First of all, the grain arrives at the cereal factor before being inspected and cleaned. It can be used in the form of whole grains or it may require further processing. Usually, the whole grain is crushed between large metal rollers to remove the outer layer of bran. This will enable it to be ground more finely into flour.
The grains are then mixed with additives such as flavoring, vitamins, minerals, sweeteners, salt, and water. Everything is then placed into a large rotating pressure cooker. The time, temperature, and speed of rotation depends entirely on the type of grain being cooked.
The cooked grain is then placed onto a conveyor belt, which passes through a drying oven. However, despite the drying oven’s effects, enough of the water will remain within the cooked grain to result in a soft, solid mass that can be shaped as needed. If flour is used instead of grains, it is cooked with a cooking extruder. A cooking extruder consists of a long screw within a heated housing. The turning of the screw mixes the flour with additives such as water, flavorings, salt, sweeteners, vitamins, minerals, and food coloring (if required). The screw pushes the mixture through the extruder and cooks it while it moves along. At the end of the extruder, the cooked dough will emerge as a ribbon. A rotating knife will then cut the ribbon up into pellets. These pellets are then processed roughly the same way as cooked grains.
Some cereals (for example, shredded wheat) are fairly resistant to moisture damage. They can be placed directly into cardboard boxes with or without a plastic lining. Most cereals have to be packaged in airtight, waterproof plastic bags inside cardboard boxes in order to protect them from spoiling.
An automated machine will then package up the cereal at a speed of around 40 boxes per minute. The box is produced from a flat sheet of cardboard, which has been previously printed with the desired pattern for the outside of the box. The bottom and sides of the box are sealed with a strong glue. The bag is formed from moisture-proof plastic and inserted into the box. The cereal fills the bag and the bag is then sealed by heat. The top of the box is sealed with a weak glue which enables the consumer to open it easily. The completed boxes of cereal are packed into cartons (which usually hold 12, 24, or 36 boxes) before being shipped to the retailer.