Extrusion Technology For Foods

Extrusion is used in food production and has been used for many years. Extrusion cooking can be used to produce ready-to-eat cereals, some snack foods, dry or semi-moist pet food, candies, macaroni products, and foods containing textured soy protein. In food manufacturing, extrusion refers to the process of forcing soft, combined ingredients through holes in a perforated plate or die into a desired shape. The powder is extruded and then cut into the desired size by a blade. The device that pushes the mixture through the die is called an extruder, and the mixture is called the extrudate.

Typically, an extruder consists of a fairly large rotating screw that is rigidly mounted in a fixed barrel with a die at the end. The effect of extrusion cooking on the nutritional quality of food is controversial, as extrusion may change the carbohydrate, dietary fiber, protein and amino acid composition, vitamin and mineral content of the extrudate, and these changes may be beneficial or detrimental. Extrusion at high temperatures for a short time can "minimize the loss of vitamins and amino acids." Extrusion makes it possible to mass-produce certain foods and "denature anti-nutrients," such as eliminating toxins or killing bacteria. In addition, extrusion can affect the product's "protein quality and digestibility," as well as its form, texture, color and flavor.