Extrusion technology was first applied to food materials in the mid 1800s, when chopped meat was stuffed into casing using a piston type extruder. In the 1930s, a single extruder as introduce to the pasta industry.
It is a continuous process by which food biopolymers and ingredients are mixed, plasticized, cooked, and formed by combination of moisture, temperature, pressure, and mechanical shear.
Extrusion cooking is very efficient technology used in the processing grains particularly in processing of breakfast cereals.
It is predominantly a thermomechanical processing operation that combines several unit operations, including mixing, kneading, shearing, conveying, heating, cooling, forming, partial drying, or puffing, depending on the material and equipment used.
During extrusion cooking, the processed materials undergo significant physical and chemical changes. By appropriate selection of process parameters such as temperature, moisture and processing time, the mass becomes entirely gelatinized and cooked.
Extrusion cooking is popular for ready to eat cereals, where which they are shaped, toasted, flavored, colored and sometimes enriched or fortified before being packaged and shipped to the consumer.
Cereal extrusion
