FEATURE
Twin screw extrusion technology to produce breakfast cereal a flexible & sustainable solution
by Anne-Sophie Le Corre, Process manager at Clextral Inc R&D center, Tampa, Florida, USA
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lextral pioneered twin-screw extrusion technology for breakfast cereals in the early 1970s, introducing a process that was faster, simpler and more economical than the traditional batch processes. The advantages of the twin-screw extrusion technology compared to the traditional processes are many and include: faster manufacturing time (15 to 30 minutes for extrusion cooking versus six to 10 hours for traditional process) with less energy consumed; reduced space requirements; continuous and automated production system allowing easier traceability; quick start up, shut down and cleaning procedures; possibility to switch easily from one product to another; simplified maintenance; very large range of processed raw ingredients; and consistency of product quality. Analyses like Rapid Visco Analyser (RVA) and texture and acoustical emission have been useful in the characterisation of commercial corn flakes produced by traditional process versus twin-screw extrusion technology. Thanks to these techniques, it has been demonstrated that commercial corn flakes produced by traditional process and twin-screw extrusion technology present similar profiles and sensory analyses.
&feed milling technology
Grain
Twin-screw extrusion Twin-screw extruders (TSE) are processing machines consisting of two identical co-rotation, intermeshing, self-wiping screw profiles operating within a closed barrel. During extrusion the materials is forced to flow under controlled conditions along the length of the extruder barrel and through a
thermomechanical cooking factors, including technology design (screw profile, L/D of the machine) and operating conditions (screw speed, temperature profile, water content, dry mix rate); and die texturisation factors (die design, insert shape, opening section). Using a complex combination of all these variables allows the production of a wide vari-
shaped opening (also called die assembly) at a defined throughput. TSE can perform various functions including feeding, conveying, mixing, forming, compression, hydration, heat transfer, shaping and cooking. Variables that influence extrusion process can be separated into three main components: raw materials composition and formulation;
ety of products in a range of shapes, sizes, bulk densities and textures. Because of its operating mechanism, TSE offers many more advantages compared to single screw extruders. The TSE is a continuous mixer/cooker/former, which performs a positive pump action; it can operate at high pressures and high moisture levels and does
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