a meal or ground singly and then forced under steam and pressure through a “cooking tube”. This “cooking” helps break down fats and starches and thus improves digestion. The cooked ingredients expand and are then forced through specially shaped dies. The resultant product is then cooled. Because the products produced under extrusion are dry and somewhat expanded; oils, fats and other sprays can be easily added. Many whole grains, such as soybeans, can be extruded under pressure and friction without steam. When products are extruded, they are “cooked” and thus become very palatable. Extruded diets are lower in fat content and are usually complete diets. Added fat, vitamins, minerals and natural enzymes are then sprayed on the finished product when it is still hot and the product “soaks” up those add ons during the drying/cooling process.
Various ingredients are finely ground and then forced through a pellet machine and die so that the end result is a compacted food. Because this is a simple compaction and pressure process no real cooking occurs. Steam is applied to improve the ground ingredients ability to be compacted. Some heat is used as a result of producing steam. To preserve natural enzymes the temperature is kept under 2000° F (usually 1700°).
These mixes are combinations of various seeds, fruits and other ingredients which are combined in a mixer and then packaged. Heat and moisture are not introduced, thus maintaining the natural nutrient content. Because of varying size and weight of each ingredient, there is often “separation” during shipping and handling. Therefore, it is always recommended that those types of mixes be stirred thoroughly prior to use.
*NOTE: Extruded products are often referred to as pellets. This is incorrect. The two processes are very different and the end products are also different. Extruded products are not pellets.