There are a variety of different types of food products that are manufactured by extrusion.
The food extrusion process is using for mixing and compounding materials as well as reacting materials. Extrusion equipment is highly flexible and is designed specifically for the task at hand.
Seeing as most cereals are very rich in starch, cereal extrusion is a common process. The starch, when in its natural state is tasteless, cannot be dissolved and is basically not fit for human consumption. In order to make it edible, the starch must first be cooked. Traditionally, the cooking of starch needs the right amount of time and needs to be done at the right temperatures. Just about any cereal can be cooked using an extruder.
If adding dimension to the product is the goal, then the number of cereals you can use are limited to rice and de-germinated corn or grit. Cereal with more lipids have difficulty expanding, so this kind of cereal will need a high moisture content and high temperature in order to become puffier. Starches with a 5 to 20% amylose content will give breakfast cereals a more expanded look and better texture.
Corn is one of the most commonly used starches for breakfast cereals
Corn snacks and breakfast cereals which have been extruded are becoming very popular. Corn, which is also known as maize, is used as the primary ingredient for corn collets and other pellet products. The majority of corn based breakfast cereals are made used dry-milled cornmeal. The large amounts of cornmeal are ideal for puffed snacks and breakfast cereals which some are used to make corn chips.
The different types of dry-milled dent corn include cornmeal, corn flour, corn cones and corn grits. These usually only differ in terms of particle size distribution. The type of granulation will depend on the product being manufactured.
For corn products that have a softer bite, and a finer cell structure, the fine granulation corn meal is ideal. If you are going for a crunchy product with a larger cell structure then it is best to go with a coarser granulation. Extruders can be used for both fine and coarse granulation. De-germinated corn is used to make most breakfast cereals as well as snacks because it expands while whole corn does not.