The thermomechanical process of extrusion is described in the abstract. In the production of ready-to-eat pasta, cereals, snacks, pet meals, and textured vegetable protein (TVP), it has emerged as a crucial method of food processing. A snugly fitting screw revolving inside of a still barrel makes up an extruder. Ingredients that have already been pre ground and condition enter the screw where they are delivered, combined, and heated using various methods. The product exits the extruder through a die, where it typically puffs and transforms texture as a result of normal forces and the discharge of steam. Mathematical models for extruder flow and torque have been proven effective in understanding extrusion processes. These models have helped to determine the behaviour of raw material during extrusion. There are several food extruder designs available. The extruder is a high temperature, quick technique that minimises vitamin and amino acid losses in many of these applications. The extrusion process also affects the product's form, flavour, and colour. Extrusion is frequently used in the manufacture of wholesome meals. The increase of protein quality and digestibility, as well as the use of extrusion to denature antinutritional components, are highlighted.