A simplified twin screw co-rotating food extruder: design, fabrication and testing

Numerical study of the extrusion process in cereals production: Part I. Fluid-dynamic analysis of the extrusion system

“…1). The screws transport the food compound inside the barrel toward a die to perform the final extrusion (Senanayake & Clarke, 1999).…”

“…Screws and mixing paddles play the most important role in the extrusion process, since they transport, mix, cut and stretch the cereals inside the extruder (Singh, Smith, & Frame, 1998). The external barrel contains the material flow and acts like a heat exchanger to cook the food compound; as a final point, the die shapes the final product (Senanayake & Clarke, 1999). …”

Extrusion Process Design

“…The special features of the screw extruder are continuous processing and mixing ability, properties very different from the other two types of extruder. Single -and twin -screw extruders are the most widely used in the food and feed industry (Senanayake and Clarke, 1999 ).…”

“…The barrel is the cylindrical housing that accommodates the rotating screw(s) and should be mechanically strong enough to withstand the pressure developed in the barrel and resist wear (Senanayake and Clarke, 1999 ). A common practice is to relate the barrel length to diameter (L/D) ratio (Rosato et al ., 2003 ) with throughput of a single -screw extruder (Giles et al ., 2005 ).…”

“…These play an important role in deciding product physical properties such as density, expansion, surface texture, and fi nal shape (Senanayake and Clarke, 1999 ) based on die design, extrusion confi guration, processing conditions, and blend (Riaz, 2000 ). According to Huber (2000) , highly restrictive dies increase barrel fi ll, residence time, and energy input.…”